import { Injectable, Logger } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

@Injectable()
export class SmsService {
    private readonly logger = new Logger(SmsService.name);

    constructor(private configService: ConfigService) {}

    /**
     * Send OTP via SMS
     * @param countryCode - Country code (e.g., +1, +91)
     * @param phoneNumber - Phone number
     * @param otp - OTP code to send
     */
    async sendOTP(countryCode: string, phoneNumber: string, otp: string): Promise<boolean> {
        try {
            const fullNumber = `${countryCode}${phoneNumber}`;
            
            this.logger.log(`Sending OTP to ${fullNumber}: ${otp}`);

            // TODO: Integrate with actual SMS provider (Twilio, AWS SNS, etc.)
            // Example with Twilio:
            // const twilio = require('twilio');
            // const client = new twilio(
            //     this.configService.get('TWILIO_ACCOUNT_SID'),
            //     this.configService.get('TWILIO_AUTH_TOKEN')
            // );
            // await client.messages.create({
            //     body: `Your OTP is: ${otp}`,
            //     from: this.configService.get('TWILIO_PHONE_NUMBER'),
            //     to: fullNumber
            // });

            // Dummy SMS sending (simulate API call)
            await this.sendDummySMS(fullNumber, otp);

            this.logger.log(`OTP sent successfully to ${fullNumber}`);
            return true;
        } catch (error) {
            this.logger.error(`Failed to send OTP to ${phoneNumber}`, error.stack);
            throw error;
        }
    }

    /**
     * Send custom message via SMS
     * @param countryCode - Country code
     * @param phoneNumber - Phone number
     * @param message - Message to send
     */
    async sendMessage(countryCode: string, phoneNumber: string, message: string): Promise<boolean> {
        try {
            const fullNumber = `${countryCode}${phoneNumber}`;
            
            this.logger.log(`Sending SMS to ${fullNumber}: ${message}`);

            // TODO: Integrate with actual SMS provider
            // await this.sendViaProvider(fullNumber, message);

            // Dummy SMS sending
            await this.sendDummySMS(fullNumber, undefined, message);

            this.logger.log(`SMS sent successfully to ${fullNumber}`);
            return true;
        } catch (error) {
            this.logger.error(`Failed to send SMS to ${phoneNumber}`, error.stack);
            throw error;
        }
    }

    /**
     * Dummy SMS sending function (for development/testing)
     * Replace this with actual SMS provider integration
     */
    private async sendDummySMS(phoneNumber: string, otp?: string, message?: string): Promise<void> {
        // Simulate API delay
        await new Promise(resolve => setTimeout(resolve, 1000));

        const smsContent = otp 
            ? `Your OTP is: ${otp}` 
            : message;

        this.logger.log('========== DUMMY SMS ==========');
        this.logger.log(`To: ${phoneNumber}`);
        this.logger.log(`Message: ${smsContent}`);
        this.logger.log('================================');

        // TODO: Replace with actual SMS API call
        // Example HTTP request:
        // const response = await fetch('https://api.sms-provider.com/send', {
        //     method: 'POST',
        //     headers: {
        //         'Content-Type': 'application/json',
        //         'Authorization': `Bearer ${this.configService.get('SMS_API_KEY')}`
        //     },
        //     body: JSON.stringify({
        //         to: phoneNumber,
        //         message: smsContent
        //     })
        // });
        // 
        // if (!response.ok) {
        //     throw new Error('Failed to send SMS');
        // }
    }
}