<?php
/**
 * The Email Log plugin's table, as an import source.
 *
 * @package Adminkeep
 */

namespace Adminkeep\Service\EmailLogImport;

defined( 'ABSPATH' ) || exit;

/**
 * Reads {prefix}email_log, the table of the Email Log plugin (wordpress.org/plugins/email-log).
 *
 * What that plugin stores, read from its 2.63 source: to_email is the recipients joined with a
 * bare comma; headers are the wp_mail() headers joined with newlines; sent_date is the site's
 * local time (current_time( 'mysql' )); result is 1 unless wp_mail_failed later set it to 0,
 * with error_message (added in 2.4.0) beside it. attachments is only ever 'true' or 'false', and
 * in practice always 'false' — the plugin never records the file names — so there is nothing
 * there to bring across.
 *
 * Only the table is read. The plugin need not be active: its table outlives it.
 */
class EmailLogPluginSource implements Source {

	/** Columns this class cannot do without. error_message is optional: it arrived in 2.4.0. */
	const REQUIRED = array( 'id', 'to_email', 'subject', 'message', 'headers', 'sent_date', 'result' );

	/**
	 * The table name.
	 *
	 * @return string
	 */
	public function location() {
		global $wpdb;

		return $wpdb->prefix . 'email_log';
	}

	/**
	 * Whether the table is there with the columns this class reads.
	 *
	 * @return bool
	 */
	public function available() {
		return array() === array_diff( self::REQUIRED, $this->columns() );
	}

	/**
	 * The table's column names, or none when there is no such table.
	 *
	 * SHOW COLUMNS rather than SHOW TABLES: it also answers for a temporary table, and it tells a
	 * same-named table from some other plugin apart from the real one.
	 *
	 * @return string[]
	 */
	private function columns() {
		global $wpdb;

		$table    = $this->location();
		$suppress = $wpdb->suppress_errors( true );
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter -- a table name, built from $wpdb->prefix, cannot be a placeholder.
		$columns = $wpdb->get_col( "SHOW COLUMNS FROM `{$table}`" );
		$wpdb->suppress_errors( $suppress );

		return is_array( $columns ) ? $columns : array();
	}

	/**
	 * Rows above an id, oldest first.
	 *
	 * @param int $after_id Last id already read.
	 * @param int $limit    Rows to return at most.
	 * @return array[]
	 */
	public function rows( $after_id, $limit ) {
		global $wpdb;

		$table = $this->location();
		$error = in_array( 'error_message', $this->columns(), true ) ? 'error_message' : "'' AS error_message";

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter -- the table name and the error column are built here, not taken from input.
		$found = $wpdb->get_results( $wpdb->prepare( "SELECT id, to_email, subject, message, headers, sent_date, result, {$error} FROM `{$table}` WHERE id > %d ORDER BY id ASC LIMIT %d", (int) $after_id, max( 1, (int) $limit ) ), ARRAY_A );
		$rows  = array();

		foreach ( is_array( $found ) ? $found : array() as $row ) {
			$rows[] = array(
				'id'      => (int) $row['id'],
				'atts'    => array(
					'to'          => array_values( array_filter( array_map( 'trim', explode( ',', (string) $row['to_email'] ) ), 'strlen' ) ),
					'subject'     => (string) $row['subject'],
					'message'     => (string) $row['message'],
					'headers'     => (string) $row['headers'],
					'attachments' => array(),
				),
				'sent_at' => $this->utc( (string) $row['sent_date'] ),
				'status'  => $this->status( $row['result'] ),
				'error'   => (string) $row['error_message'],
			);
		}

		return $rows;
	}

	/**
	 * The site-local sent_date as UTC, or '' when it is not a real date.
	 *
	 * @param string $local 'Y-m-d H:i:s' in the site's time zone.
	 * @return string
	 */
	private function utc( $local ) {
		if ( ! preg_match( '/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/', $local ) || 0 === strpos( $local, '0000' ) ) {
			return '';
		}

		$date = date_create_immutable_from_format( 'Y-m-d H:i:s', $local, wp_timezone() );

		return false === $date ? '' : $date->setTimezone( new \DateTimeZone( 'UTC' ) )->format( 'Y-m-d H:i:s' );
	}

	/**
	 * The result column as a status. NULL is what a row looks like when the plugin wrote it and
	 * never heard back either way.
	 *
	 * @param mixed $result 1, 0 or NULL.
	 * @return string
	 */
	private function status( $result ) {
		if ( null === $result ) {
			return 'unconfirmed';
		}

		return 0 === (int) $result ? 'failed' : 'sent';
	}
}