diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 00000000..3b41682a
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+/mvnw text eol=lf
+*.cmd text eol=crlf
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 00000000..667aaef0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,33 @@
+HELP.md
+target/
+.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
diff --git a/.mvn/wrapper/maven-wrapper.properties b/.mvn/wrapper/maven-wrapper.properties
new file mode 100644
index 00000000..8dea6c22
--- /dev/null
+++ b/.mvn/wrapper/maven-wrapper.properties
@@ -0,0 +1,3 @@
+wrapperVersion=3.3.4
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.12/apache-maven-3.9.12-bin.zip
diff --git a/README.md b/README.md
index 1d3c661a..2b3272ff 100644
--- a/README.md
+++ b/README.md
@@ -1,108 +1,141 @@
-
+# School Management System
+
+A RESTful Spring Boot application for managing teachers, students, and courses at a school.
+
+---
-# HW | Java IronSchool (Unit 2 homework)
+## Getting Started
-## Introduction
+### Prerequisites
+- Java 17+
+- Maven 3.8+
+
+### Run the Application
+```bash
+mvn spring-boot:run
+```
+The server starts at `http://localhost:8080`.
-For this homework, you will be building a School Management System, that will help manage students, teachers and courses with some basic functionalities.
+---
-## Instructions
+## API Reference
-Let's walk through the details of the homework:
-
-### Classes
-
-Three main classes are necessary to complete this homework: **Teacher**, **Student** and **Course**.
-
-
-
-**Teacher class**
-
-This class will have:
-
-- Variable called `teacherId` of data type `string`, auto-generated (Private member)
-- Variable called `name` of data type `string` (Private member)
-- Variable called `salary` of data type `double`, representing the salary of the teacher (Private member)
-- A parameterized constructor that takes `name` and `salary`
-- Public Getter functions to access these variables
-- Public Setter functions to change these variables
-- Optional attributes are accepted if needed based on the code structure
-
-
-
-**Course class**
-
-This class will have:
-
-- Variable called `courseId` of data type `string`, auto-generated (Private member)
-- Variable called `name` of data type `string` (Private member)
-- Variable called `price` of data type `double`, representing the price of this course (Private member)
-- Variable called `money_earned` of data type `double`, representing the total money earned by this course (Private member)
-- Nullable variable called `teacher` of data type `Teacher` (Private member)
-- A parameterized constructor that takes `name` and `price`
-- Public Getter functions to access these variables
-- Public Setter functions to change these variables
-- Optional attributes are accepted if needed based on the code structure
-
-
-
-**Student class**
-
-This class will have:
-
-- Variable called `studentId` of data type `string`, auto-generated (Private member)
-- Variable called `name` of data type `string` (Private member)
-- Variable called `address` of data type `string` (Private member)
-- Variable called `email` of data type `string` (Private member)
-- Nullable variable called `course` of data type `Course`, representing the course this student is enrolled into (Private member)
-- A parameterized constructor that takes `name`, `address` and `email`
-- Public Getter functions to access these variables
-- Public Setter functions to change these variables
-- Optional attributes are accepted if needed based on the code structure
-
-## How the application works
-
-1. The application starts by asking the user for a name for the school
-2. Next, the user is asked for a number of how many teachers should be created
-3. Next, the user is prompted to enter the details of each teacher (based on the number chosen above)
-4. Next, the user is asked for the number of courses to be created (Do not specify the teacher yet, there is a command for it)
-5. Next, the user is prompted to enter details of each course based on the number chosen above
-6. Next, the user is asked for the number of students to be created (Do not specify the course yet, there is a command for it)
-7. Next, the user is prompted to enter details of each student based on the number chosen above
-8. Next, the user is now prompted to enter any command of the list below to execute a specified action in the system.
-
-The IDs should be automatically generated.
-
-## Commands
-
-- **ENROLL** **[STUDENT_ID] [COURSE_ID]**: This command will help enroll the student specified in the corresponding course. While also updating the `money_earned` of that course based on its price
-- **ASSIGN** **[TEACHER_ID] [COURSE_ID]**: This command will help assign the teacher specified to the corresponding course
-- **SHOW COURSES**: This command will display a list of all courses
-- **LOOKUP COURSE** **[COURSE_ID]**: This command will display the full details of the specified course
-- **SHOW STUDENTS**: This command will display a list of all students
-- **LOOKUP STUDENT** **[STUDENT_ID]**: This command will display the full details of the specified student
-- **SHOW TEACHERS**: This command will display a list of all teachers
-- **LOOKUP TEACHER** **[TEACHER_ID]**: This command will display the full details of the specified teacher
-- **SHOW PROFIT**: This command will calculate **(The total money earned from all courses)** - **(The sum of all the teachers' salaries)** and return the result
-
-## Requirements
-
-For this project you must accomplish all of the following:
-
-1. Navigate through a text-based menu using Standard Input and Output.
-2. Create unit tests for every method other than basic getters, setters and constructors (getters and setters with logic do require unit tests).
-3. Handle all exceptions gracefully (incorrect input should not crash the program).
-4. Create Teachers, Courses and Students specifying their full details.
-5. Handle receiving commands in the Standard Input that corresponds to actual actions in the system.
-
-### Bonus
-
-1. Add more commands that can help display more information such as (**SHOW STUDENTS** **[COURSE_ID]**, **SHOW MONEY EARNED**, **SHOW MONEY SPENT**, etc.)
-
-## Important Notes
-
-- Everyone in the squad should contribute equally to the project in time and lines of code written.
-- All code must be reviewed before it is merged into the `master` branch.
-- All squad members must participate in code review.
-- Every repository should have a README file with clear instructions, demo files, or any documentation needed so other teams don't have problems with the review.
-- This is intended to be a challenging assignment. You will have to rely heavily on your teammates and independent research. Learning independently is a hallmark of a good developer and our job is to turn you into good developers. This process may be frustrating but you will learn a ton!
\ No newline at end of file
+### Teachers
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| POST | `/teachers` | Create a teacher |
+| GET | `/teachers` | List all teachers |
+| GET | `/teachers/{id}` | Get teacher by ID |
+| PUT | `/teachers/{id}` | Update teacher |
+| DELETE | `/teachers/{id}` | Delete teacher |
+
+**Create a teacher:**
+```bash
+curl -X POST http://localhost:8080/teachers \
+ -H "Content-Type: application/json" \
+ -d '{"name": "Alice Smith", "salary": 3000.0}'
+```
+
+---
+
+### Courses
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| POST | `/courses` | Create a course |
+| GET | `/courses` | List all courses |
+| GET | `/courses/{id}` | Get course by ID |
+| PUT | `/courses/{id}` | Update course |
+| DELETE | `/courses/{id}` | Delete course |
+| POST | `/courses/{courseId}/assign-teacher/{teacherId}` | Assign teacher to course |
+| GET | `/courses/teacher/{teacherId}` | Get all courses by a teacher |
+| GET | `/courses/profit/{courseId}` | Get profit for a course |
+| GET | `/courses/total-profit` | Get total school profit |
+
+**Create a course:**
+```bash
+curl -X POST http://localhost:8080/courses \
+ -H "Content-Type: application/json" \
+ -d '{"name": "Mathematics", "price": 500.0}'
+```
+
+**Assign a teacher to a course:**
+```bash
+curl -X POST http://localhost:8080/courses/{courseId}/assign-teacher/{teacherId}
+```
+
+---
+
+### Students
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| POST | `/students` | Create a student |
+| GET | `/students/{id}` | Get student by ID |
+| PUT | `/students/{id}` | Update student |
+| DELETE | `/students/{id}` | Delete student |
+| POST | `/students/{studentId}/enroll/{courseId}` | Enroll student in course |
+| DELETE | `/students/{studentId}/unenroll` | Unenroll student |
+| GET | `/students/course/{courseId}` | Get all students in a course |
+| GET | `/students/{studentId}/course` | Get course for a student |
+
+**Create a student:**
+```bash
+curl -X POST http://localhost:8080/students \
+ -H "Content-Type: application/json" \
+ -d '{"name": "Bob Jones", "address": "123 Main St", "email": "bob@example.com"}'
+```
+
+**Enroll a student in a course:**
+```bash
+curl -X POST http://localhost:8080/students/{studentId}/enroll/{courseId}
+```
+
+---
+
+## Profit Calculation
+
+- **Course Profit**: `moneyEarned - (teacherSalary / numberOfCoursesTeacherTeaches)`
+- **Total Profit**: `totalMoneyEarned - totalTeacherSalaries`
+
+---
+
+## Error Handling
+
+All errors return a meaningful HTTP status and message body:
+
+| Situation | HTTP Status |
+|-----------|-------------|
+| Entity not found | 404 Not Found |
+| Student already enrolled | 409 Conflict |
+| Invalid input (blank, negative) | 400 Bad Request |
+| Validation failure | 400 Bad Request |
+| Unexpected error | 500 Internal Server Error |
+
+---
+
+## Project Structure
+
+```
+src/main/java/com/example/demo/
+├── controllers/
+│ ├── CourseController.java
+│ ├── StudentController.java
+│ └── TeacherController.java
+├── models/
+│ ├── Course.java
+│ ├── Student.java
+│ └── Teacher.java
+├── services/
+│ ├── CourseService.java
+│ ├── StudentService.java
+│ └── TeacherService.java
+└── Exceptions/
+ ├── GlobalExceptionHandler.java
+ ├── CourseNotFoundException.java
+ ├── StudentNotFoundException.java
+ ├── TeacherNotFoundException.java
+ ├── StudentAlreadyEnrolledException.java
+ └── InvalidInputException.java
+```
\ No newline at end of file
diff --git a/mvnw b/mvnw
new file mode 100644
index 00000000..bd8896bf
--- /dev/null
+++ b/mvnw
@@ -0,0 +1,295 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Apache Maven Wrapper startup batch script, version 3.3.4
+#
+# Optional ENV vars
+# -----------------
+# JAVA_HOME - location of a JDK home dir, required when download maven via java source
+# MVNW_REPOURL - repo url base for downloading maven distribution
+# MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
+# MVNW_VERBOSE - true: enable verbose log; debug: trace the mvnw script; others: silence the output
+# ----------------------------------------------------------------------------
+
+set -euf
+[ "${MVNW_VERBOSE-}" != debug ] || set -x
+
+# OS specific support.
