package main

import (
	"crypto/rand"
	"crypto/subtle"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/fs"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"
)

type Server struct {
	engine   *Engine
	mux      *http.ServeMux
	password string

	tokenMu sync.Mutex
	tokens  map[string]time.Time
}

func NewServer(e *Engine, static fs.FS, password string) *Server {
	s := &Server{
		engine:   e,
		mux:      http.NewServeMux(),
		password: password,
		tokens:   map[string]time.Time{},
	}
	mux := s.mux
	mux.HandleFunc("GET /api/status", s.handleStatus)
	mux.HandleFunc("GET /api/events", s.handleEvents)
	mux.HandleFunc("POST /api/login", s.handleLogin)
	mux.HandleFunc("POST /api/logout", s.handleLogout)
	mux.HandleFunc("POST /api/repos", s.handleCreate)
	mux.HandleFunc("GET /api/repos/{name}", s.wrapRepo(s.handleGet))
	mux.HandleFunc("PUT /api/repos/{name}", s.wrapRepo(s.handleUpdate))
	mux.HandleFunc("DELETE /api/repos/{name}", s.wrapRepo(s.handleDelete))
	mux.HandleFunc("POST /api/repos/{name}/start", s.wrapRepo(s.startRepo))
	mux.HandleFunc("POST /api/repos/{name}/stop", s.wrapRepo(s.stopRepo))
	mux.HandleFunc("POST /api/repos/{name}/sync", s.wrapRepo(s.syncRepo))
	mux.HandleFunc("POST /api/repos/{name}/action", s.wrapRepo(s.actionRepo))
	mux.HandleFunc("POST /api/repos/{name}/force-push", s.wrapRepo(s.forcePushRepo))
    mux.HandleFunc("POST /api/repos/{name}/abort-push", s.wrapRepo(s.abortPushRepo))
	mux.HandleFunc("GET /api/repos/{name}/conflicts", s.wrapRepo(s.conflictsRepo))
	mux.HandleFunc("GET /api/repos/{name}/log", s.wrapRepo(s.logRepo))
	mux.HandleFunc("GET /api/repos/{name}/stats", s.wrapRepo(s.statsRepo))
	mux.HandleFunc("GET /api/repos/{name}/commits", s.wrapRepo(s.commitsRepo))
	mux.HandleFunc("GET /api/repos/{name}/commits/{hash}", s.wrapRepo(s.commitDiffRepo))
	mux.Handle("/", http.FileServer(http.FS(static)))
	return s
}


func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// 访问密码保护：静态资源开放，/api/* 需要会话（登录接口除外）
	if s.password != "" && strings.HasPrefix(r.URL.Path, "/api/") &&
		r.URL.Path != "/api/login" && !s.validToken(r) {
		writeErr(w, 401, "需要登录")
		return
	}
	s.mux.ServeHTTP(w, r)
}

func (s *Server) validToken(r *http.Request) bool {
	c, err := r.Cookie("git_sync_token")
	if err != nil {
		return false
	}
	s.tokenMu.Lock()
	defer s.tokenMu.Unlock()
	exp, ok := s.tokens[c.Value]
	if !ok {
		return false
	}
	if time.Now().After(exp) {
		delete(s.tokens, c.Value)
		return false
	}
	return true
}

func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Password string `json:"password"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeErr(w, 400, "请求体格式错误")
		return
	}
	if subtle.ConstantTimeCompare([]byte(req.Password), []byte(s.password)) != 1 {
		writeErr(w, 401, "密码错误")
		return
	}
	buf := make([]byte, 32)
	if _, err := rand.Read(buf); err != nil {
		writeErr(w, 500, "生成会话失败")
		return
	}
	token := hex.EncodeToString(buf)
	s.tokenMu.Lock()
	s.tokens[token] = time.Now().Add(30 * 24 * time.Hour)
	s.tokenMu.Unlock()
	http.SetCookie(w, &http.Cookie{
		Name: "git_sync_token", Value: token, Path: "/",
		HttpOnly: true, MaxAge: 30 * 24 * 3600,
	})
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
	if c, err := r.Cookie("git_sync_token"); err == nil {
		s.tokenMu.Lock()
		delete(s.tokens, c.Value)
		s.tokenMu.Unlock()
	}
	http.SetCookie(w, &http.Cookie{Name: "git_sync_token", Value: "", Path: "/", MaxAge: -1})
	writeJSON(w, 200, map[string]any{"ok": true})
}

func writeJSON(w http.ResponseWriter, code int, v any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(code)
	_ = json.NewEncoder(w).Encode(v)
}

func writeErr(w http.ResponseWriter, code int, msg string) {
	writeJSON(w, code, map[string]string{"error": msg})
}

