package clashapi

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"net/url"
	"strconv"
	"time"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/common/badjson"
	C "github.com/sagernet/sing-box/constant"
	"github.com/sagernet/sing-box/outbound"
	"github.com/sagernet/sing/common"
	F "github.com/sagernet/sing/common/format"
	M "github.com/sagernet/sing/common/metadata"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/render"
	"sort"
)

func proxyRouter(server *Server, router adapter.Router) http.Handler {
	r := chi.NewRouter()
	r.Get("/", getProxies(server, router))

	r.Route("/{name}", func(r chi.Router) {
		r.Use(parseProxyName, findProxyByName(router))
		r.Get("/", getProxy(server))
		r.Get("/delay", getProxyDelay(server))
		r.Put("/", updateProxy)
	})
	return r
}

func parseProxyName(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		name := getEscapeParam(r, "name")
		ctx := context.WithValue(r.Context(), CtxKeyProxyName, name)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

func findProxyByName(router adapter.Router) func(next http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			name := r.Context().Value(CtxKeyProxyName).(string)
			proxy, exist := router.Outbound(name)
			if !exist {
				render.Status(r, http.StatusNotFound)
				render.JSON(w, r, ErrNotFound)
				return
			}
			ctx := context.WithValue(r.Context(), CtxKeyProxy, proxy)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

func proxyInfo(server *Server, detour adapter.Outbound) *badjson.JSONObject {
	var info badjson.JSONObject
	var clashType string
	var isSelector bool
	switch detour.Type() {
	case C.TypeDirect:
		clashType = "Direct"
	case C.TypeBlock:
		clashType = "Reject"
	case C.TypeSocks:
		clashType = "Socks"
	case C.TypeHTTP:
		clashType = "Http"
	case C.TypeShadowsocks:
		clashType = "Shadowsocks"
	case C.TypeVMess:
		clashType = "Vmess"
	case C.TypeSelector:
		clashType = "Selector"
		isSelector = true
	default:
		clashType = "Unknown"
	}
	info.Put("type", clashType)
	info.Put("name", detour.Tag())
	info.Put("udp", common.Contains(detour.Network(), C.NetworkUDP))

	var delayHistory *DelayHistory
	var loaded bool
	if isSelector {
		selector := detour.(*outbound.Selector)
		info.Put("now", selector.Now())
		info.Put("all", selector.All())
		delayHistory, loaded = server.delayHistory[selector.Now()]
	} else {
		delayHistory, loaded = server.delayHistory[detour.Tag()]
	}
	if loaded {
		info.Put("history", []*DelayHistory{delayHistory})
	} else {
		info.Put("history", []*DelayHistory{})
	}
	return &info
}

func getProxies(server *Server, router adapter.Router) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		var proxyMap badjson.JSONObject
		outbounds := common.Filter(router.Outbounds(), func(detour adapter.Outbound) bool {
			return detour.Tag() != ""
		})

		allProxies := make([]string, 0, len(outbounds))

		for _, detour := range outbounds {
			switch detour.Type() {
			case C.TypeDirect, C.TypeBlock:
				continue
			}
			allProxies = append(allProxies, detour.Tag())
		}

		defaultTag := router.DefaultOutbound(C.NetworkTCP).Tag()
		if defaultTag == "" {
			defaultTag = allProxies[0]
		}

		sort.Slice(allProxies, func(i, j int) bool {
			return allProxies[i] == defaultTag
		})

