Areej

backend/app.js

@@ -1,5 +1,45 @@
-import express from "express";
+//Express is the web framework that handles HTTP
+import express from "express"; 
+// API testing 
+import cors from "cors";
 
-const app = express();
+// Billing routes
+import billingRoutes from "./modules/billing/billing.routes.js";
 
-export default app;
+/* creates a basic node.js web server
+uses the expres faramework to respond
+with a status message when a specific
+web address is visited*/
+
+const app = express(); 
+// creates the application , foundation (as the app 
+//object(var) is used to configure routing, middle ware,server settings)
+
+app.use(express.json());
+// enables json parsing, hadles the incoming json data in the body of HTTP request
+//converts into a readable JAVASCRIPT OBJECT
+
+app.use(
+  cors({
+    //dev origin
+    origin:"http://localhost:5173"
+  })
+);
+// Simple health check 
+// GET http://localhost:5000/api/v1/health
+app.get("/api/v1/health",(req,res)=>{res.json(
+  {
+    ok  : true
+  })
+//sends the response, returns the data with a success code 200
+});
+// defines a route, for health check puropses, 
+// callback function (request(info by the user),
+// repsone(send data back to the user))=>{}
+
+app.use("/api/v1/billing", billingRoutes);
+// Mounting billing route under /api/v1/billing/items
+// So router.get("/items") becomes GET /api/v1/billing/items
+
+export default app;
+//export app, server.js would call app.listen()

backend/modules/billing/billing.controller.js

@@ -0,0 +1,97 @@
+/* 
+>>>READS THE REQUEST 
+>>> RESPONDS TEH REQUEST 
+>>> CALLS THE SPECIFICSERVICE BEING CALLED
+>>>SEND JSON OR THE ERRPOS ENCOUNTERRED
+*/
+import { GetItemByCompanyId,CreateOrderForCompany} from "./billing.service.js";
+// we are just importing the functio that is talking to the database 
+/*
+* As We might be GET-ting the response i.e /api/v1/building/items
+* There could be 3 things that teh controller function would do i.e
+*Express always gives as 
+*req->incoming requests from the user,query,body
+*res->object use to send the response
+*next-> pass errors
+*/
+//  list items is going to lists the items after retriving tem from postgresql
+export async function listItems(req,res) {
+    // now we may call the getitemfunction but we have to validate the data retreived
+    //so we are going to validate using try catch 
+    try{
+    // so the server/user wants to have access to the company id for that we will just declare a company id variable to store the requested id
+    const companyId=1; // hardcoded value else 
+    // const companyId=req.user.company_id
+
+    // Call the service ad wait for the array of items
+    const items=await GetItemByCompanyId(companyId);
+
+    //200 :OK . meaning send json (server is working) to the frontend to parse
+    // We will gte some Item data  from the DATABASE we are goig to save that data to ealiy route taht onto our FRONTEND
+    return res.status(200).json(
+        { items:items,}
+    );
+    }
+    catch(error){
+        // we will log error as well 
+        console.error("list Item error:",error);
+        // 500 -> server error 
+        return res.status(500).json(
+            {
+                message:"Failed to fetch the menu items",
+            }
+        );
+    }
+}
+
+
+
+export async function createOrder(req,res){
+
+
+    try{
+        // const companyId=req.user.company_id;
+        const companyId=1; // cause we hardcoded the value of company id
+
+        // Read cart + user-decided values from the request body
+        const {items,payment_method,tax_rate,discount_rate,extra_charge}=req.body;
+        //Validate the cart
+        if(!items || !Array.isArray(items) || items.length===0){
+            return res.status(400).json({message:"Cart is empty or invalid"});
+        }
+
+        // Pass the user's tax/discount/add-on choices to the service
+        const result=await CreateOrderForCompany(companyId,items,{
+            taxRate:tax_rate,
+            discountRate:discount_rate,
+            extraCharge:extra_charge,
+            paymentMethod:payment_method,
+        });
+        // Return the full breakdown to the client
+        return res.status(201).json({
+            order_id:result.order_id,
+            subtotal:result.subtotal,
+            discount_rate:result.discount_rate,
+            discount_amount:result.discount_amount,
+            tax_rate:result.tax_rate,
+            tax_amount:result.tax_amount,
+            extra_charge:result.extra_charge,
+            total:result.total,
+            payment_method:result.payment_method,
+            items:result.order_lines,
+        });
+        //201-> created successfully
+    }
+    catch(error){
+        console.error("create order error:",error);
+        // Match the exact messages thrown by the service
+        if (
+            error.message === "Cart is Empty!" ||
+            error.message === "Invalid Cart Item!" ||
+            error.message === "Items not found or do not belong to the company!"
+        ) {
+            return res.status(400).json({ message: error.message }); // 400 = bad request
+        }
+        return res.status(500).json({ message: "Failed to create order" }); // 500 = server error
+    }
+}

