package server

// chat_export_api.go — P3 聊天记录导出查询 API
//
// GET /api/v1/chat/export/messages?session_id=...&date_from=...&date_to=...&category=...
//
// 返回按条件过滤后的消息列表，支持客户端导出为 docx/xlsx 等格式。

import (
	"net/http"
	"strings"

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

func (s *Server) handleChatExportMessages(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
		return
	}

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

	if s.svc == nil || s.svc.ContextManager() == nil {
		http.Error(w, "context manager not initialized", http.StatusServiceUnavailable)
		return
	}

	dateFrom := strings.TrimSpace(r.URL.Query().Get("date_from"))
	dateTo := strings.TrimSpace(r.URL.Query().Get("date_to"))
	category := strings.TrimSpace(r.URL.Query().Get("category"))

	// 查询该会话的历史消息（上限 5000 条）
	msgs, err := s.svc.ContextManager().GetChatHistory(r.Context(), sessionID, 5000, 0)
	if err != nil {
		http.Error(w, "query chat history failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	// 过滤
	filtered := make([]ctxmgr.ChatMessageRecord, 0, len(msgs))
	for _, m := range msgs {
		dk := m.DayKey
		if dk == "" && !m.CreatedAt.IsZero() {
			dk = m.CreatedAt.Format("2006-01-02")
		}

		if dateFrom != "" && dk < dateFrom {
			continue
		}
		if dateTo != "" && dk > dateTo {
			continue
		}
		if category != "" && category != "all" && m.Category != category {
			continue
		}

		filtered = append(filtered, m)
	}

	writeJSONResponse(w, http.StatusOK, filtered)
}