<?php
/**
 * The in-app inbox that catches mail with nowhere to go.
 *
 * Sirius Press does not disable `wp_mail()`. That would break Contact Form 7,
 * WooCommerce receipts, newsletters — every legitimate reason a site has to
 * send a human an email — and those are not what the fork objects to. What it
 * objects to is *identity* depending on a mailbox.
 *
 * So the rule is narrow and mechanical: messages addressed to one of this
 * site's own `.invalid` placeholder addresses never leave the server. They
 * land here, in an inbox the recipient reads while signed in. That is where
 * password resets, comment-moderation pings, update nags and "your plugin
 * needs attention" notices end up — everything core and plugins send to an
 * account rather than to a person's real address.
 *
 * Mail addressed to a real domain is passed straight through to whatever the
 * site owner configured. If they set up SMTP, it sends. If they did not, it
 * fails exactly the way stock WordPress fails, which is the honest outcome.
 *
 * @package SiriusPress
 */

defined( 'ABSPATH' ) || exit;

final class SP_Inbox {

	const TABLE   = 'sirius_notices';
	const VERSION = 1;

	public static function table() {
		global $wpdb;
		return $wpdb->prefix . self::TABLE;
	}

	/** Create the table. Called on activation and on a version bump. */
	public static function install() {
		global $wpdb;
		require_once ABSPATH . 'wp-admin/includes/upgrade.php';
		$table   = self::table();
		$collate = $wpdb->get_charset_collate();
		dbDelta(
			"CREATE TABLE {$table} (
				id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
				user_id bigint(20) unsigned NOT NULL DEFAULT 0,
				created_at datetime NOT NULL,
				read_at datetime DEFAULT NULL,
				subject varchar(255) NOT NULL DEFAULT '',
				body longtext NOT NULL,
				source varchar(60) NOT NULL DEFAULT '',
				PRIMARY KEY  (id),
				KEY user_unread (user_id, read_at),
				KEY created (created_at)
			) {$collate};"
		);
		update_option( 'sirius_press_inbox_version', self::VERSION, false );
	}

	public static function hooks() {
		add_filter( 'pre_wp_mail', array( __CLASS__, 'intercept_mail' ), 10, 2 );
		add_action( 'admin_menu', array( __CLASS__, 'menu' ) );
		add_action( 'admin_bar_menu', array( __CLASS__, 'admin_bar' ), 80 );
	}

	/**
	 * Deliver a message to a user's inbox.
	 *
	 * @param int    $user_id 0 addresses every administrator.
	 * @param string $subject
	 * @param string $body    HTML allowed; rendered with wp_kses_post.
	 * @param string $source  Free-form tag, e.g. 'wp_mail' or 'export'.
	 * @return int Rows written.
	 */
	public static function add( $user_id, $subject, $body, $source = '' ) {
		global $wpdb;
		$targets = array();
		if ( (int) $user_id > 0 ) {
			$targets[] = (int) $user_id;
		} else {
			foreach ( get_users( array( 'role' => 'administrator', 'fields' => 'ID' ) ) as $id ) {
				$targets[] = (int) $id;
			}
		}
		$written = 0;
		foreach ( array_unique( $targets ) as $id ) {
			$ok = $wpdb->insert(
				self::table(),
				array(
					'user_id'    => $id,
					'created_at' => current_time( 'mysql', true ),
					'subject'    => mb_substr( wp_strip_all_tags( (string) $subject ), 0, 250 ),
					'body'       => (string) $body,
					'source'     => mb_substr( (string) $source, 0, 60 ),
				),
				array( '%d', '%s', '%s', '%s', '%s' )
			);
			$written += $ok ? 1 : 0;
		}
		return $written;
	}

