Merge pull request #1 from elimity-com/initial-version

Set up initial version

Author: jdeflander

README.md

@@ -0,0 +1,79 @@
+# Elimity backend internship exercise
+
+Thank you for applying for the **Elimity Backend Developer Intern** position! This exercise is designed to give you an
+opportunity to show off your programming skills that would be relevant to work at Elimity, and to give you an idea of
+what type of work you would be doing during your internship. The code in this repository provides a Go module as a
+starting point for the assignments. It implements `gothub`, a simple CLI for tracking public GitHub repositories. The
+actual assignments are listed below.
+
+## Installation
+
+The `gothub` CLI can be installed using `go get` with Go 1.16+:
+
+```sh
+$ go get github.com/elimity-com/backend-intern-exercise/cmd/gothub
+```
+
+## Usage
+
+```sh
+$ gothub help
+Simple CLI for tracking public GitHub repositories.
+
+Usage:
+  gothub help
+  gothub track [-interval=<interval>]
+
+Commands:
+  help  Show usage information
+  track Track public GitHub repositories
+
+Options:
+  -interval=<interval> Repository update interval, greater than zero [default: 10s]
+```
+
+## Assignments
+
+Currently `gothub` only supports regularly printing the most recently updated public GitHub repositories. The
+assignments consist of extending its functionality. More specifically, we ask you to implement these improvements:
+
+1. GitHub applies very strict rate limiting for anonymous requests, causing `gothub` to fail when it contacts the API
+   too frequently. As stated [here](https://docs.github.com/en/rest/reference/search#rate-limit), the rate limit could
+   be increased by using authenticated requests. Therefore we ask you to add a `token-file` option to the `gothub` CLI,
+   which should support authenticating requests by reading a
+   [GitHub personal access token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token)
+   read from the given file path. If not provided, `gothub` should stick to anonymous requests.
+
+2. Currently `gothub` only prints repository names. We ask you to extend this to a table-formatted output with columns
+   for the repository's owner, name, last update timestamp and star count. If the repository belongs to an organization,
+   list the organization's name in the owner column. The result should look like this (including headers):
+
+```
+Owner   | Name      | Updated at (UTC)    | Star count
+golang  | go        | 2021-03-08T11:29:52 | 12345
+google  | go-github | 2021-03-07T12:34:56 | 5432
+angular | angular   | 2021-02-29T05:43:21 | 43210
+```
+
+3. The repositories outputted by `gothub` are only filtered by their accessibility, as they are all public. We ask you
+   to add a `min-stars` option, which causes `gothub` to filter out repositories with a star count below the given
+   value. If not provided, `gothub` should use a minimum star count of zero.
+
+### Grading
+
+Your solutions for the assignments will be graded according to the following points:
+
+- compliance with the listed requirements,
+- consistency with the existing code,
+- understanding of Go fundamentals,
+- adherence to Elimity's style guidelines:
+  - strong types over implicit assumptions,
+  - immutability over mutability, and
+  - simple over clever.
+
+### Practicalities
+
+- You can use any library you want, but we prefer the standard library.
+- These practices are important on the job, but won't affect your grades:
+  - proper version control,
+  - testing (which is complex for a CLI without business logic).

cmd/gothub/main.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/elimity-com/backend-intern-exercise/internal"
+)
+
+var args = os.Args
+
+var name = makeName()
+
+func log(message string) {
+	fmt.Fprintf(os.Stderr, "%s: %s\n", name, message)
+}
+
+func main() {
+	if err := run(); err != nil {
+		message := err.Error()
+		log(message)
+		if _, ok := err.(usageError); ok {
+			message := fmt.Sprintf("run '%s help' for usage information", name)
+			log(message)
+		}
+	}
+}
+
+func makeName() string {
+	path := args[0]
+	return filepath.Base(path)
+}
+
+func parseInterval() (time.Duration, error) {
+	set := flag.NewFlagSet("", flag.ContinueOnError)
+	var interval time.Duration
+	set.DurationVar(&interval, "interval", 10*time.Second, "")
+	set.SetOutput(ioutil.Discard)
+	args := args[2:]
+	if err := set.Parse(args); err != nil {
+		return 0, errors.New("got invalid flags")
+	}
+	if interval <= 0 {
+		return 0, errors.New("got invalid interval")
+	}
+	return interval, nil
+}
+
+func run() error {
+	if nbArgs := len(args); nbArgs < 2 {
+		return usageError{message: "missing command"}
+	}
+	switch args[1] {
+	case "help":
+		const usage = `
+Simple CLI for tracking public GitHub repositories.
+
+Usage:
+  %[1]s help
+  %[1]s track [-interval=<interval>]
+
+Commands:
+  help  Show usage information
+  track Track public GitHub repositories
+
+Options:
+  -interval=<interval> Repository update interval, greater than zero [default: 10s]
+`
+		fmt.Fprintf(os.Stdout, usage, name)
+		return nil
+
+	case "track":
+		interval, err := parseInterval()
+		if err != nil {
+			message := fmt.Sprintf("failed parsing interval: %v", err)
+			return usageError{message: message}
+		}
+		if err := internal.Track(interval); err != nil {
+			return fmt.Errorf("failed tracking: %v", err)
+		}
+		return nil
+
+	default:
+		return usageError{message: "got invalid command"}
+	}
+}
+
+type usageError struct {
+	message string
+}
+
+func (e usageError) Error() string {
+	return e.message
+}

go.mod

@@ -0,0 +1,5 @@
+module github.com/elimity-com/backend-intern-exercise
+
+go 1.16
+
+require github.com/google/go-github/v33 v33.0.0

go.sum

@@ -0,0 +1,12 @@
+github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/go-github/v33 v33.0.0 h1:qAf9yP0qc54ufQxzwv+u9H0tiVOnPJxo0lI/JXqw3ZM=
+github.com/google/go-github/v33 v33.0.0/go.mod h1:GMdDnVZY/2TsWgp/lkYnpSAh6TrzhANBBwm6k6TTEXg=
+github.com/google/go-querystring v1.0.0 h1:Xkwi/a1rcvNg1PPYe5vI8GbeBY/jrVuDX5ASuANWTrk=
+github.com/google/go-querystring v1.0.0/go.mod h1:odCYkC5MyYFN7vkCjXpyrEuKhc/BUO6wN/zVPAxq5ck=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=

internal/track.go

@@ -0,0 +1,28 @@
+package internal
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/google/go-github/v33/github"
+)
+
+// Track tracks public GitHub repositories, continuously updating according to the given interval.
+//
+// The given interval must be greater than zero.
+func Track(interval time.Duration) error {
+	for ; ; <-time.Tick(interval) {
+		client := github.NewClient(nil)
+		con := context.Background()
+		listOptions := github.ListOptions{PerPage: 3}
+		searchOptions := &github.SearchOptions{ListOptions: listOptions, Sort: "updated"}
+		result, _, err := client.Search.Repositories(con, "is:public", searchOptions)
+		if err != nil {
+			return err
+		}
+		for _, repository := range result.Repositories {
+			fmt.Println(*repository.Name)
+		}
+	}
+}