import { useState, useCallback } from "react";
import { API_URL } from "../config/authConstants";
import { cachePostsFromChats, setPostForChat } from "../stores/chatPostStore";

function authHeaders() {
  return {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${localStorage.getItem("token")}`,
  };
}

export function useChats() {
  const [chats, setChats] = useState([]);
  const [loading, setLoading] = useState(false);

  const fetchChats = useCallback(async () => {
    setLoading(true);
    try {
      const res = await fetch(`${API_URL}/api/v1/chats`, { headers: authHeaders() });
      const data = await res.json();
      // API may return an array directly or a wrapper object like { items: [] } / { content: [] }
      const list = Array.isArray(data) ? data : (data.items ?? data.content ?? []);
      cachePostsFromChats(list);
      setChats(list);
    } finally {
      setLoading(false);
    }
  }, []);

  const createOrGetChat = useCallback(async (otherUserId, postId, postInfo) => {
    const url = new URL(`${API_URL}/api/v1/chats/with/${otherUserId}`);
    if (postId) url.searchParams.set("postId", postId);

    const res = await fetch(url, { method: "POST", headers: authHeaders() });
    if (!res.ok) throw new Error("Не удалось создать чат");
    const chat = await res.json();
    if (postInfo && chat.id) {
      setPostForChat(chat.id, postInfo);
    }
    return chat;
  }, []);

  const fetchMessages = useCallback(async (chatId) => {
    const res = await fetch(`${API_URL}/api/v1/chats/${chatId}/messages`, { headers: authHeaders() });
    const data = await res.json();
    // Normalize: array or wrapper object
    return Array.isArray(data) ? data : (data.items ?? data.content ?? []);
  }, []);

  const markAsRead = useCallback(async (chatId) => {
    try {
      await fetch(`${API_URL}/api/v1/chats/${chatId}/read`, {
        method: "POST",
        headers: authHeaders(),
      });
    } catch (e) {
      console.error("Failed to mark as read:", e);
    }
  }, []);

  return { chats, loading, fetchChats, createOrGetChat, fetchMessages, markAsRead };
}