<?php
/**
 * Sends emailed reports.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Email;

use TurtleReport\Reports\Comparison;
use TurtleReport\Reports\Insights;
use TurtleReport\Delivery\ReportBuilder;
use TurtleReport\Delivery\RunRepository;
use TurtleReport\Delivery\ShareLinks;
use TurtleReport\Policy\Format;
use TurtleReport\Policy\Schedule;
use TurtleReport\Profiles\Profile;
use TurtleReport\Reports\Summary;
use TurtleReport\Settings\Settings;
use TurtleReport\Support\View;

defined( 'ABSPATH' ) || exit;

/**
 * Renders a branded HTML report email and sends it with wp_mail(), one
 * message per recipient.
 *
 * The compose() method builds the message once (HTML, plain text, the PDF attachment
 * and the secure link); deliver() sends it to one address and reports that
 * address's own result, so a failure for one person is never hidden by a
 * success for another.
 *
 * wp_mail() returning true only means the site's mail system accepted the
 * message; it doesn't prove it reached the inbox. Results are labelled that way.
 */
final class ReportMailer {

	/** Attachments larger than this are left out (the email links to the report instead). */
	const MAX_ATTACHMENT = 8388608;

	/**
	 * Install-wide settings.
	 *
	 * @var Settings
	 */
	private $settings;

	/**
	 * Report builder.
	 *
	 * @var ReportBuilder
	 */
	private $builder;

	/**
	 * Constructor.
	 *
	 * @param Summary            $summary  Summary builder.
	 * @param Settings           $settings Install-wide settings.
	 * @param ReportBuilder|null $builder  Report builder; made from the other two when null.
	 */
	public function __construct( Summary $summary, Settings $settings, ?ReportBuilder $builder = null ) {
		$this->settings = $settings;
		$this->builder  = $builder ? $builder : new ReportBuilder( $summary, $settings );
	}

	/**
	 * The report builder.
	 *
	 * @return ReportBuilder
	 */
	public function builder() {
		return $this->builder;
	}

	/**
	 * Builds and sends a site's report for its current period, outside the
	 * delivery history; also used when the delivery tables are unavailable.
	 *
	 * @param Profile  $site       Site.
	 * @param string[] $recipients Email addresses.
	 * @param bool     $test       Whether this is a test send.
	 * @return true|\WP_Error True only when every recipient's email was accepted.
	 */
	public function send( Profile $site, array $recipients, $test = false ) {
		$recipients = array_values( array_filter( $recipients, 'is_email' ) );
		if ( ! $recipients ) {
			return new \WP_Error( 'turtlereport_no_recipients', __( 'No valid recipients.', 'turtlereport' ) );
		}
		$period  = Schedule::period( $site->email );
		$prep    = $this->builder->prepare( $site, $period );
		$run     = self::virtual_run( $site, $period, $prep );
		$message = $this->compose( $site, $run, $test );
		$failed  = array();
		try {
			foreach ( $recipients as $to ) {
				$ok = $this->deliver( $message, $to );
				if ( is_wp_error( $ok ) ) {
					$failed[ $to ] = $ok->get_error_message();
				}
			}
		} finally {
			$this->cleanup( $message );
		}
		return self::result( count( $recipients ), $failed );
	}

	/**
	 * True when nothing failed, otherwise an error naming how many failed.
	 *
	 * @param int                  $total  Recipients.
	 * @param array<string,string> $failed Address => error.
	 * @return true|\WP_Error
	 */
	public static function result( $total, array $failed ) {
		if ( ! $failed ) {
			return true;
		}
		$first = reset( $failed );
		if ( count( $failed ) === (int) $total ) {
			return new \WP_Error( 'turtlereport_mail_failed', $first, array( 'failed' => $failed ) );
		}
		return new \WP_Error(
			'turtlereport_mail_partial',
			sprintf(
				/* translators: 1: failed count, 2: total, 3: error message. */
				__( '%1$d of %2$d emails failed: %3$s', 'turtlereport' ),
				count( $failed ),
				(int) $total,
				$first
			),
			array( 'failed' => $failed )
		);
	}

