BETTERZON-48: Adding API functionality to get best available deals (#20)

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Patrick 2021-04-05 16:34:11 +02:00 committed by GitHub
parent 997b68abf4
commit 1b1cdb59f6
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3 changed files with 118 additions and 2 deletions

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@ -4,4 +4,7 @@ export interface Price {
vendor_id: number; vendor_id: number;
price_in_cents: number; price_in_cents: number;
timestamp: Date; timestamp: Date;
// Only for deals
amazonDifference?: number;
amazonDifferencePercent?: number;
} }

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@ -19,7 +19,7 @@ export const pricesRouter = express.Router();
* Controller Definitions * Controller Definitions
*/ */
// GET items/ // GET prices/
pricesRouter.get('/', async (req: Request, res: Response) => { pricesRouter.get('/', async (req: Request, res: Response) => {
try { try {
@ -44,7 +44,7 @@ pricesRouter.get('/', async (req: Request, res: Response) => {
} }
}); });
// GET items/:id // GET prices/:id
pricesRouter.get('/:id', async (req: Request, res: Response) => { pricesRouter.get('/:id', async (req: Request, res: Response) => {
const id: number = parseInt(req.params.id, 10); const id: number = parseInt(req.params.id, 10);
@ -63,6 +63,25 @@ pricesRouter.get('/:id', async (req: Request, res: Response) => {
} }
}); });
// GET prices/bestDeals
pricesRouter.get('/bestDeals/:amount', async (req: Request, res: Response) => {
const amount: number = parseInt(req.params.amount, 10);
if (!amount) {
res.status(400).send('Missing parameters.');
return;
}
try {
const prices: Prices = await PriceService.getBestDeals(amount);
res.status(200).send(prices);
} catch (e) {
res.status(404).send(e.message);
}
});
// POST items/ // POST items/
// pricesRouter.post('/', async (req: Request, res: Response) => { // pricesRouter.post('/', async (req: Request, res: Response) => {

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@ -186,6 +186,100 @@ export const findByVendor = async (product: string, vendor: string, type: string
return priceRows; return priceRows;
}; };
export const getBestDeals = async (amount: number): Promise<Prices> => {
let conn;
let priceRows = [];
try {
conn = await pool.getConnection();
let allPrices: Record<number, Price[]> = {};
// Get newest prices for every product at every vendor
const rows = await conn.query(
'WITH summary AS (\n' +
' SELECT p.product_id,\n' +
' p.vendor_id,\n' +
' p.price_in_cents,\n' +
' p.timestamp,\n' +
' ROW_NUMBER() OVER(\n' +
' PARTITION BY p.product_id, p.vendor_id\n' +
' ORDER BY p.timestamp DESC) AS rk\n' +
' FROM prices p)\n' +
'SELECT s.*\n' +
'FROM summary s\n' +
'WHERE s.rk = 1');
// Write returned values to allPrices map with product id as key and a list of prices as value
for (let row in rows) {
if (row !== 'meta') {
if (!allPrices[parseInt(rows[row].product_id)]) {
allPrices[parseInt(rows[row].product_id)] = [];
}
allPrices[parseInt(rows[row].product_id)].push(rows[row]);
}
}
// Iterate over all prices to find the products with the biggest difference between amazon and other vendor
let deals = [];
for (let productId in Object.keys(allPrices)) {
if (allPrices[productId]) {
let pricesForProd = allPrices[productId];
// Get amazon price and lowest price from other vendor
let amazonPrice = {} as Price;
let lowestPrice = {} as Price;
pricesForProd.forEach(function(price, priceIndex) {
if (price.vendor_id === 1) {
amazonPrice = price;
} else {
if (!lowestPrice.price_in_cents || lowestPrice.price_in_cents > price.price_in_cents) {
lowestPrice = price;
}
}
});
// Create deal object and add it to list
let deal = {
'product_id': lowestPrice.product_id,
'vendor_id': lowestPrice.vendor_id,
'price_in_cents': lowestPrice.price_in_cents,
'timestamp' :lowestPrice.timestamp,
'amazonDifference': (amazonPrice.price_in_cents - lowestPrice.price_in_cents),
'amazonDifferencePercent': ((1 - (lowestPrice.price_in_cents / amazonPrice.price_in_cents)) * 100),
};
// Push only deals were the amazon price is actually higher
if(deal.amazonDifferencePercent > 0) {
deals.push(deal);
}
}
}
// Sort to have the best deals on the top
deals.sort((a, b) => a.amazonDifferencePercent < b.amazonDifferencePercent ? 1 : -1);
// Return only as many records as requested or the maximum amount of found deals, whatever is less
let maxAmt = Math.min(amount, deals.length);
for (let dealIndex = 0; dealIndex < maxAmt; dealIndex++){
//console.log(deals[dealIndex]);
priceRows.push(deals[dealIndex] as Price);
}
} catch (err) {
console.log(err);
throw err;
} finally {
if (conn) {
conn.end();
}
}
return priceRows;
};
// export const create = async (newItem: Product): Promise<void> => { // export const create = async (newItem: Product): Promise<void> => {
// let conn; // let conn;
// try { // try {