package main

import (
    "context"
    "encoding/json"
    "fmt"
    "log"
    "net"
    "net/http"
    "time"

    "github.com/Shopify/sarama"
    "github.com/gorilla/websocket"
    uuid "github.com/satori/go.uuid"
)

//客户端管理
type ClientManager struct {
    //客户端 map 储存并管理所有的长连接client，在线的为true，不在的为false
    clients map[string]*Client
    //web端发送来的的message我们用broadcast来接收，并最后分发给所有的client
    broadcast chan []byte
    //新创建的长连接client
    register chan *Client
    //新注销的长连接client
    unregister chan *Client
}

//客户端 Client
type Client struct {
    //用户id
    id string
    //连接的socket
    socket *websocket.Conn
    //发送的消息
    send chan []byte
    //服务器IP
    ip string
}

//会把Message格式化成json
type Message struct {
    //消息struct
    Sender    string `json:"sender,omitempty"`    //发送者
    Recipient string `json:"recipient,omitempty"` //接收者
    Content   string `json:"content,omitempty"`   //内容
}

//创建客户端管理者
var manager = ClientManager{
    broadcast:  make(chan []byte),
    register:   make(chan *Client),
    unregister: make(chan *Client),
    clients:    make(map[string]*Client),
}

func (manager *ClientManager) start() {
    for {
        select {
        case conn := <-manager.register:
            manager.clients[conn.id] = conn
            //把返回连接成功的消息json格式化
            jsonMessage, _ := json.Marshal(&Message{Content: "/A new socket has connected. " + conn.ip, Sender: conn.id})
            //manager.send(jsonMessage)
            syncProducer(jsonMessage)
            //如果连接断开了
        case conn := <-manager.unregister:
            //判断连接的状态，如果是true,就关闭send，删除连接client的值
            if _, ok := manager.clients[conn.id]; ok {
                close(conn.send)
                delete(manager.clients, conn.id)
                jsonMessage, _ := json.Marshal(&Message{Content: "/A socket has disconnected. " + conn.ip, Sender: conn.id})
                //manager.send(jsonMessage)
                syncProducer(jsonMessage)
            }
            //广播
        case message := <-manager.broadcast:
            manager.send(message)
        }
    }
}

//定义客户端管理的send方法
func (manager *ClientManager) send(message []byte) {
    obj := &Message{}
    _ = json.Unmarshal(message, obj)
    for id, conn := range manager.clients {
        if obj.Sender == id {
            //continue
        }
        if obj.Recipient == conn.id || len(obj.Recipient) < 1 {
            conn.send <- message
        }
    }
}

//定义客户端结构体的read方法
func (c *Client) read() {
    defer func() {
        manager.unregister <- c
        _ = c.socket.Close()
    }()

    for {
        //读取消息
        _, str, err := c.socket.ReadMessage()
        //如果有错误信息，就注销这个连接然后关闭
        if err != nil {
            manager.unregister <- c
            _ = c.socket.Close()
            break
        }
        //如果没有错误信息就把信息放入broadcast
        message := &Message{}
        _ = json.Unmarshal(str, message)
        message.Sender = c.id
        jsonMessage, _ := json.Marshal(&message)
        fmt.Println(fmt.Sprintf("read Id:%s, msg:%s", c.id, string(jsonMessage)))
        //manager.broadcast <- jsonMessage
        syncProducer(jsonMessage)
    }
}

func (c *Client) write() {
    defer func() {
        _ = c.socket.Close()
    }()

    for {
        select {
        //从send里读消息
        case message, ok := <-c.send:
            //如果没有消息
            if !ok {
                _ = c.socket.WriteMessage(websocket.CloseMessage, []byte{})
                return
            }
            //有消息就写入，发送给web端
            _ = c.socket.WriteMessage(websocket.TextMessage, message)
            fmt.Println(fmt.Sprintf("write Id:%s, msg:%s", c.id, string(message)))
        }
    }
}

func main() {
    fmt.Println("Starting application...")
    //开一个goroutine执行开始程序
    go manager.start()
    initial()
    //注册默认路由为 /ws ，并使用wsHandler这个方法
    http.HandleFunc("/ws", wsHandler)
    http.HandleFunc("/health", healthHandler)
    //监听本地的8011端口
    fmt.Println("chat server start.....")
    _ = http.ListenAndServe(":8080", nil)
}

func wsHandler(res http.ResponseWriter, req *http.Request) {
    //将http协议升级成websocket协议
    conn, err := (&websocket.Upgrader{CheckOrigin: func(r *http.Request) bool { return true }}).Upgrade(res, req, nil)
    if err != nil {
        http.NotFound(res, req)
        return
    }

    //每一次连接都会新开一个client，client.id通过uuid生成保证每次都是不同的
    client := &Client{id: uuid.Must(uuid.NewV4(),nil).String(), socket: conn, send: make(chan []byte), ip: LocalIp()}
    //注册一个新的链接
    manager.register <- client

    //启动协程收web端传过来的消息
    go client.read()
    //启动协程把消息返回给web端
    go client.write()
}

func healthHandler(res http.ResponseWriter, _ *http.Request) {
    _, _ = res.Write([]byte("ok"))
}

func LocalIp() string {
    address, _ := net.InterfaceAddrs()
    var ip = "localhost"
    for _, address := range address {
        if ipAddress, ok := address.(*net.IPNet); ok && !ipAddress.IP.IsLoopback() {
            if ipAddress.IP.To4() != nil {
                ip = ipAddress.IP.String()
            }
        }
    }
    return ip
}

