<?php
/**
 * Secret public link to the client report.
 *
 * @package Maintained_Log
 */

namespace Maintained_Log;

defined( 'ABSPATH' ) || exit;

/**
 * Serves the report as a web page at an unguessable URL, so the client can
 * open it in a browser, forward it or save it as PDF. Anyone with the link
 * can see it; regenerating the token invalidates old links.
 */
class Public_Report {

	const QUERY_VAR    = 'maintained-log-report';
	const TOKEN_OPTION = 'maintained_log_public_token';

	/**
	 * Registers hooks.
	 */
	public static function register() {
		add_action( 'template_redirect', array( __CLASS__, 'maybe_render' ), 0 );
	}

	/**
	 * Whether public links are enabled.
	 *
	 * @return bool
	 */
	public static function is_enabled() {
		return (bool) Settings::get( 'public_report_enabled' );
	}

	/**
	 * Current token, created on first use.
	 *
	 * @return string
	 */
	public static function token() {
		$token = (string) get_option( self::TOKEN_OPTION );
		if ( strlen( $token ) < 32 ) {
			$token = self::regenerate();
		}
		return $token;
	}

	/**
	 * Replaces the token, invalidating every link shared so far.
	 *
	 * @return string New token.
	 */
	public static function regenerate() {
		$token = wp_generate_password( 40, false, false );
		update_option( self::TOKEN_OPTION, $token, false );
		return $token;
	}

	/**
	 * Public URL of a report period, or of the latest report when no period is given.
	 *
	 * @param \DateTimeImmutable|null $from Start (site timezone).
	 * @param \DateTimeImmutable|null $to   End, exclusive (site timezone).
	 * @return string Empty when disabled.
	 */
	public static function url( $from = null, $to = null ) {
		if ( ! self::is_enabled() ) {
			return '';
		}
		$args = array( self::QUERY_VAR => self::token() );
		if ( $from && $to ) {
			$args['from'] = $from->format( 'Y-m-d\TH:i:s' );
			$args['to']   = $to->format( 'Y-m-d\TH:i:s' );
		}
		return add_query_arg( $args, home_url( '/' ) );
	}

	/**
	 * Reports already sent to the client, newest first.
	 *
	 * @param int $limit Maximum number.
	 * @return array[] Each with from, to (DateTimeImmutable) and entry.
	 */
	public static function sent_reports( $limit = 12 ) {
		$tz      = wp_timezone();
		$reports = array();
		foreach ( Log::query(
			array(
				'type'     => Log::TYPE_REPORT,
				'per_page' => 100,
			)
		) as $entry ) {
			if ( Log::STATUS_SUCCESS !== $entry->status || empty( $entry->details['from'] ) || empty( $entry->details['to'] ) ) {
				continue;
			}
			$key = $entry->details['from'] . '|' . $entry->details['to'];
			if ( isset( $reports[ $key ] ) ) {
				continue;
			}
			$reports[ $key ] = array(
				'from'  => ( new \DateTimeImmutable( $entry->details['from'] ) )->setTimezone( $tz ),
				'to'    => ( new \DateTimeImmutable( $entry->details['to'] ) )->setTimezone( $tz ),
				'entry' => $entry,
			);
			if ( count( $reports ) >= $limit ) {
				break;
			}
		}
		return array_values( $reports );
	}

	/**
	 * Registers the page styles and script; the template prints them, as it
	 * is a standalone page without the theme's header and footer.
	 */
	private static function enqueue_assets() {
		wp_enqueue_style( 'maintained-log-report', MAINTAINED_LOG_URL . 'assets/report.css', array(), MAINTAINED_LOG_VERSION );
		wp_add_inline_style( 'maintained-log-report', ':root { --ml-color: ' . sanitize_hex_color( Settings::get( 'brand_color' ) ) . '; }' );
		wp_enqueue_script( 'maintained-log-report', MAINTAINED_LOG_URL . 'assets/report.js', array(), MAINTAINED_LOG_VERSION, true );
	}

	/**
	 * Renders the report page when the URL carries a valid token.
	 */
	public static function maybe_render() {
		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- Access is controlled by the secret token.
		if ( ! isset( $_GET[ self::QUERY_VAR ] ) ) {
			return;
		}

		$given = sanitize_text_field( wp_unslash( $_GET[ self::QUERY_VAR ] ) );
		if ( ! self::is_enabled() || ! hash_equals( self::token(), $given ) ) {
			status_header( 404 );
			nocache_headers();
			wp_die( esc_html__( 'This report link is not valid. Ask your web maintenance team for a new one.', 'maintained-log' ), '', array( 'response' => 404 ) );
		}

		$period = self::period_from_request(
			isset( $_GET['from'] ) ? sanitize_text_field( wp_unslash( $_GET['from'] ) ) : '',
			isset( $_GET['to'] ) ? sanitize_text_field( wp_unslash( $_GET['to'] ) ) : ''
		);
		// phpcs:enable

		nocache_headers();
		header( 'X-Robots-Tag: noindex, nofollow', true );
		header( 'Referrer-Policy: no-referrer', true );
		header( 'Content-Type: text/html; charset=UTF-8' );

		self::enqueue_assets();
		$report = Reporter::build( $period['from'], $period['to'] );
		echo Reporter::render( $report, 'web' ); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- The template escapes its output.
		exit;
	}

	/**
	 * Period requested in the URL, falling back to the latest report sent.
	 *
	 * @param string $from Requested start.
	 * @param string $to   Requested end.
	 * @return array{from:\DateTimeImmutable,to:\DateTimeImmutable}
	 */
	private static function period_from_request( $from, $to ) {
		$tz    = wp_timezone();
		$start = \DateTimeImmutable::createFromFormat( 'Y-m-d\TH:i:s', $from, $tz );
		$end   = \DateTimeImmutable::createFromFormat( 'Y-m-d\TH:i:s', $to, $tz );

		if ( $start && $end && $start < $end && $end->getTimestamp() - $start->getTimestamp() <= 400 * DAY_IN_SECONDS ) {
			return array(
				'from' => $start,
				'to'   => $end,
			);
		}

		$sent = self::sent_reports( 1 );
		if ( $sent ) {
			return array(
				'from' => $sent[0]['from'],
				'to'   => $sent[0]['to'],
			);
		}
		return Reporter::manual_period();
	}
}