<?php

namespace AdFuz\Services;

use AdFuz\Database\DB;
use AdFuz\Helpers\TableName;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class QueueService {

	/**
	 * Create and record a new background job.
	 *
	 * @param  string $type     Job type identifier (e.g. 'ai_generate_ad', 'stats_export').
	 * @param  array  $payload  Input parameters.
	 * @param  int    $ttlDays  Days until job record expires.
	 * @return array  Created job details including 'job_key'.
	 */
	public static function createJob( string $type, array $payload = array(), int $ttlDays = 7 ): array {
		$now     = current_time( 'mysql' );
		$job_key = sanitize_key( $type ) . '_' . wp_generate_password( 24, false, false );
		$expires = gmdate( 'Y-m-d H:i:s', strtotime( "+{$ttlDays} days", time() ) );

		$jobData = array(
			'job_key'       => $job_key,
			'job_type'      => $type,
			'status'        => 'queued',
			'progress_step' => __( 'Job queued for processing...', 'ad-fuz' ),
			'payload'       => wp_json_encode( $payload ),
			'result'        => null,
			'error_message' => null,
			'created_at'    => $now,
			'started_at'    => null,
			'completed_at'  => null,
			'expires_at'    => $expires,
		);

		try {
			$id            = DB::get( TableName::ADFUZ_JOBS() )->insert( $jobData );
			$jobData['id'] = $id;
		} catch ( \Throwable $e ) {
			// Fallback: Ensure table is created if missing and retry once
			\AdFuz\Database\Migrations\V1_3_1_CreateJobsTable::up();
			$id            = DB::get( TableName::ADFUZ_JOBS() )->insert( $jobData );
			$jobData['id'] = $id;
		}

		return $jobData;
	}

	/**
	 * Dispatch a job to the asynchronous background worker via a non-blocking loopback request.
	 *
	 * @param  string $jobKey
	 */
	public static function dispatch( string $jobKey ): void {
		$token = self::generateToken( $jobKey );

		$url  = admin_url( 'admin-ajax.php' );
		$args = array(
			'timeout'   => 0.01,
			'blocking'  => false,
			'sslverify' => apply_filters( 'https_local_ssl_verify', false ),
			'body'      => array(
				'action'  => 'adfuz_process_job',
				'job_key' => $jobKey,
				'token'   => $token,
			),
		);

		// Force IPv4 if applicable
		AIService::ensureFastCurl();

		wp_remote_post( $url, $args );
	}

	/**
	 * Retrieve a job by its unique job_key.
	 *
	 * @param  string $jobKey
	 * @return array|null
	 */
	public static function getJob( string $jobKey ): ?array {
		$job = DB::get( TableName::ADFUZ_JOBS() )
			->where( 'job_key', $jobKey )
			->first();

		if ( empty( $job ) ) {
			return null;
		}

		if ( ! empty( $job['payload'] ) && is_string( $job['payload'] ) ) {
			$job['payload'] = json_decode( $job['payload'], true ) ?: array();
		}

		if ( ! empty( $job['result'] ) && is_string( $job['result'] ) ) {
			$job['result'] = json_decode( $job['result'], true ) ?: array();
		}

		return $job;
	}

	/**
	 * Update the progress step of an active job.
	 *
	 * @param  string $jobKey
	 * @param  string $stepText
	 */
	public static function updateProgress( string $jobKey, string $stepText ): void {
		$job = DB::get( TableName::ADFUZ_JOBS() )
			->where( 'job_key', $jobKey )
			->first();

		if ( empty( $job ) ) {
			return;
		}

		$update = array(
			'status'        => 'processing',
			'progress_step' => $stepText,
		);

		if ( empty( $job['started_at'] ) ) {
			$update['started_at'] = current_time( 'mysql' );
		}

		DB::get( TableName::ADFUZ_JOBS() )->update( (int) $job['id'], $update );
	}

	/**
	 * Mark a job as completed and store the result payload.
	 *
	 * @param  string $jobKey
	 * @param  array  $result
	 */
	public static function completeJob( string $jobKey, array $result = array() ): void {
		$job = DB::get( TableName::ADFUZ_JOBS() )
			->where( 'job_key', $jobKey )
			->first();

		if ( empty( $job ) ) {
			return;
		}

		DB::get( TableName::ADFUZ_JOBS() )->update(
			(int) $job['id'],
			array(
				'status'        => 'completed',
				'progress_step' => __( 'Completed successfully!', 'ad-fuz' ),
				'result'        => wp_json_encode( $result ),
				'completed_at'  => current_time( 'mysql' ),
				'error_message' => null,
			)
		);
	}

	/**
	 * Mark a job as failed with an error message and optional code.
	 *
	 * @param  string      $jobKey
	 * @param  string      $errorMessage
	 * @param  string|null $errorCode
	 */
	public static function failJob( string $jobKey, string $errorMessage, ?string $errorCode = null ): void {
		$job = DB::get( TableName::ADFUZ_JOBS() )
			->where( 'job_key', $jobKey )
			->first();

		if ( empty( $job ) ) {
			return;
		}

		$result = array(
			'code'    => $errorCode ?: 'job_failed',
			'message' => $errorMessage,
		);

		DB::get( TableName::ADFUZ_JOBS() )->update(
			(int) $job['id'],
			array(
				'status'        => 'failed',
				'progress_step' => __( 'Failed', 'ad-fuz' ),
				'result'        => wp_json_encode( $result ),
				'error_message' => $errorMessage,
				'completed_at'  => current_time( 'mysql' ),
			)
		);
	}

	/**
	 * Generate an internal HMAC verification token for a job.
	 *
	 * @param  string $jobKey
	 * @return string
	 */
	public static function generateToken( string $jobKey ): string {
		$salt = wp_salt( 'auth' );
		return hash_hmac( 'sha256', $jobKey, $salt );
	}

	/**
	 * Verify an internal HMAC token for a job.
	 *
	 * @param  string $jobKey
	 * @param  string $token
	 * @return bool
	 */
	public static function verifyToken( string $jobKey, string $token ): bool {
		$expected = self::generateToken( $jobKey );
		return hash_equals( $expected, $token );
	}
}