+native_path() { printf %s\\n "$1"; }
+case "$(uname)" in
+CYGWIN* | MINGW*)
+ [ -z "${JAVA_HOME-}" ] || JAVA_HOME="$(cygpath --unix "$JAVA_HOME")"
+ native_path() { cygpath --path --windows "$1"; }
+ ;;
+esac
+
+# set JAVACMD and JAVACCMD
+set_java_home() {
+ # For Cygwin and MinGW, ensure paths are in Unix format before anything is touched
+ if [ -n "${JAVA_HOME-}" ]; then
+ if [ -x "$JAVA_HOME/jre/sh/java" ]; then
+ # IBM's JDK on AIX uses strange locations for the executables
+ JAVACMD="$JAVA_HOME/jre/sh/java"
+ JAVACCMD="$JAVA_HOME/jre/sh/javac"
+ else
+ JAVACMD="$JAVA_HOME/bin/java"
+ JAVACCMD="$JAVA_HOME/bin/javac"
+
+ if [ ! -x "$JAVACMD" ] || [ ! -x "$JAVACCMD" ]; then
+ echo "The JAVA_HOME environment variable is not defined correctly, so mvnw cannot run." >&2
+ echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" or \"\$JAVA_HOME/bin/javac\" does not exist." >&2
+ return 1
+ fi
+ fi
+ else
+ JAVACMD="$(
+ 'set' +e
+ 'unset' -f command 2>/dev/null
+ 'command' -v java
+ )" || :
+ JAVACCMD="$(
+ 'set' +e
+ 'unset' -f command 2>/dev/null
+ 'command' -v javac
+ )" || :
+
+ if [ ! -x "${JAVACMD-}" ] || [ ! -x "${JAVACCMD-}" ]; then
+ echo "The java/javac command does not exist in PATH nor is JAVA_HOME set, so mvnw cannot run." >&2
+ return 1
+ fi
+ fi
+}
+
+# hash string like Java String::hashCode
+hash_string() {
+ str="${1:-}" h=0
+ while [ -n "$str" ]; do
+ char="${str%"${str#?}"}"
+ h=$(((h * 31 + $(LC_CTYPE=C printf %d "'$char")) % 4294967296))
+ str="${str#?}"
+ done
+ printf %x\\n $h
+}
+
+verbose() { :; }
+[ "${MVNW_VERBOSE-}" != true ] || verbose() { printf %s\\n "${1-}"; }
+
+die() {
+ printf %s\\n "$1" >&2
+ exit 1
+}
+
+trim() {
+ # MWRAPPER-139:
+ # Trims trailing and leading whitespace, carriage returns, tabs, and linefeeds.
+ # Needed for removing poorly interpreted newline sequences when running in more
+ # exotic environments such as mingw bash on Windows.
+ printf "%s" "${1}" | tr -d '[:space:]'
+}
+
+scriptDir="$(dirname "$0")"
+scriptName="$(basename "$0")"
+
+# parse distributionUrl and optional distributionSha256Sum, requires .mvn/wrapper/maven-wrapper.properties
+while IFS="=" read -r key value; do
+ case "${key-}" in
+ distributionUrl) distributionUrl=$(trim "${value-}") ;;
+ distributionSha256Sum) distributionSha256Sum=$(trim "${value-}") ;;
+ esac
+done <"$scriptDir/.mvn/wrapper/maven-wrapper.properties"
+[ -n "${distributionUrl-}" ] || die "cannot read distributionUrl property in $scriptDir/.mvn/wrapper/maven-wrapper.properties"
+
+case "${distributionUrl##*/}" in
+maven-mvnd-*bin.*)
+ MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/
+ case "${PROCESSOR_ARCHITECTURE-}${PROCESSOR_ARCHITEW6432-}:$(uname -a)" in
+ *AMD64:CYGWIN* | *AMD64:MINGW*) distributionPlatform=windows-amd64 ;;
+ :Darwin*x86_64) distributionPlatform=darwin-amd64 ;;
+ :Darwin*arm64) distributionPlatform=darwin-aarch64 ;;
+ :Linux*x86_64*) distributionPlatform=linux-amd64 ;;
+ *)
+ echo "Cannot detect native platform for mvnd on $(uname)-$(uname -m), use pure java version" >&2
+ distributionPlatform=linux-amd64
+ ;;
+ esac
+ distributionUrl="${distributionUrl%-bin.*}-$distributionPlatform.zip"
+ ;;
+maven-mvnd-*) MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/ ;;
+*) MVN_CMD="mvn${scriptName#mvnw}" _MVNW_REPO_PATTERN=/org/apache/maven/ ;;
+esac
+
+# apply MVNW_REPOURL and calculate MAVEN_HOME
+# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-,maven-mvnd--}/
+[ -z "${MVNW_REPOURL-}" ] || distributionUrl="$MVNW_REPOURL$_MVNW_REPO_PATTERN${distributionUrl#*"$_MVNW_REPO_PATTERN"}"
+distributionUrlName="${distributionUrl##*/}"
+distributionUrlNameMain="${distributionUrlName%.*}"
+distributionUrlNameMain="${distributionUrlNameMain%-bin}"
+MAVEN_USER_HOME="${MAVEN_USER_HOME:-${HOME}/.m2}"
+MAVEN_HOME="${MAVEN_USER_HOME}/wrapper/dists/${distributionUrlNameMain-}/$(hash_string "$distributionUrl")"
+
+exec_maven() {
+ unset MVNW_VERBOSE MVNW_USERNAME MVNW_PASSWORD MVNW_REPOURL || :
+ exec "$MAVEN_HOME/bin/$MVN_CMD" "$@" || die "cannot exec $MAVEN_HOME/bin/$MVN_CMD"
+}
+
+if [ -d "$MAVEN_HOME" ]; then
+ verbose "found existing MAVEN_HOME at $MAVEN_HOME"
+ exec_maven "$@"
+fi
+
+case "${distributionUrl-}" in
+*?-bin.zip | *?maven-mvnd-?*-?*.zip) ;;
+*) die "distributionUrl is not valid, must match *-bin.zip or maven-mvnd-*.zip, but found '${distributionUrl-}'" ;;
+esac
+
+# prepare tmp dir
+if TMP_DOWNLOAD_DIR="$(mktemp -d)" && [ -d "$TMP_DOWNLOAD_DIR" ]; then
+ clean() { rm -rf -- "$TMP_DOWNLOAD_DIR"; }
+ trap clean HUP INT TERM EXIT
+else
+ die "cannot create temp dir"
+fi
+
+mkdir -p -- "${MAVEN_HOME%/*}"
+
+# Download and Install Apache Maven
+verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
+verbose "Downloading from: $distributionUrl"
+verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"
+
+# select .zip or .tar.gz
+if ! command -v unzip >/dev/null; then
+ distributionUrl="${distributionUrl%.zip}.tar.gz"
+ distributionUrlName="${distributionUrl##*/}"
+fi
+
+# verbose opt
+__MVNW_QUIET_WGET=--quiet __MVNW_QUIET_CURL=--silent __MVNW_QUIET_UNZIP=-q __MVNW_QUIET_TAR=''
+[ "${MVNW_VERBOSE-}" != true ] || __MVNW_QUIET_WGET='' __MVNW_QUIET_CURL='' __MVNW_QUIET_UNZIP='' __MVNW_QUIET_TAR=v
+
+# normalize http auth
+case "${MVNW_PASSWORD:+has-password}" in
+'') MVNW_USERNAME='' MVNW_PASSWORD='' ;;
+has-password) [ -n "${MVNW_USERNAME-}" ] || MVNW_USERNAME='' MVNW_PASSWORD='' ;;
+esac
+
+if [ -z "${MVNW_USERNAME-}" ] && command -v wget >/dev/null; then
+ verbose "Found wget ... using wget"
+ wget ${__MVNW_QUIET_WGET:+"$__MVNW_QUIET_WGET"} "$distributionUrl" -O "$TMP_DOWNLOAD_DIR/$distributionUrlName" || die "wget: Failed to fetch $distributionUrl"
+elif [ -z "${MVNW_USERNAME-}" ] && command -v curl >/dev/null; then
+ verbose "Found curl ... using curl"
+ curl ${__MVNW_QUIET_CURL:+"$__MVNW_QUIET_CURL"} -f -L -o "$TMP_DOWNLOAD_DIR/$distributionUrlName" "$distributionUrl" || die "curl: Failed to fetch $distributionUrl"
+elif set_java_home; then
+ verbose "Falling back to use Java to download"
+ javaSource="$TMP_DOWNLOAD_DIR/Downloader.java"
+ targetZip="$TMP_DOWNLOAD_DIR/$distributionUrlName"
+ cat >"$javaSource" <<-END
+ public class Downloader extends java.net.Authenticator
+ {
+ protected java.net.PasswordAuthentication getPasswordAuthentication()
+ {
+ return new java.net.PasswordAuthentication( System.getenv( "MVNW_USERNAME" ), System.getenv( "MVNW_PASSWORD" ).toCharArray() );
+ }
+ public static void main( String[] args ) throws Exception
+ {
+ setDefault( new Downloader() );
+ java.nio.file.Files.copy( java.net.URI.create( args[0] ).toURL().openStream(), java.nio.file.Paths.get( args[1] ).toAbsolutePath().normalize() );
+ }
+ }
+ END
+ # For Cygwin/MinGW, switch paths to Windows format before running javac and java
+ verbose " - Compiling Downloader.java ..."