	/**
	 * A run-shaped array for a report built on the fly (not stored).
	 *
	 * @param Profile $site   Site.
	 * @param array   $period Period.
	 * @param array   $prep   Result of ReportBuilder::prepare().
	 * @return array
	 */
	public static function virtual_run( Profile $site, array $period, array $prep ) {
		return array(
			'id'            => 0,
			'site_id'       => $site->id,
			'kind'          => RunRepository::KIND_TEST,
			'period_start'  => $period['s'],
			'period_end'    => $period['e'],
			'compare_start' => $period['ps'],
			'compare_end'   => $period['pe'],
			'status'        => RunRepository::PREPARING,
			'readiness'     => $prep['readiness']['level'],
			'checks'        => $prep['readiness'],
			'insights'      => $prep['insights'],
			'notes'         => '',
			'snapshot'      => array(
				'data' => $prep['data'],
				'full' => $prep['full'],
			),
			'meta'          => array(
				'frequency' => $site->email['frequency'],
				'compare'   => $site->email['compare'],
			),
			'reviewed_at'   => 0,
		);
	}

	/**
	 * Builds the message for a run once, ready to send to each recipient.
	 *
	 * @param Profile $site Site.
	 * @param array   $run  Run with snapshot.
	 * @param bool    $test Test send.
	 * @return array{subject:string,html:string,text:string,headers:string[],attachments:string[],tmp:string,pdf_error:string,share_url:string}
	 * @throws \Throwable After cleaning attachments if composition fails.
	 */
	public function compose( Profile $site, array $run, $test = false ) {
		$ctx         = $this->builder->context( $site, $run, $test );
		$attachments = array();
		$tmp         = '';
		$pdf_error   = '';
		try {
			if ( ! empty( $site->delivery['attach_pdf'] ) ) {
				$pdf = $this->builder->pdf( $site, $run );
				if ( is_wp_error( $pdf ) ) {
					$pdf_error = $pdf->get_error_message();
				} elseif ( strlen( $pdf ) > self::MAX_ATTACHMENT ) {
					$pdf_error = __( 'The PDF was too large to attach.', 'turtlereport' );
				} else {
					$tmp  = self::temp_dir();
					$file = '' !== $tmp ? $tmp . '/' . ReportBuilder::pdf_name( $site, $run ) : '';
					if ( '' !== $file && self::write_attachment( $file, $pdf ) ) {
						$attachments[] = $file;
					} else {
						$pdf_error = __( 'The PDF couldn\'t be saved for attaching (the server\'s temporary folder isn\'t writable).', 'turtlereport' );
					}
				}
			}
			$share_url     = ! empty( $run['id'] ) ? ShareLinks::url( $site, (int) $run['id'] ) : '';
			$share_expires = '' !== $share_url ? ShareLinks::expiry( $site ) : 0;

			$args    = array_merge(
				$ctx,
				array(
					'color'         => $ctx['brand']['color'],
					'logo'          => $ctx['brand']['logo'],
					'client_logo'   => $ctx['brand']['client_logo'],
					'footer'        => $ctx['brand']['footer'],
					'credit'        => $ctx['brand']['credit'],
					'brand'         => $ctx['brand']['name'],
					'url'           => $ctx['report_url'],
					'pdf_attached'  => (bool) $attachments,
					'pdf_error'     => $pdf_error,
					'share_url'     => $share_url,
					'share_expires' => $share_expires,
				)
			);
			$html    = $this->render( $args );
			$text    = $this->plain_text( $args );
			$subject = ( $test ? '[' . __( 'Test', 'turtlereport' ) . '] ' : '' ) . $site->display_name() . ' · ' . $ctx['label'];

			$headers  = array( 'Content-Type: text/html; charset=UTF-8' );
			$reply_to = (string) $this->settings->get( 'email_reply_to' );
			if ( is_email( $reply_to ) ) {
				$headers[] = 'Reply-To: ' . $reply_to;
			}
			return array(
				'subject'     => $subject,
				'html'        => $html,
				'text'        => $text,
				'headers'     => $headers,
				'attachments' => $attachments,
				'tmp'         => $tmp,
				'pdf_error'   => $pdf_error,
				'share_url'   => $share_url,
			);
		} catch ( \Throwable $e ) {
			$this->cleanup(
				array(
					'attachments' => $attachments,
					'tmp'         => $tmp,
				)
			);
			throw $e;
		}
	}

