Merge pull request #1 from ruihildt/completed-backend

Completed backend with documentation

README.md

@@ -0,0 +1,136 @@
+# dijkstra-backend
+
+Dijkstra is an app thas uses Dijkstra algorithm to display the shortest path between different cities in Belgium.
+
+Deployed backend: https://dijkstra-backend.herokuapp.com/
+
+## API Documentation
+___
+> Values required in **`bold`**.
+
+### COUNTRIES **`countries`**
+| field    | data type         | metadata                                            |
+| :--------| :---------------- | :-------------------------------------------------- |
+| id       | unsigned integer  | primary key, auto-increments, generated by database |
+| name     | string            |                                                     |
+
+#### Get countries list
+**`GET /api/countries/:country_id`**
+
+##### Response
+An array of json objects with a list of cities in the selected country with `name`, `id` and `country_id`.
+
+```
+[
+  {
+    "id": 1,
+    "name": "bruges",
+    "country_id": 1
+  },
+  {
+    "id": 2,
+    "name": "antwerp",
+    "country_id": 1
+  },
+  {
+    "id": 3,
+    "name": "ghent",
+    "country_id": 1
+  },
+]
+```
+
+### CITIES **`cities`**
+| field      | data type              | metadata                                            |
+| :----------| :--------------------- | :-------------------------------------------------- |
+| id         | unsigned integer       | primary key, auto-increments, generated by database |
+| name       | string                 |                                                     |
+| country_id | unsigned integer       | foreign key referencing `countries.id`              |
+
+#### Get cities list
+**`GET /api/cities`**
+
+##### Response
+An array of json objects with `id`, `name` and `country_id`.
+
+```
+[
+  {
+    "id": 1,
+    "name": 'bruges',
+    "country_id": 1
+  }
+]
+```
+
+### ROADS **`roads`**
+| field         | data type        | metadata                                            |
+| :-------------| :--------------- | :-------------------------------------------------- |
+| id            | unsigned integer | primary key, auto-increments, generated by database |
+| start_city_id | string           | required                                            |
+| end_city_id   | string           | required                                            |
+| distance      | unsigned integer |                                                     |
+
+#### Get roads list
+**`GET /api/roads`**
+
+##### Response
+A array of json objects with `id`, `start_city_id`, 'end_city_id` and `distance`.
+
+```
+[
+  {
+    "id": 1,
+    "start_city_id": 1,
+    "end_city_id": 3,
+    "distance": 50
+  }
+]
+```
+
+### Shortest Path **`cities`**
+
+#### Get the shortest path between two cities and the total distance
+**`GET /api/path`**
+
+##### Request
+Add the **`start_city_id`** and **`end_city_id`** as query strings to the url.
+
+```
+/api/path?start_city_id=2?end_city_id=9
+```
+
+##### Response
+A json object composed of the `path` correctly ordered and the total `distance`.
+
+```
+{
+  "path": [
+    {
+      "id": 2,
+      "name": "antwerp"
+    },
+    {
+      "id": 4,
+      "name": "mechelen"
+    },
+    {
+      "id": 5,
+      "name": "brussels"
+    },
+    {
+      "id": 8,
+      "name": "liege"
+    },
+    {
+      "id": 7,
+      "name": "namur"
+    },
+    {
+      "id": 9,
+      "name": "arlon"
+    }
+  ],
+  "distance": 337
+}
+```

api/models/citiesModel.js

@@ -0,0 +1,22 @@
+const db = require('../../data/dbConfig');
+
+module.exports = {
+	getCities,
+    getCitiesByCountry
+    // getCity,
+};
+
+function getCities() {
+	return db('cities')
+}
+
+function getCitiesByCountry(country_id) {
+	return db('cities')
+	.where({ country_id })
+}
+
+// function getCity(name) {
+// 	return db('cities')
+// 		.where({ name })
+// 		.first()
+// }

api/models/countriesModel.js

@@ -1,4 +1,4 @@
-const db = require('../data/dbConfig');
+const db = require('../../data/dbConfig');
 
 module.exports = {
 	getCountries,

api/models/roadsModel.js

@@ -0,0 +1,9 @@
+const db = require('../../data/dbConfig');
+
+module.exports = {
+	getRoads
+};
+
+function getRoads() {
+	return db('roads')
+}

api/routes/citiesRouter.js

@@ -0,0 +1,14 @@
+const router = require('express').Router();
+
+const Cities = require('../models/citiesModel');
+
+router.get('', async (req, res) => {
+    try {
+        const cities = await Cities.getCities();
+        res.status(200).json(cities);
+    } catch (e) {
+        res.status(500).json(e);
+    }
+})
+
+module.exports = router;

api/routes/countriesRouter.js

@@ -0,0 +1,14 @@
+const router = require('express').Router();
+const Cities = require('../models/citiesModel');
+
+router.get('/:country_id', async (req, res) => {
+    const { country_id } = req.params;
+    try {
+        const cities = await Cities.getCitiesByCountry(country_id);
+        res.status(200).json(cities);
+    } catch (e) {
+        res.status(500).json(e);
+    }
+})
+
+module.exports = router;

api/routes/pathRouter.js

@@ -0,0 +1,43 @@
+const router = require('express').Router();
+
+const Roads = require('../models/roadsModel');
+const Cities = require('../models/citiesModel');
+
+const findShortestPath = require('../../helpers/dijkstra_algo');
+
+router.get('', async (req, res) => {
+    const { start_city_id, end_city_id } = req.query;
+
+    start = Math.floor(start_city_id);
+    end = Math.floor(end_city_id);
+
+    try {
+        const cities = await Cities.getCities();
+        const roads = await Roads.getRoads();
+
+        let { path, distance } = findShortestPath(cities, roads, start, end);
+        const shortestPath = formatPath(path, cities)
+
+        let response = { path: shortestPath, distance }
+
+        res.status(200).json(response);
+    } catch (e) {
+        res.status(500).json(e);
+    }
+})
+
+function formatPath(path, cities) {
+    const complete_path = []
+
+    for (let path_city of path) {
+        for (let city of cities) {
+            if (city.id == path_city) {
+                complete_path.push({ id: city.id, name: city.name });
+            }
+        }
+    }
+
+    return complete_path
+}
+
+module.exports = router;

