<?php
/**
 * Listening Tracker AJAX Handler.
 *
 * Handles AJAX requests for listening tracking and statistics.
 *
 * @package Accessibility_Audio_TTS\Handlers
 */

namespace Accessibility_Audio_TTS\Handlers;

use Accessibility_Audio_TTS\Admin\Listening_Statistics;

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

/**
 * Processes AJAX requests for listening statistics.
 */
class Listening_Tracker_Ajax {

	/**
	 * Listening statistics service.
	 *
	 * @var Listening_Statistics
	 */
	private $listening_stats;

	/**
	 * Constructor.
	 */
	public function __construct() {
		$this->listening_stats = new Listening_Statistics();

		// Register AJAX hooks.
		add_action( 'wp_ajax_accessibility_audio_tts_track_listening', array( $this, 'handle_track_listening' ) );
		add_action( 'wp_ajax_nopriv_accessibility_audio_tts_track_listening', array( $this, 'handle_track_listening' ) );

		add_action( 'wp_ajax_accessibility_audio_tts_get_post_stats', array( $this, 'handle_get_post_stats' ) );
		add_action( 'wp_ajax_nopriv_accessibility_audio_tts_get_post_stats', array( $this, 'handle_get_post_stats' ) );
	}

	/**
	 * Handle AJAX request to track listening event.
	 *
	 * @return void
	 */
	public function handle_track_listening() {
		// Check if request method is POST.
		if ( ! isset( $_SERVER['REQUEST_METHOD'] ) || 'POST' !== sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ) ) ) {
			wp_send_json_error( __( 'Invalid request method', 'accessibility-audio-tts-text-to-speech-for-articles' ), 405 );
			return;
		}

		// Check for required CSRF token.
		if ( ! check_ajax_referer( 'accessibility_audio_tts_listening_nonce', 'nonce', false ) ) {
			wp_send_json_error( array( 'error' => __( 'Security check failed', 'accessibility-audio-tts-text-to-speech-for-articles' ) ), 403 );
			return;
		}

		// Optional analytics is disabled by default and requires a consent declaration from the CMP bridge.
		if ( 'consented' !== \Accessibility_Audio_TTS\Core\Privacy_Settings::get( 'analytics_mode' ) || '1' !== ( $_POST['analytics_consent'] ?? '' ) ) {
			wp_send_json_error( array( 'error' => __( 'Listening statistics require enabled analytics and visitor consent.', 'accessibility-audio-tts-text-to-speech-for-articles' ) ), 403 );
			return;
		}

		// Sanitize and validate input.
		$post_id = filter_var( $_POST['post_id'] ?? '', FILTER_VALIDATE_INT, array( 'options' => array( 'min_range' => 1 ) ) );
		$listen_duration = filter_var( $_POST['listen_duration'] ?? '', FILTER_VALIDATE_INT, array( 'options' => array( 'min_range' => 5, 'max_range' => 21600 ) ) );
		$audio_duration = isset( $_POST['audio_duration'] ) ? filter_var( $_POST['audio_duration'], FILTER_VALIDATE_INT, array( 'options' => array( 'min_range' => 1, 'max_range' => 21600 ) ) ) : null;
		if ( false === $post_id || false === $listen_duration || false === $audio_duration || ( null !== $audio_duration && $listen_duration > $audio_duration + 1 ) ) {
			wp_send_json_error( array( 'error' => __( 'Invalid listening duration or post ID', 'accessibility-audio-tts-text-to-speech-for-articles' ) ), 400 );
			return;
		}

		if ( 0 >= $post_id ) {
			wp_send_json_error( array( 'error' => __( 'Invalid post ID', 'accessibility-audio-tts-text-to-speech-for-articles' ) ) );
			return;
		}

		if ( $listen_duration < 5 ) {
			wp_send_json_error( array( 'error' => __( 'Listen duration must be at least 5 seconds', 'accessibility-audio-tts-text-to-speech-for-articles' ) ) );
			return;
		}

		// Verify post exists and has audio.
		if ( ! $this->post_has_audio( $post_id ) ) {
			wp_send_json_error( array( 'error' => __( 'Post does not have audio or does not exist', 'accessibility-audio-tts-text-to-speech-for-articles' ) ) );
			return;
		}