+ "$(native_path "$JAVACCMD")" "$(native_path "$javaSource")" || die "Failed to compile Downloader.java"
+ verbose " - Running Downloader.java ..."
+ "$(native_path "$JAVACMD")" -cp "$(native_path "$TMP_DOWNLOAD_DIR")" Downloader "$distributionUrl" "$(native_path "$targetZip")"
+fi
+
+# If specified, validate the SHA-256 sum of the Maven distribution zip file
+if [ -n "${distributionSha256Sum-}" ]; then
+ distributionSha256Result=false
+ if [ "$MVN_CMD" = mvnd.sh ]; then
+ echo "Checksum validation is not supported for maven-mvnd." >&2
+ echo "Please disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
+ exit 1
+ elif command -v sha256sum >/dev/null; then
+ if echo "$distributionSha256Sum $TMP_DOWNLOAD_DIR/$distributionUrlName" | sha256sum -c - >/dev/null 2>&1; then
+ distributionSha256Result=true
+ fi
+ elif command -v shasum >/dev/null; then
+ if echo "$distributionSha256Sum $TMP_DOWNLOAD_DIR/$distributionUrlName" | shasum -a 256 -c >/dev/null 2>&1; then
+ distributionSha256Result=true
+ fi
+ else
+ echo "Checksum validation was requested but neither 'sha256sum' or 'shasum' are available." >&2
+ echo "Please install either command, or disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
+ exit 1
+ fi
+ if [ $distributionSha256Result = false ]; then
+ echo "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised." >&2
+ echo "If you updated your Maven version, you need to update the specified distributionSha256Sum property." >&2
+ exit 1
+ fi
+fi
+
+# unzip and move
+if command -v unzip >/dev/null; then
+ unzip ${__MVNW_QUIET_UNZIP:+"$__MVNW_QUIET_UNZIP"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -d "$TMP_DOWNLOAD_DIR" || die "failed to unzip"
+else
+ tar xzf${__MVNW_QUIET_TAR:+"$__MVNW_QUIET_TAR"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -C "$TMP_DOWNLOAD_DIR" || die "failed to untar"
+fi
+
+# Find the actual extracted directory name (handles snapshots where filename != directory name)
+actualDistributionDir=""
+
+# First try the expected directory name (for regular distributions)
+if [ -d "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain" ]; then
+ if [ -f "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain/bin/$MVN_CMD" ]; then
+ actualDistributionDir="$distributionUrlNameMain"
+ fi
+fi
+
+# If not found, search for any directory with the Maven executable (for snapshots)
+if [ -z "$actualDistributionDir" ]; then
+ # enable globbing to iterate over items
+ set +f
+ for dir in "$TMP_DOWNLOAD_DIR"/*; do
+ if [ -d "$dir" ]; then
+ if [ -f "$dir/bin/$MVN_CMD" ]; then
+ actualDistributionDir="$(basename "$dir")"
+ break
+ fi
+ fi
+ done
+ set -f
+fi
+
+if [ -z "$actualDistributionDir" ]; then
+ verbose "Contents of $TMP_DOWNLOAD_DIR:"
+ verbose "$(ls -la "$TMP_DOWNLOAD_DIR")"
+ die "Could not find Maven distribution directory in extracted archive"
+fi
+
+verbose "Found extracted Maven distribution directory: $actualDistributionDir"
+printf %s\\n "$distributionUrl" >"$TMP_DOWNLOAD_DIR/$actualDistributionDir/mvnw.url"
+mv -- "$TMP_DOWNLOAD_DIR/$actualDistributionDir" "$MAVEN_HOME" || [ -d "$MAVEN_HOME" ] || die "fail to move MAVEN_HOME"
+
+clean || :
+exec_maven "$@"
diff --git a/mvnw.cmd b/mvnw.cmd
new file mode 100644
index 00000000..92450f93
--- /dev/null
+++ b/mvnw.cmd
@@ -0,0 +1,189 @@
+<# : batch portion
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements. See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership. The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License. You may obtain a copy of the License at
+@REM
+@REM http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied. See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Apache Maven Wrapper startup batch script, version 3.3.4
+@REM
+@REM Optional ENV vars
+@REM MVNW_REPOURL - repo url base for downloading maven distribution
+@REM MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
+@REM MVNW_VERBOSE - true: enable verbose log; others: silence the output
+@REM ----------------------------------------------------------------------------
+
+@IF "%__MVNW_ARG0_NAME__%"=="" (SET __MVNW_ARG0_NAME__=%~nx0)
+@SET __MVNW_CMD__=
+@SET __MVNW_ERROR__=
+@SET __MVNW_PSMODULEP_SAVE=%PSModulePath%
+@SET PSModulePath=
+@FOR /F "usebackq tokens=1* delims==" %%A IN (`powershell -noprofile "& {$scriptDir='%~dp0'; $script='%__MVNW_ARG0_NAME__%'; icm -ScriptBlock ([Scriptblock]::Create((Get-Content -Raw '%~f0'))) -NoNewScope}"`) DO @(
+ IF "%%A"=="MVN_CMD" (set __MVNW_CMD__=%%B) ELSE IF "%%B"=="" (echo %%A) ELSE (echo %%A=%%B)
+)
+@SET PSModulePath=%__MVNW_PSMODULEP_SAVE%
+@SET __MVNW_PSMODULEP_SAVE=
+@SET __MVNW_ARG0_NAME__=
+@SET MVNW_USERNAME=
+@SET MVNW_PASSWORD=
+@IF NOT "%__MVNW_CMD__%"=="" ("%__MVNW_CMD__%" %*)
+@echo Cannot start maven from wrapper >&2 && exit /b 1
+@GOTO :EOF
+: end batch / begin powershell #>
+
+$ErrorActionPreference = "Stop"
+if ($env:MVNW_VERBOSE -eq "true") {
+ $VerbosePreference = "Continue"
+}
+
+# calculate distributionUrl, requires .mvn/wrapper/maven-wrapper.properties
+$distributionUrl = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionUrl
+if (!$distributionUrl) {
+ Write-Error "cannot read distributionUrl property in $scriptDir/.mvn/wrapper/maven-wrapper.properties"
+}
+
+switch -wildcard -casesensitive ( $($distributionUrl -replace '^.*/','') ) {
+ "maven-mvnd-*" {
+ $USE_MVND = $true
+ $distributionUrl = $distributionUrl -replace '-bin\.[^.]*$',"-windows-amd64.zip"
+ $MVN_CMD = "mvnd.cmd"
+ break
+ }
+ default {
+ $USE_MVND = $false
+ $MVN_CMD = $script -replace '^mvnw','mvn'
+ break
+ }
+}
+
+# apply MVNW_REPOURL and calculate MAVEN_HOME
+# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-,maven-mvnd--}/
+if ($env:MVNW_REPOURL) {
+ $MVNW_REPO_PATTERN = if ($USE_MVND -eq $False) { "/org/apache/maven/" } else { "/maven/mvnd/" }
+ $distributionUrl = "$env:MVNW_REPOURL$MVNW_REPO_PATTERN$($distributionUrl -replace "^.*$MVNW_REPO_PATTERN",'')"
+}
+$distributionUrlName = $distributionUrl -replace '^.*/',''
+$distributionUrlNameMain = $distributionUrlName -replace '\.[^.]*$','' -replace '-bin$',''
+
+$MAVEN_M2_PATH = "$HOME/.m2"
+if ($env:MAVEN_USER_HOME) {
+ $MAVEN_M2_PATH = "$env:MAVEN_USER_HOME"
+}
+
+if (-not (Test-Path -Path $MAVEN_M2_PATH)) {
+ New-Item -Path $MAVEN_M2_PATH -ItemType Directory | Out-Null
+}
+
+$MAVEN_WRAPPER_DISTS = $null
+if ((Get-Item $MAVEN_M2_PATH).Target[0] -eq $null) {
+ $MAVEN_WRAPPER_DISTS = "$MAVEN_M2_PATH/wrapper/dists"
+} else {
+ $MAVEN_WRAPPER_DISTS = (Get-Item $MAVEN_M2_PATH).Target[0] + "/wrapper/dists"
+}
+
+$MAVEN_HOME_PARENT = "$MAVEN_WRAPPER_DISTS/$distributionUrlNameMain"
+$MAVEN_HOME_NAME = ([System.Security.Cryptography.SHA256]::Create().ComputeHash([byte[]][char[]]$distributionUrl) | ForEach-Object {$_.ToString("x2")}) -join ''
+$MAVEN_HOME = "$MAVEN_HOME_PARENT/$MAVEN_HOME_NAME"
+
+if (Test-Path -Path "$MAVEN_HOME" -PathType Container) {
+ Write-Verbose "found existing MAVEN_HOME at $MAVEN_HOME"
+ Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"
+ exit $?
