import crypto from 'crypto';
import { SystemConfig } from '@/models';
import dbConnect from './dbConnect';

interface AlipayConfig {
    appId: string;
    privateKey: string;
    alipayPublicKey: string;
    gateway: string;
    notifyUrl: string;
    returnUrl?: string;
}

export class AlipayService {
    private config: AlipayConfig | null = null;

    async init() {
        if (this.config) return;

        await dbConnect();
        const systemConfig = await SystemConfig.findOne({ 配置标识: 'default' }).select('+支付宝设置.AppID +支付宝设置.应用私钥 +支付宝设置.公钥 +支付宝设置.网关地址 +支付宝设置.回调URL');

        if (!systemConfig || !systemConfig.支付宝设置) {
            throw new Error('Alipay configuration not found');
        }

        const { AppID, 应用私钥, 公钥, 网关地址, 回调URL } = systemConfig.支付宝设置;

        this.config = {
            appId: AppID,
            privateKey: this.convertBase64ToPem(应用私钥, 'PRIVATE KEY'),
            alipayPublicKey: this.convertBase64ToPem(公钥, 'PUBLIC KEY'),
            gateway: 网关地址 || 'https://openapi.alipay.com/gateway.do',
            notifyUrl: 回调URL
        };
    }

    /**
     * 将 Base64 编码的密钥转换为 PEM 格式
     */
    private convertBase64ToPem(base64Key: string, keyType: 'PRIVATE KEY' | 'PUBLIC KEY'): string {
        // 如果已经是 PEM 格式（包含 BEGIN），直接返回
        if (base64Key.includes('-----BEGIN')) {
            return base64Key;
        }

        // 移除所有空白字符
        const cleanKey = base64Key.replace(/\s/g, '');

        // 每 64 个字符插入一个换行符
        const formattedKey = cleanKey.match(/.{1,64}/g)?.join('\n') || cleanKey;

        return `-----BEGIN ${keyType}-----\n${formattedKey}\n-----END ${keyType}-----`;
    }

    /**
     * Generate Alipay Page Pay URL
     */
    async generatePagePayUrl(order: { outTradeNo: string; totalAmount: string; subject: string; body?: string; returnUrl?: string }) {
        await this.init();
        if (!this.config) throw new Error('Alipay not initialized');

        const params: Record<string, string> = {
            app_id: this.config.appId,
            method: 'alipay.trade.page.pay',
            format: 'JSON',
            charset: 'utf-8',
            sign_type: 'RSA2',
            timestamp: new Date().toISOString().replace('T', ' ').split('.')[0],
            version: '1.0',
            notify_url: `${this.config.notifyUrl}/api/payment/notify`,
            return_url: order.returnUrl || `${this.config.notifyUrl}/api/payment/return`, // 优先使用传入的跳转地址
            biz_content: JSON.stringify({
                out_trade_no: order.outTradeNo,
                product_code: 'FAST_INSTANT_TRADE_PAY',
                total_amount: order.totalAmount,
                subject: order.subject,
                body: order.body,
            }),
        };

        params.sign = this.sign(params);

        const query = Object.keys(params)
            .map((key) => `${key}=${encodeURIComponent(params[key])}`)
            .join('&');

        return `${this.config.gateway}?${query}`;
    }

    /**
     * Verify Alipay Signature
     */
    async verifySignature(params: Record<string, string>): Promise<boolean> {
        await this.init();
        if (!this.config) throw new Error('Alipay not initialized');

        const { sign, sign_type, ...rest } = params;
        if (!sign) return false;

        // Sort and stringify params
        const content = Object.keys(rest)
            .sort()
            .map((key) => {
                const value = rest[key];
                return value !== '' && value !== undefined && value !== null ? `${key}=${value}` : null;
            })
            .filter(Boolean)
            .join('&');

        const verify = crypto.createVerify('RSA-SHA256');
        verify.update(content);

        return verify.verify(this.config.alipayPublicKey, sign, 'base64');
    }

    /**
     * Internal Sign Method
     */
    private sign(params: Record<string, string>): string {
        if (!this.config) throw new Error('Alipay not initialized');

        const content = Object.keys(params)
            .sort()
            .map((key) => {
                const value = params[key];
                return value !== '' && value !== undefined && value !== null ? `${key}=${value}` : null;
            })
            .filter(Boolean)
            .join('&');

        const sign = crypto.createSign('RSA-SHA256');
        sign.update(content);
        return sign.sign(this.config.privateKey, 'base64');
    }
}

export const alipayService = new AlipayService();