package server

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"chat-agent-system/internal/auth"
	"chat-agent-system/internal/bizdev"
	"chat-agent-system/internal/chat"
	"chat-agent-system/internal/config"
	"chat-agent-system/internal/coordinator"
	"chat-agent-system/internal/intent"
)

// Server 提供基于 HTTP RESTful 与 SSE 的商务与研发参谋接口服务
type Server struct {
	cfg        *config.Config
	svc        *bizdev.Service
	rec        intent.Recognizer
	engine     *coordinator.CoordinatorEngine
	authSvc    *auth.Service
	sessions   map[string]*chat.Session
	sessionsMu sync.RWMutex
	httpServer *http.Server
}

// NewServer 构造函数
func NewServer(cfg *config.Config, svc *bizdev.Service) *Server {
	if cfg == nil {
		cfg, _ = config.Load("")
	}
	if svc == nil {
		svc = bizdev.NewService(cfg)
	}

	rec := intent.NewRecognizer()
	coordEngine := coordinator.NewCoordinatorEngine(svc)
	authStore := auth.NewMemoryStore(cfg)
	authSvc := auth.NewService(authStore, cfg)

	s := &Server{
		cfg:      cfg,
		svc:      svc,
		rec:      rec,
		engine:   coordEngine,
		authSvc:  authSvc,
		sessions: make(map[string]*chat.Session),
	}
	return s
}

// AuthService 获取认证服务
func (s *Server) AuthService() *auth.Service {
	return s.authSvc
}

// Routes 构建 HTTP 路由分发器
func (s *Server) Routes() http.Handler {
	mux := http.NewServeMux()

	// 1. 健康检查与系统自检
	mux.HandleFunc("GET /health", s.handleHealth)
	mux.HandleFunc("GET /api/v1/health", s.handleHealth)

	// 2. 项目状态与会话查询
	mux.HandleFunc("GET /api/v1/projects", s.handleGetProject)

	// 3. 对话协同服务 (标准 JSON 阻塞)
	mux.HandleFunc("POST /api/v1/chat", s.handleChat)

	// 4. 对话协同服务 (核心 SSE 流式长连接)
	mux.HandleFunc("POST /api/v1/chat/stream", s.handleChatStream)
	mux.HandleFunc("GET /api/v1/chat/stream", s.handleChatStream)

	// 5. 独立任务 / 阶段执行
	mux.HandleFunc("POST /api/v1/tasks/run", s.handleRunTask)
	mux.HandleFunc("POST /api/v1/tasks/run/stream", s.handleRunTaskStream)
	mux.HandleFunc("GET /api/v1/tasks/run/stream", s.handleRunTaskStream)

	// 6. 多级上下文与偏好记忆管理
	mux.HandleFunc("GET /api/v1/context/user", s.handleGetUserContext)
	mux.HandleFunc("PUT /api/v1/context/user/preference", s.handleUpdateUserPreference)
	mux.HandleFunc("GET /api/v1/context/project", s.handleGetProjectContext)

	// 7. 历史多轮会话管理与标杆案例语义检索
	mux.HandleFunc("GET /api/v1/chat/sessions", s.handleListChatSessions)
	mux.HandleFunc("GET /api/v1/chat/messages", s.handleGetChatMessages)
	mux.HandleFunc("GET /api/v1/context/cases/recommend", s.handleRecommendCases)

	// 8. 受控文档编制、审核、批准生命周期与认领治理
	mux.HandleFunc("GET /api/v1/docgov/document", s.handleDocGovGetDocument)
	mux.HandleFunc("POST /api/v1/docgov/claim", s.handleDocGovClaim)
	mux.HandleFunc("POST /api/v1/docgov/submit-review", s.handleDocGovSubmitReview)
	mux.HandleFunc("POST /api/v1/docgov/review-decision", s.handleDocGovReviewDecision)
	mux.HandleFunc("POST /api/v1/docgov/approver-decision", s.handleDocGovApproverDecision)
	mux.HandleFunc("POST /api/v1/docgov/proposal/decide", s.handleDocGovDecideProposal)
	mux.HandleFunc("GET /api/v1/docgov/comments", s.handleDocGovListComments)
	mux.HandleFunc("POST /api/v1/docgov/comments", s.handleDocGovAddComment)
	mux.HandleFunc("GET /api/v1/docgov/audit-logs", s.handleDocGovListAuditLogs)

	// 9. 用户认证、安全改密与超级管理员后台接口
	mux.HandleFunc("POST /api/v1/auth/login", s.handleAuthLogin)
	mux.HandleFunc("POST /api/v1/auth/register", s.handleAuthRegister)
	mux.HandleFunc("POST /api/v1/auth/logout", s.handleAuthLogout)
	mux.HandleFunc("POST /api/v1/auth/change-password", s.handleAuthChangePassword)
	mux.HandleFunc("GET /api/v1/auth/me", s.handleAuthMe)
	mux.HandleFunc("GET /api/v1/admin/users", s.handleAdminUsers)
	mux.HandleFunc("POST /api/v1/admin/users", s.handleAdminUsers)
	mux.HandleFunc("PUT /api/v1/admin/users/{id}/role", s.handleAdminUpdateRole)
	mux.HandleFunc("PUT /api/v1/admin/users/{id}/status", s.handleAdminUpdateStatus)
	mux.HandleFunc("GET /api/v1/admin/config", s.handleAdminConfig)
	mux.HandleFunc("PUT /api/v1/admin/config", s.handleAdminConfig)