+}
+
+if (! $distributionUrlNameMain -or ($distributionUrlName -eq $distributionUrlNameMain)) {
+ Write-Error "distributionUrl is not valid, must end with *-bin.zip, but found $distributionUrl"
+}
+
+# prepare tmp dir
+$TMP_DOWNLOAD_DIR_HOLDER = New-TemporaryFile
+$TMP_DOWNLOAD_DIR = New-Item -Itemtype Directory -Path "$TMP_DOWNLOAD_DIR_HOLDER.dir"
+$TMP_DOWNLOAD_DIR_HOLDER.Delete() | Out-Null
+trap {
+ if ($TMP_DOWNLOAD_DIR.Exists) {
+ try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
+ catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
+ }
+}
+
+New-Item -Itemtype Directory -Path "$MAVEN_HOME_PARENT" -Force | Out-Null
+
+# Download and Install Apache Maven
+Write-Verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
+Write-Verbose "Downloading from: $distributionUrl"
+Write-Verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"
+
+$webclient = New-Object System.Net.WebClient
+if ($env:MVNW_USERNAME -and $env:MVNW_PASSWORD) {
+ $webclient.Credentials = New-Object System.Net.NetworkCredential($env:MVNW_USERNAME, $env:MVNW_PASSWORD)
+}
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+$webclient.DownloadFile($distributionUrl, "$TMP_DOWNLOAD_DIR/$distributionUrlName") | Out-Null
+
+# If specified, validate the SHA-256 sum of the Maven distribution zip file
+$distributionSha256Sum = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionSha256Sum
+if ($distributionSha256Sum) {
+ if ($USE_MVND) {
+ Write-Error "Checksum validation is not supported for maven-mvnd. `nPlease disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties."
+ }
+ Import-Module $PSHOME\Modules\Microsoft.PowerShell.Utility -Function Get-FileHash
+ if ((Get-FileHash "$TMP_DOWNLOAD_DIR/$distributionUrlName" -Algorithm SHA256).Hash.ToLower() -ne $distributionSha256Sum) {
+ Write-Error "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised. If you updated your Maven version, you need to update the specified distributionSha256Sum property."
+ }
+}
+
+# unzip and move
+Expand-Archive "$TMP_DOWNLOAD_DIR/$distributionUrlName" -DestinationPath "$TMP_DOWNLOAD_DIR" | Out-Null
+
+# Find the actual extracted directory name (handles snapshots where filename != directory name)
+$actualDistributionDir = ""
+
+# First try the expected directory name (for regular distributions)
+$expectedPath = Join-Path "$TMP_DOWNLOAD_DIR" "$distributionUrlNameMain"
+$expectedMvnPath = Join-Path "$expectedPath" "bin/$MVN_CMD"
+if ((Test-Path -Path $expectedPath -PathType Container) -and (Test-Path -Path $expectedMvnPath -PathType Leaf)) {
+ $actualDistributionDir = $distributionUrlNameMain
+}
+
+# If not found, search for any directory with the Maven executable (for snapshots)
+if (!$actualDistributionDir) {
+ Get-ChildItem -Path "$TMP_DOWNLOAD_DIR" -Directory | ForEach-Object {
+ $testPath = Join-Path $_.FullName "bin/$MVN_CMD"
+ if (Test-Path -Path $testPath -PathType Leaf) {
+ $actualDistributionDir = $_.Name
+ }
+ }
+}
+
+if (!$actualDistributionDir) {
+ Write-Error "Could not find Maven distribution directory in extracted archive"
+}
+
+Write-Verbose "Found extracted Maven distribution directory: $actualDistributionDir"
+Rename-Item -Path "$TMP_DOWNLOAD_DIR/$actualDistributionDir" -NewName $MAVEN_HOME_NAME | Out-Null
+try {
+ Move-Item -Path "$TMP_DOWNLOAD_DIR/$MAVEN_HOME_NAME" -Destination $MAVEN_HOME_PARENT | Out-Null
+} catch {
+ if (! (Test-Path -Path "$MAVEN_HOME" -PathType Container)) {
+ Write-Error "fail to move MAVEN_HOME"
+ }
+} finally {
+ try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
+ catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
+}
+
+Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 00000000..9bce8acd
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,63 @@
+
+
+ 4.0.0
+
+ org.springframework.boot
+ spring-boot-starter-parent
+ 4.0.3
+
+
+ com.example
+ demo
+ 0.0.1-SNAPSHOT
+ demo
+ Demo project for Spring Boot
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 17
+
+
+
+ org.springframework.boot
+ spring-boot-starter-webmvc
+
+
+ org.springframework.boot
+ spring-boot-starter-validation
+
+
+ org.springframework.boot
+ spring-boot-devtools
+ runtime
+ true
+
+
+ org.springframework.boot
+ spring-boot-starter-webmvc-test
+ test
+
+
+
+
+
+
+ org.springframework.boot
+ spring-boot-maven-plugin
+
+
+
+
+
diff --git a/src/main/java/com/example/demo/DemoApplication.java b/src/main/java/com/example/demo/DemoApplication.java
new file mode 100644
index 00000000..64b538a1
--- /dev/null
+++ b/src/main/java/com/example/demo/DemoApplication.java
@@ -0,0 +1,13 @@
+package com.example.demo;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class DemoApplication {
+
+ public static void main(String[] args) {
+ SpringApplication.run(DemoApplication.class, args);
+ }
+
+}
diff --git a/src/main/java/com/example/demo/Exceptions/CourseNotFoundException.java b/src/main/java/com/example/demo/Exceptions/CourseNotFoundException.java
new file mode 100644
index 00000000..57d2a8e6
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/CourseNotFoundException.java
@@ -0,0 +1,8 @@
+package com.example.demo.Exceptions;
+
+/** Thrown when a course with the specified ID cannot be found. */
+public class CourseNotFoundException extends RuntimeException {
+ public CourseNotFoundException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/Exceptions/GlobalExceptionHandler.java b/src/main/java/com/example/demo/Exceptions/GlobalExceptionHandler.java
new file mode 100644
index 00000000..58067155
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/GlobalExceptionHandler.java
@@ -0,0 +1,87 @@
+package com.example.demo.Exceptions;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+import java.util.stream.Collectors;
+
+/**
+ * Global exception handler for all REST controllers.
+ * Intercepts exceptions thrown during request processing and maps them
+ * to appropriate HTTP responses, ensuring the application never crashes
+ * due to unhandled errors.
+ */
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+ /**
+ * Handles cases where a requested student does not exist.
+ * Returns HTTP 404 Not Found.
+ */
+ @ExceptionHandler(StudentNotFoundException.class)
+ public ResponseEntity handleStudentNotFound(StudentNotFoundException ex) {
+ return ResponseEntity.status(HttpStatus.NOT_FOUND).body(ex.getMessage());
+ }
+
+ /**
+ * Handles cases where a requested teacher does not exist.
+ * Returns HTTP 404 Not Found.
+ */
+ @ExceptionHandler(TeacherNotFoundException.class)
+ public ResponseEntity handleTeacherNotFound(TeacherNotFoundException ex) {
+ return ResponseEntity.status(HttpStatus.NOT_FOUND).body(ex.getMessage());
+ }
+
+ /**
+ * Handles cases where a requested course does not exist.
+ * Returns HTTP 404 Not Found.
+ */
+ @ExceptionHandler(CourseNotFoundException.class)
+ public ResponseEntity handleCourseNotFound(CourseNotFoundException ex) {
+ return ResponseEntity.status(HttpStatus.NOT_FOUND).body(ex.getMessage());
+ }
+
+ /**
+ * Handles cases where a student attempts to enroll in a course they are already enrolled in.
+ * Returns HTTP 409 Conflict.
+ */
+ @ExceptionHandler(StudentAlreadyEnrolledException.class)
+ public ResponseEntity handleStudentAlreadyEnrolled(StudentAlreadyEnrolledException ex) {
+ return ResponseEntity.status(HttpStatus.CONFLICT).body(ex.getMessage());
+ }
+
+ /**
+ * Handles invalid input provided by the caller (e.g., null IDs, blank names).
+ * Returns HTTP 400 Bad Request.