backend/modules/billing/billing.routes.js

@@ -0,0 +1,22 @@
+// routing i.e. connecting HTTP method and path to make the controller function
+import { Router } from "express";
+
+// Router lets us group the related routes in one file
+import { listItems,createOrder } from "./billing.controller.js";
+
+
+//we will import the controller function for this route
+// created a constant variable  for to create a mini-app router for billing endpoints
+const router=Router(); 
+
+// when someone sends GET request to get items of a specific company
+// full path -- mounted on app.js
+router.get("/items",listItems);
+
+//POST request for adding orders i.e POST /api/v1/billing/order
+//Process: When someone sends POST to "/orders" then 
+//we will simulatenouly createOrder function
+router.post("/orders",createOrder);
+
+// export so app.js can import and mount this router
+export default router;

backend/modules/billing/billing.service.js

@@ -0,0 +1,171 @@
+//run SQL and return rows.
+import pool from "../../database.js";
+//import the shared postgresql connection pool from database.js
+// pool is the name that we will refre to pool in this project
+/*GOAL: 
+ * Fetch teh menu items from the DB that belong to one specific company  
+ * Now to access the specific data of a company we eed to have access to
+ * comapnyId ----> provided my controller (a specific companies POS)
+*/
+// export async function name(params) { logic}
+export async function GetItemByCompanyId(companyId) {
+    // this function would help us to pass the query in the postgres database
+    //we will only select the relevant data that we need
+    // we have defined a query constant variable
+// query for selecting the items that the company have
+    const query=
+    `SELECT
+    id,name,price,type
+    FROM items
+    WHERE company_id = $1
+    ORDER BY name ASC`;
+// $1 is a placeholder — pool.query replaces it safely with companyId (prevents SQL injection) //ordering ascending order
+// now the query works as a SPARK for the database to initiate the reponse
+const result = await pool.query(query,[companyId])
+//awaits -->pauses until POSTGRES ANSWERES
+//pool.query (sql,[values]) replaces placeholder with id safely 8-)
+//pool saves the sql row into JSON FORMAT
+// i.e result.rows is an array of object (you can take it as a dictionary as well)
+/*[{ id:1,
+    name:"CHB",
+    price:"12.00",
+    type:"Full"},....]*/
+    return result.rows; // returns the array of object
+} 
+/* AS now company has to make a sale,
+for calculating a specific cart selected by one customer  we will
+
+cartItem=[{item_id:1,quantity:2...}]
+options={ taxRate, discountRate, extraCharge, paymentMethod } — decided by the user */
+
+export async function CreateOrderForCompany(companyId,cartItems,options={}){
+    // Read user-decided values; default to 0 / CASH if missing
+    const taxRate=Number(options.taxRate)||0;         // percent
+    const discountRate=Number(options.discountRate)||0; // percent
+    const extraCharge=Number(options.extraCharge)||0;   // Rs add-on
+    const paymentMethod=options.paymentMethod||"CASH";
+    if (!Array.isArray(cartItems)|| cartItems.length===0){
+        throw new Error("Cart is Empty!");
+    }
+    // if cart is empty we will get the error
+
+    for (const line of cartItems){
+        if(!line.item_id || !line.quantity || line.quantity<=0) {
+            throw new Error("Invalid Cart Item!")
+        }
+    }
+    // Check for valid IDS Items
+    //Extract all item ids from the cart
+    const itemIds=cartItems.map((line) => line.item_id);
+
+    //$1  id in the query is replaced by itemIds array
+    //$2 id in the query is replaced by companyId
+    // IN regex $1 and $2 are used to replace the placeholders 
+    // in the query with the actual values
+    const itemQuery=`
+    SELECT id,name,price,type
+    FROM items
+    WHERE id=ANY($1) 
+    AND company_id=$2`;
+    //query to find the items that are in the cart and belong to the company
+    const itemsResult=await  pool.query(itemQuery,[itemIds,companyId]);
+    //awaits the query to be executed and returns the result
