package server

import (
	"bufio"
	"errors"
	"github.com/siddontang/go/hack"
	"github.com/siddontang/go/log"
	"github.com/siddontang/go/num"
	"github.com/siddontang/ledisdb/ledis"
	"io"
	"net"
	"runtime"
	"strconv"
	"strings"
)

var errReadRequest = errors.New("invalid request protocol")

type respClient struct {
	*client

	conn net.Conn
	rb   *bufio.Reader
}

type respWriter struct {
	buff *bufio.Writer
}

func newClientRESP(conn net.Conn, app *App) {
	c := new(respClient)

	c.client = newClient(app)
	c.conn = conn

	if tcpConn, ok := conn.(*net.TCPConn); ok {
		tcpConn.SetReadBuffer(app.cfg.ConnReadBufferSize)
		tcpConn.SetWriteBuffer(app.cfg.ConnWriteBufferSize)
	}

	c.rb = bufio.NewReaderSize(conn, app.cfg.ConnReadBufferSize)

	c.resp = newWriterRESP(conn, app.cfg.ConnWriteBufferSize)
	c.remoteAddr = conn.RemoteAddr().String()

	go c.run()
}

func (c *respClient) run() {
	defer func() {
		if e := recover(); e != nil {
			buf := make([]byte, 4096)
			n := runtime.Stack(buf, false)
			buf = buf[0:n]

			log.Fatal("client run panic %s:%v", buf, e)
		}

		handleQuit := true
		if c.conn != nil {
			//if handle quit command before, conn is nil
			handleQuit = false
			c.conn.Close()
		}

		if c.tx != nil {
			c.tx.Rollback()
			c.tx = nil
		}

		c.app.removeSlave(c.client, handleQuit)
	}()

	for {
		reqData, err := c.readRequest()
		if err != nil {
			return
		}

		c.handleRequest(reqData)
	}
}

func (c *respClient) readLine() ([]byte, error) {
	return ReadLine(c.rb)
}

//A client sends to the Redis server a RESP Array consisting of just Bulk Strings.
// func (c *respClient) readRequest() ([][]byte, error) {
// 	l, err := c.readLine()
// 	if err != nil {
// 		return nil, err
// 	} else if len(l) == 0 || l[0] != '*' {
// 		return nil, errReadRequest
// 	}

// 	var nparams int
// 	if nparams, err = strconv.Atoi(hack.String(l[1:])); err != nil {
// 		return nil, err
// 	} else if nparams <= 0 {
// 		return nil, errReadRequest
// 	}

// 	req := make([][]byte, 0, nparams)
// 	var n int
// 	for i := 0; i < nparams; i++ {
// 		if l, err = c.readLine(); err != nil {
// 			return nil, err
// 		}

// 		if len(l) == 0 {
// 			return nil, errReadRequest
// 		} else if l[0] == '$' {
// 			//handle resp string
// 			if n, err = strconv.Atoi(hack.String(l[1:])); err != nil {
// 				return nil, err
// 			} else if n == -1 {
// 				req = append(req, nil)
// 			} else {
// 				buf := make([]byte, n+2)
// 				if _, err = io.ReadFull(c.rb, buf); err != nil {
// 					return nil, err
// 				}

// 				if buf[len(buf)-2] != '\r' && buf[len(buf)-1] != '\n' {
// 					return nil, errors.New("bad bulk string format")
// 				}

// 				// if l, err = c.readLine(); err != nil {
// 				// 	return nil, err
// 				// } else if len(l) != 0 {
// 				// 	return nil, errors.New("bad bulk string format")
// 				// }

// 				req = append(req, buf[0:len(buf)-2])

// 			}

// 		} else {
// 			return nil, errReadRequest
// 		}
// 	}

// 	return req, nil
// }

func (c *respClient) readRequest() ([][]byte, error) {
	code, err := c.rb.ReadByte()
	if err != nil {
		return nil, err
	}

	if code != '*' {
		return nil, errReadRequest
	}

	var nparams int64
	if nparams, err = readLong(c.rb); err != nil {
		return nil, err
	} else if nparams <= 0 {
		return nil, errReadRequest
	}

	req := make([][]byte, nparams)
	for i := range req {
		if code, err = c.rb.ReadByte(); err != nil {
			return nil, err
		} else if code != '$' {
			return nil, errReadRequest
		}

		if req[i], err = readBytes(c.rb); err != nil {
			return nil, err
		}
	}
	return req, nil
}

