/**
 * API客户端 - 处理所有AJAX请求
 */
class APIClient {
    constructor(baseURL = '/api') {
        this.baseURL = baseURL;
        this.defaultHeaders = {
            'Content-Type': 'application/json',
            'Accept': 'application/json'
        };
        this.cache = new Map();
        this.cacheTimeout = 5 * 60 * 1000; // 5分钟缓存
    }

    /**
     * 获取所有数据表列表
     */
    async getTables() {
        const cacheKey = 'tables';
        
        // 检查缓存
        if (this.cache.has(cacheKey)) {
            const cached = this.cache.get(cacheKey);
            if (Date.now() - cached.timestamp < this.cacheTimeout) {
                return cached.data;
            }
        }

        const response = await fetch(`${this.baseURL}/tables`);
        if (!response.ok) throw new Error('Failed to fetch tables');
        
        const data = await response.json();
        this.cache.set(cacheKey, { data, timestamp: Date.now() });
        return data;
    }

    /**
     * 获取数据表数据
     * @param {string} tableAlias - 表别名
     * @param {Object} params - 查询参数
     */
    async getTableData(tableAlias, params = {}) {
        const url = new URL(`${this.baseURL}/data/${tableAlias}`, window.location.origin);
        
        // 添加查询参数
        Object.keys(params).forEach(key => {
            if (params[key] !== undefined && params[key] !== '') {
                url.searchParams.append(key, params[key]);
            }
        });

        const cacheKey = url.toString();
        
        // 检查缓存（搜索参数相关的缓存）
        if (this.cache.has(cacheKey) && !params.search) {
            const cached = this.cache.get(cacheKey);
            if (Date.now() - cached.timestamp < this.cacheTimeout) {
                return cached.data;
            }
        }

        // 使用 AbortController 支持请求取消
        const controller = new AbortController();
        const timeoutId = setTimeout(() => controller.abort(), 10000); // 10秒超时

        try {
            const response = await fetch(url, {
                signal: controller.signal,
                headers: this.defaultHeaders
            });
            
            clearTimeout(timeoutId);
            
            if (!response.ok) throw new Error('Failed to fetch table data');
            
            const data = await response.json();
            
            // 缓存非搜索请求的结果
            if (!params.search) {
                this.cache.set(cacheKey, { data, timestamp: Date.now() });
            }
            
            return data;
        } catch (error) {
            clearTimeout(timeoutId);
            throw error;
        }
    }

    /**
     * 获取数据详情
     * @param {string} tableAlias - 表别名
     * @param {string|number} id - 记录ID
     */
    async getRecordDetail(tableAlias, id) {
        const cacheKey = `detail:${tableAlias}:${id}`;
        
        // 检查缓存
        if (this.cache.has(cacheKey)) {
            const cached = this.cache.get(cacheKey);
            if (Date.now() - cached.timestamp < this.cacheTimeout) {
                return cached.data;
            }
        }

        const controller = new AbortController();
        const timeoutId = setTimeout(() => controller.abort(), 5000);

        try {
            const response = await fetch(`${this.baseURL}/data/${tableAlias}/detail/${id}`, {
                signal: controller.signal
            });
            
            clearTimeout(timeoutId);
            
            if (!response.ok) throw new Error('Failed to fetch record detail');
            
            const data = await response.json();
            this.cache.set(cacheKey, { data, timestamp: Date.now() });
            return data;
        } catch (error) {
            clearTimeout(timeoutId);
            throw error;
        }
    }

    /**
     * 获取可用模板列表
     * @param {string} tableName - 表名
     */
    async getAvailableTemplates(tableName) {
        const cacheKey = `templates:${tableName}`;
        
        // 检查缓存
        if (this.cache.has(cacheKey)) {
            const cached = this.cache.get(cacheKey);
            if (Date.now() - cached.timestamp < this.cacheTimeout) {
                return cached.data;
            }
        }

        const response = await fetch(`/api/templates/${tableName}/available`);
        if (!response.ok) throw new Error('Failed to fetch templates');
        
        const data = await response.json();
        this.cache.set(cacheKey, { data, timestamp: Date.now() });
        return data;
    }

    /**
     * 验证模板
     * @param {string} tableName - 表名
     * @param {string} templateType - 模板类型
     */
    async validateTemplate(tableName, templateType) {
        const response = await fetch(`/api/templates/${tableName}/validate?type=${templateType}`);
        return response.json();
    }

    /**
     * 获取模板预览
     * @param {string} tableName - 表名
     * @param {string} templateType - 模板类型
     */
    async getTemplatePreview(tableName, templateType) {
        const response = await fetch(`/api/templates/${tableName}/preview?type=${templateType}`);
        if (!response.ok) throw new Error('Failed to fetch template preview');
        return response.text();
    }

    /**
     * 清空缓存
     */
    clearCache() {
        this.cache.clear();
    }
}

// 全局API客户端实例
window.apiClient = new APIClient();