Update group.js

- Adding getBestPairs
- best pair of orders (buy, sell) can be fetched using the new functions

src/group.js

@@ -13,54 +13,100 @@ function addTag(floID, tag) {
     });
 }
 
-function getBest() {
+function getBestPairs(currentRate) {
     return new Promise((resolve, reject) => {
-        DB.query("SELECT tag FROM TagList ORDER BY priority DESC").then(result => {
-            let tags = result.map(r => r.tag);
-            recursiveGetBest(tags)
-                .then(result => resolve(result))
-                .catch(error => reject(error))
+        DB.query("SELECT tag FROM TagList ORDER BY priority").then(result => {
+            let tags = result.map(r => r.tag) //Sorted in Ascending (ie, stack; pop for highest)
+            resolve(new bestPair(tags, currentRate));
+        }).catch(error => reject(error))
+    })
+}
+
+const bestPair = function(tags, currentRate) {
+
+    const getSellOrder = () => {
+        let cache = getSellOrder.cache;
+        return new Promise((resolve, reject) => {
+            if (cache.cur_order) { //If cache already has a pending order
+                checkMinimumGain(cache.cur_order, currentRate).then(result => {
+                    cache.cur_order = result.sellOrder;
+                    resolve(result);
+                }).catch(error => {
+                    if (error !== false)
+                        return reject(error);
+                    //Order not valid (minimum gain)
+                    cache.cur_order = null;
+                    getSellOrder()
+                        .then(result => resolve(result))
+                        .catch(error => reject(error))
+                })
+            } else if (cache.orders && cache.orders.length) { //If cache already has orders in priority
+                getTopValidOrder(cache.orders, currentRate).then(result => {
+                    cache.cur_order = result.sellOrder;
+                    resolve(result);
+                }).catch(error => {
+                    if (error !== false)
+                        return reject(error);
+                    //No valid order found in current tag
+                    cache.orders = null;
+                    getSellOrder()
+                        .then(result => resolve(result))
+                        .catch(error => reject(error))
+                })
+            } else if (cache.tags.length) { //If cache has remaining tags
+                cache.cur_tag = cache.tags.pop();
+                getOrdersInTag(cache.cur_tag, currentRate).then(orders => {
+                    cache.orders = orders;
+                    getSellOrder()
+                        .then(result => resolve(result))
+                        .catch(error => reject(error))
+                }).catch(error => reject(error));
+            } else if (!cache.end) { //Un-tagged floID's orders  (do only once)
+                getUntaggedOrders(currentRate).then(orders => {
+                    cache.orders = orders;
+                    cache.end = true;
+                    getSellOrder()
+                        .then(result => resolve(result))
+                        .catch(error => reject(error))
+                }).catch(error => reject(error));
+            }
         })
-    })
+    };
+    getSeller.cache = {
+        tags: Array.from(tags)
+    };
+
+    const getBuyOrder = () => {};
+    getBuyOrder.cache = {
+        tags: Array.from(tags) //Maybe diff for buy and sell ?
+    };
 }
 
-function recursiveGetBest(tags) {
+function getUntaggedOrders(cur_price) {
     return new Promise((resolve, reject) => {
-        let tag = tags.shift();
-        getBestInTag(tag)
-            .then(result => resolve(result))
-            .catch(error => {
-                if (error !== false)
-                    return reject(error);
-                else
-                    recursiveGetBest(tags)
-                    .then(result => resolve(result))
-                    .catch(error => reject(error))
-            })
+        DB.query("SELECT SellOrder.id, SellOrder.floID, SellOrder.quantity FROM SellOrder" +
+                " LEFT JOIN Tags ON Tags.floID = SellOrder.floID" +
+                " WHERE Tags.floID IS NULL AND SellOrder.minPrice <=? ORDER BY SellOrder.time_placed", [cur_price])
+            .then(orders => resolve(orders))
+            .catch(error => reject(error))
     })
 }
 
-function getBestInTag(tag, cur_price) {
+function getOrdersInTag(tag, cur_price) {
     return new Promise((resolve, reject) => {
         DB.query("SELECT SellOrder.id, SellOrder.floID, SellOrder.quantity FROM SellOrder" +
             " INNER JOIN Tags ON Tags.floID = SellOrder.floID" +
-            " WHERE Tags.tag = ? AND minPrice <=? ORDER BY time_placed", [tag, cur_price]).then(orders => {
-            if (orders.length === 0)
-                reject(false);
-            else if (orders.length === 1)
-                checkMinimumGain(orders[0])
-                .then(result => resolve(result))
-                .catch(error => reject(error))
+            " WHERE Tags.tag = ? AND SellOrder.minPrice <=? ORDER BY SellOrder.time_placed", [tag, cur_price]).then(orders => {
+            if (orders.length <= 1) // No (or) Only-one order, hence priority sort not required.
+                resolve(orders);
             else
                 getPointsFromAPI(orders.map(o => o.floID)).then(points => {
                     let orders_sorted = orders.map(o => [o, points[o.floID]])
                         .sort((a, b) => a[1] < b[1] ? -1 : a[1] > b[1] ? 1 : 0) //sort by points (ascending)
                         .map(x => x[0]);
-                    getTopValidOrder(orders_sorted)
-                        .then(result => resolve(result))
-                        .catch(error => reject(error))
+                    resolve(orders_sorted);
                 }).catch(error => reject(error))
-        })
+        }).catch(error => reject(error))
     });
 }
 
@@ -86,24 +132,23 @@ function fetch_api(api, id) {
     })
 }
 
-function getTopValidOrder(orders) {
+function getTopValidOrder(orders, cur_price) {
     return new Promise((resolve, reject) => {
         if (!orders.length)
             return reject(false)
-        checkMinimumGain(orders.pop()) //pop: as the orders are sorted in ascending (highest point should be checked 1st)
+        checkMinimumGain(orders.pop(), cur_price) //pop: as the orders are sorted in ascending (highest point should be checked 1st)
             .then(result => resolve(result))
             .catch(error => {
                 if (error !== false)
                     return reject(error);
-                else
-                    getTopValidOrder(orders)
+                getTopValidOrder(orders, cur_price)
                     .then(result => resolve(result))
                     .catch(error => reject(error));
             });
     });
 }
 
-function checkMinimumGain(sellOrder) {
+function checkMinimumGain(sellOrder, cur_price) {
     return new Promise((resolve, reject) => {
         DB.query("SELECT id, quantity, base FROM Vault WHERE floID=? ORDER BY base", [sellOrder.floID]).then(result => {
             let rem = Math.min(sellOrder.quantity, maxQuantity),
@@ -145,6 +190,8 @@ function checkMinimumGain(sellOrder) {
 }
 
 module.exports = {
+    addTag,
+    getBestPairs,
     set DB(db) {
         DB = db;
     }