import { Injectable, Logger } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { Tenant } from '../../database/entities/tenant.entity';
import {
  PaymentAdapter,
  ChargeContext,
  ChargeResult,
  WebhookResult,
} from './payment-adapter.interface';

/**
 * بوابة MTN للدفع الإلكتروني — MTN Mobile Money / MTN Payment Gateway.
 *
 * تدفق العمل:
 * 1. `POST /api/v1/requestToPay` — طلب دفع من المستخدم.
 * 2. يُرجع `referenceId` — التطبيق يتابع الحالة عبر polling.
 * 3. webhook / polling يؤكد النجاح.
 *
 * الاعتمادات تُقرأ من `tenant.settings.payments.mtn` أولاً، ثم env vars.
 */
@Injectable()
export class MtnAdapter implements PaymentAdapter {
  readonly name = 'mtn';
  private readonly logger = new Logger('MTN');

  constructor(private readonly config: ConfigService) {}

  private get baseUrl(): string {
    return this.config.get<string>('mtn.baseUrl') ?? 'https://proxy.momoapi.mtn.com';
  }

  private creds(tenant: Tenant) {
    const t = tenant?.settings?.payments?.mtn ?? {};
    return {
      apiKey: t.apiKey ?? this.config.get<string>('mtn.apiKey') ?? '',
      apiUser: t.apiUser ?? this.config.get<string>('mtn.apiUser') ?? '',
      subscriptionKey: t.subscriptionKey ?? this.config.get<string>('mtn.subscriptionKey') ?? '',
      environment: t.environment ?? this.config.get<string>('mtn.environment') ?? 'sandbox',
    };
  }

  private async getAccessToken(creds: { apiKey: string; apiUser: string; subscriptionKey: string }): Promise<string> {
    const res = await fetch(`${this.baseUrl}/collection/token/`, {
      method: 'POST',
      headers: {
        Authorization: `Basic ${Buffer.from(`${creds.apiUser}:${creds.apiKey}`).toString('base64')}`,
        'Ocp-Apim-Subscription-Key': creds.subscriptionKey,
      },
    });
    if (!res.ok) throw new Error(`MTN token failed: ${res.status}`);
    const data = await res.json();
    return data.access_token;
  }

  async charge(ctx: ChargeContext, tenant: Tenant): Promise<ChargeResult> {
    const creds = this.creds(tenant);
    if (!creds.apiKey || !creds.apiUser) {
      this.logger.warn('MTN credentials not configured — falling back to invoice');
      return {
        mode: 'invoice',
        reference: `MTN-${ctx.paymentId.slice(0, 8)}-${Date.now().toString(36)}`,
        instructions: 'MTN credentials not configured',
      };
    }

    try {
      const token = await this.getAccessToken(creds);
      const referenceId = ctx.paymentId;

      const res = await fetch(`${this.baseUrl}/collection/v1_0/requestToPay`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          Authorization: `Bearer ${token}`,
          'X-Reference-Id': referenceId,
          'X-Target-Environment': creds.environment,
          'Ocp-Apim-Subscription-Key': creds.subscriptionKey,
        },
        body: JSON.stringify({
          amount: String(ctx.amount),
          currency: ctx.currency,
          externalId: ctx.paymentId,
          payer: { partyIdType: 'MSISDN', partyId: ctx.userPhone ?? '' },
          payerMessage: 'Tripz payment',
          payeeNote: `Payment for trip ${ctx.paymentId}`,
        }),
      });

      if (!res.ok && res.status !== 202) {
        const body = await res.text();
        this.logger.error(`MTN charge failed: ${res.status} ${body}`);
        throw new Error(`MTN API ${res.status}`);
      }

      // MTN يرجع 202 Accepted — التأكيد عبر polling أو webhook.
      return {
        mode: 'redirect',
        redirectUrl: `${this.baseUrl}/collection/v1_0/requestToPay/${referenceId}`,
        providerRef: referenceId,
      };
    } catch (e: any) {
      this.logger.error(`MTN charge error: ${e?.message}`);
      throw e;
    }
  }

  verifyWebhook(headers: Record<string, any>, rawBody: any, tenant: Tenant): boolean {
    const creds = this.creds(tenant);
    const signature = headers['x-mtn-signature'] ?? headers['x-signature'] ?? '';
    if (!signature || !creds.subscriptionKey) return false;

    const { createHmac, timingSafeEqual } = require('crypto');
    const expected = createHmac('sha256', creds.subscriptionKey)
      .update(typeof rawBody === 'string' ? rawBody : JSON.stringify(rawBody))
      .digest('hex');
    try {
      return timingSafeEqual(Buffer.from(signature), Buffer.from(expected));
    } catch {
      return false;
    }
  }

  parseWebhook(payload: any): WebhookResult | null {
    if (!payload) return null;
    const status = payload.status ?? payload.financialTransaction?.status;
    if (!status) return null;
    return {
      providerRef: payload.referenceId ?? payload.externalId ?? '',
      success: status === 'SUCCESSFUL' || status === 'completed',
      amount: payload.amount ? Number(payload.amount) : undefined,
    };
  }
}