<?php
/**
 * AIT Easy Post Customization - Email Notifications
 *
 * Sends email alerts to post authors a configurable number of days
 * before their post expires. Includes per-user unsubscribe support.
 *
 * @package AIT Easy Post Customization
 */

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

// ---------------------------------------------------------------------------
// Settings registration
// ---------------------------------------------------------------------------

/**
 * Register email notification options via Settings API.
 * These are saved under the 'aitepc_notifications_group' settings group,
 * rendered in the Email Notifications tab.
 */
function aitepc_register_email_notification_settings() {
	register_setting(
		'aitepc_notifications_group',
		'aitepc_email_notifications_enabled',
		array(
			'sanitize_callback' => 'absint',
			'default'           => 0,
		)
	);

	register_setting(
		'aitepc_notifications_group',
		'aitepc_email_notification_days',
		array(
			'sanitize_callback' => 'aitepc_sanitize_notification_days',
			'default'           => array( 7, 3, 1 ),
		)
	);

	register_setting(
		'aitepc_notifications_group',
		'aitepc_email_from_name',
		array(
			'sanitize_callback' => 'sanitize_text_field',
			'default'           => get_bloginfo( 'name' ),
		)
	);

	register_setting(
		'aitepc_notifications_group',
		'aitepc_email_from_address',
		array(
			'sanitize_callback' => 'sanitize_email',
			'default'           => get_option( 'admin_email' ),
		)
	);
}
add_action( 'admin_init', 'aitepc_register_email_notification_settings' );

/**
 * Sanitize notification day intervals — only allow known values.
 *
 * @param  mixed $input Raw input (expected array of integers).
 * @return array        Validated array of allowed day intervals.
 */
function aitepc_sanitize_notification_days( $input ) {
	$allowed = array( 1, 3, 7, 14, 30 );

	if ( ! is_array( $input ) ) {
		return array();
	}

	return array_values(
		array_intersect(
			array_map( 'absint', $input ),
			$allowed
		)
	);
}

// ---------------------------------------------------------------------------
// Cron: send notifications
// ---------------------------------------------------------------------------

/**
 * Query posts whose expiry date is exactly X days away and send email alerts.
 * Runs daily via the 'aitepc_check_expiry_notifications_event' cron hook.
 * A post meta log prevents duplicate emails per interval.
 */
function aitepc_check_expiry_notifications() {
	if ( ! get_option( 'aitepc_email_notifications_enabled', 0 ) ) {
		return;
	}

	$days_before = get_option( 'aitepc_email_notification_days', array( 7, 3, 1 ) );
	if ( empty( $days_before ) || ! is_array( $days_before ) ) {
		return;
	}

	$post_types = get_option( 'aitepc_expiry_date_post_types', array( 'post' ) );
	if ( empty( $post_types ) ) {
		return;
	}

	foreach ( $days_before as $interval ) {
		$interval    = absint( $interval );
		$target_date = gmdate( 'Y-m-d', strtotime( '+' . $interval . ' days' ) );

		$post_ids = get_posts(
			array(
				'post_type'      => $post_types,
				'post_status'    => 'publish',
				'posts_per_page' => -1,
				'fields'         => 'ids',
				'no_found_rows'  => true,
				'meta_query'     => array(
					array(
						'key'     => '_aitepc_expiry_date',
						'value'   => $target_date,
						'compare' => '=',
						'type'    => 'DATE',
					),
				),
			)
		);

		foreach ( $post_ids as $post_id ) {
			// Skip if we already sent this interval's notification for this post.
			$already_sent = get_post_meta( $post_id, '_aitepc_email_sent_days', true );
			if ( ! is_array( $already_sent ) ) {
				$already_sent = array();
			}
			if ( in_array( $interval, $already_sent, true ) ) {
				continue;
			}

			// Respect per-user unsubscribe preference.
			$author_id = (int) get_post_field( 'post_author', $post_id );
			if ( get_user_meta( $author_id, 'aitepc_email_unsubscribe', true ) === '1' ) {
				continue;
			}

			$sent = aitepc_send_expiry_notification_email( $post_id, $interval );

			if ( $sent ) {
				$already_sent[] = $interval;
				update_post_meta( $post_id, '_aitepc_email_sent_days', $already_sent );
			}
		}
	}
}
add_action( 'aitepc_check_expiry_notifications_event', 'aitepc_check_expiry_notifications' );

// ---------------------------------------------------------------------------
// Email sending
// ---------------------------------------------------------------------------