	/**
	 * Short-circuit wp_mail for placeholder recipients.
	 *
	 * Returning a non-null value from `pre_wp_mail` tells WordPress the send
	 * is handled. Returning `true` specifically means "delivered", which is
	 * the truth here — it was delivered, to the inbox.
	 *
	 * @param null|bool $short  Whatever an earlier filter decided.
	 * @param array     $atts   wp_mail()'s arguments.
	 * @return null|bool
	 */
	public static function intercept_mail( $short, $atts ) {
		if ( null !== $short ) {
			return $short; // Somebody else already claimed this send.
		}
		$to = isset( $atts['to'] ) ? $atts['to'] : array();
		if ( ! is_array( $to ) ) {
			$to = explode( ',', (string) $to );
		}
		$stub_domain = strtolower( SP_Settings::stub_email_domain() );

		$captured = array();
		$passing  = array();
		foreach ( $to as $recipient ) {
			$addr = strtolower( trim( self::bare_address( $recipient ) ) );
			if ( '' === $addr ) {
				continue;
			}
			// Any .invalid recipient is ours by definition — RFC 2606 says the
			// TLD never resolves, so passing it to a mailer only produces a
			// bounce or a hard error in the log.
			if ( substr( $addr, -strlen( $stub_domain ) - 1 ) === '@' . $stub_domain
				|| preg_match( '/@[^@]*\.invalid$/', $addr ) ) {
				$captured[] = $addr;
			} else {
				$passing[] = $recipient;
			}
		}

		if ( ! $captured ) {
			return null; // Nothing of ours — let the normal mailer have it.
		}

		$subject = isset( $atts['subject'] ) ? (string) $atts['subject'] : __( '(no subject)', 'sirius-press' );
		$body    = isset( $atts['message'] ) ? (string) $atts['message'] : '';
		foreach ( $captured as $addr ) {
			$user = get_user_by( 'email', $addr );
			self::add( $user ? (int) $user->ID : 0, $subject, self::to_html( $body ), 'wp_mail' );
		}

		if ( $passing ) {
			// A mixed send: the real recipients still deserve their copy, so
			// re-enter wp_mail with only those. `pre_wp_mail` is not re-entered
			// for them because their addresses are not placeholders.
			$rest         = $atts;
			$rest['to']   = $passing;
			wp_mail(
				$rest['to'],
				$subject,
				$body,
				isset( $rest['headers'] ) ? $rest['headers'] : '',
				isset( $rest['attachments'] ) ? $rest['attachments'] : array()
			);
		}
		return true;
	}

	/** Pull `foo@bar` out of `Name <foo@bar>`. */
	private static function bare_address( $recipient ) {
		$recipient = (string) $recipient;
		if ( preg_match( '/<([^>]+)>/', $recipient, $m ) ) {
			return $m[1];
		}
		return $recipient;
	}

	/** Plain-text mail bodies are the common case; keep their line breaks. */
	private static function to_html( $body ) {
		if ( preg_match( '/<(a|p|br|div|table|html)\b/i', $body ) ) {
			return $body;
		}
		return wpautop( make_clickable( esc_html( $body ) ) );
	}

	// ------------------------------------------------------------- reading it

	public static function unread_count( $user_id ) {
		global $wpdb;
		$table = self::table();
		return (int) $wpdb->get_var(
			$wpdb->prepare( "SELECT COUNT(*) FROM {$table} WHERE user_id = %d AND read_at IS NULL", (int) $user_id ) // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		);
	}

	public static function recent( $user_id, $limit = 50, $offset = 0 ) {
		global $wpdb;
		$table = self::table();
		return (array) $wpdb->get_results(
			$wpdb->prepare( "SELECT * FROM {$table} WHERE user_id = %d ORDER BY created_at DESC, id DESC LIMIT %d OFFSET %d", (int) $user_id, (int) $limit, (int) $offset ) // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		);
	}

	public static function mark_all_read( $user_id ) {
		global $wpdb;
		$table = self::table();
		return (int) $wpdb->query(
			$wpdb->prepare( "UPDATE {$table} SET read_at = %s WHERE user_id = %d AND read_at IS NULL", current_time( 'mysql', true ), (int) $user_id ) // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		);
	}

	public static function delete_all( $user_id ) {
		global $wpdb;
		return (int) $wpdb->delete( self::table(), array( 'user_id' => (int) $user_id ), array( '%d' ) );
	}

