/**
 * API 服務層 - 處理所有後端 API 呼叫
 */

const API_BASE_URL = '/api/v1';

class ApiService {
    constructor() {
        this.baseUrl = API_BASE_URL;
    }

    /**
     * 取得認證 Token
     */
    getToken() {
        return localStorage.getItem('token');
    }

    /**
     * 設定認證 Token
     */
    setToken(token) {
        localStorage.setItem('token', token);
    }

    /**
     * 清除認證 Token
     */
    clearToken() {
        localStorage.removeItem('token');
        localStorage.removeItem('user');
    }

    /**
     * 建立請求標頭
     */
    getHeaders(includeAuth = true) {
        const headers = {
            'Content-Type': 'application/json'
        };
        if (includeAuth) {
            const token = this.getToken();
            if (token) {
                headers['Authorization'] = `Bearer ${token}`;
            }
        }
        return headers;
    }

    /**
     * 發送 API 請求
     */
    async request(endpoint, options = {}) {
        const url = `${this.baseUrl}${endpoint}`;
        const config = {
            headers: this.getHeaders(options.auth !== false),
            ...options
        };

        try {
            const response = await fetch(url, config);

            // 處理 401 未授權
            if (response.status === 401) {
                this.clearToken();
                window.location.reload();
                throw new Error('登入已過期，請重新登入');
            }

            // 處理 204 無內容
            if (response.status === 204) {
                return { success: true };
            }

            const data = await response.json();

            if (!response.ok) {
                throw new Error(data.detail || '請求失敗');
            }

            return data;
        } catch (error) {
            console.error('API Error:', error);
            throw error;
        }
    }

    /**
     * GET 請求
     */
    async get(endpoint, params = {}) {
        const queryString = new URLSearchParams(params).toString();
        const url = queryString ? `${endpoint}?${queryString}` : endpoint;
        return this.request(url, { method: 'GET' });
    }

    /**
     * POST 請求
     */
    async post(endpoint, data = {}, options = {}) {
        return this.request(endpoint, {
            method: 'POST',
            body: JSON.stringify(data),
            ...options
        });
    }

    /**
     * PUT 請求
     */
    async put(endpoint, data = {}) {
        return this.request(endpoint, {
            method: 'PUT',
            body: JSON.stringify(data)
        });
    }

    /**
     * DELETE 請求
     */
    async delete(endpoint) {
        return this.request(endpoint, { method: 'DELETE' });
    }

    /**
     * 上傳檔案
     */
    async upload(endpoint, formData) {
        const token = this.getToken();
        const headers = {};
        if (token) {
            headers['Authorization'] = `Bearer ${token}`;
        }

        const response = await fetch(`${this.baseUrl}${endpoint}`, {
            method: 'POST',
            headers,
            body: formData
        });

        if (!response.ok) {
            const data = await response.json();
            throw new Error(data.detail || '上傳失敗');
        }

        return response.json();
    }
}

// 建立全域 API 實例 (必須在其他 API 模組之前)
const api = new ApiService();

// ============ 認證 API ============
const authApi = {
    /**
     * 登入
     */
    async login(username, password, authType = 'local') {
        const response = await api.post('/auth/login', {
            username,
            password,
            auth_type: authType
        }, { auth: false });

        if (response.token) {
            api.setToken(response.token);
            localStorage.setItem('user', JSON.stringify(response.user));
        }
        return response;
    },

    /**
     * 登出
     */
    async logout() {
        try {
            await api.post('/auth/logout');
        } finally {
            api.clearToken();
        }
    },

    /**
     * 取得當前用戶
     */
    async getMe() {
        return api.get('/auth/me');
    },

    /**
     * 檢查是否已登入
     */
    isLoggedIn() {
        return !!api.getToken();
    },

    /**
     * 取得本地儲存的用戶資訊
     */
    getUser() {
        const user = localStorage.getItem('user');
        return user ? JSON.parse(user) : null;
    }
};

// ============ 用戶管理 API ============
const usersApi = {
    /**
     * 取得用戶列表
     */
    async getList(params = {}) {
        return api.get('/users', params);
    },

    /**
     * 取得單一用戶
     */
    async getById(userId) {
        return api.get(`/users/${userId}`);
    },

