<?php
/**
 * Amazon SNS SMS Provider
 *
 * SMS provider implementation for Amazon SNS/SMS
 */
class TWP_SMS_Provider_SNS implements TWP_SMS_Provider {

    private $sns_client;
    private $default_sender_id;

    /**
     * Constructor
     */
    public function __construct() {
        $aws_access_key = get_option('twp_aws_access_key');
        $aws_secret_key = get_option('twp_aws_secret_key');
        $aws_region = get_option('twp_aws_region', 'us-east-1');
        $this->default_sender_id = get_option('twp_aws_sns_sender_id', '');

        // Initialize AWS SNS client if credentials are available
        if (!empty($aws_access_key) && !empty($aws_secret_key)) {
            try {
                // Check if AWS SDK is available
                if (!class_exists('Aws\Sns\SnsClient')) {
                    error_log('TWP SNS Error: AWS SDK not found. Please install via Composer: composer require aws/aws-sdk-php');
                    return;
                }

                $this->sns_client = new Aws\Sns\SnsClient([
                    'version' => 'latest',
                    'region' => $aws_region,
                    'credentials' => [
                        'key' => $aws_access_key,
                        'secret' => $aws_secret_key
                    ]
                ]);
            } catch (Exception $e) {
                error_log('TWP SNS Error: Failed to initialize SNS client: ' . $e->getMessage());
            }
        }
    }

    /**
     * Send an SMS message
     *
     * @param string $to_number Recipient phone number (E.164 format)
     * @param string $message Message body
     * @param string $from_number Sender phone number or Sender ID (not used by SNS in the same way)
     * @return array Response array with 'success' and 'data' or 'error'
     */
    public function send_sms($to_number, $message, $from_number = null) {
        try {
            if (!$this->sns_client) {
                return [
                    'success' => false,
                    'error' => 'AWS SNS client not initialized. Check AWS credentials and ensure AWS SDK is installed.'
                ];
            }

            // Prepare message attributes
            $message_attributes = [
                'AWS.SNS.SMS.SMSType' => [
                    'DataType' => 'String',
                    'StringValue' => 'Transactional' // Transactional for higher reliability
                ]
            ];

            // Use sender ID if provided or use default
            $sender_id = $from_number ?: $this->default_sender_id;
            if (!empty($sender_id)) {
                // Remove '+' and non-alphanumeric characters for Sender ID
                // Note: Sender ID is alphanumeric (3-11 chars) in many countries
                $sender_id_clean = preg_replace('/[^a-zA-Z0-9]/', '', $sender_id);
                if (strlen($sender_id_clean) >= 3 && strlen($sender_id_clean) <= 11) {
                    $message_attributes['AWS.SNS.SMS.SenderID'] = [
                        'DataType' => 'String',
                        'StringValue' => $sender_id_clean
                    ];
                }
            }

            // Send SMS via SNS
            $result = $this->sns_client->publish([
                'Message' => $message,
                'PhoneNumber' => $to_number,
                'MessageAttributes' => $message_attributes
            ]);

            return [
                'success' => true,
                'provider' => 'aws_sns',
                'data' => [
                    'message_id' => $result['MessageId'],
                    'to' => $to_number,
                    'body' => $message,
                    'sender_id' => !empty($sender_id_clean) ? $sender_id_clean : null
                ]
            ];
        } catch (Aws\Exception\AwsException $e) {
            return [
                'success' => false,
                'provider' => 'aws_sns',
                'error' => $e->getAwsErrorMessage(),
                'code' => $e->getAwsErrorCode()
            ];
        } catch (Exception $e) {
            return [
                'success' => false,
                'provider' => 'aws_sns',
                'error' => $e->getMessage()
            ];
        }
    }

    /**
     * Get provider name
     *
     * @return string Provider name
     */
    public function get_provider_name() {
        return 'Amazon SNS';
    }

    /**
     * Validate provider configuration
     *
     * @return array Response array with 'success' and 'message' or 'error'
     */
    public function validate_configuration() {
        // Check if AWS SDK is available
        if (!class_exists('Aws\Sns\SnsClient')) {
            return [
                'success' => false,
                'error' => 'AWS SDK not installed. Please run: composer require aws/aws-sdk-php'
            ];
        }

        $aws_access_key = get_option('twp_aws_access_key');
        $aws_secret_key = get_option('twp_aws_secret_key');
        $aws_region = get_option('twp_aws_region');

        if (empty($aws_access_key)) {
            return [
                'success' => false,
                'error' => 'AWS Access Key is not configured'
            ];
        }

        if (empty($aws_secret_key)) {
            return [
                'success' => false,
                'error' => 'AWS Secret Key is not configured'
            ];
        }

        if (empty($aws_region)) {
            return [
                'success' => false,
                'error' => 'AWS Region is not configured'
            ];
        }

        if (!$this->sns_client) {
            return [
                'success' => false,
                'error' => 'Failed to initialize AWS SNS client'
            ];
        }

        return [
            'success' => true,
            'message' => 'Amazon SNS SMS provider is properly configured'
        ];
    }

    /**
     * Set SMS spending limit (optional administrative function)
     *
     * @param float $monthly_limit Monthly spending limit in USD
     * @return array Response array
     */
    public function set_spending_limit($monthly_limit) {
        try {
            if (!$this->sns_client) {
                return ['success' => false, 'error' => 'SNS client not initialized'];
            }

            $this->sns_client->setSMSAttributes([
                'attributes' => [
                    'MonthlySpendLimit' => (string)$monthly_limit
                ]
            ]);

            return [
                'success' => true,
                'message' => "SMS spending limit set to \$$monthly_limit per month"
            ];
        } catch (Exception $e) {
            return [
                'success' => false,
                'error' => $e->getMessage()
            ];
        }
    }
}