package server

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

	"chat-agent-system/internal/app/chatflow"
	"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.chatLog == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager not initialized")
		return
	}

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

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

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

	res, err := s.chatLog.GetWindow(r.Context(), s.chatPrincipal(user, chatflow.ActionReadWindow), ctxmgr.ChatWindowQuery{
		SessionID: sessionID,
		Days:      days,
		BeforeDay: r.URL.Query().Get("before_day"),
	})
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}

	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.chatLog == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager not initialized")
		return
	}

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

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

	beforeID, _ := strconv.ParseInt(r.URL.Query().Get("before_id"), 10, 64)
	afterID, _ := strconv.ParseInt(r.URL.Query().Get("after_id"), 10, 64)
	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
	if limit <= 0 {
		limit = 100
	}

	res, err := s.chatLog.GetDay(r.Context(), s.chatPrincipal(user, chatflow.ActionReadDay), chatflow.DayQuery{
		SessionID: sessionID,
		Date:      date,
		AnchorID:  anchorID,
		BeforeID:  beforeID,
		AfterID:   afterID,
		Limit:     limit,
	})
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}

	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.chatLog == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager not initialized")
		return
	}

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

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

	res, err := s.chatLog.DateStats(r.Context(), s.chatPrincipal(user, chatflow.ActionReadStats), sessionID)
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}

	writeJSONResponse(w, http.StatusOK, res)
}

// 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.chatLog == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager not initialized")
		return
	}

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

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

	res, err := s.chatLog.CategoryStats(r.Context(), s.chatPrincipal(user, chatflow.ActionReadStats), sessionID)
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}

	writeJSONResponse(w, http.StatusOK, res)
}

// 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.ctxMgr() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager not initialized")
		return
	}

	// 安全门禁：生产环境默认禁止调用，仅在显式 dev 或 ENABLE_DEV_IMPORT 时开放
	isDev := s.cfg.Env == "dev" || s.cfg.Env == "development" || os.Getenv("ENABLE_DEV_IMPORT") == "true"
	if !isDev {
		writeSafeError(w, r, http.StatusForbidden, "chat messages import endpoint is only available in dev/demo environment")
		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 {
		writeDomainError(w, r, http.StatusBadRequest, err)
		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.ctxMgr().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),
	})
}