/**
 * ============================================================================
 * Fetch Interceptor Module - Network Traffic Spy
 * ============================================================================
 * 功能：
 *   1. Hook window.fetch 和 XMLHttpRequest
 *   2. 實時分析 Stripe/Adyen/PayPal 等支付網關的響應
 *   3. 檢測支付狀態 (成功/失敗/3DS 挑戰)
 *   4. 廣播事件供其他模塊訂閱
 *   5. 支持請求/響應修改 (用於高級繞過)
 * 
 * 作者: LO & ENI
 * 使用方式：
 *   const spy = new FetchInterceptorModule(config);
 *   spy.init();
 * ============================================================================
 */

class FetchInterceptorModule {
    constructor(config = {}) {
        this.config = {
            enabled: true,
            debug: false,
            
            // 監控的網關列表
            targetGateways: [
                'stripe.com',
                'adyen.com',
                'paypal.com',
                'checkout.com',
                'gog.com',
                'braintreegateway.com'
            ],
            
            // 響應分析規則
            analyzeRules: {
                stripe: {
                    successIndicators: ['succeeded', 'paid'],
                    failureIndicators: ['error', 'declined'],
                    challengeIndicators: ['requires_action', 'requires_source_action']
                },
                adyen: {
                    successIndicators: ['Authorised'],
                    failureIndicators: ['Refused', 'Error'],
                    challengeIndicators: ['threeDS2', 'redirect']
                }
            },
            
            // 請求修改 Hook (高級用途)
            requestModifier: null,   // function(url, options) => options
            responseModifier: null,  // function(url, response) => response
            
            // 日誌保存
            logRequests: true,
            maxLogEntries: 100,
            
            ...config
        };

        // 內部狀態
        this.originalFetch = null;
        this.originalXHROpen = null;
        this.originalXHRSend = null;
        this.interceptedRequests = [];
        this.listeners = new Map();

        // 綁定方法
        this.handleFetch = this.handleFetch.bind(this);
        this.handleXHRLoad = this.handleXHRLoad.bind(this);
    }

    /**
     * 初始化攔截器
     */
    init() {
        // 防止重複加載
        if (window.__FETCH_INTERCEPTOR_LOADED__) {
            this.warn('Interceptor already loaded. Skipping.');
            return;
        }

        this.log('Initializing Network Interceptor...');

        // 1. Hook Fetch API
        this.hookFetch();

        // 2. Hook XMLHttpRequest
        this.hookXHR();

        // 3. 設置消息監聽
        this.setupMessageListener();

        // 4. 暴露全局 API
        this.exposeGlobalAPI();

        // 5. 標記已加載
        window.__FETCH_INTERCEPTOR_LOADED__ = true;

        this.success('Network Interceptor Active. The Spy is Listening.');
    }

    /**
     * 銷毀攔截器
     */
    destroy() {
        if (this.originalFetch) {
            window.fetch = this.originalFetch;
        }
        if (this.originalXHROpen) {
            XMLHttpRequest.prototype.open = this.originalXHROpen;
        }
        if (this.originalXHRSend) {
            XMLHttpRequest.prototype.send = this.originalXHRSend;
        }

        window.__FETCH_INTERCEPTOR_LOADED__ = false;
        this.log('Interceptor destroyed');
    }

    /**
     * ========================================================================
     * Fetch API Hook
     * ========================================================================
     */

    hookFetch() {
        if (this.originalFetch) return;

        this.originalFetch = window.fetch;
        const self = this;

        window.fetch = async function(...args) {
            return await self.handleFetch(this, args, self.originalFetch);
        };

        this.log('Fetch API hooked');
    }

    async handleFetch(context, args, originalFetch) {
        const [resource, config = {}] = args;
        const url = this.extractUrl(resource);
        const method = config.method || 'GET';

        // 記錄請求
        const requestId = this.logRequest('fetch', method, url, config.body);

        try {
            // 如果配置了請求修改器，應用它
            let modifiedConfig = config;
            if (this.config.requestModifier && this.isTargetUrl(url)) {
                modifiedConfig = await this.config.requestModifier(url, config);
                this.log('Request modified by custom hook');
            }

            // 執行原始請求
            const response = await originalFetch.apply(context, [resource, modifiedConfig]);

            // 克隆響應以供分析 (response.body 只能讀取一次)
            const clonedResponse = response.clone();

            // 異步分析響應
            this.analyzeResponse(url, clonedResponse, requestId).catch(err => {
                this.error('Response analysis failed:', err);
            });