func (s *Server) wrapRepo(h func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		name := r.PathValue("name")
		if s.engine.get(name) == nil {
			writeErr(w, 404, "配置不存在: "+name)
			return
		}
		h(w, r, name)
	}
}

func (s *Server) handleStatus(w http.ResponseWriter, r *http.Request) {
	writeJSON(w, 200, map[string]any{"repos": s.engine.Snapshots(true)})
}

func (s *Server) handleGet(w http.ResponseWriter, r *http.Request, name string) {
	if st := s.engine.get(name); st != nil {
		writeJSON(w, 200, st.snapshot(true))
		return
	}
	writeErr(w, 404, "配置不存在")
}

func (s *Server) handleCreate(w http.ResponseWriter, r *http.Request) {
	var cfg RepoConfig
	if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
		writeErr(w, 400, "请求体格式错误: "+err.Error())
		return
	}
	if err := s.engine.Create(&cfg); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true, "name": cfg.Name})
}

func (s *Server) handleUpdate(w http.ResponseWriter, r *http.Request, name string) {
	var cfg RepoConfig
	if err := json.NewDecoder(r.Body).Decode(&cfg); err != nil {
		writeErr(w, 400, "请求体格式错误: "+err.Error())
		return
	}
	cfg.Name = name
	if err := s.engine.Update(&cfg); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) handleDelete(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.Delete(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) startRepo(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.Start(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) stopRepo(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.Stop(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) syncRepo(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.SyncNow(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) actionRepo(w http.ResponseWriter, r *http.Request, name string) {
	var req struct {
		Action string `json:"action"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeErr(w, 400, "请求体格式错误")
		return
	}
	switch req.Action {
	case "abort":
		if err := s.engine.ConflictAbort(name); err != nil {
			writeErr(w, 500, err.Error())
			return
		}
	case "resolve":
		if err := s.engine.ConflictResolve(name); err != nil {
			writeErr(w, 500, err.Error())
			return
		}
	case "fetch", "pull", "push":
		if err := s.engine.ManualGit(name, req.Action); err != nil {
			writeErr(w, 500, err.Error())
			return
		}
	default:
		writeErr(w, 400, "未知操作: "+req.Action)
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) conflictsRepo(w http.ResponseWriter, r *http.Request, name string) {
	writeJSON(w, 200, s.engine.ConflictDiffs(name))
}

func (s *Server) logRepo(w http.ResponseWriter, r *http.Request, name string) {
	n := 300
	if v, err := strconv.Atoi(r.URL.Query().Get("lines")); err == nil && v > 0 && v <= 5000 {
		n = v
	}
	writeJSON(w, 200, map[string]any{"lines": s.engine.ReadLog(name, n)})
}

func (s *Server) statsRepo(w http.ResponseWriter, r *http.Request, name string) {
	writeJSON(w, 200, s.engine.ReadStats(name))
}

func (s *Server) commitsRepo(w http.ResponseWriter, r *http.Request, name string) {
	limit := 50
	if v, err := strconv.Atoi(r.URL.Query().Get("limit")); err == nil && v > 0 && v <= 200 {
		limit = v
	}
	writeJSON(w, 200, s.engine.ReadCommits(name, limit))
}

func (s *Server) commitDiffRepo(w http.ResponseWriter, r *http.Request, name string) {
	diff, err := s.engine.ReadCommitDiff(name, r.PathValue("hash"))
	if err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]string{"diff": diff})
}

func (s *Server) handleEvents(w http.ResponseWriter, r *http.Request) {
	fl, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "streaming unsupported", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("X-Accel-Buffering", "no")

	id, ch := s.engine.Bus().Subscribe()
	defer s.engine.Bus().Unsubscribe(id)

	if snap, err := json.Marshal(map[string]any{"type": "snapshot", "data": s.engine.Snapshots(true)}); err == nil {
		fmt.Fprintf(w, "data: %s\n\n", snap)
		fl.Flush()
	}

	tick := time.NewTicker(25 * time.Second)
	defer tick.Stop()
	ctx := r.Context()
	for {
		select {
		case <-ctx.Done():
			return
		case <-tick.C:
			fmt.Fprint(w, ": ping\n\n")
			fl.Flush()
		case data, ok := <-ch:
			if !ok {
				return
			}
			fmt.Fprintf(w, "data: %s\n\n", data)
			fl.Flush()
		}
	}
}

func (s *Server) forcePushRepo(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.ForcePush(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}

func (s *Server) abortPushRepo(w http.ResponseWriter, r *http.Request, name string) {
	if err := s.engine.AbortPush(name); err != nil {
		writeErr(w, 400, err.Error())
		return
	}
	writeJSON(w, 200, map[string]any{"ok": true})
}