+ */
+ @ExceptionHandler(InvalidInputException.class)
+ public ResponseEntity handleInvalidInput(InvalidInputException ex) {
+ return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(ex.getMessage());
+ }
+
+ /**
+ * Handles validation failures triggered by @Valid on request bodies.
+ * Collects all field error messages and returns them as a combined response.
+ * Returns HTTP 400 Bad Request.
+ */
+ @ExceptionHandler(MethodArgumentNotValidException.class)
+ public ResponseEntity handleValidationErrors(MethodArgumentNotValidException ex) {
+ String errors = ex.getBindingResult().getFieldErrors().stream()
+ .map(error -> error.getField() + ": " + error.getDefaultMessage())
+ .collect(Collectors.joining(", "));
+ return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("Validation failed: " + errors);
+ }
+
+ /**
+ * Catch-all handler for any unexpected exceptions not explicitly handled above.
+ * Returns HTTP 500 Internal Server Error to avoid exposing internal details.
+ */
+ @ExceptionHandler(Exception.class)
+ public ResponseEntity handleGenericException(Exception ex) {
+ return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
+ .body("An unexpected error occurred: " + ex.getMessage());
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/Exceptions/InvalidInputException.java b/src/main/java/com/example/demo/Exceptions/InvalidInputException.java
new file mode 100644
index 00000000..5f44773c
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/InvalidInputException.java
@@ -0,0 +1,8 @@
+package com.example.demo.Exceptions;
+
+/** Thrown when a caller provides invalid or missing input (e.g., blank name, negative price). */
+public class InvalidInputException extends RuntimeException {
+ public InvalidInputException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/Exceptions/StudentAlreadyEnrolledException.java b/src/main/java/com/example/demo/Exceptions/StudentAlreadyEnrolledException.java
new file mode 100644
index 00000000..d0631a6f
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/StudentAlreadyEnrolledException.java
@@ -0,0 +1,8 @@
+package com.example.demo.Exceptions;
+
+/** Thrown when a student attempts to enroll in a course they are already enrolled in. */
+public class StudentAlreadyEnrolledException extends RuntimeException {
+ public StudentAlreadyEnrolledException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/Exceptions/StudentNotFoundException.java b/src/main/java/com/example/demo/Exceptions/StudentNotFoundException.java
new file mode 100644
index 00000000..23db7893
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/StudentNotFoundException.java
@@ -0,0 +1,8 @@
+package com.example.demo.Exceptions;
+
+/** Thrown when a student with the specified ID cannot be found. */
+public class StudentNotFoundException extends RuntimeException {
+ public StudentNotFoundException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/Exceptions/TeacherNotFoundException.java b/src/main/java/com/example/demo/Exceptions/TeacherNotFoundException.java
new file mode 100644
index 00000000..1db32906
--- /dev/null
+++ b/src/main/java/com/example/demo/Exceptions/TeacherNotFoundException.java
@@ -0,0 +1,8 @@
+package com.example.demo.Exceptions;
+
+/** Thrown when a teacher with the specified ID cannot be found. */
+public class TeacherNotFoundException extends RuntimeException {
+ public TeacherNotFoundException(String message) {
+ super(message);
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/controllers/CourseController.java b/src/main/java/com/example/demo/controllers/CourseController.java
new file mode 100644
index 00000000..2319cc76
--- /dev/null
+++ b/src/main/java/com/example/demo/controllers/CourseController.java
@@ -0,0 +1,86 @@
+package com.example.demo.controllers;
+
+import com.example.demo.models.Course;
+import com.example.demo.services.CourseService;
+import jakarta.validation.Valid;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * REST controller for Course-related operations.
+ *
+ * Endpoints:
+ * GET /courses - List all courses
+ * POST /courses - Create a new course
+ * GET /courses/{courseId} - Get a course by ID
+ * PUT /courses/{courseId} - Update a course
+ * DELETE /courses/{courseId} - Delete a course
+ * POST /courses/{courseId}/assign-teacher/{teacherId} - Assign a teacher to a course
+ * GET /courses/teacher/{teacherId} - Get all courses by a teacher
+ * GET /courses/profit/{courseId} - Get profit for a specific course
+ * GET /courses/total-profit - Get total profit across all courses
+ */
+@RestController
+@RequestMapping("/courses")
+public class CourseController {
+
+ private final CourseService courseService;
+
+ public CourseController(CourseService courseService) {
+ this.courseService = courseService;
+ }
+
+ @GetMapping
+ public ResponseEntity> getAllCourses() {
+ return ResponseEntity.ok(courseService.getAllCourses());
+ }
+
+ @PostMapping
+ public ResponseEntity createCourse(@Valid @RequestBody Course course) {
+ Course created = courseService.createCourse(course.getName(), course.getPrice());
+ return ResponseEntity.ok(created);
+ }
+
+ @GetMapping("/{courseId}")
+ public ResponseEntity getCourseById(@PathVariable String courseId) {
+ return ResponseEntity.ok(courseService.getCourseById(courseId));
+ }
+
+ @PutMapping("/{courseId}")
+ public ResponseEntity updateCourse(@PathVariable String courseId, @RequestBody Map updates) {
+ String newName = (String) updates.get("name");
+ Double newPrice = updates.containsKey("price") ? ((Number) updates.get("price")).doubleValue() : null;
+ courseService.updateCourse(courseId, newName, newPrice);
+ return ResponseEntity.ok().build();
+ }
+
+ @DeleteMapping("/{courseId}")
+ public ResponseEntity deleteCourse(@PathVariable String courseId) {
+ courseService.deleteCourse(courseId);
+ return ResponseEntity.ok().build();
+ }
+
+ @PostMapping("/{courseId}/assign-teacher/{teacherId}")
+ public ResponseEntity assignTeacherToCourse(@PathVariable String courseId, @PathVariable String teacherId) {
+ courseService.assignTeacherToCourse(courseId, teacherId);
+ return ResponseEntity.ok().build();
+ }
+
+ @GetMapping("/teacher/{teacherId}")
+ public ResponseEntity> getCoursesByTeacher(@PathVariable String teacherId) {
+ return ResponseEntity.ok(courseService.getCoursesByTeacher(teacherId));
+ }
+
+ @GetMapping("/profit/{courseId}")
+ public ResponseEntity getCourseProfit(@PathVariable String courseId) {
+ return ResponseEntity.ok(courseService.getCourseProfit(courseId));
+ }
+
+ @GetMapping("/total-profit")
+ public ResponseEntity getTotalProfit() {
+ return ResponseEntity.ok(courseService.getTotalProfit());
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/controllers/StudentController.java b/src/main/java/com/example/demo/controllers/StudentController.java
new file mode 100644
index 00000000..790a4539
--- /dev/null
+++ b/src/main/java/com/example/demo/controllers/StudentController.java
@@ -0,0 +1,83 @@
+package com.example.demo.controllers;
+
+import com.example.demo.models.Course;
+import com.example.demo.models.Student;
+import com.example.demo.services.StudentService;
+import jakarta.validation.Valid;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * REST controller for Student-related operations.
+ *
+ * Endpoints:
+ * POST /students - Create a new student
+ * GET /students/{studentId} - Get a student by ID
+ * PUT /students/{studentId} - Update a student
+ * DELETE /students/{studentId} - Delete a student
+ * POST /students/{studentId}/enroll/{courseId} - Enroll student in a course
+ * DELETE /students/{studentId}/unenroll - Unenroll student from their course
+ * GET /students/course/{courseId} - Get all students enrolled in a course
+ * GET /students/{studentId}/course - Get the course a student is enrolled in
+ */
+@RestController
+@RequestMapping("/students")
+public class StudentController {
+
+ private final StudentService studentService;
+
+ public StudentController(StudentService studentService) {
+ this.studentService = studentService;
+ }
+
+ @PostMapping
+ public ResponseEntity createStudent(@Valid @RequestBody Student student) {
+ Student created = studentService.createStudent(student.getName(), student.getAddress(), student.getEmail());
+ return ResponseEntity.ok(created);
+ }
+
+ @GetMapping("/{studentId}")
+ public ResponseEntity getStudentById(@PathVariable String studentId) {
+ return ResponseEntity.ok(studentService.getStudentById(studentId));
+ }
+
+ @PutMapping("/{studentId}")
+ public ResponseEntity updateStudent(@PathVariable String studentId, @RequestBody Map updates) {
+ String newName = updates.get("name");
+ String newAddress = updates.get("address");
+ String newEmail = updates.get("email");
+ studentService.updateStudent(studentId, newName, newAddress, newEmail);
+ return ResponseEntity.ok().build();
+ }
+
+ @DeleteMapping("/{studentId}")
+ public ResponseEntity deleteStudent(@PathVariable String studentId) {
+ studentService.deleteStudent(studentId);
+ return ResponseEntity.ok().build();
+ }
+
+ @PostMapping("/{studentId}/enroll/{courseId}")
+ public ResponseEntity enrollStudentInCourse(@PathVariable String studentId, @PathVariable String courseId) {
+ studentService.enrollStudentInCourse(studentId, courseId);
+ return ResponseEntity.ok().build();
+ }
+
+ @DeleteMapping("/{studentId}/unenroll")
+ public ResponseEntity unenrollStudentFromCourse(@PathVariable String studentId) {
+ studentService.unenrollStudentFromCourse(studentId);
+ return ResponseEntity.ok().build();
+ }
+
+ @GetMapping("/course/{courseId}")
+ public ResponseEntity> getEnrolledStudents(@PathVariable String courseId) {
+ return ResponseEntity.ok(studentService.getEnrolledStudents(courseId));
+ }
+
+ @GetMapping("/{studentId}/course")
+ public ResponseEntity getCourseForStudent(@PathVariable String studentId) {
+ return ResponseEntity.ok(studentService.getCourseForStudent(studentId));
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/controllers/TeacherController.java b/src/main/java/com/example/demo/controllers/TeacherController.java
new file mode 100644
index 00000000..9ad78b4a
--- /dev/null
+++ b/src/main/java/com/example/demo/controllers/TeacherController.java
@@ -0,0 +1,61 @@
+package com.example.demo.controllers;
+
+import com.example.demo.models.Teacher;
+import com.example.demo.services.TeacherService;
+import jakarta.validation.Valid;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * REST controller for Teacher-related operations.