		// fix clash dashboard
		proxyMap.Put("GLOBAL", map[string]any{
			"type":    "Fallback",
			"name":    "GLOBAL",
			"udp":     true,
			"history": []*DelayHistory{},
			"all":     allProxies,
			"now":     defaultTag,
		})

		for i, detour := range outbounds {
			var tag string
			if detour.Tag() == "" {
				tag = F.ToString(i)
			} else {
				tag = detour.Tag()
			}
			proxyMap.Put(tag, proxyInfo(server, detour))
		}
		var responseMap badjson.JSONObject
		responseMap.Put("proxies", &proxyMap)
		response, err := responseMap.MarshalJSON()
		if err != nil {
			render.Status(r, http.StatusInternalServerError)
			render.JSON(w, r, newError(err.Error()))
			return
		}
		w.Write(response)
	}
}

func getProxy(server *Server) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		proxy := r.Context().Value(CtxKeyProxy).(adapter.Outbound)
		response, err := proxyInfo(server, proxy).MarshalJSON()
		if err != nil {
			render.Status(r, http.StatusInternalServerError)
			render.JSON(w, r, newError(err.Error()))
			return
		}
		w.Write(response)
	}
}

type UpdateProxyRequest struct {
	Name string `json:"name"`
}

func updateProxy(w http.ResponseWriter, r *http.Request) {
	req := UpdateProxyRequest{}
	if err := render.DecodeJSON(r.Body, &req); err != nil {
		render.Status(r, http.StatusBadRequest)
		render.JSON(w, r, ErrBadRequest)
		return
	}

	proxy := r.Context().Value(CtxKeyProxy).(adapter.Outbound)
	selector, ok := proxy.(*outbound.Selector)
	if !ok {
		render.Status(r, http.StatusBadRequest)
		render.JSON(w, r, newError("Must be a Selector"))
		return
	}

	if !selector.SelectOutbound(req.Name) {
		render.Status(r, http.StatusBadRequest)
		render.JSON(w, r, newError(fmt.Sprintf("Selector update error: not found")))
		return
	}

	render.NoContent(w, r)
}

func getProxyDelay(server *Server) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		query := r.URL.Query()
		url := query.Get("url")
		timeout, err := strconv.ParseInt(query.Get("timeout"), 10, 16)
		if err != nil {
			render.Status(r, http.StatusBadRequest)
			render.JSON(w, r, ErrBadRequest)
			return
		}

		proxy := r.Context().Value(CtxKeyProxy).(adapter.Outbound)
		ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond*time.Duration(timeout))
		defer cancel()

		delay, err := URLTest(ctx, url, proxy)
		if ctx.Err() != nil {
			render.Status(r, http.StatusGatewayTimeout)
			render.JSON(w, r, ErrRequestTimeout)
			return
		}

		if err != nil || delay == 0 {
			render.Status(r, http.StatusServiceUnavailable)
			render.JSON(w, r, newError("An error occurred in the delay test"))
			return
		}

		server.delayHistory[proxy.Tag()] = &DelayHistory{
			Time:  time.Now(),
			Delay: delay,
		}

		render.JSON(w, r, render.M{
			"delay": delay,
		})
	}
}

func URLTest(ctx context.Context, link string, detour adapter.Outbound) (t uint16, err error) {
	linkURL, err := url.Parse(link)
	if err != nil {
		return
	}
	hostname := linkURL.Hostname()
	port := linkURL.Port()
	if port == "" {
		switch linkURL.Scheme {
		case "http":
			port = "80"
		case "https":
			port = "443"
		}
	}

	start := time.Now()
	instance, err := detour.DialContext(ctx, "tcp", M.ParseSocksaddrHostPortStr(hostname, port))
	if err != nil {
		return
	}
	defer instance.Close()

	req, err := http.NewRequest(http.MethodHead, link, nil)
	if err != nil {
		return
	}
	req = req.WithContext(ctx)

	transport := &http.Transport{
		Dial: func(string, string) (net.Conn, error) {
			return instance, nil
		},
		// from http.DefaultTransport
		MaxIdleConns:          100,
		IdleConnTimeout:       90 * time.Second,
		TLSHandshakeTimeout:   10 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
	}

	client := http.Client{
		Transport: transport,
		CheckRedirect: func(req *http.Request, via []*http.Request) error {
			return http.ErrUseLastResponse
		},
	}
	defer client.CloseIdleConnections()

	resp, err := client.Do(req)
	if err != nil {
		return
	}
	resp.Body.Close()
	t = uint16(time.Since(start) / time.Millisecond)
	return
}