+    const database_items=itemsResult.rows;       
+    //database_items is an array of objects
+    // key value pairs= [{id:1,name:"CHB",price:"12.00",type:"Full"},....]
+
+    if (database_items.length !== itemIds.length){
+        throw new Error("Items not found or do not belong to the company!");
+    }//If itemid=99 sent but it doesnt exist for the company, reject the order
+
+    const itemMap={}; // create a map to store the items by their id
+    for (const item of database_items){
+        itemMap[item.id]=item;//set property
+
+        // BUILDING A LOOKUP MAP {1:{id,name,price,type},2:{id,name,price,type}...}
+    }
+
+    // Calculate total price
+    let subtotal=0;
+    //building the order lines for the order
+    const orderLines= cartItems.map((line)=>{
+        const database_item=itemMap[line.item_id];//get verified item from the map
+        const lineTotal=Number(database_item.price)*line.quantity;// price*quantity
+        subtotal+=lineTotal;// add to running subtotal
+
+        return{
+            item_id:database_item.id,// accessing the id of the item from the database
+            // name:database_item.name,
+            // type:database_item.type,
+            quantity:line.quantity, // quantity of the item
+            price:Number(database_item.price),// price of one item -- converting the string to number
+            line_total:lineTotal,// total price for the line item
+        };
+    });
+    // Discount comes off the subtotal first
+    const discountAmount=Number((subtotal*(discountRate/100)).toFixed(2));
+    const taxableBase=subtotal-discountAmount;
+    // Tax applies to the amount left after discount
+    const tax=Number((taxableBase*(taxRate/100)).toFixed(2));
+    // Add-on charge is added on top of everything
+    const total=Number((taxableBase+tax+extraCharge).toFixed(2));
+
+    // Saving the order and order lines to the database
+    const client=await pool.connect();// get a client from the pool
+    try{
+        await client.query("BEGIN"); //Start a transaction
+        // Order Insert Query — store the full money breakdown
+        const orderInsertQuery=`
+        INSERT INTO orders
+        (company_id, subtotal, discount_rate, discount_amount, tax_rate, tax_amount, extra_charge, total, payment_method)
+        VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9)
+        RETURNING id`;
+        const orderResult=await client.query(orderInsertQuery,[
+            companyId, subtotal, discountRate, discountAmount,
+            taxRate, tax, extraCharge, total, paymentMethod,
+        ]);
+        const orderId=orderResult.rows[0].id; 
+        // get the order id from the result (newly created order 
+        // automatically created by the database)
+
+
+        for (const line of orderLines){
+            await client.query(
+                `INSERT INTO order_items(order_id, item_id, quantity) VALUES($1, $2,$3)`,
+                [orderId,line.item_id,line.quantity])
+
+                // .query(function,[values]) executes the query with the provided values
+        }
+        await client.query("COMMIT"); // Commit the transaction 
+        //if all queries are successful, save changes to the database.
+        return{
+            order_id:orderId,
+            subtotal,
+            discount_rate:discountRate,
+            discount_amount:discountAmount,
+            tax_rate:taxRate,
+            tax_amount:tax,
+            extra_charge:extraCharge,
+            total,
+            payment_method:paymentMethod,
+            order_lines:orderLines,
+        };
+    } 
+    catch(error)
+    {
+        // If any query fails, rollback the transactions cause we dont want to save partial data ;]
+        await client.query("ROLLBACK");
+        throw error; // rethrow the error
+    } finally
+    {
+        //Connecting to the database, storing the data, 
+        //releasing the connection back to the pool for reuse.
+        client.release();
+    }
+}
+
+
+
+
+// in this file controllers( read,response to a request) are used to initiate the system
+// This file is done:)