	// ------------------------------------------------------------------- UI

	public static function menu() {
		$count = self::unread_count( get_current_user_id() );
		$label = __( 'Inbox', 'sirius-press' );
		if ( $count > 0 ) {
			$label .= sprintf( ' <span class="awaiting-mod"><span class="pending-count">%d</span></span>', $count );
		}
		add_menu_page(
			__( 'Inbox', 'sirius-press' ),
			$label,
			'read',
			'sirius-inbox',
			array( __CLASS__, 'render_page' ),
			'dashicons-email-alt',
			72
		);
	}

	public static function admin_bar( $bar ) {
		if ( ! is_user_logged_in() ) {
			return;
		}
		$count = self::unread_count( get_current_user_id() );
		$bar->add_node(
			array(
				'id'    => 'sirius-inbox',
				'title' => '<span class="ab-icon dashicons dashicons-email-alt" style="top:2px"></span>'
					. ( $count > 0 ? '<span class="ab-label">' . (int) $count . '</span>' : '' ),
				'href'  => admin_url( 'admin.php?page=sirius-inbox' ),
				'meta'  => array( 'title' => __( 'Sirius Press inbox', 'sirius-press' ) ),
			)
		);
	}

	public static function render_page() {
		$user_id = get_current_user_id();

		if ( isset( $_POST['sirius_inbox_action'] ) && check_admin_referer( 'sirius_inbox' ) ) {
			$action = sanitize_key( wp_unslash( $_POST['sirius_inbox_action'] ) );
			if ( 'read_all' === $action ) {
				self::mark_all_read( $user_id );
			} elseif ( 'delete_all' === $action ) {
				self::delete_all( $user_id );
			}
		}

		$items = self::recent( $user_id, 100 );
		echo '<div class="wrap"><h1>' . esc_html__( 'Inbox', 'sirius-press' ) . '</h1>';
		echo '<p class="description">' . esc_html__( 'Messages this site would have emailed to your account. Nothing here was sent anywhere.', 'sirius-press' ) . '</p>';

		echo '<form method="post" style="margin:12px 0">';
		wp_nonce_field( 'sirius_inbox' );
		echo '<button class="button" name="sirius_inbox_action" value="read_all">' . esc_html__( 'Mark all read', 'sirius-press' ) . '</button> ';
		echo '<button class="button" name="sirius_inbox_action" value="delete_all" onclick="return confirm(' . esc_attr( wp_json_encode( __( 'Delete every message in your inbox?', 'sirius-press' ) ) ) . ')">' . esc_html__( 'Delete all', 'sirius-press' ) . '</button>';
		echo '</form>';

		if ( ! $items ) {
			echo '<p>' . esc_html__( 'Nothing here yet.', 'sirius-press' ) . '</p></div>';
			return;
		}

		echo '<table class="widefat striped"><thead><tr>';
		echo '<th style="width:160px">' . esc_html__( 'When', 'sirius-press' ) . '</th>';
		echo '<th>' . esc_html__( 'Message', 'sirius-press' ) . '</th>';
		echo '</tr></thead><tbody>';
		foreach ( $items as $item ) {
			$unread = empty( $item->read_at );
			printf(
				'<tr%s><td>%s<br><small>%s</small></td><td><strong>%s</strong><div style="margin-top:6px">%s</div></td></tr>',
				$unread ? ' style="font-weight:600;background:#fff8e5"' : '',
				esc_html( mysql2date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), $item->created_at ) ),
				esc_html( $item->source ),
				esc_html( $item->subject ),
				wp_kses_post( $item->body )
			);
		}
		echo '</tbody></table></div>';

		self::mark_all_read( $user_id );
	}
}