	/**
	 * Sends a composed message to one address.
	 *
	 * @param array  $message Result of compose().
	 * @param string $to      Address.
	 * @return true|\WP_Error True when the mail system accepted it.
	 */
	public function deliver( array $message, $to ) {
		if ( ! is_email( $to ) ) {
			return new \WP_Error( 'turtlereport_bad_address', __( 'This isn\'t a valid email address.', 'turtlereport' ), array( 'permanent' => true ) );
		}
		$from_name = (string) $this->settings->get( 'email_from_name' );
		$from_name = '' !== $from_name ? $from_name : $this->settings->brand_name();
		$text      = $message['text'];
		$set_name  = static function () use ( $from_name ) {
			return $from_name;
		};
		$set_alt   = static function ( $mailer ) use ( $text ) {
			$mailer->AltBody = $text; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- PHPMailer property.
		};
		$error     = null;
		$on_error  = static function ( $wp_error ) use ( &$error ) {
			$error = $wp_error;
		};
		add_filter( 'wp_mail_from_name', $set_name );
		add_action( 'phpmailer_init', $set_alt );
		add_action( 'wp_mail_failed', $on_error );
		try {
			$ok = wp_mail( $to, $message['subject'], $message['html'], $message['headers'], $message['attachments'] );
		} catch ( \Throwable $e ) {
			$ok    = false;
			$error = new \WP_Error( 'turtlereport_mail_exception', $e->getMessage() );
		}
		remove_filter( 'wp_mail_from_name', $set_name );
		remove_action( 'phpmailer_init', $set_alt );
		remove_action( 'wp_mail_failed', $on_error );
		if ( $ok ) {
			return true;
		}
		return $error instanceof \WP_Error ? new \WP_Error( 'turtlereport_mail_failed', self::clean_error( $error->get_error_message() ) ) : new \WP_Error( 'turtlereport_mail_failed', __( 'WordPress couldn\'t send the email. Check your site\'s mail setup (an SMTP plugin is recommended).', 'turtlereport' ) );
	}

	/**
	 * Shortens a mail error and strips anything that looks like a password.
	 *
	 * @param string $message Error.
	 * @return string
	 */
	private static function clean_error( $message ) {
		$message = (string) preg_replace( '/(pass(word)?|auth|token)[^\s]*\s*[:=]\s*\S+/i', '$1=***', wp_strip_all_tags( (string) $message ) );
		$message = trim( $message );
		return '' !== $message ? substr( $message, 0, 500 ) : __( 'The mail system refused the message.', 'turtlereport' );
	}

	/**
	 * Deletes a composed message's temporary files.
	 *
	 * @param array $message Result of compose().
	 * @return void
	 */
	public function cleanup( array $message ) {
		foreach ( $message['attachments'] as $file ) {
			if ( is_file( $file ) ) {
				wp_delete_file( $file );
			}
		}
		if ( '' !== $message['tmp'] && is_dir( $message['tmp'] ) ) {
			@rmdir( $message['tmp'] ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_rmdir, WordPress.PHP.NoSilencedErrors.Discouraged -- Empty temporary folder this plugin created.
		}
	}

	/**
	 * A private temporary folder, so the attachment keeps a readable file name.
	 *
	 * @return string Path, or '' when none can be made.
	 */
	private static function temp_dir() {
		$base = untrailingslashit( get_temp_dir() );
		$dir  = $base . '/turtlereport-' . wp_generate_password( 16, false, false );
		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_mkdir, WordPress.PHP.NoSilencedErrors.Discouraged -- Exclusive owned temp directory; failure becomes an attachment error.
		if ( ! @mkdir( $dir, 0700 ) ) {
			return '';
		}
		clearstatcache( true, $dir );
		if ( is_link( $dir ) || false === fileperms( $dir ) || 0700 !== ( fileperms( $dir ) & 0777 ) ) {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_rmdir, WordPress.PHP.NoSilencedErrors.Discouraged -- Only the directory just created; fail closed if privacy cannot be verified.
			@rmdir( $dir );
			return '';
		}
		return $dir;
	}

	/**
	 * Writes a private attachment without overwriting an existing path.
	 *
	 * @param string $file Owned private path.
	 * @param string $pdf  PDF bytes.
	 * @return bool
	 */
	private static function write_attachment( $file, $pdf ) {
		$mask = umask( 0077 );
		try {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen, WordPress.PHP.NoSilencedErrors.Discouraged -- Exclusive file inside the verified owner-only directory; failure is reported by compose().
			$handle = @fopen( $file, 'x+b' );
		} finally {
			umask( $mask );
		}
		if ( false === $handle ) {
			return false;
		}
		$ok = false;
		try {
			$stat = fstat( $handle );
			if ( ! $stat || 0600 !== ( $stat['mode'] & 0777 ) ) {
				return false;
			}
			$length = strlen( $pdf );
			$offset = 0;
			while ( $offset < $length ) {
				// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fwrite, WordPress.PHP.NoSilencedErrors.Discouraged -- Private temporary stream; short/failing writes are rejected.
				$written = @fwrite( $handle, substr( $pdf, $offset ) );
				if ( false === $written || 0 === $written ) {
					return false;
				}
				$offset += $written;
			}
			$ok = fflush( $handle );
			return $ok;
		} finally {
			// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose -- Owned temporary stream.
			fclose( $handle );
			if ( ! $ok ) {
				wp_delete_file( $file );
			}
		}
	}