+ *
+ * Endpoints:
+ * POST /teachers - Create a new teacher
+ * GET /teachers/{teacherId} - Get a teacher by ID
+ * GET /teachers - List all teachers
+ * PUT /teachers/{teacherId} - Update a teacher
+ * DELETE /teachers/{teacherId} - Delete a teacher
+ */
+@RestController
+@RequestMapping("/teachers")
+public class TeacherController {
+
+ private final TeacherService teacherService;
+
+ public TeacherController(TeacherService teacherService) {
+ this.teacherService = teacherService;
+ }
+
+ @PostMapping
+ public ResponseEntity createTeacher(@Valid @RequestBody Teacher teacher) {
+ Teacher created = teacherService.createTeacher(teacher.getName(), teacher.getSalary());
+ return ResponseEntity.ok(created);
+ }
+
+ @GetMapping("/{teacherId}")
+ public ResponseEntity getTeacherById(@PathVariable String teacherId) {
+ return ResponseEntity.ok(teacherService.getTeacherById(teacherId));
+ }
+
+ @GetMapping
+ public ResponseEntity> getAllTeachers() {
+ return ResponseEntity.ok(teacherService.getAllTeachers());
+ }
+
+ @PutMapping("/{teacherId}")
+ public ResponseEntity updateTeacher(@PathVariable String teacherId, @RequestBody Map updates) {
+ String newName = (String) updates.get("name");
+ Double newSalary = updates.containsKey("salary") ? ((Number) updates.get("salary")).doubleValue() : null;
+ teacherService.updateTeacher(teacherId, newName, newSalary);
+ return ResponseEntity.ok().build();
+ }
+
+ @DeleteMapping("/{teacherId}")
+ public ResponseEntity deleteTeacher(@PathVariable String teacherId) {
+ teacherService.deleteTeacher(teacherId);
+ return ResponseEntity.ok().build();
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/models/Course.java b/src/main/java/com/example/demo/models/Course.java
new file mode 100644
index 00000000..87191e95
--- /dev/null
+++ b/src/main/java/com/example/demo/models/Course.java
@@ -0,0 +1,72 @@
+package com.example.demo.models;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Positive;
+
+import java.util.UUID;
+
+/**
+ * Represents a course offered by the school.
+ * ID is auto-generated upon construction using UUID.
+ */
+public class Course {
+
+ private String courseId;
+
+ @NotBlank(message = "Course name cannot be blank")
+ private String name;
+
+ @Positive(message = "Price must be positive")
+ private double price;
+
+ private double moneyEarned;
+
+ private Teacher teacher;
+
+ public Course(String name, double price) {
+ this.courseId = UUID.randomUUID().toString(); // Auto-generate ID in constructor
+ this.name = name;
+ this.price = price;
+ this.moneyEarned = 0.0;
+ }
+
+ public String getCourseId() {
+ return courseId;
+ }
+
+ public void setCourseId(String courseId) {
+ this.courseId = courseId;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public void setName(String name) {
+ this.name = name;
+ }
+
+ public double getPrice() {
+ return price;
+ }
+
+ public void setPrice(double price) {
+ this.price = price;
+ }
+
+ public double getMoneyEarned() {
+ return moneyEarned;
+ }
+
+ public void setMoneyEarned(double moneyEarned) {
+ this.moneyEarned = moneyEarned;
+ }
+
+ public Teacher getTeacher() {
+ return teacher;
+ }
+
+ public void setTeacher(Teacher teacher) {
+ this.teacher = teacher;
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/models/Student.java b/src/main/java/com/example/demo/models/Student.java
new file mode 100644
index 00000000..77ddd9b6
--- /dev/null
+++ b/src/main/java/com/example/demo/models/Student.java
@@ -0,0 +1,74 @@
+package com.example.demo.models;
+
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+
+import java.util.UUID;
+
+/**
+ * Represents a student enrolled in the school.
+ * ID is auto-generated upon construction using UUID.
+ */
+public class Student {
+
+ private String studentId;
+
+ @NotBlank(message = "Student name cannot be blank")
+ private String name;
+
+ @NotBlank(message = "Student address cannot be blank")
+ private String address;
+
+ @NotBlank(message = "Student email cannot be blank")
+ @Email(message = "Student email must be a valid email address")
+ private String email;
+
+ private Course course;
+
+ public Student(String name, String address, String email) {
+ this.studentId = UUID.randomUUID().toString(); // Auto-generate ID in constructor
+ this.name = name;
+ this.address = address;
+ this.email = email;
+ }
+
+ public String getStudentId() {
+ return studentId;
+ }
+
+ public void setStudentId(String studentId) {
+ this.studentId = studentId;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public void setName(String name) {
+ this.name = name;
+ }
+
+ public String getAddress() {
+ return address;
+ }
+
+ public void setAddress(String address) {
+ this.address = address;
+ }
+
+ public String getEmail() {
+ return email;
+ }
+
+ public void setEmail(String email) {
+ this.email = email;
+ }
+
+ public Course getCourse() {
+ return course;
+ }
+
+ public void setCourse(Course course) {
+ this.course = course;
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/models/Teacher.java b/src/main/java/com/example/demo/models/Teacher.java
new file mode 100644
index 00000000..cf1513c7
--- /dev/null
+++ b/src/main/java/com/example/demo/models/Teacher.java
@@ -0,0 +1,51 @@
+package com.example.demo.models;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.PositiveOrZero;
+
+import java.util.UUID;
+
+/**
+ * Represents a teacher employed by the school.
+ * ID is auto-generated upon construction using UUID.
+ */
+public class Teacher {
+
+ private String teacherId;
+
+ @NotBlank(message = "Teacher name cannot be blank")
+ private String name;
+
+ @PositiveOrZero(message = "Salary cannot be negative")
+ private double salary;
+
+ public Teacher(String name, double salary) {
+ this.teacherId = UUID.randomUUID().toString(); // Auto-generate ID in constructor
+ this.name = name;
+ this.salary = salary;
+ }
+
+ public String getTeacherId() {
+ return teacherId;
+ }
+
+ public void setTeacherId(String teacherId) {
+ this.teacherId = teacherId;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public void setName(String name) {
+ this.name = name;
+ }
+
+ public double getSalary() {
+ return salary;
+ }
+
+ public void setSalary(double salary) {
+ this.salary = salary;
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/services/CourseService.java b/src/main/java/com/example/demo/services/CourseService.java
new file mode 100644
index 00000000..0542e5d0
--- /dev/null
+++ b/src/main/java/com/example/demo/services/CourseService.java
@@ -0,0 +1,150 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.CourseNotFoundException;
+import com.example.demo.Exceptions.InvalidInputException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Teacher;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Lazy;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Service layer for managing Course entities.
+ * Handles creation, retrieval, updating, deletion, teacher assignment, and profit calculation.
+ */
+@Service
+public class CourseService {
+
+ private final Map courseMap = new HashMap<>();
+ private final TeacherService teacherService;
+
+ @Autowired
+ public CourseService(@Lazy TeacherService teacherService) {
+ this.teacherService = teacherService;
+ }
+
+ /**
+ * Creates a new course with the given name and price.
+ * The course ID is auto-generated inside the Course constructor.
+ */
+ public Course createCourse(String name, double price) {
+ if (name == null || name.isBlank()) {
+ throw new InvalidInputException("Course name cannot be empty");
+ }
+ if (price <= 0) {
+ throw new InvalidInputException("Price must be positive");
+ }
+ Course course = new Course(name, price); // ID auto-generated in constructor
+ courseMap.put(course.getCourseId(), course);
+ return course;
+ }
+
+ /**
+ * Retrieves a course by its ID.
+ * Throws CourseNotFoundException if no course matches the given ID.
+ */
+ public Course getCourseById(String courseId) {
+ if (courseId == null) {
+ throw new InvalidInputException("Course ID cannot be null");
+ }
+ Course course = courseMap.get(courseId);
+ if (course == null) {
+ throw new CourseNotFoundException("Course not found with ID: " + courseId);
+ }
+ return course;
+ }
+
+ /**
+ * Returns all courses in the system.
