package nnet

import (
	"git.noahlan.cn/noahlan/nnet/config"
	"git.noahlan.cn/noahlan/nnet/conn"
	"git.noahlan.cn/noahlan/nnet/event"
	"git.noahlan.cn/noahlan/nnet/packet"
	rt "git.noahlan.cn/noahlan/nnet/router"
	"git.noahlan.cn/noahlan/nnet/session"
	"git.noahlan.cn/noahlan/ntool/ndef"
	"git.noahlan.cn/noahlan/ntool/nlog"
	"github.com/panjf2000/ants/v2"
	"math"
	"net"
	"time"
)

// Engine 引擎
type Engine struct {
	config.EngineConf                      // 引擎配置
	middlewares       []rt.Middleware      // 中间件
	routes            []rt.Route           // 路由
	router            rt.Router            // 消息处理器
	dieChan           chan struct{}        // 应用程序退出信号
	packerBuilder     packet.PackerBuilder // 封包、拆包器
	serializer        ndef.Serializer      // 消息 序列化/反序列化
	pool              *ants.Pool           // goroutine池
	connMgr           *conn.ConnManager    // 连接管理器
	evtMgr            event.EventManager   // 事件管理器
	sessIdMgr         *session.IDMgr       // SessionId管理器
}

func NewEngine(conf config.EngineConf, opts ...RunOption) *Engine {
	ngin := &Engine{
		EngineConf:  conf,
		middlewares: make([]rt.Middleware, 0),
		routes:      make([]rt.Route, 0),
		router:      rt.NewDefaultRouter(),
		dieChan:     make(chan struct{}),
		connMgr:     conn.NewConnManager(),
		evtMgr:      event.NewEventManager(),
		sessIdMgr:   session.NewSessionIDMgr(),
		packerBuilder: func() packet.Packer {
			return nil
		},
	}

	for _, opt := range opts {
		opt(ngin)
	}

	if ngin.EngineConf.SendChannelSize == 0 {
		ngin.EngineConf.SendChannelSize = config.DefaultSendChannelSize
	}
	if ngin.EngineConf.WriteChannelSize == 0 {
		ngin.EngineConf.WriteChannelSize = config.DefaultWriteChannelSize
	}

	if ngin.pool == nil {
		ngin.pool, _ = ants.NewPool(math.MaxInt32)
	}

	return ngin
}

func (ngin *Engine) Pool() *ants.Pool {
	return ngin.pool
}

func (ngin *Engine) Use(middleware ...rt.Middleware) {
	ngin.middlewares = append(ngin.middlewares, middleware...)
}

func (ngin *Engine) AddRoutes(rs ...rt.Route) {
	ngin.routes = append(ngin.routes, rs...)
	err := ngin.bindRoutes()
	nlog.Must(err)
}

func (ngin *Engine) bindRoutes() error {
	for _, fr := range ngin.routes {
		if err := ngin.bindRoute(fr); err != nil {
			return err
		}
	}
	return nil
}

func (ngin *Engine) bindRoute(route rt.Route) error {
	// TODO default middleware
	chain := rt.NewChain()
	// build chain
	for _, middleware := range ngin.middlewares {
		chain.Append(rt.ConvertMiddleware(middleware))
	}
	return ngin.router.Register(route.Matches, route.Handler)
}

func (ngin *Engine) setup() error {
	if err := ngin.bindRoutes(); err != nil {
		return err
	}
	return nil
}

func (ngin *Engine) Stop() {
	nlog.Infof("%s server is stopping...", ngin.LogPrefix())

	ngin.connMgr.PeekConn(func(_ int64, c *conn.Connection) bool {
		_ = c.Close()
		return false
	})
	close(ngin.dieChan)
}

func (ngin *Engine) handle(rawC net.Conn) *conn.Connection {
	nc := conn.NewConnection(ngin.sessIdMgr.SessionID(), rawC, ngin.SendChannelSize, ngin.WriteChannelSize)

	ngin.evtMgr.OnConnected(nc)

	ngin.serveConn(nc, ngin.packerBuilder())

	err := ngin.connMgr.Store(conn.DefaultGroupName, nc)
	nlog.Must(err)
	return nc
}

func (ngin *Engine) serveConn(nc *conn.Connection, packer packet.Packer) {
	_ = ngin.pool.Submit(func() {
		ngin.readLoop(nc, packer)
	})

	_ = ngin.pool.Submit(func() {
		ngin.writeLoop(nc, packer)
	})

	_ = ngin.pool.Submit(func() {
		select {
		case <-nc.ChDie():
			if ngin.ShallLogDebug() {
				nlog.Debugf("%s Close connection, ID=%d, Remote=%s", ngin.LogPrefix(), nc.ID(), nc.Conn().RemoteAddr().String())
			}
			_ = ngin.connMgr.Remove(nc)
			ngin.evtMgr.OnClose(nc)
		}
	})
}

func (ngin *Engine) readLoop(nc *conn.Connection, packer packet.Packer) {
	defer func() {
		_ = nc.Close()