	/**
	 * HTML body.
	 *
	 * @param array $args Template data.
	 * @return string
	 */
	private function render( array $args ) {
		ob_start();
		View::render( 'email/report', $args );
		return (string) ob_get_clean();
	}

	/**
	 * Plain-text alternative for mail clients that don't show HTML.
	 *
	 * @param array $args Template data.
	 * @return string
	 */
	private function plain_text( array $args ) {
		$site   = $args['site'];
		$period = $args['period'];
		$data   = $args['data'];
		$lines  = array( $site->display_name() . ' — ' . $args['label'], Format::range( $period['s'], $period['e'] ), '' );
		foreach ( $args['problems'] as $problem ) {
			if ( in_array( $problem['level'], array( 'blocked', 'warning' ), true ) ) {
				$lines[] = '! ' . $problem['message'];
			}
		}
		if ( $args['problems'] ) {
			$lines[] = '';
		}
		$rows = Comparison::rows( (array) $data, $site );
		if ( $rows ) {
			$overall = Comparison::overall( $rows );
			$cols    = Comparison::columns( $period );
			/* translators: 1: overall change, e.g. "−12%", 2: comparison period, 3: improved count, 4: declined count. */
			$lines[] = sprintf( __( 'Overall change: %1$s vs %2$s (%3$d improved, %4$d declined)', 'turtlereport' ), $overall['text'], $cols[1], $overall['better'], $overall['worse'] );
			$lines[] = '';
			$section = '';
			foreach ( $rows as $row ) {
				if ( $row['section'] !== $section ) {
					$section = $row['section'];
					$lines[] = $section;
				}
				/* translators: 1: measure, 2: value now, 3: comparison period, 4: value then, 5: change. */
				$lines[] = sprintf( __( '%1$s: %2$s (%3$s: %4$s, %5$s)', 'turtlereport' ), ( $row['sub'] ? '  ' : '' ) . $row['label'], $row['cur'], $cols[1], $row['prev'], $row['change']['text'] );
			}
		}
		$groups = Insights::grouped( $args['insights'] );
		foreach ( Insights::headings() as $kind => $heading ) {
			if ( $groups[ $kind ] ) {
				$lines[] = '';
				$lines[] = $heading;
				foreach ( $groups[ $kind ] as $line ) {
					$lines[] = '- ' . $line;
				}
			}
		}
		foreach ( array( $args['site_note'], $args['notes'] ) as $note ) {
			if ( '' !== $note ) {
				$lines[] = '';
				$lines[] = $note;
			}
		}
		$lines[] = '';
		if ( '' !== $args['share_url'] ) {
			/* translators: %s: URL of the PDF. */
			$lines[] = sprintf( __( 'Download the PDF: %s', 'turtlereport' ), $args['share_url'] );
		}
		if ( $args['pdf_attached'] ) {
			$lines[] = __( 'The full report is attached as a two-page PDF.', 'turtlereport' );
		}
		return implode( "\n", $lines );
	}

	/**
	 * Title for the period an email covers: "Weekly report", "Last 2 weeks",
	 * "September 2026" or "Q3 2026". Kept for extensions; reports now use
	 * ReportBuilder::label(), which names the exact dates.
	 *
	 * @param string $frequency Interval.
	 * @param array  $period    Period.
	 * @return string
	 */
	public static function label( $frequency, array $period ) {
		$start = strtotime( $period['s'] . ' 12:00:00 UTC' );
		switch ( $frequency ) {
			case Schedule::WEEKLY:
				return __( 'Weekly report', 'turtlereport' );
			case Schedule::BIWEEKLY:
				return __( 'Last 2 weeks', 'turtlereport' );
			case Schedule::QUARTERLY:
				/* translators: 1: quarter number (1-4), 2: year. */
				return sprintf( __( 'Q%1$d %2$s', 'turtlereport' ), (int) ceil( (int) gmdate( 'n', $start ) / 3 ), gmdate( 'Y', $start ) );
			default:
				return wp_date( 'F Y', $start, new \DateTimeZone( 'UTC' ) );
		}
	}
}