import { BotContext } from '../types/botTypes';
import axios from 'axios';
import { createLogger } from '../../utils/logger';

const logger = createLogger('PayPalService');

// PayPal API Response Types
interface PayPalLink {
  href: string;
  rel: string;
  method: string;
}

interface PayPalOrder {
  id: string;
  status: string;
  links: PayPalLink[];
}

interface PayPalTokenResponse {
  access_token: string;
  token_type: string;
  expires_in: number;
}

export class PayPalService {
  private static instance: PayPalService;
  private readonly clientId: string;
  private readonly clientSecret: string;
  private readonly isProduction: boolean;

  private constructor(ctx: BotContext) {
    this.clientId = ctx.botData?.paypal_client_id || '';
    this.clientSecret = ctx.botData?.paypal_client_secret || '';
    this.isProduction = ctx.botData?.settings?.paypal_environment === 'production';
  }

  public static getInstance(ctx: BotContext): PayPalService {
    if (!PayPalService.instance) {
      PayPalService.instance = new PayPalService(ctx);
    }
    return PayPalService.instance;
  }

  async createPaymentLink(userId: string, amount: number): Promise<string> {
    try {
      const accessToken = await this.getAccessToken();
      const order = await this.createPayPalOrder(amount, userId);
      
      // Find the approval URL from the order links
      const approvalLink = order.links.find(link => link.rel === 'approve');
      if (!approvalLink) {
        throw new Error('No approval URL found in PayPal order');
      }
      
      return approvalLink.href;
    } catch (error: any) {
      logger.error(`Error creating PayPal payment link: ${error.message}`);
      throw new Error(`Failed to create payment link: ${error.message}`);
    }
  }

  private async createPayPalOrder(amount: number, paymentId: string): Promise<PayPalOrder> {
    try {
      const accessToken = await this.getAccessToken();
      const baseUrl = this.isProduction 
        ? 'https://api-m.paypal.com' 
        : 'https://api-m.sandbox.paypal.com';

      const response = await axios.post(
        `${baseUrl}/v2/checkout/orders`,
        {
          intent: 'CAPTURE',
          purchase_units: [{
            amount: {
              currency_code: 'USD',
              value: amount.toString()
            },
            custom_id: paymentId
          }]
        },
        {
          headers: {
            'Authorization': `Bearer ${accessToken}`,
            'Content-Type': 'application/json'
          }
        }
      );

      return response.data;
    } catch (error: any) {
      logger.error(`Error creating PayPal order: ${error.message}`);
      throw new Error(`Failed to create PayPal order: ${error.message}`);
    }
  }

  private async getAccessToken(): Promise<string> {
    try {
      const baseUrl = this.isProduction 
        ? 'https://api-m.paypal.com' 
        : 'https://api-m.sandbox.paypal.com';

      const response = await axios.post(
        `${baseUrl}/v1/oauth2/token`,
        'grant_type=client_credentials',
        {
          headers: {
            'Authorization': `Basic ${Buffer.from(`${this.clientId}:${this.clientSecret}`).toString('base64')}`,
            'Content-Type': 'application/x-www-form-urlencoded'
          }
        }
      );

      const data = response.data as PayPalTokenResponse;
      return data.access_token;
    } catch (error: any) {
      logger.error(`Error getting PayPal access token: ${error.message}`);
      throw new Error(`Failed to get PayPal access token: ${error.message}`);
    }
  }
}