+ */
+ public List getAllCourses() {
+ return new ArrayList<>(courseMap.values());
+ }
+
+ /**
+ * Updates the name and/or price of an existing course.
+ * Only non-null and valid values are applied.
+ */
+ public void updateCourse(String courseId, String newName, Double newPrice) {
+ Course course = getCourseById(courseId);
+ if (newName != null && !newName.isBlank()) {
+ course.setName(newName);
+ }
+ if (newPrice != null && newPrice > 0) {
+ course.setPrice(newPrice);
+ }
+ }
+
+ /**
+ * Deletes a course by its ID.
+ * Throws CourseNotFoundException if the course does not exist.
+ */
+ public void deleteCourse(String courseId) {
+ getCourseById(courseId); // Validates existence
+ courseMap.remove(courseId);
+ }
+
+ /**
+ * Assigns a teacher to a course.
+ * Both the course and teacher must already exist.
+ */
+ public void assignTeacherToCourse(String courseId, String teacherId) {
+ Course course = getCourseById(courseId);
+ Teacher teacher = teacherService.getTeacherById(teacherId);
+ course.setTeacher(teacher);
+ }
+
+ /**
+ * Returns all courses assigned to a specific teacher.
+ */
+ public List getCoursesByTeacher(String teacherId) {
+ teacherService.getTeacherById(teacherId); // Validates teacher existence
+ List teacherCourses = new ArrayList<>();
+ for (Course course : courseMap.values()) {
+ if (course.getTeacher() != null && course.getTeacher().getTeacherId().equals(teacherId)) {
+ teacherCourses.add(course);
+ }
+ }
+ return teacherCourses;
+ }
+
+ /**
+ * Calculates profit for a specific course.
+ * Profit = moneyEarned - (teacher salary / number of courses the teacher teaches).
+ * Teacher salary is distributed evenly across all courses they teach.
+ * If no teacher is assigned, profit equals total money earned.
+ */
+ public double getCourseProfit(String courseId) {
+ Course course = getCourseById(courseId);
+ double earned = course.getMoneyEarned();
+
+ if (course.getTeacher() == null) {
+ return earned;
+ }
+
+ String teacherId = course.getTeacher().getTeacherId();
+ double teacherSalary = course.getTeacher().getSalary();
+ long teacherCourseCount = courseMap.values().stream()
+ .filter(c -> c.getTeacher() != null && c.getTeacher().getTeacherId().equals(teacherId))
+ .count();
+
+ // Distribute salary evenly across all courses this teacher teaches
+ double salaryShare = teacherCourseCount > 0 ? teacherSalary / teacherCourseCount : 0;
+ return earned - salaryShare;
+ }
+
+ /**
+ * Calculates total profit across all courses.
+ * Total Profit = total money earned from all courses - total salaries of all teachers.
+ */
+ public double getTotalProfit() {
+ double totalEarned = courseMap.values().stream().mapToDouble(Course::getMoneyEarned).sum();
+ double totalSalaries = teacherService.getAllTeachers().stream().mapToDouble(Teacher::getSalary).sum();
+ return totalEarned - totalSalaries;
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/services/StudentService.java b/src/main/java/com/example/demo/services/StudentService.java
new file mode 100644
index 00000000..940da700
--- /dev/null
+++ b/src/main/java/com/example/demo/services/StudentService.java
@@ -0,0 +1,159 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.InvalidInputException;
+import com.example.demo.Exceptions.StudentAlreadyEnrolledException;
+import com.example.demo.Exceptions.StudentNotFoundException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Student;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Service layer for managing Student entities.
+ * Handles creation, retrieval, updating, deletion, enrollment, and unenrollment.
+ */
+@Service
+public class StudentService {
+
+ private final Map studentMap = new HashMap<>();
+ private final CourseService courseService;
+
+ @Autowired
+ public StudentService(CourseService courseService) {
+ this.courseService = courseService;
+ }
+
+ /**
+ * Creates a new student with the given name, address, and email.
+ * The student ID is auto-generated inside the Student constructor.
+ */
+ public Student createStudent(String name, String address, String email) {
+ if (name == null || name.isBlank()) {
+ throw new InvalidInputException("Student name cannot be empty");
+ }
+ if (address == null || address.isBlank()) {
+ throw new InvalidInputException("Student address cannot be empty");
+ }
+ if (email == null || email.isBlank()) {
+ throw new InvalidInputException("Student email cannot be empty");
+ }
+ Student student = new Student(name, address, email); // ID auto-generated in constructor
+ studentMap.put(student.getStudentId(), student);
+ return student;
+ }
+
+ /**
+ * Retrieves a student by their ID.
+ * Throws StudentNotFoundException if no student matches the given ID.
+ */
+ public Student getStudentById(String studentId) {
+ if (studentId == null) {
+ throw new InvalidInputException("Student ID cannot be null");
+ }
+ Student student = studentMap.get(studentId);
+ if (student == null) {
+ throw new StudentNotFoundException("Student not found with ID: " + studentId);
+ }
+ return student;
+ }
+
+ /**
+ * Returns all students in the system.
+ */
+ public List getAllStudents() {
+ return new ArrayList<>(studentMap.values());
+ }
+
+ /**
+ * Updates one or more fields of an existing student.
+ * Only non-null and non-blank values are applied.
+ */
+ public void updateStudent(String studentId, String newName, String newAddress, String newEmail) {
+ Student student = getStudentById(studentId);
+ if (newName != null && !newName.isBlank()) {
+ student.setName(newName);
+ }
+ if (newAddress != null && !newAddress.isBlank()) {
+ student.setAddress(newAddress);
+ }
+ if (newEmail != null && !newEmail.isBlank()) {
+ student.setEmail(newEmail);
+ }
+ }
+
+ /**
+ * Deletes a student by their ID.
+ * If the student is enrolled in a course, they are unenrolled first to maintain data integrity.
+ */
+ public void deleteStudent(String studentId) {
+ Student student = getStudentById(studentId);
+ if (student.getCourse() != null) {
+ unenrollStudentFromCourse(studentId); // Clean up enrollment before deletion
+ }
+ studentMap.remove(studentId);
+ }
+
+ /**
+ * Enrolls a student in a course.
+ * If already enrolled in the same course, throws StudentAlreadyEnrolledException.
+ * If enrolled in a different course, automatically unenrolls from the previous course first.
+ */
+ public void enrollStudentInCourse(String studentId, String courseId) {
+ Student student = getStudentById(studentId);
+ Course newCourse = courseService.getCourseById(courseId);
+
+ if (student.getCourse() != null && student.getCourse().getCourseId().equals(courseId)) {
+ throw new StudentAlreadyEnrolledException("Student is already enrolled in this course");
+ }
+
+ // If switching courses, subtract earnings from the old course
+ if (student.getCourse() != null) {
+ student.getCourse().setMoneyEarned(student.getCourse().getMoneyEarned() - student.getCourse().getPrice());
+ }
+
+ student.setCourse(newCourse);
+ newCourse.setMoneyEarned(newCourse.getMoneyEarned() + newCourse.getPrice());
+ }
+
+ /**
+ * Unenrolls a student from their current course.
+ * Throws InvalidInputException if the student is not currently enrolled.
+ */
+ public void unenrollStudentFromCourse(String studentId) {
+ Student student = getStudentById(studentId);
+ Course course = student.getCourse();
+ if (course == null) {
+ throw new InvalidInputException("Student is not enrolled in any course");
+ }
+ course.setMoneyEarned(course.getMoneyEarned() - course.getPrice());
+ student.setCourse(null);
+ }
+
+ /**
+ * Returns all students currently enrolled in the specified course.
+ */
+ public List getEnrolledStudents(String courseId) {
+ courseService.getCourseById(courseId); // Validates course existence
+ List enrolledStudents = new ArrayList<>();
+ for (Student student : studentMap.values()) {
+ if (student.getCourse() != null && student.getCourse().getCourseId().equals(courseId)) {
+ enrolledStudents.add(student);
+ }
+ }
+ return enrolledStudents;
+ }
+
+ /**
+ * Returns the course a student is currently enrolled in.
+ * Returns null if the student is not enrolled in any course.
+ */
+ public Course getCourseForStudent(String studentId) {
+ Student student = getStudentById(studentId);
+ return student.getCourse();
+ }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/demo/services/TeacherService.java b/src/main/java/com/example/demo/services/TeacherService.java
new file mode 100644
index 00000000..ff026d63
--- /dev/null
+++ b/src/main/java/com/example/demo/services/TeacherService.java
@@ -0,0 +1,97 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.InvalidInputException;
+import com.example.demo.Exceptions.TeacherNotFoundException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Teacher;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Lazy;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Service layer for managing Teacher entities.
+ * Handles creation, retrieval, updating, and deletion of teachers.
+ * On deletion, unassigns the teacher from all their courses.
+ */
+@Service
+public class TeacherService {
+
+ private final Map teacherMap = new HashMap<>();
+ private final CourseService courseService;
+
+ @Autowired
+ public TeacherService(@Lazy CourseService courseService) {
+ this.courseService = courseService;
+ }
+
+ /**
+ * Creates a new teacher with the given name and salary.
+ * The teacher ID is auto-generated inside the Teacher constructor.
