Enhance DIGIPIN API with full input validation, improved error handling, and middleware upgrades

server.js

@@ -4,5 +4,5 @@ const app = require('./src/app');
 const PORT = process.env.PORT || 5000;
 
 app.listen(PORT, () => {
-console.log(`DIGIPIN API is running and API docs can be found at at http://localhost:${PORT}/api-docs`);
+    console.log(`DIGIPIN API is running and API docs can be found at http://localhost:${PORT}/api-docs`);
 });

src/app.js

@@ -12,15 +12,45 @@ const swaggerDocument = YAML.parse(fs.readFileSync(path.join(__dirname, '../swag
 
 const app = express();
 
-// Middleware
+// Custom middleware: Validate JSON content-type for POST requests
+const validateJsonContentType = (req, res, next) => {
+  if (req.method === 'POST' || req.method === 'PUT' || req.method === 'PATCH') {
+    const contentType = req.headers['content-type'];
+    if (!contentType || !contentType.includes('application/json')) {
+      return res.status(415).json({
+        error: 'Unsupported Media Type: Content-Type must be application/json',
+        code: 'INVALID_CONTENT_TYPE',
+        receivedContentType: contentType || 'none',
+        expectedContentType: 'application/json'
+      });
+    }
+  }
+  next();
+};
+
+// Middleware (order matters - validateJsonContentType before express.json())
+app.use(validateJsonContentType);
 app.use(cors());
 app.use(express.json());
 app.use(morgan('dev'));
 
+// Error handler for JSON parsing errors (specifically for malformed JSON)
+app.use((err, req, res, next) => {
+  // Check if it's a JSON parsing error from express.json()
+  if (err instanceof SyntaxError && err.status === 400 && 'body' in err) {
+    return res.status(400).json({
+      error: 'Invalid JSON payload: ' + err.message,
+      code: 'INVALID_JSON_SYNTAX',
+      details: 'Ensure your JSON is properly formatted with correct syntax'
+    });
+  }
+  next(err);
+});
+
 // Swagger Docs Route
 app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerDocument));
 
 // DIGIPIN API Routes
 app.use('/api/digipin', digipinRoutes);
 
-module.exports = app;
+module.exports = app;

src/routes/digipin.routes.js

@@ -2,29 +2,204 @@ const express = require('express');
 const router = express.Router();
 const { getDigiPin, getLatLngFromDigiPin } = require('../digipin');
 
