package server

// chat_unread_api.go — P3 / Step 2 双轨制未读消息与位点推进 API
//
// GET  /api/v1/chat/unread?session_id=...&since_message_id=...
// POST /api/v1/chat/read
//
// user_id 只取自登录 Principal，忽略 query/body 中的身份字段。

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

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

func (s *Server) handleChatUnread(w http.ResponseWriter, r *http.Request) {
	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")
		return
	}

	var sinceID int64
	if sinceStr := r.URL.Query().Get("since_message_id"); sinceStr != "" {
		if id, err := strconv.ParseInt(sinceStr, 10, 64); err == nil {
			sinceID = id
		}
	}

	if s.chatLog == nil {
		writeJSONResponse(w, http.StatusOK, ctxmgr.ChatUnreadSummary{
			Total:            0,
			NextMessageID:    0,
			UnreadMessageIDs: []int64{},
			Items:            []ctxmgr.UnreadDayItem{},
		})
		return
	}

	summary, err := s.chatLog.Unread(r.Context(), s.chatPrincipal(user, chatflow.ActionUnread), chatflow.UnreadQuery{
		SessionID:      sessionID,
		SinceMessageID: sinceID,
	})
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}
	if summary == nil {
		summary = &ctxmgr.ChatUnreadSummary{
			UnreadMessageIDs: []int64{},
			Items:            []ctxmgr.UnreadDayItem{},
		}
	}

	writeJSONResponse(w, http.StatusOK, summary)
}

func (s *Server) handleChatRead(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		writeSafeError(w, r, http.StatusMethodNotAllowed, "method not allowed")
		return
	}

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

	var req ctxmgr.MarkChatReadRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeSafeError(w, r, http.StatusBadRequest, "invalid request body: "+err.Error())
		return
	}
	if req.SessionID == "" {
		writeSafeError(w, r, http.StatusBadRequest, "missing session_id")
		return
	}

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

	pos, err := s.chatLog.MarkRead(r.Context(), s.chatPrincipal(user, chatflow.ActionUnread), req)
	if err != nil {
		s.writeChatLogError(w, err)
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"ok":                   true,
		"session_id":           pos.SessionID,
		"user_id":              pos.UserID,
		"last_read_message_id": pos.LastReadMessageID,
		"dismissed_unread_ids": pos.DismissedUnreadIDs,
		"updated_at":           pos.UpdatedAt,
	})
}