		//if ngin.ShallLogDebug() {
		//	nlog.Debugf("%s [readLoop] connection read goroutine exit, ID=%d, UID=%s, Remote=%s",
		//		ngin.LogPrefix(), nc.ID(), nc.Session().UID(), nc.Conn().RemoteAddr())
		//}
	}()

	buf := make([]byte, 4096)
	for {
		select {
		case <-nc.ChDie(): // connection close signal
			return
		default:
			if ngin.Deadline != 0 {
				_ = nc.Conn().SetDeadline(time.Now().Add(ngin.Deadline))
			}
			if ngin.ReadDeadline != 0 {
				_ = nc.Conn().SetReadDeadline(time.Now().Add(ngin.ReadDeadline))
			}
			var (
				err    error
				n      int
				msgTyp int
			)
			// 兼容websocket
			if nc.Type() == conn.ConnTypeWS {
				var bb []byte
				if msgTyp, bb, err = nc.WsConn().ReadMessage(); err == nil {
					copy(buf, bb)
					n = len(bb)
				}
			} else {
				n, err = nc.Conn().Read(buf)
			}
			if err != nil {
				ngin.evtMgr.OnDisconnected(nc, err)
				// TODO 断线重连 (仅限客户端)
				nlog.Errorf("%s [readLoop] Read message error: %s, session will be closed immediately",
					ngin.LogPrefix(), err.Error())
				return
			}

			if n == 0 {
				ngin.evtMgr.OnReceiveError(nc, conn.ErrReceiveZero)
				nlog.Errorf("%s [readLoop] Read empty message, session will be closed immediately",
					ngin.LogPrefix())
				return
			}

			// 兼容websocket
			if nc.Type() == conn.ConnTypeWS {
				ngin.processPacket(nc, packet.NewWSPacket(msgTyp, buf[:n]))
			} else {
				if packer == nil {
					ngin.evtMgr.OnReceiveError(nc, conn.ErrNoPacker)
					nlog.Errorf("%s [readLoop] unexpected error: packer is nil", ngin.LogPrefix())
					return
				}

				//nlog.Debugf("receive data %v", buf[:n])
				// warning: 为性能考虑，复用slice处理数据，buf传入后必须要copy再处理
				packets, err := packer.Unpack(buf[:n])
				if err != nil {
					ngin.evtMgr.OnReceiveError(nc, conn.ErrUnpack)
					nlog.Errorf("%s unpack err: %s", ngin.LogPrefix(), err.Error())
				}
				// packets 处理
				for _, p := range packets {
					ngin.processPacket(nc, p)
				}
			}
		}
	}
}

func (ngin *Engine) writeLoop(nc *conn.Connection, packer packet.Packer) {
	defer func() {
		_ = nc.Close()

		//if ngin.ShallLogDebug() {
		//	nlog.Debugf("%s [writeLoop] connection write goroutine exit, ID=%d, UID=%s, Remote=%s",
		//		ngin.LogPrefix(), nc.ID(), nc.Session().UID(), nc.Conn().RemoteAddr())
		//}
	}()

	for {
		select {
		case data := <-nc.ChSend():
			// marshal packet body (data)
			if ngin.serializer == nil {
				if _, ok := data.Payload.([]byte); !ok {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrSendPayload)
					nlog.Errorf("%s [writeLoop] serializer is nil, but payload type not []byte", ngin.LogPrefix())
					break
				}
			} else {
				payload, err := ngin.serializer.Marshal(data.Payload)
				if err != nil {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrSendMarshal)
					nlog.Errorf("%s [writeLoop] message body marshal err: %v", ngin.LogPrefix(), err)
					break
				}
				data.Payload = payload
			}

			// 对websocket的兼容
			if nc.Type() == conn.ConnTypeWS {
				messageTyp, ok := data.Header.(int)
				if !ok {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrSendWSType)
					nlog.Errorf("%s [writeLoop] websocket message type not found", ngin.LogPrefix())
					break
				}
				// deadline
				if ngin.Deadline != 0 {
					_ = nc.Conn().SetDeadline(time.Now().Add(ngin.Deadline))
				}
				if ngin.WriteDeadline != 0 {
					_ = nc.Conn().SetWriteDeadline(time.Now().Add(ngin.WriteDeadline))
				}
				err := nc.WsConn().WriteMessage(messageTyp, data.Payload.([]byte))
				if err != nil {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrSend)
					nlog.Errorf("%s [writeLoop] write data err: %v", ngin.LogPrefix(), err)
					break
				}
				// event
				ngin.evtMgr.OnSend(nc, data)
			} else {
				// packet pack data
				if packer == nil {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrNoPacker)
					nlog.Errorf("%s [writeLoop] unexpected error: packer is nil", ngin.LogPrefix())
					break
				}
				p, err := packer.Pack(data.Header, data.Payload.([]byte))
				if err != nil {
					ngin.evtMgr.OnSendError(nc, data, conn.ErrPack)
					nlog.Errorf("%s [writeLoop] pack err: %v", ngin.LogPrefix(), err)
					break
				}
				nc.ChWrite() <- p
			}
		case data := <-nc.ChWrite():
			// 回写数据
			if ngin.Deadline != 0 {
				_ = nc.Conn().SetDeadline(time.Now().Add(ngin.Deadline))
			}
			if ngin.WriteDeadline != 0 {
				_ = nc.Conn().SetWriteDeadline(time.Now().Add(ngin.WriteDeadline))
			}
			if _, err := nc.Conn().Write(data); err != nil {
				ngin.evtMgr.OnSendError(nc, data, conn.ErrSend)
				nlog.Errorf("%s [writeLoop] write data err: %v", ngin.LogPrefix(), err)
				break
			}
			// event
			ngin.evtMgr.OnSend(nc, data)

			//nlog.Debugf("write data %v", data)
		case <-nc.ChDie(): // connection close signal
			return
		}
	}
}

func (ngin *Engine) processPacket(nc *conn.Connection, p packet.IPacket) {
	// event
	ngin.evtMgr.OnReceive(nc, p)

	if nc.Status() == conn.StatusWorking {
		// 处理包消息
		_ = ngin.pool.Submit(func() {
			ngin.router.Handle(nc, p)
		})
	}
}