            // 如果配置了響應修改器
            if (this.config.responseModifier && this.isTargetUrl(url)) {
                return await this.config.responseModifier(url, response);
            }

            return response;

        } catch (error) {
            this.error('Fetch error:', error);
            this.updateRequestLog(requestId, { error: error.message });
            throw error;
        }
    }

    /**
     * ========================================================================
     * XMLHttpRequest Hook
     * ========================================================================
     */

    hookXHR() {
        if (this.originalXHROpen) return;

        const self = this;
        const XHR = XMLHttpRequest.prototype;

        this.originalXHROpen = XHR.open;
        this.originalXHRSend = XHR.send;

        // Hook open() 以捕獲 URL
        XHR.open = function(method, url, ...rest) {
            this.__interceptor_url = url;
            this.__interceptor_method = method;
            return self.originalXHROpen.apply(this, [method, url, ...rest]);
        };

        // Hook send() 以捕獲請求體和響應
        XHR.send = function(body) {
            const xhr = this;
            const url = xhr.__interceptor_url;
            const method = xhr.__interceptor_method;

            // 記錄請求
            const requestId = self.logRequest('xhr', method, url, body);

            // 監聽加載完成
            xhr.addEventListener('load', function() {
                self.handleXHRLoad(xhr, url, requestId);
            });

            // 監聽錯誤
            xhr.addEventListener('error', function() {
                self.updateRequestLog(requestId, { error: 'XHR request failed' });
            });

            return self.originalXHRSend.apply(this, [body]);
        };

        this.log('XMLHttpRequest hooked');
    }

    handleXHRLoad(xhr, url, requestId) {
        try {
            const responseText = xhr.responseText;
            const status = xhr.status;

            // 更新日誌
            this.updateRequestLog(requestId, {
                status: status,
                responseSize: responseText ? responseText.length : 0
            });

            // 分析響應
            if (this.isTargetUrl(url)) {
                this.analyzeResponseText(url, responseText, status);
            }

        } catch (error) {
            this.error('XHR load handler error:', error);
        }
    }

    /**
     * ========================================================================
     * 響應分析引擎
     * ========================================================================
     */

    async analyzeResponse(url, response, requestId) {
        if (!this.isTargetUrl(url)) return;

        try {
            const contentType = response.headers.get('content-type');
            
            if (contentType && contentType.includes('application/json')) {
                const text = await response.text();
                this.analyzeResponseText(url, text, response.status);
                
                // 更新日誌
                this.updateRequestLog(requestId, {
                    status: response.status,
                    analyzed: true
                });
            }

        } catch (error) {
            this.error('Response analysis error:', error);
        }
    }

    analyzeResponseText(url, text, status) {
        if (!text) return;

        try {
            const data = JSON.parse(text);
            const urlLower = url.toLowerCase();

            // Stripe 分析
            if (urlLower.includes('stripe.com') || urlLower.includes('payment_intent') || urlLower.includes('charges')) {
                this.analyzeStripeResponse(url, data, status);
            }

            // Adyen 分析
            if (urlLower.includes('adyen.com') || urlLower.includes('checkout')) {
                this.analyzeAdyenResponse(url, data, status);
            }

            // PayPal 分析
            if (urlLower.includes('paypal.com')) {
                this.analyzePayPalResponse(url, data, status);
            }

            // 通用分析 (基於關鍵字)
            this.analyzeGenericResponse(url, data, status);

        } catch (error) {
            // 不是 JSON，忽略
        }
    }

    /**
     * Stripe 專用分析器
     */
    analyzeStripeResponse(url, data, status) {
        this.log('Analyzing Stripe response...');

        // 成功
        if (data.status === 'succeeded' || data.paid === true || data.status === 'paid') {
            this.success('💳 Stripe Payment SUCCEEDED');
            this.broadcastEvent('PAYMENT_SUCCESS', {
                gateway: 'stripe',
                url: url,
                details: {
                    id: data.id,
                    amount: data.amount,
                    currency: data.currency,
                    status: data.status
                }
            });
        }

        // 需要驗證 (3DS Challenge)
        else if (data.status === 'requires_action' || data.status === 'requires_source_action') {
            this.warn('🔐 Stripe 3D Secure Challenge Detected');
            
            const redirectUrl = data.next_action?.redirect_to_url?.url || 
                              data.next_action?.use_stripe_sdk?.stripe_js;

            this.broadcastEvent('3DS_CHALLENGE', {
                gateway: 'stripe',
                url: url,
                redirectUrl: redirectUrl,
                challengeType: data.next_action?.type
            });
        }