/**
 * Send a single expiry notification email to the post author.
 *
 * @param  int $post_id     Post ID.
 * @param  int $days_before Days until the post expires.
 * @return bool             True if wp_mail() accepted the message.
 */
function aitepc_send_expiry_notification_email( $post_id, $days_before ) {
	$post = get_post( $post_id );
	if ( ! $post ) {
		return false;
	}

	$author = get_userdata( (int) $post->post_author );
	if ( ! $author || ! is_email( $author->user_email ) ) {
		return false;
	}

	$from_name  = get_option( 'aitepc_email_from_name', get_bloginfo( 'name' ) );
	$from_email = get_option( 'aitepc_email_from_address', get_option( 'admin_email' ) );

	if ( ! is_email( $from_email ) ) {
		$from_email = get_option( 'admin_email' );
	}

	$days_before = absint( $days_before );
	$site_name   = get_bloginfo( 'name' );
	$post_title  = get_the_title( $post_id );

	/* translators: 1: site name, 2: post title, 3: days before expiry */
	$subject = sprintf(
		__( '[%1$s] Your post "%2$s" expires in %3$d day(s)', 'ait-easy-post-customization' ),
		$site_name,
		$post_title,
		$days_before
	);

	$body = aitepc_get_email_template( $post_id, $days_before, $author );

	$headers = array(
		'Content-Type: text/html; charset=UTF-8',
		'From: ' . sanitize_text_field( $from_name ) . ' <' . sanitize_email( $from_email ) . '>',
	);

	/**
	 * Filter the email data before sending a notification.
	 *
	 * @param array $data        Keys: to, subject, body, headers.
	 * @param int   $post_id     Post ID.
	 * @param int   $days_before Days before expiry.
	 */
	$data = apply_filters(
		'aitepc_notification_email_data',
		array(
			'to'      => $author->user_email,
			'subject' => $subject,
			'body'    => $body,
			'headers' => $headers,
		),
		$post_id,
		$days_before
	);

	return wp_mail(
		sanitize_email( $data['to'] ),
		$data['subject'],
		$data['body'],
		$data['headers']
	);
}

/**
 * Build the HTML email body for an expiry notification.
 * Uses inline CSS only — no external fonts or images — for maximum
 * email client compatibility.
 *
 * @param  int     $post_id     Post ID.
 * @param  int     $days_before Days before expiry.
 * @param  WP_User $author      Post author user object.
 * @return string               Full HTML email body.
 */
function aitepc_get_email_template( $post_id, $days_before, $author ) {
	$site_name   = esc_html( get_bloginfo( 'name' ) );
	$site_url    = esc_url( home_url( '/' ) );
	$post_title  = esc_html( get_the_title( $post_id ) );
	$expiry_date = esc_html( get_post_meta( $post_id, '_aitepc_expiry_date', true ) );
	$edit_url    = esc_url( get_edit_post_link( $post_id, 'raw' ) );
	$post_url    = esc_url( get_permalink( $post_id ) );
	$author_name = esc_html( $author->display_name );
	$days_before = absint( $days_before );

	$days_text = ( 1 === $days_before )
		? esc_html__( '1 day', 'ait-easy-post-customization' )
		: sprintf(
			/* translators: number of days */
			esc_html__( '%d days', 'ait-easy-post-customization' ),
			$days_before
		);

	// Stateless unsubscribe token using wp_hash — no DB entry needed.
	$token       = wp_hash( $author->ID . $author->user_email );
	$unsub_url   = esc_url(
		add_query_arg(
			array(
				'user_id' => $author->ID,
				'token'   => $token,
			),
			rest_url( 'aitepc/v1/unsubscribe' )
		)
	);

	ob_start();
	?>
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title><?php echo $site_name; ?></title>
</head>
<body style="margin:0;padding:0;background-color:#f4f6f9;font-family:Arial,Helvetica,sans-serif;-webkit-font-smoothing:antialiased;">
<table width="100%" cellpadding="0" cellspacing="0" border="0" style="background-color:#f4f6f9;padding:30px 0;">
	<tr>
		<td align="center">
			<table width="600" cellpadding="0" cellspacing="0" border="0" style="max-width:600px;width:100%;background-color:#ffffff;border-radius:12px;overflow:hidden;box-shadow:0 4px 20px rgba(0,0,0,0.08);">