    /**
     * 建立用戶
     */
    async create(userData) {
        return api.post('/users', userData);
    },

    /**
     * 更新用戶
     */
    async update(userId, userData) {
        return api.put(`/users/${userId}`, userData);
    },

    /**
     * 刪除用戶
     */
    async delete(userId) {
        return api.delete(`/users/${userId}`);
    }
};

// ============ 群組管理 API ============
const groupsApi = {
    /**
     * 取得群組列表
     */
    async getList(params = {}) {
        return api.get('/groups', params);
    },

    /**
     * 取得群組詳情
     */
    async getById(groupId) {
        return api.get(`/groups/${groupId}`);
    },

    /**
     * 建立群組
     */
    async create(groupData) {
        return api.post('/groups', groupData);
    },

    /**
     * 更新群組
     */
    async update(groupId, groupData) {
        return api.put(`/groups/${groupId}`, groupData);
    },

    /**
     * 刪除群組
     */
    async delete(groupId) {
        return api.delete(`/groups/${groupId}`);
    },

    /**
     * 取得群組關鍵字
     */
    async getKeywords(groupId) {
        return api.get(`/groups/${groupId}/keywords`);
    },

    /**
     * 新增關鍵字
     */
    async addKeyword(groupId, keyword) {
        return api.post(`/groups/${groupId}/keywords`, { keyword });
    },

    /**
     * 刪除關鍵字
     */
    async deleteKeyword(groupId, keywordId) {
        return api.delete(`/groups/${groupId}/keywords/${keywordId}`);
    }
};

// ============ 訂閱管理 API ============
const subscriptionsApi = {
    /**
     * 取得我的訂閱
     */
    async getMySubscriptions() {
        return api.get('/subscriptions');
    },

    /**
     * 更新訂閱
     */
    async update(subscriptions) {
        return api.put('/subscriptions', { subscriptions });
    }
};

// ============ 報告管理 API ============
const reportsApi = {
    /**
     * 取得報告列表
     */
    async getList(params = {}) {
        return api.get('/reports', params);
    },

    /**
     * 取得今日報告
     */
    async getToday() {
        return api.get('/reports/today');
    },

    /**
     * 取得報告詳情
     */
    async getById(reportId) {
        return api.get(`/reports/${reportId}`);
    },

    /**
     * 更新報告
     */
    async update(reportId, reportData) {
        return api.put(`/reports/${reportId}`, reportData);
    },

    /**
     * 發布報告
     */
    async publish(reportId) {
        return api.post(`/reports/${reportId}/publish`);
    },

    /**
     * 重新產生 AI 摘要
     */
    async regenerateSummary(reportId) {
        return api.post(`/reports/${reportId}/regenerate-summary`);
    },

    /**
     * 匯出報告 PDF
     */
    async exportPdf(reportId) {
        const token = api.getToken();
        const response = await fetch(`${API_BASE_URL}/reports/${reportId}/export`, {
            headers: {
                'Authorization': `Bearer ${token}`
            }
        });

        if (!response.ok) {
            throw new Error('匯出失敗');
        }

        return response.blob();
    }
};

// ============ 系統設定 API ============
const settingsApi = {
    /**
     * 取得系統設定
     */
    async get() {
        return api.get('/settings');
    },

    /**
     * 更新系統設定
     */
    async update(settings) {
        return api.put('/settings', settings);
    },

    /**
     * 測試 LLM 連線
     */
    async testLlm() {
        return api.post('/settings/llm/test');
    },

    /**
     * 上傳 PDF Logo
     */
    async uploadLogo(file) {
        const formData = new FormData();
        formData.append('logo', file);
        return api.upload('/settings/pdf/logo', formData);
    },

    /**
     * 取得管理員儀表板數據
     */
    async getAdminDashboard() {
        return api.get('/settings/dashboard/admin');
    }
};

// 匯出所有 API 到 window
window.api = api;
window.authApi = authApi;
window.usersApi = usersApi;
window.groupsApi = groupsApi;
window.subscriptionsApi = subscriptionsApi;
window.reportsApi = reportsApi;
window.settingsApi = settingsApi;