api/routes/roadsRouter.js

@@ -0,0 +1,13 @@
+const router = require('express').Router();
+const Roads = require('../models/roadsModel');
+
+router.get('', async (req, res) => {
+    try {
+        const roads = await Roads.getRoads();
+        res.status(200).json(roads);
+    } catch (e) {
+        res.status(500).json(e);
+    }
+})
+
+module.exports = router;

api/server.js

@@ -1,17 +1,21 @@
 const express = require("express");
+const helmet = require('helmet');
+const cors = require('cors');
 
-// const authRouter = require('../services/auth/authRouter');
+const citiesRouter = require('./routes/citiesRouter');
-// const usersRouter = require('../services/users/usersRouter');
+const roadsRouter = require('./routes/roadsRouter');
-// const sessionsRouter = require('../services/sessions/sessionsRouter');
+const countriesRouter = require('./routes/countriesRouter');
-// const dailyAveragesRouter = require('../services/dailyAverages/dailyAveragesRouter');
+const pathRouter = require('./routes/pathRouter')
 
 const server = express();
 
+server.use(helmet());
 server.use(express.json());
+server.use(cors());
 
-// server.use('/api/auth', authRouter);
+server.use('/api/cities', citiesRouter);
-// server.use('/api/users', authenticate, usersRouter);
+server.use('/api/roads', roadsRouter);
-// server.use('/api/users', authenticate, sessionsRouter);
+server.use('/api/countries', countriesRouter);
-// server.use('/api/users', authenticate, dailyAveragesRouter);
+server.use('/api/path', pathRouter);
 
 module.exports = server;

helpers/dijkstra_algo.js

@@ -0,0 +1,55 @@
+const Queue = require('./queue');
+const Graph = require('./graph');
+
+function findPathWithDijkstra(cities, roads, startNode, endNode) {
+    const graph = new Graph();
+    
+    // Add cities and roads to graph
+    for (let city of cities) {
+        graph.addNode(city.id)
+    }
+
+    for (let { start_city_id, end_city_id, distance } of roads) {
+        graph.addEdge(start_city_id, end_city_id, distance)
+    }
+    
+    // Dijkstra path search algo
+    let times = {};
+    let backtrace = {};
+    let queue = new Queue();
+
+    times[startNode] = 0;
+
+    graph.nodes.forEach(node => {
+        if (node !== startNode) {
+            times[node] = Infinity
+        }
+    });
+
+    queue.enqueue([startNode, 0]);
+
+    while (queue.size()) {
+        let shortestStep = queue.dequeue();
+        let currentNode = shortestStep[0];   
+        graph.adjacencyList[currentNode].forEach(neighbor => {
+            let time = times[currentNode] + neighbor.distance;
+        
+            if (time < times[neighbor.node]) {
+                times[neighbor.node] = time;
+                backtrace[neighbor.node] = currentNode;
+                queue.enqueue([neighbor.node, time]);
+            }
+        });
+    }
+
+    let path = [endNode];
+    let lastStep = endNode;  while(lastStep !== startNode) {
+        path.unshift(backtrace[lastStep])
+        lastStep = backtrace[lastStep]
+    } 
+    
+    // return `Path is ${path} and time is ${times[endNode]}`
+    return {path, distance: times[endNode]}
+}
+
+module.exports = findPathWithDijkstra;

helpers/graph.js

@@ -0,0 +1,18 @@
+class Graph {
+    constructor() {
+        this.nodes = [];
+        this.adjacencyList = {};
+    }
+
+    addNode(node) {
+        this.nodes.push(node); 
+        this.adjacencyList[node] = [];
+    }
+
+    addEdge(node1, node2, distance) {
+        this.adjacencyList[node1].push({node:node2, distance});
+        this.adjacencyList[node2].push({node:node1, distance});
+    }
+}
+
+module.exports = Graph;

helpers/queue.js

@@ -0,0 +1,21 @@
+class Queue {
+    constructor() {
+    this.store = [];
+    }
+
+    size() {
+        return this.store.length
+    }
+
+    enqueue(node) {
+        this.store.push(node);
+    }
+
+    dequeue() {
+        if (this.size() > 0) {
+            return this.store.shift();
+        }
+    } 
+}
+
+module.exports = Queue;

index.js

@@ -3,7 +3,7 @@ const server = require("./api/server");
 server.get("/", (req, res) => {
 	res.json({
 		message: `API server for Dijkstra. :)`,
-		documentation: `Coming`
+		documentation: `Check out: https://github.com/ruihildt/dijkstra/tree/completed-backend`
 	});
 });
 

package.json

@@ -4,14 +4,18 @@
   "description": "",
   "main": "index.js",
   "dependencies": {
+    "cors": "^2.8.5",
     "express": "^4.17.1",
+    "helmet": "^3.21.2",
     "knex": "^0.20.8",
     "nodejs": "^0.0.0",
     "sqlite3": "^4.1.1"
   },
-  "devDependencies": {},
+  "devDependencies": {
+    "nodemon": "^2.0.2"
+  },
   "scripts": {
-    "test": "test",
+    "watch": "nodemon index.js",
     "start": "node index.js"
   },
   "author": "",