/////kafka

var topic = "chat"
var producer sarama.SyncProducer

func initial() {
    config := sarama.NewConfig()
    // Version 必须大于等于  V0_10_2_0
    config.Version = sarama.V0_10_2_1
    config.Consumer.Return.Errors = true
    fmt.Println("start connect kafka")
    // 开始连接kafka服务器
    address := []string{"192.168.100.30:9092"}
    client, err := sarama.NewClient(address, config)
    if err != nil {
        fmt.Println("connect kafka failed; err", err)
        return
    }

    groupId := LocalIp()
    group, err := sarama.NewConsumerGroupFromClient(groupId, client)
    if err != nil {
        fmt.Println("connect kafka failed; err", err)
        return
    }
    go ConsumerGroup(group, []string{topic})

    config = sarama.NewConfig()
    // 等待服务器所有副本都保存成功后的响应
    config.Producer.RequiredAcks = sarama.WaitForAll
    // 随机的分区类型：返回一个分区器，该分区器每次选择一个随机分区
    config.Producer.Partitioner = sarama.NewRandomPartitioner
    // 是否等待成功和失败后的响应
    config.Producer.Return.Successes = true
    config.Producer.Timeout = 5 * time.Second
    producer, err = sarama.NewSyncProducer(address, config)
    if err != nil {
        log.Printf("sarama.NewSyncProducer err, message=%s \n", err)
    }
}

//同生产步消息模式
func syncProducer(data []byte) {
    msg := &sarama.ProducerMessage{
        Topic:     topic,
        Partition: 0,
        Value:     sarama.ByteEncoder(data),
    }
    partition, offset, err := producer.SendMessage(msg)
    if err != nil {
        fmt.Println(fmt.Sprintf("Send message Fail %v", err))
    }
    fmt.Printf("send message success topic=%s Partition = %d, offset=%d content:=%s \n", topic, partition, offset ,string(data))
}

func ConsumerGroup(group sarama.ConsumerGroup, topics []string) {
    // 检查错误
    go func() {
        for err := range group.Errors() {
            fmt.Println("group errors : ", err)
        }
    }()
    ctx := context.Background()
    fmt.Println("start get msg")
    // for 是应对 consumer rebalance
    for {
        // 需要监听的主题
        handler := ConsumerGroupHandler{}
        // 启动kafka消费组模式，消费的逻辑在上面的 ConsumeClaim 这个方法里
        err := group.Consume(ctx, topics, handler)

        if err != nil {
            fmt.Println("consume failed; err : ", err)
            return
        }
    }
}

type ConsumerGroupHandler struct{}

func (ConsumerGroupHandler) Setup(sess sarama.ConsumerGroupSession) error {
    //sess.MarkOffset(topic, 0, 0, "")
    return nil
}

func (ConsumerGroupHandler) Cleanup(sess sarama.ConsumerGroupSession) error {
    return nil
}

// 这个方法用来消费消息的
func (h ConsumerGroupHandler) ConsumeClaim(sess sarama.ConsumerGroupSession, claim sarama.ConsumerGroupClaim) error {
    // 获取消息
    for msg := range claim.Messages() {
        fmt.Printf("kafka receive message %s---Partition:%d, Offset:%d, Key:%s, Value:%s\n", msg.Topic, msg.Partition, msg.Offset, string(msg.Key), string(msg.Value))
        //发送消息
        manager.send(msg.Value)

        // 将消息标记为已使用
        sess.MarkMessage(msg, "")
        sess.Commit()
    }

    return nil
}

<html>
<head>
    <title>Golang Chat</title>
    <script type="application/javascript" src="jquery-1.12.4.js"></script>
    <script type="text/javascript">
        $(function() {
            var conn;
            var msg = $("#msg");
            var log = $("#log");
            var recipient =$("#recipient")
            function appendLog(msg) {
                var d = log[0]
                var doScroll = d.scrollTop == d.scrollHeight - d.clientHeight;
                msg.appendTo(log)
                if (doScroll) {
                    d.scrollTop = d.scrollHeight - d.clientHeight;
                }
            }

            $("#form").submit(function() {
                if (!conn) {
                    return false;
                }
                if (!msg.val()) {
                    return false;
                }
                content= JSON.stringify({"content":msg.val(),"recipient" :recipient.val()})
                conn.send(content);
                msg.val("");
                return false
            });

            if (window["WebSocket"]) {
                conn = new WebSocket("ws://chatserver.go.com/ws");
                conn.onclose = function(evt) {
                    appendLog($("<div><b>Connection Closed.</b></div>"))
                }
                conn.onmessage = function(evt) {
                    appendLog($("<div/>").text(evt.data))
                }
            } else {
                appendLog($("<div><b>WebSockets Not Support.</b></div>"))
            }
        });
    </script>
    <style type="text/css">
        html {
            overflow: hidden;
        }

        body {
            overflow: hidden;
            padding: 0;
            margin: 0;
            width: 100%;
            height: 100%;
            background: gray;
        }

        #log {
            background: white;
            margin: 0;
            padding: 0.5em 0.5em 0.5em 0.5em;
            position: absolute;
            top: 0.5em;
            left: 0.5em;
            right: 0.5em;
            bottom: 3em;
            overflow: auto;
        }

        #form {
            padding: 0 0.5em 0 0.5em;
            margin: 0;
            position: absolute;
            bottom: 1em;
            left: 0px;
            width: 100%;
            overflow: hidden;
        }

    </style>
</head>
<body>
<div id="log"></div>
<form id="form">
       <label>接受者<label><input type="text" id ="recipient"/> <input type="submit" value="发送" /> <input type="text" id="msg" size="64"/>
</form>
</body>
</html>