package redirect

import (
	"context"
	"fmt"
	"net"
	"time"

	"github.com/go-gost/core/chain"
	"github.com/go-gost/core/handler"
	md "github.com/go-gost/core/metadata"
	netpkg "github.com/go-gost/x/internal/net"
	"github.com/go-gost/x/registry"
)

func init() {
	registry.HandlerRegistry().Register("redu", NewHandler)
}

type redirectHandler struct {
	router  *chain.Router
	md      metadata
	options handler.Options
}

func NewHandler(opts ...handler.Option) handler.Handler {
	options := handler.Options{}
	for _, opt := range opts {
		opt(&options)
	}

	return &redirectHandler{
		options: options,
	}
}

func (h *redirectHandler) Init(md md.Metadata) (err error) {
	if err = h.parseMetadata(md); err != nil {
		return
	}

	h.router = h.options.Router
	if h.router == nil {
		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
	}

	return
}

func (h *redirectHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
	defer conn.Close()

	start := time.Now()
	log := h.options.Logger.WithFields(map[string]any{
		"remote": conn.RemoteAddr().String(),
		"local":  conn.LocalAddr().String(),
	})

	log.Infof("%s <> %s", conn.RemoteAddr(), conn.LocalAddr())
	defer func() {
		log.WithFields(map[string]any{
			"duration": time.Since(start),
		}).Infof("%s >< %s", conn.RemoteAddr(), conn.LocalAddr())
	}()

	if !h.checkRateLimit(conn.RemoteAddr()) {
		return nil
	}

	dstAddr := conn.LocalAddr()

	log = log.WithFields(map[string]any{
		"dst": fmt.Sprintf("%s/%s", dstAddr, dstAddr.Network()),
	})

	log.Debugf("%s >> %s", conn.RemoteAddr(), dstAddr)

	if h.options.Bypass != nil && h.options.Bypass.Contains(dstAddr.String()) {
		log.Debug("bypass: ", dstAddr)
		return nil
	}

	cc, err := h.router.Dial(ctx, dstAddr.Network(), dstAddr.String())
	if err != nil {
		log.Error(err)
		return err
	}
	defer cc.Close()

	t := time.Now()
	log.Debugf("%s <-> %s", conn.RemoteAddr(), dstAddr)
	netpkg.Transport(conn, cc)
	log.WithFields(map[string]any{
		"duration": time.Since(t),
	}).Debugf("%s >-< %s", conn.RemoteAddr(), dstAddr)

	return nil
}

func (h *redirectHandler) checkRateLimit(addr net.Addr) bool {
	if h.options.RateLimiter == nil {
		return true
	}
	host, _, _ := net.SplitHostPort(addr.String())
	if limiter := h.options.RateLimiter.Limiter(host); limiter != nil {
		return limiter.Allow(1)
	}

	return true
}