feat: add environment variable validation

backend/index.js

@@ -1,9 +1,14 @@
 /* eslint-disable no-undef */
 const express = require("express");
 require("dotenv").config();
+const { validateEnv } = require("./utils/envValidator");
 const botRouter = require("./routes/botRoutes");
+const { errorHandler } = require("./middleware/validation");
 const cors = require("cors");
 
+// Validate environment variables on startup
+validateEnv();
+
 const app = express();
 app.use(
   cors({
@@ -23,6 +28,9 @@ app.get("/", (req, res) => {
   res.send("Backend is Running!");
 });
 
+// Error handling middleware (must be last)
+app.use(errorHandler);
+
 app.listen(port, () => {
   console.log(`Server is running at http://localhost:${port}`);
 });

backend/utils/envValidator.js

@@ -0,0 +1,214 @@
+/**
+ * Environment Variable Validation Utility
+ * Validates required environment variables on application startup
+ */
+
+/**
+ * Configuration for required environment variables
+ */
+const envConfig = {
+  required: [
+    {
+      name: 'NODE_ENV',
+      description: 'Application environment (development, production, test)',
+      defaultValue: 'development',
+    },
+    {
+      name: 'SERVER_PORT',
+      description: 'Port number for the server',
+      defaultValue: '3000',
+    },
+  ],
+  optional: [
+    {
+      name: 'FRONTEND_URL',
+      description: 'URL of the frontend application',
+      defaultValue: 'http://localhost:5173',
+    },
+    {
+      name: 'GEMINI_API_KEY',
+      description: 'Google Gemini API key for chatbot',
+    },
+    {
+      name: 'DATABASE_URL',
+      description: 'Database connection string',
+    },
+    {
+      name: 'JWT_SECRET',
+      description: 'Secret key for JWT token generation',
+    },
+    {
+      name: 'EMAIL_HOST',
+      description: 'SMTP host for sending emails',
+    },
+    {
+      name: 'EMAIL_PORT',
+      description: 'SMTP port',
+    },
+    {
+      name: 'EMAIL_USER',
+      description: 'Email username',
+    },
+    {
+      name: 'EMAIL_PASSWORD',
+      description: 'Email password',
+    },
+  ],
+};
+
+/**
+ * Validate a single environment variable
+ */
+const validateEnvVar = (config, isRequired) => {
+  const value = process.env[config.name];
+
+  if (!value) {
+    if (config.defaultValue) {
+      process.env[config.name] = config.defaultValue;
+      return {
+        status: 'default',
+        name: config.name,
+        value: config.defaultValue,
+        description: config.description,
+      };
+    }
+
+    return {
+      status: isRequired ? 'missing' : 'optional',
+      name: config.name,
+      description: config.description,
+    };
+  }
+
+  return {
+    status: 'valid',
+    name: config.name,
+    value: value.substring(0, 20) + (value.length > 20 ? '...' : ''),
+    description: config.description,
+  };
+};
+
+/**
+ * Validate all environment variables
+ */
+const validateEnv = () => {
+  console.log('\n🔍 Validating environment variables...\n');
+
+  const results = {
+    valid: [],
+    defaults: [],
+    missing: [],
+    optional: [],
+  };
+
+  // Check required variables
+  envConfig.required.forEach((config) => {
+    const result = validateEnvVar(config, true);
+
+    if (result.status === 'valid') {
+      results.valid.push(result);
+    } else if (result.status === 'default') {
+      results.defaults.push(result);
+    } else if (result.status === 'missing') {
+      results.missing.push(result);
+    }
+  });
+
+  // Check optional variables
+  envConfig.optional.forEach((config) => {
+    const result = validateEnvVar(config, false);
+
+    if (result.status === 'valid') {
+      results.valid.push(result);
+    } else if (result.status === 'default') {
+      results.defaults.push(result);
+    } else {
+      results.optional.push(result);
+    }
+  });
+
+  // Display results
+  if (results.valid.length > 0) {
+    console.log('✓ Valid environment variables:');
+    results.valid.forEach((item) => {
+      console.log(`  ✓ ${item.name} - ${item.description}`);
+    });
+    console.log('');
+  }
+
+  if (results.defaults.length > 0) {
+    console.log('⚠ Using default values:');
+    results.defaults.forEach((item) => {
+      console.log(`  ⚠ ${item.name} = ${item.value} (${item.description})`);
+    });
+    console.log('');
+  }
+
+  if (results.optional.length > 0) {
+    console.log('ℹ Optional variables not set:');
+    results.optional.forEach((item) => {
+      console.log(`  ℹ ${item.name} - ${item.description}`);
+    });
+    console.log('');
+  }
+
+  if (results.missing.length > 0) {
+    console.log('✖ Missing required environment variables:');
+    results.missing.forEach((item) => {
+      console.log(`  ✖ ${item.name} - ${item.description}`);
+    });
+    console.log('');
+    console.log('Please set the missing environment variables in your .env file');
+    console.log('See .env.example for reference\n');
+
+    if (process.env.NODE_ENV === 'production') {
+      process.exit(1);
+    } else {
+      console.log('Running in development mode - continuing with warnings\n');
+    }
+  } else {
+    console.log('✓ All required environment variables are set!\n');
+  }
+
+  return results;
+};
+
+/**
+ * Generate .env.example file based on config
+ */
+const generateEnvExample = () => {
+  const lines = [
+    '# Environment Variables Configuration',
+    '# Copy this file to .env and fill in your values',
+    '',
+    '# Required Variables',
+    '',
+  ];
+
+  envConfig.required.forEach((config) => {
+    lines.push(`# ${config.description}`);
+    if (config.defaultValue) {
+      lines.push(`${config.name}=${config.defaultValue}`);
+    } else {
+      lines.push(`${config.name}=`);
+    }
+    lines.push('');
+  });
+
+  lines.push('# Optional Variables');
+  lines.push('');
+
+  envConfig.optional.forEach((config) => {
+    lines.push(`# ${config.description}`);
+    lines.push(`${config.name}=`);
+    lines.push('');
+  });
+
+  return lines.join('\n');
+};
+
+module.exports = {
+  validateEnv,
+  generateEnvExample,
+  envConfig,
+};