	// 10. 现代 SPA 前端页面与静态资产托管
	mux.HandleFunc("GET /", s.serveSPA)

	return s.corsMiddleware(mux)
}

// serveSPA 托管 web/dist 静态产物并提供前端路由自动回退
func (s *Server) serveSPA(w http.ResponseWriter, r *http.Request) {
	if strings.HasPrefix(r.URL.Path, "/api/") {
		http.NotFound(w, r)
		return
	}

	candidates := []string{
		"web/dist",
		"../web/dist",
		"../../web/dist",
		filepath.Join(s.cfg.DataDir, "web/dist"),
		filepath.Join(s.cfg.DataDir, "../web/dist"),
	}

	var distDir string
	for _, dir := range candidates {
		if fi, err := os.Stat(filepath.Join(dir, "index.html")); err == nil && !fi.IsDir() {
			distDir = dir
			break
		}
	}

	if distDir == "" {
		http.NotFound(w, r)
		return
	}

	reqPath := filepath.Clean(r.URL.Path)
	if reqPath == "/" {
		http.ServeFile(w, r, filepath.Join(distDir, "index.html"))
		return
	}

	targetFile := filepath.Join(distDir, reqPath)
	if fi, err := os.Stat(targetFile); err == nil && !fi.IsDir() {
		http.ServeFile(w, r, targetFile)
		return
	}

	// SPA Fallback 默认回退 index.html
	http.ServeFile(w, r, filepath.Join(distDir, "index.html"))
}

// Start 启动 HTTP 守护进程
func (s *Server) Start() error {
	addr := fmt.Sprintf("%s:%d", s.cfg.HTTPHost, s.cfg.HTTPPort)
	s.httpServer = &http.Server{
		Addr:              addr,
		Handler:           s.Routes(),
		ReadHeaderTimeout: 10 * time.Second,
	}

	return s.httpServer.ListenAndServe()
}

// Shutdown 优雅停机
func (s *Server) Shutdown(ctx context.Context) error {
	if s.httpServer != nil {
		return s.httpServer.Shutdown(ctx)
	}
	return nil
}

// getOrCreateSession 获取或动态构建会话
func (s *Server) getOrCreateSession(
	sessionID string,
	projectName string,
	customerName string,
	deviceType string,
	intendedUse string,
	targetMarket string,
	workDir string,
	userName string,
	userRole string,
) *chat.Session {
	if sessionID == "" {
		sessionID = fmt.Sprintf("sess_%d", time.Now().UnixNano())
	}

	s.sessionsMu.RLock()
	existing, exists := s.sessions[sessionID]
	s.sessionsMu.RUnlock()
	if exists && existing != nil {
		return existing
	}

	s.sessionsMu.Lock()
	defer s.sessionsMu.Unlock()
	// 双重检查
	if existing, exists := s.sessions[sessionID]; exists && existing != nil {
		return existing
	}

	if userName == "" {
		userName = "用户"
	}
	if userRole == "" {
		userRole = "engineer"
	}

	u := coordinator.UserInfo{
		ID:          "u_" + sessionID,
		Name:        userName,
		Role:        userRole,
		ProjectRole: "composer",
	}

	var userCtx *coordinator.UserProjectContext
	if workDir != "" {
		assembler := coordinator.NewContextAssembler()
		userCtx, _ = assembler.AssembleFromWorkspace(workDir, u)
	}

	if userCtx == nil {
		if projectName == "" {
			projectName = "医疗器械研发项目"
		}
		if customerName == "" {
			customerName = "水木东方客户"
		}
		userCtx = &coordinator.UserProjectContext{
			SnapshotID:  fmt.Sprintf("ctx_%d", time.Now().UnixNano()),
			AssembledAt: time.Now(),
			User:        u,
			WorkDir:     workDir,
			Project: coordinator.ProjectInfo{
				Name:            projectName,
				CustomerName:    customerName,
				DeviceType:      deviceType,
				IntendedUse:     intendedUse,
				TargetMarket:    targetMarket,
				CurrentWorkflow: "intake",
				CurrentStage:    bizdev.StageV01_Triage,
			},
			BlackboardFacts:  make(map[string]string),
			AvailableActions: coordinator.ComputeAvailableActions(bizdev.StageV01_Triage, u.ProjectRole),
		}
		if targetMarket != "" {
			userCtx.BlackboardFacts["target_market"] = targetMarket
		}
		if deviceType != "" {
			userCtx.BlackboardFacts["device_type"] = deviceType
		}
	}

	sess := chat.NewSession(sessionID, userCtx, s.rec, s.engine)
	if s.svc != nil {
		sess.CtxMgr = s.svc.ContextManager()
	}
	s.sessions[sessionID] = sess
	return sess
}

func (s *Server) corsMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS, PUT, DELETE")
		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization, Accept")
		if r.Method == http.MethodOptions {
			w.WriteHeader(http.StatusNoContent)
			return
		}
		next.ServeHTTP(w, r)
	})
}