From 02ea940173715eb9e95f061bce3015f47e6f5245 Mon Sep 17 00:00:00 2001
From: Le Minh Tan <v.tanlm2@vinfast.vn>
Date: Fri, 30 Jul 2021 08:52:27 +0700
Subject: [PATCH] implement websocket to view the dashboard of top ten product

---
 go.mod                       |  5 +++-
 go.sum                       |  7 +++++
 product/product.data.go      | 28 +++++++++++++++++++
 product/product.service.go   |  2 ++
 product/product.websocket.go | 53 ++++++++++++++++++++++++++++++++++++
 5 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 product/product.websocket.go

diff --git a/go.mod b/go.mod
index 8177617..157aebc 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,7 @@ module github.com/dutroctu/go-webservice
 
 go 1.16
 
-require github.com/go-sql-driver/mysql v1.6.0 // indirect
+require (
+	github.com/go-sql-driver/mysql v1.6.0 // indirect
+	golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985 // indirect
+)
diff --git a/go.sum b/go.sum
index 20c16d6..b6109d2 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,9 @@
 github.com/go-sql-driver/mysql v1.6.0 h1:BCTh4TKNUYmOmMUcQ3IipzF5prigylS7XXjEkfCHuOE=
 github.com/go-sql-driver/mysql v1.6.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
+golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985 h1:4CSI6oo7cOjJKajidEljs9h+uP0rRZBPPPhcCbj5mw8=
+golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
diff --git a/product/product.data.go b/product/product.data.go
index 5a0a4a1..e62eda5 100644
--- a/product/product.data.go
+++ b/product/product.data.go
@@ -158,3 +158,31 @@ func updateProduct(product Product) error {
 	}
 	return nil
 }
+
+func GetTopTenProducts() ([]Product, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	results, err := database.DbConn.QueryContext(ctx, `SELECT productId,
+	manufacturer,
+	sku,
+	upc,
+	pricePerUnit,
+	quantityOnHand,
+	productName
+	FROM products ORDER BY quantityOnHand DESC LIMIT 10`)
+	if err != nil {
+		log.Println(err.Error())
+		return nil, err
+	}
+	defer results.Close()
+	products := make([]Product, 0)
+	for results.Next() {
+		var product Product
+		results.Scan(&product.ProductID, &product.Manufacturer,
+			&product.Sku, &product.Upc, &product.PricePerUnit,
+			&product.QuantityOnHand, &product.ProductName)
+		products = append(products, product)
+	}
+	return products, nil
+}
diff --git a/product/product.service.go b/product/product.service.go
index 38d9715..eadd966 100644
--- a/product/product.service.go
+++ b/product/product.service.go
@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/dutroctu/go-webservice/cors"
+	"golang.org/x/net/websocket"
 )
 
 const productsBasePath = "products"
@@ -18,6 +19,7 @@ const productsBasePath = "products"
 func SetupRoutes(apiBasePath string) {
 	handleProducts := http.HandlerFunc(productsHandler)
 	handleProduct := http.HandlerFunc(productHandler)
+	http.Handle("/websocket", websocket.Handler(productSocket))
 	http.Handle(fmt.Sprintf("%s/%s", apiBasePath, productsBasePath), cors.Middleware(handleProducts))
 	http.Handle(fmt.Sprintf("%s/%s/", apiBasePath, productsBasePath), cors.Middleware(handleProduct))
 }
diff --git a/product/product.websocket.go b/product/product.websocket.go
new file mode 100644
index 0000000..4b4b403
--- /dev/null
+++ b/product/product.websocket.go
@@ -0,0 +1,53 @@
+package product
+
+import (
+	"fmt"
+	"log"
+	"time"
+
+	"golang.org/x/net/websocket"
+)
+
+type message struct {
+	Data string `json:"data"`
+	Type string `json:"type"`
+}
+
+func productSocket(ws *websocket.Conn) {
+	done := make(chan struct{})
+	fmt.Println("new websocket connection established")
+	go func(c *websocket.Conn) {
+
+		for {
+			var msg message
+			if err := websocket.JSON.Receive(ws, &msg); err != nil {
+				log.Println(err)
+				break
+			}
+			fmt.Println("received message ", msg.Data)
+		}
+		close(done)
+	}(ws)
+
+loop:
+	for {
+		select {
+		case <-done:
+			fmt.Println("connection was closed, lets break out of here")
+			break loop
+		default:
+			products, err := GetTopTenProducts()
+			if err != nil {
+				log.Println(err)
+				break
+			}
+			if err := websocket.JSON.Send(ws, products); err != nil {
+				log.Println(err)
+				break
+			}
+			time.Sleep(10 * time.Second)
+		}
+	}
+	fmt.Println("close websocket")
+	defer ws.Close()
+}