/**
 * API模块 - 封装所有后端API调用
 */
const API = (function() {
    const BASE_URL = '/api';
    
    // 通用请求方法
    async function request(url, options = {}) {
        const defaultOptions = {
            headers: {
                'Content-Type': 'application/json'
            }
        };
        
        const config = { ...defaultOptions, ...options };
        
        try {
            const response = await fetch(BASE_URL + url, config);
            
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            
            // 204 No Content
            if (response.status === 204) {
                return null;
            }
            
            return await response.json();
        } catch (error) {
            console.error('API请求失败:', error);
            throw error;
        }
    }
    
    // GET请求
    function get(url, params = {}) {
        const queryString = new URLSearchParams(params).toString();
        const fullUrl = queryString ? `${url}?${queryString}` : url;
        return request(fullUrl);
    }
    
    // POST请求
    function post(url, data) {
        return request(url, {
            method: 'POST',
            body: JSON.stringify(data)
        });
    }
    
    // DELETE请求
    function del(url, params = {}) {
        const queryString = new URLSearchParams(params).toString();
        const fullUrl = queryString ? `${url}?${queryString}` : url;
        return request(fullUrl, { method: 'DELETE' });
    }
    
    // ========== 小说相关API ==========
    
    /**
     * 搜索小说
     * @param {Object} params - { keyword, tag, page, size }
     */
    function searchNovels(params = {}) {
        return get('/novels', params);
    }
    
    /**
     * 获取小说详情
     * @param {string} novelId
     */
    function getNovelDetail(novelId) {
        return get(`/novels/${novelId}`);
    }
    
    /**
     * 获取章节列表
     * @param {string} novelId
     * @param {Object} params - { page, size }
     */
    function getChapters(novelId, params = {}) {
        return get(`/novels/${novelId}/chapters`, params);
    }
    
    /**
     * 获取热门标签
     * @param {number} limit
     */
    function getPopularTags(limit = 20) {
        return get('/novels/tags/popular', { limit });
    }

    /**
     * 随机获取小说
     * @param {number} size 数量
     */
    function getRandomNovels(size = 10) {
        return get('/novels/random', { size });
    }
    
    // ========== 章节相关API ==========
    
    /**
     * 根据章节ID获取内容
     * @param {string} chapterId
     */
    function getChapterById(chapterId) {
        return get(`/chapters/${chapterId}`);
    }
    
    /**
     * 根据小说ID和索引获取章节
     * @param {string} novelId
     * @param {number} index
     */
    function getChapterByIndex(novelId, index) {
        return get(`/chapters/novel/${novelId}`, { index });
    }
    
    /**
     * 获取下一章
     * @param {string} novelId
     * @param {number} currentIndex
     */
    function getNextChapter(novelId, currentIndex) {
        return get(`/chapters/novel/${novelId}/next`, { currentIndex });
    }
    
    /**
     * 获取上一章
     * @param {string} novelId
     * @param {number} currentIndex
     */
    function getPrevChapter(novelId, currentIndex) {
        return get(`/chapters/novel/${novelId}/prev`, { currentIndex });
    }
    
    /**
     * 获取第一章
     * @param {string} novelId
     */
    function getFirstChapter(novelId) {
        return get(`/chapters/novel/${novelId}/first`);
    }
    
    // ========== 书架相关API ==========
    
    /**
     * 获取书架列表
     * @param {Object} params - { userId, page, size }
     */
    function getShelf(params = {}) {
        return get('/shelf', params);
    }
    
    /**
     * 加入书架
     * @param {Object} data - { userId, novelId, tags }
     */
    function addToShelf(data) {
        return post('/shelf', data);
    }
    
    /**
     * 从书架移除
     * @param {string} novelId
     * @param {string} userId
     */
    function removeFromShelf(novelId, userId) {
        return del(`/shelf/${novelId}`, userId ? { userId } : {});
    }
    
    /**
     * 检查是否在书架
     * @param {string} novelId
     * @param {string} userId
     */
    function isInShelf(novelId, userId) {
        return get(`/shelf/${novelId}/exists`, userId ? { userId } : {});
    }
    
    // ========== 历史相关API ==========
    
    /**
     * 获取阅读历史
     * @param {Object} params - { userId, page, size }
     */
    function getHistory(params = {}) {
        return get('/history', params);
    }
    
    /**
     * 获取某本书的历史进度
     * @param {string} novelId
     * @param {string} userId
     */
    function getHistoryByNovel(novelId, userId) {
        return get(`/history/novel/${novelId}`, userId ? { userId } : {});
    }
    
    /**
     * 更新阅读进度
     * @param {Object} data - { userId, novelId, chapterId, position }
     */
    function updateHistory(data) {
        return post('/history', data);
    }
    
    /**
     * 删除历史记录
     * @param {string} novelId
     * @param {string} userId
     */
    function deleteHistory(novelId, userId) {
        return del(`/history/novel/${novelId}`, userId ? { userId } : {});
    }
    
    // ========== 书签相关API ==========
    
    /**
     * 获取书签列表
     * @param {Object} params - { userId, page, size }
     */
    function getBookmarks(params = {}) {
        return get('/bookmarks', params);
    }
    
    /**
     * 获取某本书的书签
     * @param {string} novelId
     * @param {string} userId
     */
    function getBookmarksByNovel(novelId, userId) {
        return get(`/bookmarks/novel/${novelId}`, userId ? { userId } : {});
    }
    
    /**
     * 创建书签
     * @param {Object} data - { userId, novelId, chapterId, position, note }
     */
    function createBookmark(data) {
        return post('/bookmarks', data);
    }
    
    /**
     * 删除书签
     * @param {string} bookmarkId
     * @param {string} userId
     */
    function deleteBookmark(bookmarkId, userId) {
        return del(`/bookmarks/${bookmarkId}`, userId ? { userId } : {});
    }
    
    // 公开API
    return {
        // 小说
        searchNovels,
        getNovelDetail,
        getChapters,
        getPopularTags,
        getRandomNovels,
        
        // 章节
        getChapterById,
        getChapterByIndex,
        getNextChapter,
        getPrevChapter,
        getFirstChapter,
        
        // 书架
        getShelf,
        addToShelf,
        removeFromShelf,
        isInShelf,
        
        // 历史
        getHistory,
        getHistoryByNovel,
        updateHistory,
        deleteHistory,
        
        // 书签
        getBookmarks,
        getBookmarksByNovel,
        createBookmark,
        deleteBookmark
    };
})();