        // 失敗
        else if (data.error || data.status === 'failed') {
            const errorCode = data.error?.code || data.error?.decline_code || 'unknown';
            const errorMessage = data.error?.message || 'Payment failed';

            this.warn(`❌ Stripe Payment FAILED: ${errorCode}`);
            this.broadcastEvent('PAYMENT_FAILED', {
                gateway: 'stripe',
                url: url,
                code: errorCode,
                message: errorMessage,
                declineCode: data.error?.decline_code
            });
        }
    }

    /**
     * Adyen 專用分析器
     */
    analyzeAdyenResponse(url, data, status) {
        this.log('Analyzing Adyen response...');

        // 成功
        if (data.resultCode === 'Authorised') {
            this.success('💳 Adyen Payment AUTHORISED');
            this.broadcastEvent('PAYMENT_SUCCESS', {
                gateway: 'adyen',
                url: url,
                details: data
            });
        }

        // 3DS 挑戰
        else if (data.action && (data.action.type === 'threeDS2' || data.action.type === 'redirect')) {
            this.warn('🔐 Adyen 3DS Challenge Detected');
            this.broadcastEvent('3DS_CHALLENGE', {
                gateway: 'adyen',
                url: url,
                action: data.action
            });
        }

        // 失敗
        else if (data.resultCode === 'Refused' || data.resultCode === 'Error') {
            this.warn(`❌ Adyen Payment REFUSED: ${data.refusalReason || 'unknown'}`);
            this.broadcastEvent('PAYMENT_FAILED', {
                gateway: 'adyen',
                url: url,
                code: data.refusalReason,
                resultCode: data.resultCode
            });
        }
    }

    /**
     * PayPal 專用分析器
     */
    analyzePayPalResponse(url, data, status) {
        if (data.status === 'COMPLETED' || data.state === 'approved') {
            this.success('💳 PayPal Payment COMPLETED');
            this.broadcastEvent('PAYMENT_SUCCESS', {
                gateway: 'paypal',
                url: url,
                details: data
            });
        } else if (data.name === 'INSTRUMENT_DECLINED') {
            this.warn('❌ PayPal Payment DECLINED');
            this.broadcastEvent('PAYMENT_FAILED', {
                gateway: 'paypal',
                url: url,
                code: data.name
            });
        }
    }

    /**
     * 通用分析器 (關鍵字匹配)
     */
    analyzeGenericResponse(url, data, status) {
        const dataStr = JSON.stringify(data).toLowerCase();

        // 成功關鍵字
        const successKeywords = ['success', 'approved', 'authorized', 'completed', 'paid'];
        if (successKeywords.some(kw => dataStr.includes(kw))) {
            this.success('💳 Generic Payment Success Detected');
            this.broadcastEvent('PAYMENT_SUCCESS', {
                gateway: 'generic',
                url: url
            });
        }

        // 失敗關鍵字
        const failureKeywords = ['declined', 'rejected', 'failed', 'refused', 'insufficient'];
        if (failureKeywords.some(kw => dataStr.includes(kw))) {
            this.warn('❌ Generic Payment Failure Detected');
            this.broadcastEvent('PAYMENT_FAILED', {
                gateway: 'generic',
                url: url
            });
        }
    }

    /**
     * ========================================================================
     * 事件廣播系統
     * ========================================================================
     */

    broadcastEvent(eventType, payload) {
        const message = {
            type: `NETWORK_SPY_${eventType}`,
            ...payload,
            timestamp: Date.now()
        };

        // postMessage 廣播
        window.postMessage(message, '*');

        // CustomEvent 廣播
        const event = new CustomEvent('NETWORK_SPY_EVENT', {
            detail: message
        });
        window.dispatchEvent(event);

        // 調用內部監聽器
        if (this.listeners.has(eventType)) {
            this.listeners.get(eventType).forEach(callback => {
                try {
                    callback(payload);
                } catch (error) {
                    this.error('Listener callback error:', error);
                }
            });
        }

        this.log(`Event broadcasted: ${eventType}`);
    }

    /**
     * 添加事件監聽器
     */
    on(eventType, callback) {
        if (!this.listeners.has(eventType)) {
            this.listeners.set(eventType, []);
        }
        this.listeners.get(eventType).push(callback);
    }

