package cli

import (
	"context"
	"fmt"
	"math"
	"net"
	"net/url"
	"os"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"git.nobla.cn/golang/aeus/metadata"
	"git.nobla.cn/golang/aeus/middleware"
	"git.nobla.cn/golang/aeus/pkg/errors"
	"git.nobla.cn/golang/aeus/pkg/logger"
	netutil "git.nobla.cn/golang/aeus/pkg/net"
)

type Server struct {
	ctx            context.Context
	router         *Router
	opts           *options
	listener       net.Listener
	sequenceLocker sync.Mutex
	sequence       int64
	ctxMap         sync.Map
	uri            *url.URL
	exitFlag       int32
	middleware     []middleware.Middleware
	Logger         logger.Logger
}

func (svr *Server) Use(middlewares ...middleware.Middleware) {
	svr.middleware = append(svr.middleware, middlewares...)
}

func (svr *Server) Handle(pathname string, desc string, cb HandleFunc) {
	svr.router.Handle(pathname, svr.wrapCommand(pathname, desc, cb))
}

func (svr *Server) wrapCommand(pathname, desc string, cb HandleFunc) Command {
	h := func(ctx *Context) (err error) {
		return cb(ctx)
	}
	if desc == "" {
		desc = strings.Join(strings.Split(strings.TrimPrefix(pathname, "/"), "/"), " ")
	}
	return Command{
		Path:        pathname,
		Handle:      h,
		Description: desc,
	}
}

func (s *Server) createListener() (err error) {
	if s.listener != nil {
		return
	}
	if s.listener, err = net.Listen(s.opts.network, s.opts.address); err == nil {
		s.uri.Host = netutil.TrulyAddr(s.opts.address, s.listener)
	}
	return
}

func (s *Server) applyContext() *Context {
	if v := ctxPool.Get(); v != nil {
		if ctx, ok := v.(*Context); ok {
			return ctx
		}
	}
	return &Context{}
}

func (s *Server) releaseContext(ctx *Context) {
	ctxPool.Put(ctx)
}

func (s *Server) execute(ctx *Context, frame *Frame) (err error) {
	var (
		params map[string]string
		tokens []string
		args   []string
		r      *Router
	)
	cmd := string(frame.Data)
	tokens = strings.Fields(cmd)
	if frame.Timeout > 0 {
		childCtx, cancelFunc := context.WithTimeout(s.ctx, time.Duration(frame.Timeout))
		ctx.setContext(childCtx)
		defer func() {
			cancelFunc()
		}()
	} else {
		ctx.setContext(s.ctx)
	}
	if r, args, err = s.router.Lookup(tokens); err != nil {
		if errors.Is(err, ErrNotFound) {
			err = ctx.Error(errors.NotFound, fmt.Sprintf("Command %s not found", cmd))
		} else {
			err = ctx.Error(errors.Unavailable, err.Error())
		}
	} else {
		if len(r.params) > len(args) {
			err = ctx.Error(errors.Unavailable, r.Usage())
			return
		}
		if len(r.params) > 0 {
			params = make(map[string]string)
			for i, s := range r.params {
				params[s] = args[i]
			}
		}
		ctx.setArgs(args)
		ctx.setParam(params)
		h := func(c context.Context) error {
			return r.command.Handle(ctx)
		}
		next := middleware.Chain(s.middleware...)(h)
		md := metadata.FromContext(ctx.ctx)
		md.Set(metadata.RequestPathKey, r.command.Path)
		md.Set(metadata.RequestProtocolKey, Protocol)
		md.TeeReader(&cliMetadataReader{ctx: ctx})
		md.TeeWriter(&cliMetadataWriter{ctx: ctx})
		ctx.ctx = metadata.NewContext(ctx.ctx, md)
		err = next(ctx.ctx)
	}
	return
}

func (svr *Server) nextSequence() int64 {
	svr.sequenceLocker.Lock()
	defer svr.sequenceLocker.Unlock()
	if svr.sequence == math.MaxInt64 {
		svr.sequence = 1
	}
	svr.sequence++
	return svr.sequence
}

func (svr *Server) process(conn net.Conn) {
	var (
		err   error
		ctx   *Context
		frame *Frame
	)
	ctx = svr.applyContext()
	ctx.reset(svr.nextSequence(), conn)
	svr.ctxMap.Store(ctx.Id, ctx)
	defer func() {
		_ = conn.Close()
		svr.ctxMap.Delete(ctx.Id)
		svr.releaseContext(ctx)
	}()
	for {
		if frame, err = readFrame(conn); err != nil {
			break
		}
		//reset frame
		ctx.seq = frame.Seq
		switch frame.Type {
		case PacketTypeHandshake:
			if err = ctx.send(responsePayload{
				Type: PacketTypeHandshake,
				Data: &handshake{
					ID:         ctx.Id,
					Name:       "",
					Version:    "",
					OS:         runtime.GOOS,
					ServerTime: time.Now(),
					RemoteAddr: conn.RemoteAddr().String(),
				},
			}); err != nil {
				break
			}
		case PacketTypeCompleter:
			if err = ctx.send(responsePayload{
				Type: PacketTypeCompleter,
				Data: svr.router.Completer(strings.Fields(string(frame.Data))...),
			}); err != nil {
				break
			}
		case PacketTypeCommand:
			if err = svr.execute(ctx, frame); err != nil {
				break
			}
		default:
			break
		}
	}
}

func (s *Server) serve() (err error) {
	for {
		conn, err := s.listener.Accept()
		if err != nil {
			if atomic.LoadInt32(&s.exitFlag) == 1 {
				return nil
			}
			return err
		}
		go s.process(conn)
	}
}

func (s *Server) Start(ctx context.Context) (err error) {
	s.ctx = ctx
	if s.opts.logger != nil {
		s.Logger = s.opts.logger
	}
	if s.Logger == nil {
		s.Logger = logger.Default()
	}
	if err = s.createListener(); err != nil {
		return
	}
	s.Logger.Infof(ctx, "cli server listen on: %s", s.uri.Host)
	s.Handle("/help", "Display help information", func(ctx *Context) (err error) {
		return ctx.Success(s.router.String())
	})
	err = s.serve()
	return
}

func (s *Server) Stop(ctx context.Context) (err error) {
	if !atomic.CompareAndSwapInt32(&s.exitFlag, 0, 1) {
		return
	}
	if s.listener != nil {
		if err = s.listener.Close(); err != nil {
			s.Logger.Warnf(ctx, "cli listener close error: %v", err)
		}
	}
	s.ctxMap.Range(func(key, value any) bool {
		if ctx, ok := value.(*Context); ok {
			err = ctx.Close()
		}
		return true
	})
	s.Logger.Info(ctx, "cli server stopped")
	return
}

func New(cbs ...Option) *Server {
	srv := &Server{
		opts: &options{
			network: "tcp",
			address: ":0",
		},
		uri:    &url.URL{Scheme: "cli"},
		router: newRouter(""),
	}
	port, _ := strconv.Atoi(os.Getenv("CLI_PORT"))
	srv.opts.address = fmt.Sprintf(":%d", port)
	for _, cb := range cbs {
		cb(srv.opts)
	}
	return srv
}