+ */
+ public Teacher createTeacher(String name, double salary) {
+ if (name == null || name.isBlank()) {
+ throw new InvalidInputException("Teacher name cannot be empty");
+ }
+ if (salary < 0) {
+ throw new InvalidInputException("Salary cannot be negative");
+ }
+ Teacher teacher = new Teacher(name, salary); // ID auto-generated in constructor
+ teacherMap.put(teacher.getTeacherId(), teacher);
+ return teacher;
+ }
+
+ /**
+ * Retrieves a teacher by their ID.
+ * Throws TeacherNotFoundException if no teacher matches the given ID.
+ */
+ public Teacher getTeacherById(String teacherId) {
+ if (teacherId == null) {
+ throw new InvalidInputException("Teacher ID cannot be null");
+ }
+ Teacher teacher = teacherMap.get(teacherId);
+ if (teacher == null) {
+ throw new TeacherNotFoundException("Teacher not found with ID: " + teacherId);
+ }
+ return teacher;
+ }
+
+ /**
+ * Returns all teachers in the system.
+ */
+ public List getAllTeachers() {
+ return new ArrayList<>(teacherMap.values());
+ }
+
+ /**
+ * Updates one or more fields of an existing teacher.
+ * Only non-null and valid values are applied.
+ */
+ public void updateTeacher(String teacherId, String newName, Double newSalary) {
+ Teacher teacher = getTeacherById(teacherId);
+ if (newName != null && !newName.isBlank()) {
+ teacher.setName(newName);
+ }
+ if (newSalary != null && newSalary >= 0) {
+ teacher.setSalary(newSalary);
+ }
+ }
+
+ /**
+ * Deletes a teacher by their ID.
+ * Before removal, unassigns the teacher from all courses they are teaching
+ * to maintain data integrity.
+ */
+ public void deleteTeacher(String teacherId) {
+ getTeacherById(teacherId); // Validates existence
+ List courses = courseService.getCoursesByTeacher(teacherId);
+ for (Course course : courses) {
+ course.setTeacher(null); // Unassign teacher from all their courses
+ }
+ teacherMap.remove(teacherId);
+ }
+}
\ No newline at end of file
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
new file mode 100644
index 00000000..2109a440
--- /dev/null
+++ b/src/main/resources/application.properties
@@ -0,0 +1 @@
+spring.application.name=demo
diff --git a/src/test/java/com/example/demo/DemoApplicationTests.java b/src/test/java/com/example/demo/DemoApplicationTests.java
new file mode 100644
index 00000000..2778a6a7
--- /dev/null
+++ b/src/test/java/com/example/demo/DemoApplicationTests.java
@@ -0,0 +1,13 @@
+package com.example.demo;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class DemoApplicationTests {
+
+ @Test
+ void contextLoads() {
+ }
+
+}
diff --git a/src/test/java/com/example/demo/services/CourseServiceTest.java b/src/test/java/com/example/demo/services/CourseServiceTest.java
new file mode 100644
index 00000000..21695da7
--- /dev/null
+++ b/src/test/java/com/example/demo/services/CourseServiceTest.java
@@ -0,0 +1,59 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.InvalidInputException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Teacher;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CourseServiceTest {
+
+ private CourseService courseService;
+ private TeacherService teacherService;
+
+ @BeforeEach
+ void setUp() {
+ teacherService = new TeacherService(null);
+ courseService = new CourseService(teacherService);
+
+ }
+
+ @Test
+ void createCourseValid() {
+ Course course = courseService.createCourse("Math", 100.0);
+ assertNotNull(course.getCourseId());
+ assertEquals("Math", course.getName());
+ assertEquals(100.0, course.getPrice());
+ }
+
+ @Test
+ void createCourseInvalidName() {
+ assertThrows(InvalidInputException.class, () -> courseService.createCourse("", 100.0));
+ }
+
+ @Test
+ void getCourseById() {
+ Course course = courseService.createCourse("Math", 100.0);
+ Course found = courseService.getCourseById(course.getCourseId());
+ assertEquals(course, found);
+ }
+
+ @Test
+ void assignTeacherToCourse() {
+ Teacher teacher = teacherService.createTeacher("John", 500.0);
+ Course course = courseService.createCourse("Math", 100.0);
+ courseService.assignTeacherToCourse(course.getCourseId(), teacher.getTeacherId());
+ assertEquals(teacher, course.getTeacher());
+ }
+
+ @Test
+ void getCourseProfit() {
+ Course course = courseService.createCourse("Math", 100.0);
+ course.setMoneyEarned(200.0);
+ Teacher teacher = teacherService.createTeacher("John", 50.0);
+ course.setTeacher(teacher);
+ assertEquals(150.0, courseService.getCourseProfit(course.getCourseId()));
+ }
+}
\ No newline at end of file
diff --git a/src/test/java/com/example/demo/services/StudentServiceTest.java b/src/test/java/com/example/demo/services/StudentServiceTest.java
new file mode 100644
index 00000000..c6aaa83b
--- /dev/null
+++ b/src/test/java/com/example/demo/services/StudentServiceTest.java
@@ -0,0 +1,58 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.StudentAlreadyEnrolledException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Student;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class StudentServiceTest {
+
+ private StudentService studentService;
+ private CourseService courseService;
+
+ @BeforeEach
+ void setUp() {
+ TeacherService teacherService = new TeacherService(null);
+ courseService = new CourseService(teacherService);
+
+ studentService = new StudentService(courseService);
+ }
+
+ @Test
+ void createStudentValid() {
+ Student student = studentService.createStudent("Alice", "123 St", "alice@email.com");
+ assertNotNull(student.getStudentId());
+ assertEquals("Alice", student.getName());
+ }
+
+ @Test
+ void enrollStudentInCourse() {
+ Course course = courseService.createCourse("Math", 100.0);
+ Student student = studentService.createStudent("Alice", "123 St", "alice@email.com");
+ studentService.enrollStudentInCourse(student.getStudentId(), course.getCourseId());
+ assertEquals(course, student.getCourse());
+ assertEquals(100.0, course.getMoneyEarned());
+ }
+
+ @Test
+ void enrollAlreadyEnrolledSameCourse() {
+ Course course = courseService.createCourse("Math", 100.0);
+ Student student = studentService.createStudent("Alice", "123 St", "alice@email.com");
+ studentService.enrollStudentInCourse(student.getStudentId(), course.getCourseId());
+ assertThrows(StudentAlreadyEnrolledException.class,
+ () -> studentService.enrollStudentInCourse(student.getStudentId(), course.getCourseId()));
+ }
+
+ @Test
+ void unenrollStudentFromCourse() {
+ Course course = courseService.createCourse("Math", 100.0);
+ Student student = studentService.createStudent("Alice", "123 St", "alice@email.com");
+ studentService.enrollStudentInCourse(student.getStudentId(), course.getCourseId());
+ studentService.unenrollStudentFromCourse(student.getStudentId());
+ assertNull(student.getCourse());
+ assertEquals(0.0, course.getMoneyEarned());
+ }
+}
\ No newline at end of file
diff --git a/src/test/java/com/example/demo/services/TeacherServiceTest.java b/src/test/java/com/example/demo/services/TeacherServiceTest.java
new file mode 100644
index 00000000..dad2f9fb
--- /dev/null
+++ b/src/test/java/com/example/demo/services/TeacherServiceTest.java
@@ -0,0 +1,58 @@
+package com.example.demo.services;
+
+import com.example.demo.Exceptions.InvalidInputException;
+import com.example.demo.models.Course;
+import com.example.demo.models.Teacher;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TeacherServiceTest {
+
+ private TeacherService teacherService;
+ private CourseService courseService;
+
+ @BeforeEach
+ void setUp() {
+ courseService = new CourseService(null);
+ teacherService = new TeacherService(courseService);
+ }
+
+ @Test
+ void createTeacherValid() {
+ Teacher teacher = teacherService.createTeacher("John", 500.0);
+ assertNotNull(teacher.getTeacherId());
+ assertEquals("John", teacher.getName());
+ assertEquals(500.0, teacher.getSalary());
+ }
+
+ @Test
+ void createTeacherInvalidSalary() {
+ assertThrows(InvalidInputException.class, () -> teacherService.createTeacher("John", -100.0));
+ }
+
+ @Test
+ void deleteTeacherUnassignsCourses() {
+ Teacher teacher = teacherService.createTeacher("John", 500.0);
+
+ CourseService realCourseService = new CourseService(teacherService);
+ TeacherService realTeacherService = new TeacherService(realCourseService);
+
+ Teacher t = realTeacherService.createTeacher("John", 500.0);
+ Course course = realCourseService.createCourse("Math", 100.0);
+
+ realCourseService.assignTeacherToCourse(course.getCourseId(), t.getTeacherId());
+ realTeacherService.deleteTeacher(t.getTeacherId());
+
+ assertNull(course.getTeacher());
+ }
+
+ @Test
+ void updateTeacher() {
+ Teacher teacher = teacherService.createTeacher("John", 500.0);
+ teacherService.updateTeacher(teacher.getTeacherId(), "Jane", 600.0);
+ assertEquals("Jane", teacher.getName());
+ assertEquals(600.0, teacher.getSalary());
+ }
+}
\ No newline at end of file