-router.post('/encode', (req, res) => { const { latitude, longitude } = req.body; try { const code = getDigiPin(latitude, longitude); res.json({ digipin: code }); } catch (e) { res.status(400).json({ error: e.message }); } });
-
-router.post('/decode', (req, res) => { const { digipin } = req.body; try { const coords = getLatLngFromDigiPin(digipin); res.json(coords); } catch (e) { res.status(400).json({ error: e.message }); } });
-
-  router.get('/encode', (req, res) => {
-    const { latitude, longitude } = req.query;
-    try {
-      const code = getDigiPin(parseFloat(latitude), parseFloat(longitude));
-      res.json({ digipin: code });
-    } catch (e) {
-      res.status(400).json({ error: e.message });
-    }
-  });
-
-  router.get('/decode', (req, res) => {
-    const { digipin } = req.query;
-    try {
-      const coords = getLatLngFromDigiPin(digipin);
-      res.json(coords);
-    } catch (e) {
-      res.status(400).json({ error: e.message });
-    }
-  });
-
-
+/**
+ * Validation helper: Check if value is a valid number
+ * @param {*} value - Value to validate
+ * @returns {boolean} - True if value is a valid number
+ */
+function isValidNumber(value) {
+  const num = typeof value === 'string' ? parseFloat(value) : value;
+  return typeof num === 'number' && !isNaN(num) && isFinite(num);
+}
+
+/**
+ * Validation helper: Check if value is a non-empty string
+ * @param {*} value - Value to validate
+ * @returns {boolean} - True if value is a non-empty string
+ */
+function isValidString(value) {
+  return typeof value === 'string' && value.trim().length > 0;
+}
+
+/**
+ * POST /encode - Encode latitude and longitude into DIGIPIN
+ * @body {number} latitude - Latitude coordinate
+ * @body {number} longitude - Longitude coordinate
+ * @returns {object} {digipin: string} - Encoded DIGIPIN code
+ */
+router.post('/encode', (req, res) => {
+  const { latitude, longitude } = req.body;
+
+  // Validate inputs
+  if (latitude === undefined || latitude === null) {
+    return res.status(400).json({
+      error: 'Missing required field: latitude',
+      code: 'MISSING_LATITUDE'
+    });
+  }
+
+  if (longitude === undefined || longitude === null) {
+    return res.status(400).json({
+      error: 'Missing required field: longitude',
+      code: 'MISSING_LONGITUDE'
+    });
+  }
+
+  if (!isValidNumber(latitude)) {
+    return res.status(400).json({
+      error: 'Invalid latitude: must be a valid number',
+      code: 'INVALID_LATITUDE'
+    });
+  }
+
+  if (!isValidNumber(longitude)) {
+    return res.status(400).json({
+      error: 'Invalid longitude: must be a valid number',
+      code: 'INVALID_LONGITUDE'
+    });
+  }
+
+  try {
+    const latNum = parseFloat(latitude);
+    const lonNum = parseFloat(longitude);
+    const code = getDigiPin(latNum, lonNum);
+    res.status(200).json({ digipin: code });
+  } catch (error) {
+    res.status(400).json({
+      error: error.message,
+      code: 'ENCODING_FAILED'
+    });
+  }
+});
+
+/**
+ * POST /decode - Decode DIGIPIN to coordinates
+ * @body {string} digipin - DIGIPIN code to decode
+ * @returns {object} {latitude: string, longitude: string} - Decoded coordinates
+ */
+router.post('/decode', (req, res) => {
+  const { digipin } = req.body;
+
+  // Validate input
+  if (digipin === undefined || digipin === null) {
+    return res.status(400).json({
+      error: 'Missing required field: digipin',
+      code: 'MISSING_DIGIPIN'
+    });
+  }
+
+  // Validate digipin is a string type
+  if (typeof digipin !== 'string') {
+    return res.status(400).json({
+      error: `Invalid digipin type: expected string, received ${typeof digipin}`,
+      code: 'INVALID_DIGIPIN_TYPE',
+      receivedType: typeof digipin
+    });
+  }
+
+  if (!isValidString(digipin)) {
+    return res.status(400).json({
+      error: 'Invalid digipin: must be a non-empty string',
+      code: 'INVALID_DIGIPIN'
+    });
+  }
+
+  try {
+    const coords = getLatLngFromDigiPin(digipin);
+    res.status(200).json(coords);
+  } catch (error) {
+    res.status(400).json({
+      error: error.message,
+      code: 'DECODING_FAILED'
+    });
+  }
+});
+
+/**
+ * GET /encode - Encode latitude and longitude into DIGIPIN
+ * @query {number} latitude - Latitude coordinate
+ * @query {number} longitude - Longitude coordinate
+ * @returns {object} {digipin: string} - Encoded DIGIPIN code
+ */
+router.get('/encode', (req, res) => {
+  const { latitude, longitude } = req.query;
+
+  // Validate inputs
+  if (!latitude || !longitude) {
+    return res.status(400).json({
+      error: 'Missing required query parameters: latitude and longitude',
+      code: 'MISSING_PARAMETERS'
+    });
+  }
+
+  if (!isValidNumber(latitude)) {
+    return res.status(400).json({
+      error: 'Invalid latitude: must be a valid number',
+      code: 'INVALID_LATITUDE'
+    });
+  }
+
+  if (!isValidNumber(longitude)) {
+    return res.status(400).json({
+      error: 'Invalid longitude: must be a valid number',
+      code: 'INVALID_LONGITUDE'
+    });
+  }
+
+  try {
+    const latNum = parseFloat(latitude);
+    const lonNum = parseFloat(longitude);
+    const code = getDigiPin(latNum, lonNum);
+    res.status(200).json({ digipin: code });
+  } catch (error) {
+    res.status(400).json({
+      error: error.message,
+      code: 'ENCODING_FAILED'
+    });
+  }
+});
+
+/**
+ * GET /decode - Decode DIGIPIN to coordinates
+ * @query {string} digipin - DIGIPIN code to decode
+ * @returns {object} {latitude: string, longitude: string} - Decoded coordinates
+ */
+router.get('/decode', (req, res) => {
+  const { digipin } = req.query;
+
+  // Validate input
+  if (!digipin) {
+    return res.status(400).json({
+      error: 'Missing required query parameter: digipin',
+      code: 'MISSING_DIGIPIN'
+    });
+  }
+
+  // Validate digipin is a string type (query params are always strings, but for safety)
+  if (typeof digipin !== 'string') {
+    return res.status(400).json({
+      error: `Invalid digipin type: expected string, received ${typeof digipin}`,
+      code: 'INVALID_DIGIPIN_TYPE',
+      receivedType: typeof digipin
+    });
+  }
+
+  if (!isValidString(digipin)) {
+    return res.status(400).json({
+      error: 'Invalid digipin: must be a non-empty string',
+      code: 'INVALID_DIGIPIN'
+    });
+  }
+
+  try {
+    const coords = getLatLngFromDigiPin(digipin);
+    res.status(200).json(coords);
+  } catch (error) {
+    res.status(400).json({
+      error: error.message,
+      code: 'DECODING_FAILED'
+    });
+  }
+});
+
 module.exports = router;