		// The client cannot choose the recording's trusted length.
		$file = \Accessibility_Audio_TTS\Core\Audio_Access::resolve_audio_file( $post_id );
		if ( ! $file ) { wp_send_json_error( array( 'error' => 'Recording is unavailable.' ), 400 ); return; }
		$duration_key = 'aat_audio_length_' . hash( 'sha256', $file['path'] . ':' . filemtime( $file['path'] ) . ':' . filesize( $file['path'] ) );
		$trusted_duration = get_transient( $duration_key );
		if ( false === $trusted_duration ) {
			require_once ABSPATH . 'wp-admin/includes/media.php';
			$metadata = wp_read_audio_metadata( $file['path'] );
			$trusted_duration = is_array( $metadata ) && isset( $metadata['length'] ) ? (float) $metadata['length'] : 0;
			if ( $trusted_duration > 0 ) { set_transient( $duration_key, $trusted_duration, DAY_IN_SECONDS ); }
		}
		if ( $trusted_duration <= 0 || $listen_duration > min( 21600, (int) ceil( $trusted_duration ) + 1 ) ) { wp_send_json_error( array( 'error' => 'Listening duration exceeds the recording length.' ), 400 ); return; }
		$audio_duration = (int) ceil( $trusted_duration );
		$client = hash_hmac( 'sha256', (string) ( $_SERVER['REMOTE_ADDR'] ?? '' ), wp_salt( 'nonce' ) );
		$bucket_key = hash( 'sha256', $client . ':' . (int) floor( time() / 60 ) );
		if ( ! $this->listening_stats->reserve_request_slot( $bucket_key, time() + 120, 600 ) ) { wp_send_json_error( array( 'error' => 'Too many listening events.' ), 429 ); return; }
		$event = $_POST['event_id'] ?? '';
		if ( ! is_string( $event ) || ! preg_match( '/^[a-zA-Z0-9-]{16,64}$/D', $event ) ) { wp_send_json_error( array( 'error' => 'Invalid event identifier.' ), 400 ); return; }
		$event_key = hash( 'sha256', $post_id . ':' . $event );
		// Repeated event IDs carry cumulative progress; the service adds only deltas.
		$result = $this->listening_stats->record_listening_event( $post_id, $listen_duration, $audio_duration, $event_key, true );

		if ( $result ) {
			// Log safely.
			accessibility_audio_tts_debug_log(
				sprintf(
					'AJAX: Listening tracked for post %d, duration %ds',
					absint( $post_id ),
					absint( $listen_duration )
				)
			);

			wp_send_json_success(
				array(
					'message'  => __( 'Listening event recorded successfully', 'accessibility-audio-tts-text-to-speech-for-articles' ),
					'post_id'  => $post_id,
					'duration' => $listen_duration,
				)
			);
		} elseif ( $this->listening_stats->event_exists( $event_key ) ) {
			wp_send_json_success( array( 'post_id' => $post_id, 'duplicate' => true ) );
		} else {
			wp_send_json_error( array( 'error' => __( 'Failed to record listening event', 'accessibility-audio-tts-text-to-speech-for-articles' ) ) );
		}
	}

	/**
	 * Handle AJAX request to get post statistics.
	 *
	 * @return void
	 */
	public function handle_get_post_stats() {
		// Check if request method is POST.
		if ( ! isset( $_SERVER['REQUEST_METHOD'] ) || 'POST' !== sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ) ) ) {
			wp_send_json_error( __( 'Invalid request method', 'accessibility-audio-tts-text-to-speech-for-articles' ), 405 );
			return;
		}

		// Check for required CSRF token.
		if ( ! check_ajax_referer( 'accessibility_audio_tts_listening_nonce', 'nonce', false ) ) {
			wp_send_json_error( array( 'error' => __( 'Security check failed', 'accessibility-audio-tts-text-to-speech-for-articles' ) ), 403 );
			return;
		}

		$post_id = isset( $_POST['post_id'] ) ? absint( $_POST['post_id'] ) : 0;

		if ( 0 >= $post_id ) {
			wp_send_json_error( array( 'error' => __( 'Invalid post ID', 'accessibility-audio-tts-text-to-speech-for-articles' ) ) );
			return;
		}

		if ( ! $this->post_has_audio( $post_id ) ) { wp_send_json_error( array( 'error' => 'Recording is unavailable.' ), 403 ); return; }

		// Get statistics for the post.
		$stats = $this->listening_stats->get_post_listening_stats( $post_id );

		wp_send_json_success(
			array(
				'stats'   => $stats,
				'post_id' => $post_id,
			)
		);
	}

	/**
	 * Verify if post exists and has audio.
	 *
	 * @param int $post_id Post ID.
	 * @return bool True if audio exists for the post.
	 */
	private function post_has_audio( $post_id ) {
		$post_id = absint( $post_id );
		$post    = get_post( $post_id );

		if ( \Accessibility_Audio_TTS\Core\Audio_Access::is_restricted( $post ) ) {
			return false;
		}

		// Check if post has generated audio.
		$audio_url = get_post_meta( $post_id, 'accessibility_audio_tts_url', true );
		return ! empty( $audio_url );
	}

	/**
	 * Get listening statistics for admin dashboard.
	 *
	 * @return array Dashboard statistics.
	 */
	public function get_dashboard_stats() {
		return array(
			'total_audio_requests'  => $this->listening_stats->get_total_audio_requests(),
			'recent_audio_requests' => $this->listening_stats->get_recent_audio_requests(),
			'audio_request_trend'   => $this->listening_stats->get_audio_request_trend(),
			'total_active_listens'  => $this->listening_stats->get_total_active_listens(),
			'recent_active_listens' => $this->listening_stats->get_recent_active_listens(),
			'listening_trend'       => $this->listening_stats->get_listening_trend(),
		);
	}

}