func (c *respClient) handleRequest(reqData [][]byte) {
	if len(reqData) == 0 {
		c.cmd = ""
		c.args = reqData[0:0]
	} else {
		c.cmd = strings.ToLower(hack.String(reqData[0]))
		c.args = reqData[1:]
	}
	if c.cmd == "quit" {
		c.resp.writeStatus(OK)
		c.resp.flush()
		c.conn.Close()
		c.conn = nil
		return
	}

	c.perform()

	return
}

//	response writer

func newWriterRESP(conn net.Conn, size int) *respWriter {
	w := new(respWriter)
	w.buff = bufio.NewWriterSize(conn, size)
	return w
}

func (w *respWriter) writeError(err error) {
	w.buff.Write(hack.Slice("-ERR"))
	if err != nil {
		w.buff.WriteByte(' ')
		w.buff.Write(hack.Slice(err.Error()))
	}
	w.buff.Write(Delims)
}

func (w *respWriter) writeStatus(status string) {
	w.buff.WriteByte('+')
	w.buff.Write(hack.Slice(status))
	w.buff.Write(Delims)
}

func (w *respWriter) writeInteger(n int64) {
	w.buff.WriteByte(':')
	w.buff.Write(num.FormatInt64ToSlice(n))
	w.buff.Write(Delims)
}

func (w *respWriter) writeBulk(b []byte) {
	w.buff.WriteByte('$')
	if b == nil {
		w.buff.Write(NullBulk)
	} else {
		w.buff.Write(hack.Slice(strconv.Itoa(len(b))))
		w.buff.Write(Delims)
		w.buff.Write(b)
	}

	w.buff.Write(Delims)
}

func (w *respWriter) writeArray(lst []interface{}) {
	w.buff.WriteByte('*')
	if lst == nil {
		w.buff.Write(NullArray)
		w.buff.Write(Delims)
	} else {
		w.buff.Write(hack.Slice(strconv.Itoa(len(lst))))
		w.buff.Write(Delims)

		for i := 0; i < len(lst); i++ {
			switch v := lst[i].(type) {
			case []interface{}:
				w.writeArray(v)
			case [][]byte:
				w.writeSliceArray(v)
			case []byte:
				w.writeBulk(v)
			case nil:
				w.writeBulk(nil)
			case int64:
				w.writeInteger(v)
			default:
				panic("invalid array type")
			}
		}
	}
}

func (w *respWriter) writeSliceArray(lst [][]byte) {
	w.buff.WriteByte('*')
	if lst == nil {
		w.buff.Write(NullArray)
		w.buff.Write(Delims)
	} else {
		w.buff.Write(hack.Slice(strconv.Itoa(len(lst))))
		w.buff.Write(Delims)

		for i := 0; i < len(lst); i++ {
			w.writeBulk(lst[i])
		}
	}
}

func (w *respWriter) writeFVPairArray(lst []ledis.FVPair) {
	w.buff.WriteByte('*')
	if lst == nil {
		w.buff.Write(NullArray)
		w.buff.Write(Delims)
	} else {
		w.buff.Write(hack.Slice(strconv.Itoa(len(lst) * 2)))
		w.buff.Write(Delims)

		for i := 0; i < len(lst); i++ {
			w.writeBulk(lst[i].Field)
			w.writeBulk(lst[i].Value)
		}
	}
}

func (w *respWriter) writeScorePairArray(lst []ledis.ScorePair, withScores bool) {
	w.buff.WriteByte('*')
	if lst == nil {
		w.buff.Write(NullArray)
		w.buff.Write(Delims)
	} else {
		if withScores {
			w.buff.Write(hack.Slice(strconv.Itoa(len(lst) * 2)))
			w.buff.Write(Delims)
		} else {
			w.buff.Write(hack.Slice(strconv.Itoa(len(lst))))
			w.buff.Write(Delims)

		}

		for i := 0; i < len(lst); i++ {
			w.writeBulk(lst[i].Member)

			if withScores {
				w.writeBulk(num.FormatInt64ToSlice(lst[i].Score))
			}
		}
	}
}

func (w *respWriter) writeBulkFrom(n int64, rb io.Reader) {
	w.buff.WriteByte('$')
	w.buff.Write(hack.Slice(strconv.FormatInt(n, 10)))
	w.buff.Write(Delims)

	io.Copy(w.buff, rb)
	w.buff.Write(Delims)
}

func (w *respWriter) flush() {
	w.buff.Flush()
}