				<!-- Header -->
				<tr>
					<td style="background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);padding:36px 40px;text-align:center;">
						<h1 style="color:#ffffff;margin:0;font-size:22px;font-weight:700;letter-spacing:-0.3px;"><?php echo $site_name; ?></h1>
						<p style="color:rgba(255,255,255,0.85);margin:8px 0 0;font-size:14px;"><?php esc_html_e( 'Post Expiry Notification', 'ait-easy-post-customization' ); ?></p>
					</td>
				</tr>

				<!-- Body -->
				<tr>
					<td style="padding:36px 40px;">

						<!-- Greeting -->
						<p style="color:#374151;font-size:15px;line-height:1.6;margin:0 0 16px;">
							<?php
							printf(
								/* translators: %s: author display name */
								esc_html__( 'Hi %s,', 'ait-easy-post-customization' ),
								$author_name
							);
							?>
						</p>

						<!-- Message -->
						<p style="color:#374151;font-size:15px;line-height:1.6;margin:0 0 28px;">
							<?php
							printf(
								/* translators: 1: post title (bold), 2: days remaining (bold) */
								esc_html__( 'Your post %1$s is expiring in %2$s. Please review it and update the expiry date if you\'d like to keep it published.', 'ait-easy-post-customization' ),
								'<strong>' . $post_title . '</strong>',
								'<strong>' . $days_text . '</strong>'
							);
							?>
						</p>

						<!-- Info box -->
						<table width="100%" cellpadding="0" cellspacing="0" border="0" style="background-color:#f0f4ff;border-left:4px solid #667eea;border-radius:6px;margin-bottom:28px;">
							<tr>
								<td style="padding:16px 20px;">
									<p style="margin:0 0 8px;color:#4b5563;font-size:12px;font-weight:700;text-transform:uppercase;letter-spacing:0.8px;"><?php esc_html_e( 'Post Details', 'ait-easy-post-customization' ); ?></p>
									<p style="margin:0 0 4px;color:#374151;font-size:14px;"><strong><?php esc_html_e( 'Title:', 'ait-easy-post-customization' ); ?></strong>&nbsp;<?php echo $post_title; ?></p>
									<p style="margin:0;color:#374151;font-size:14px;"><strong><?php esc_html_e( 'Expiry Date:', 'ait-easy-post-customization' ); ?></strong>&nbsp;<?php echo $expiry_date; ?></p>
								</td>
							</tr>
						</table>

						<!-- CTA Buttons -->
						<table cellpadding="0" cellspacing="0" border="0">
							<tr>
								<td style="padding-right:12px;">
									<a href="<?php echo $edit_url; ?>" style="display:inline-block;background:linear-gradient(135deg,#667eea 0%,#764ba2 100%);color:#ffffff;text-decoration:none;padding:12px 24px;border-radius:8px;font-size:14px;font-weight:700;letter-spacing:0.3px;">
										<?php esc_html_e( 'Edit Post', 'ait-easy-post-customization' ); ?>
									</a>
								</td>
								<td>
									<a href="<?php echo $post_url; ?>" style="display:inline-block;background:#ffffff;color:#667eea;text-decoration:none;padding:11px 24px;border-radius:8px;font-size:14px;font-weight:700;letter-spacing:0.3px;border:2px solid #667eea;">
										<?php esc_html_e( 'View Post', 'ait-easy-post-customization' ); ?>
									</a>
								</td>
							</tr>
						</table>

					</td>
				</tr>

				<!-- Divider -->
				<tr>
					<td style="padding:0 40px;"><hr style="border:none;border-top:1px solid #e5e7eb;margin:0;"></td>
				</tr>

				<!-- Footer -->
				<tr>
					<td style="background-color:#f9fafb;padding:20px 40px;text-align:center;border-radius:0 0 12px 12px;">
						<p style="color:#9ca3af;font-size:12px;margin:0 0 6px;">
							<?php
							printf(
								/* translators: %s: site name wrapped in a link */
								esc_html__( 'Sent by %s', 'ait-easy-post-customization' ),
								'<a href="' . $site_url . '" style="color:#667eea;text-decoration:none;">' . $site_name . '</a>'
							);
							?>
						</p>
						<p style="color:#9ca3af;font-size:12px;margin:0;">
							<a href="<?php echo $unsub_url; ?>" style="color:#9ca3af;text-decoration:underline;">
								<?php esc_html_e( 'Unsubscribe from expiry notifications', 'ait-easy-post-customization' ); ?>
							</a>
						</p>
					</td>
				</tr>

			</table>
		</td>
	</tr>
</table>
</body>
</html>
	<?php
	return ob_get_clean();
}