package server

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

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

// handleGetChatTurn 查询回合状态（断线续接）
func (s *Server) handleGetChatTurn(w http.ResponseWriter, r *http.Request) {
	user, ok := s.requirePrincipal(w, r)
	if !ok {
		return
	}
	clientTurnID := r.PathValue("client_turn_id")
	sessionID := r.URL.Query().Get("session_id")
	if clientTurnID == "" || sessionID == "" {
		writeSafeError(w, r, http.StatusBadRequest, "client_turn_id and session_id required")
		return
	}

	ctxMgr := s.ctxMgr()
	if ctxMgr == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "context manager unavailable")
		return
	}

	// 归属校验：只允许查询本人会话的回合状态
	if !s.assertSessionOwnedByUser(w, r, sessionID, user.ID) {
		return
	}

	rec, err := ctxMgr.GetChatTurn(r.Context(), sessionID, clientTurnID)
	if errors.Is(err, ctxmgr.ErrChatTurnNotFound) {
		writeSafeError(w, r, http.StatusNotFound, "turn not found")
		return
	}
	if err != nil {
		writeDomainError(w, r, http.StatusInternalServerError, err)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(map[string]any{
		"session_id":           rec.SessionID,
		"client_turn_id":       rec.ClientTurnID,
		"status":               rec.Status,
		"user_message_id":      rec.UserMessageID,
		"assistant_message_id": rec.AssistantMessageID,
		"attempt_count":        rec.AttemptCount,
	})
}