From 6338060b7825ea8d497a534416d6388223280dd6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20M=C3=BCller?= <patrick@mueller-patrick.tech>
Date: Wed, 9 Dec 2020 17:26:56 +0100
Subject: [PATCH] BETTERZON-38: Adjusted prices API

---
 Backend/src/models/prices/prices.router.ts  | 35 ++++-----
 Backend/src/models/prices/prices.service.ts | 80 +++++++++++++++++++++
 2 files changed, 94 insertions(+), 21 deletions(-)

diff --git a/Backend/src/models/prices/prices.router.ts b/Backend/src/models/prices/prices.router.ts
index 976cc9f..9672efa 100644
--- a/Backend/src/models/prices/prices.router.ts
+++ b/Backend/src/models/prices/prices.router.ts
@@ -23,7 +23,20 @@ export const pricesRouter = express.Router();
 
 pricesRouter.get('/', async (req: Request, res: Response) => {
     try {
-        const prices: Prices = await PriceService.findAll();
+        let prices: Prices = [];
+        const product = req.query.product;
+        const vendor = req.query.vendor;
+        const type = req.query.type;
+
+        if (product) {
+            if (vendor) {
+                prices = await PriceService.findByVendor(<string> product, <string> vendor, <string> type);
+            } else {
+                prices = await PriceService.findByType(<string> product, <string> type);
+            }
+        } else {
+            prices = await PriceService.findAll();
+        }
 
         res.status(200).send(prices);
     } catch (e) {
@@ -50,26 +63,6 @@ pricesRouter.get('/:id', async (req: Request, res: Response) => {
     }
 });
 
-// GET items/:name
-
-pricesRouter.get('/products/:id', async (req: Request, res: Response) => {
-    const id: number = parseInt(req.params.id, 10);
-
-    if (!id) {
-        res.status(400).send('Missing parameters.');
-        return;
-    }
-
-    try {
-        const prices: Prices = await PriceService.findByProduct(id);
-
-        res.status(200).send(prices);
-    } catch (e) {
-        res.status(404).send(e.message);
-    }
-});
-
-
 // POST items/
 
 // pricesRouter.post('/', async (req: Request, res: Response) => {
diff --git a/Backend/src/models/prices/prices.service.ts b/Backend/src/models/prices/prices.service.ts
index 81915e7..14846fe 100644
--- a/Backend/src/models/prices/prices.service.ts
+++ b/Backend/src/models/prices/prices.service.ts
@@ -106,6 +106,86 @@ export const findByProduct = async (product: number): Promise<Prices> => {
     return priceRows;
 };
 
+export const findByType = async (product: string, type: string): Promise<Prices> => {
+    let conn;
+    let priceRows = [];
+    try {
+        conn = await pool.getConnection();
+        let rows = [];
+        if (type === 'newest') {
+            // Used to get the newest price for this product per vendor
+            rows = await conn.query(('WITH summary AS ( ' +
+                'SELECT p.product_id, ' +
+                'p.vendor_id, ' +
+                'p.price_in_cents, ' +
+                'p.timestamp, ' +
+                'ROW_NUMBER() OVER( ' +
+                'PARTITION BY p.vendor_id ' +
+                'ORDER BY p.timestamp DESC) AS rk ' +
+                'FROM prices p ' +
+                'WHERE product_id = ?) ' +
+                'SELECT s.* ' +
+                'FROM summary s ' +
+                'WHERE s.rk = 1 '), product);
+        } else if (type === 'lowest') {
+            // Used to get the lowest prices for this product over a period of time
+            rows = await conn.query('SELECT price_id, product_id, vendor_id, MIN(price_in_cents) as price_in_cents, timestamp FROM prices WHERE product_id = ? GROUP BY DAY(timestamp) ORDER BY timestamp', product);
+        } else {
+            // If no type is given, return all prices for this product
+            rows = await conn.query('SELECT price_id, product_id, vendor_id, price_in_cents, timestamp FROM prices WHERE product_id = ?', product);
+        }
+
+        for (let row in rows) {
+            if (row !== 'meta') {
+                priceRows.push(rows[row]);
+            }
+        }
+
+    } catch (err) {
+        throw err;
+    } finally {
+        if (conn) {
+            conn.end();
+        }
+    }
+
+    return priceRows;
+};
+
+export const findByVendor = async (product: string, vendor: string, type: string): Promise<Prices> => {
+    let conn;
+    let priceRows = [];
+    try {
+        conn = await pool.getConnection();
+        let rows = [];
+        if (type === 'newest') {
+            // Used to get the newest price for this product and vendor
+            rows = await conn.query('SELECT price_id, product_id, vendor_id, price_in_cents, timestamp FROM prices WHERE product_id = ? AND vendor_id = ? ORDER BY timestamp DESC LIMIT 1', [product, vendor]);
+        } else if (type === 'lowest') {
+            // Used to get the lowest prices for this product and vendor in all time
+            rows = await conn.query('SELECT price_id, product_id, vendor_id, MIN(price_in_cents) as price_in_cents, timestamp FROM prices WHERE product_id = ? AND vendor_id = ? LIMIT 1', [product, vendor]);
+        } else {
+            // If no type is given, return all prices for this product and vendor
+            rows = await conn.query('SELECT price_id, product_id, vendor_id, price_in_cents, timestamp FROM prices WHERE product_id = ? AND vendor_id = ?', [product, vendor]);
+        }
+
+        for (let row in rows) {
+            if (row !== 'meta') {
+                priceRows.push(rows[row]);
+            }
+        }
+
+    } catch (err) {
+        throw err;
+    } finally {
+        if (conn) {
+            conn.end();
+        }
+    }
+
+    return priceRows;
+};
+
 // export const create = async (newItem: Product): Promise<void> => {
 //     let conn;
 //     try {