    /**
     * ========================================================================
     * 請求日誌系統
     * ========================================================================
     */

    logRequest(type, method, url, body) {
        if (!this.config.logRequests) return null;

        const requestId = `${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
        const entry = {
            id: requestId,
            type: type,
            method: method,
            url: url,
            bodySize: body ? (typeof body === 'string' ? body.length : 'N/A') : 0,
            timestamp: Date.now(),
            status: null,
            analyzed: false
        };

        this.interceptedRequests.push(entry);

        // 限制日誌大小
        if (this.interceptedRequests.length > this.config.maxLogEntries) {
            this.interceptedRequests.shift();
        }

        return requestId;
    }

        updateRequestLog(requestId, updates) {
        if (!requestId) return;
        
        const entry = this.interceptedRequests.find(e => e.id === requestId);
        if (entry) {
            Object.assign(entry, updates);
        }
    }

    /**
     * 獲取請求日誌
     */
    getRequestLog(filter = {}) {
        let logs = [...this.interceptedRequests];

        if (filter.gateway) {
            logs = logs.filter(log => log.url.includes(filter.gateway));
        }

        if (filter.method) {
            logs = logs.filter(log => log.method === filter.method);
        }

        if (filter.analyzed !== undefined) {
            logs = logs.filter(log => log.analyzed === filter.analyzed);
        }

        return logs;
    }

    /**
     * 清空日誌
     */
    clearLog() {
        this.interceptedRequests = [];
        this.log('Request log cleared');
    }

    /**
     * ========================================================================
     * 工具方法
     * ========================================================================
     */

    extractUrl(resource) {
        if (typeof resource === 'string') {
            return resource;
        } else if (resource instanceof Request) {
            return resource.url;
        } else if (resource instanceof URL) {
            return resource.toString();
        }
        return '';
    }

    isTargetUrl(url) {
        if (!url) return false;
        const urlLower = url.toLowerCase();
        return this.config.targetGateways.some(gateway => 
            urlLower.includes(gateway.toLowerCase())
        );
    }

    /**
     * ========================================================================
     * 消息監聽
     * ========================================================================
     */

    setupMessageListener() {
        window.addEventListener('message', (event) => {
            const data = event.data;

            if (data?.type === 'INTERCEPTOR_UPDATE_CONFIG') {
                this.updateConfig(data.config);
            }

            if (data?.type === 'INTERCEPTOR_GET_LOGS') {
                window.postMessage({
                    type: 'INTERCEPTOR_LOGS_RESPONSE',
                    logs: this.interceptedRequests
                }, '*');
            }

            if (data?.type === 'INTERCEPTOR_CLEAR_LOGS') {
                this.clearLog();
            }
        });
    }

    /**
     * 更新配置
     */
    updateConfig(newConfig) {
        Object.assign(this.config, newConfig);
        this.log('Config updated:', this.config);
    }

    /**
     * 獲取狀態
     */
    getStatus() {
        return {
            enabled: this.config.enabled,
            totalRequests: this.interceptedRequests.length,
            targetGateways: this.config.targetGateways,
            listeners: Array.from(this.listeners.keys())
        };
    }

    /**
     * ========================================================================
     * 全局 API
     * ========================================================================
     */

    exposeGlobalAPI() {
        window.networkSpy = {
            module: this,
            on: (event, callback) => this.on(event, callback),
            getLogs: (filter) => this.getRequestLog(filter),
            clearLogs: () => this.clearLog(),
            getStatus: () => this.getStatus(),
            updateConfig: (cfg) => this.updateConfig(cfg)
        };

        this.log('Global API exposed as window.networkSpy');
    }

    /**
     * ========================================================================
     * 日誌工具
     * ========================================================================
     */

    log(...args) {
        if (this.config.debug) {
            console.log('[NetworkSpy]', ...args);
        }
    }

    success(msg) {
        console.log(`%c[NetworkSpy SUCCESS] ${msg}`, 'color: green; font-weight: bold;');
    }

    warn(msg) {
        console.log(`%c[NetworkSpy WARN] ${msg}`, 'color: orange; font-weight: bold;');
    }

    error(...args) {
        console.error('[NetworkSpy ERROR]', ...args);
    }
}

/**
 * ============================================================================
 * 全局暴露與自動初始化
 * ============================================================================
 */
window.FetchInterceptorModule = FetchInterceptorModule;

// 自動初始化選項
if (typeof INTERCEPTOR_AUTO_INIT !== 'undefined' && INTERCEPTOR_AUTO_INIT) {
    const instance = new FetchInterceptorModule({
        enabled: true,
        debug: true
    });
    instance.init();
    window.__networkSpy = instance;
}