package server

import (
	"encoding/json"
	"net/http"
	"os"
	"strconv"

	"chat-agent-system/internal/ctxmgr"
)

// handleGetChatWindow 获取指定会话最近 N 日的消息窗口
// GET /api/v1/chat/messages/window?session_id=&days=&before_day=
func (s *Server) handleGetChatWindow(w http.ResponseWriter, r *http.Request) {
	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	user, ok := s.requireAuthenticatedUser(w, r)
	if !ok {
		return
	}

	sessionID := r.URL.Query().Get("session_id")
	if sessionID == "" {
		http.Error(w, "missing session_id query param", http.StatusBadRequest)
		return
	}

	daysStr := r.URL.Query().Get("days")
	days, _ := strconv.Atoi(daysStr)
	if days <= 0 {
		days = ctxmgr.DefaultWindowDays
	}
	beforeDay := r.URL.Query().Get("before_day")

	res, err := s.svc.ContextManager().GetChatWindow(r.Context(), ctxmgr.ChatWindowQuery{
		SessionID: sessionID,
		Days:      days,
		BeforeDay: beforeDay,
	})
	if err != nil {
		http.Error(w, "get chat window failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	if projectID, pidErr := s.svc.ContextManager().GetSessionProjectID(r.Context(), sessionID); pidErr == nil && projectID > 0 {
		s.applyChatWindowStageFilter(r.Context(), projectID, user.ID, res)
	}

	writeJSONResponse(w, http.StatusOK, res)
}

// handleGetChatDayMessages 获取指定日消息 (支持 anchor_id 上下文补齐或游标分页)
// GET /api/v1/chat/messages/day?session_id=&date=&anchor_id=&before_id=&after_id=&limit=
func (s *Server) handleGetChatDayMessages(w http.ResponseWriter, r *http.Request) {
	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	user, ok := s.requireAuthenticatedUser(w, r)
	if !ok {
		return
	}

	sessionID := r.URL.Query().Get("session_id")
	if sessionID == "" {
		http.Error(w, "missing session_id query param", http.StatusBadRequest)
		return
	}
	date := r.URL.Query().Get("date")
	if date == "" {
		date = r.URL.Query().Get("day_key")
	}

	anchorIDStr := r.URL.Query().Get("anchor_id")
	anchorID, _ := strconv.ParseInt(anchorIDStr, 10, 64)

	if date == "" && anchorID <= 0 {
		http.Error(w, "missing date/day_key or anchor_id query param", http.StatusBadRequest)
		return
	}

	beforeIDStr := r.URL.Query().Get("before_id")
	beforeID, _ := strconv.ParseInt(beforeIDStr, 10, 64)

	afterIDStr := r.URL.Query().Get("after_id")
	afterID, _ := strconv.ParseInt(afterIDStr, 10, 64)

	limitStr := r.URL.Query().Get("limit")
	limit, _ := strconv.Atoi(limitStr)
	if limit <= 0 {
		limit = 100
	}

	res, err := s.svc.ContextManager().GetChatDayMessages(r.Context(), sessionID, date, anchorID, beforeID, afterID, limit)
	if err != nil {
		http.Error(w, "get chat day messages failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	if projectID, pidErr := s.svc.ContextManager().GetSessionProjectID(r.Context(), sessionID); pidErr == nil && projectID > 0 {
		res.Messages = s.filterChatMessagesByStageAccess(r.Context(), projectID, user.ID, res.Messages)
	}

	writeJSONResponse(w, http.StatusOK, res)
}

// handleListChatDates 列出会话有消息的全部日期 (用于日历打点)
// GET /api/v1/chat/dates?session_id=
func (s *Server) handleListChatDates(w http.ResponseWriter, r *http.Request) {
	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	sessionID := r.URL.Query().Get("session_id")
	if sessionID == "" {
		http.Error(w, "missing session_id query param", http.StatusBadRequest)
		return
	}

	stats, err := s.svc.ContextManager().ListChatDates(r.Context(), sessionID)
	if err != nil {
		http.Error(w, "list chat dates failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	writeJSONResponse(w, http.StatusOK, stats)
}

// handleListChatCategories 列出会话各分类消息统计 (用于分类筛选条)
// GET /api/v1/chat/categories?session_id=
func (s *Server) handleListChatCategories(w http.ResponseWriter, r *http.Request) {
	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	sessionID := r.URL.Query().Get("session_id")
	if sessionID == "" {
		http.Error(w, "missing session_id query param", http.StatusBadRequest)
		return
	}

	stats, err := s.svc.ContextManager().ListChatCategories(r.Context(), sessionID)
	if err != nil {
		http.Error(w, "list chat categories failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	writeJSONResponse(w, http.StatusOK, stats)
}

// handleImportChatMessages 一次性批量回填历史消息 (仅允许在 dev/demo 环境下调用)
// POST /api/v1/chat/messages/import
func (s *Server) handleImportChatMessages(w http.ResponseWriter, r *http.Request) {
	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	// 安全门禁：生产环境默认禁止调用，仅在 dev 或显式开启时开放
	isDev := s.cfg.Env == "dev" || s.cfg.Env == "development" || s.cfg.Env == "" || os.Getenv("ENABLE_DEV_IMPORT") == "true"
	if !isDev {
		http.Error(w, "chat messages import endpoint is only available in dev/demo environment", http.StatusForbidden)
		return
	}

	type importMessageItem struct {
		SessionID string         `json:"session_id"`
		UserID    int64          `json:"user_id"`
		Role      string         `json:"role"`
		Content   string         `json:"content"`
		Intent    string         `json:"intent"`
		Branch    string         `json:"branch"`
		Metadata  map[string]any `json:"metadata"`
		DayKey    string         `json:"day_key"`
		CreatedAt string         `json:"created_at"`
	}

	var items []importMessageItem
	if err := json.NewDecoder(r.Body).Decode(&items); err != nil {
		http.Error(w, "invalid request body: "+err.Error(), http.StatusBadRequest)
		return
	}

	imported := 0
	for _, item := range items {
		if item.SessionID == "" || item.Content == "" {
			continue
		}
		if item.Metadata == nil {
			item.Metadata = make(map[string]any)
		}
		if item.DayKey != "" {
			item.Metadata["day_key"] = item.DayKey
		}
		if item.CreatedAt != "" {
			item.Metadata["created_at"] = item.CreatedAt
		}

		_, err := s.svc.ContextManager().RecordUserMessageWithID(
			r.Context(),
			item.SessionID,
			item.UserID,
			item.Role,
			item.Content,
			item.Intent,
			item.Branch,
			item.Metadata,
		)
		if err == nil {
			imported++
		}
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"imported_count": imported,
		"total":          len(items),
	})
}