<?php
/**
 * The Founder Weekly Brief.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Attention;

use TurtleReport\Support\AdminLinks;
use TurtleReport\Email\ReportMailer;
use TurtleReport\Profiles\ProfileRepository;
use TurtleReport\Settings\Settings;
use TurtleReport\Support\Periods;
use TurtleReport\Support\OptionLock;
use TurtleReport\Support\View;

defined( 'ABSPATH' ) || exit;

/**
 * A short weekly email for the agency's founder: how many clients there are,
 * how many need attention, the three issues that matter most (the clients'
 * own priorities first) with what to do about each, and a link to the Client
 * Monitor.
 *
 * Built only from the Client Monitor's stored alerts, which come from the
 * clients' Search Console and GA4 data; no AI and no extra Google requests.
 * Sent through the same mail path as the report emails, from the hourly job.
 */
final class Brief {

	/** Last claimed scheduled attempt (Unix time), not proof of delivery. */
	const SENT = 'turtlereport_brief_sent';

	/** Safe outcome of the last scheduled attempt; no recipients or error text. */
	const OUTCOME = 'turtlereport_brief_outcome';

	/** Seconds a scheduled attempt may hold its lock; an older "attempted" outcome was interrupted. */
	const LOCK_TTL = 600;

	/** Issues in the brief. */
	const TOP = 3;

	/** Business impact order, the same as the Client Monitor screen. */
	const IMPACT = array(
		'tracking_stopped' => 0,
		'leads_drop'       => 1,
		'no_clicks'        => 2,
		'clicks_drop'      => 3,
		'sessions_drop'    => 4,
		'page_drop'        => 5,
		'rankings_drop'    => 6,
	);

	/**
	 * Sites.
	 *
	 * @var ProfileRepository
	 */
	private $sites;

	/**
	 * Client Monitor.
	 *
	 * @var Monitor
	 */
	private $monitor;

	/**
	 * Settings.
	 *
	 * @var Settings
	 */
	private $settings;

	/**
	 * Mailer used for report emails.
	 *
	 * @var ReportMailer
	 */
	private $mailer;

	/**
	 * Constructor.
	 *
	 * @param ProfileRepository $sites    Sites.
	 * @param Monitor           $monitor  Client Monitor.
	 * @param Settings          $settings Settings.
	 * @param ReportMailer      $mailer   Mailer.
	 */
	public function __construct( ProfileRepository $sites, Monitor $monitor, Settings $settings, ReportMailer $mailer ) {
		$this->sites    = $sites;
		$this->monitor  = $monitor;
		$this->settings = $settings;
		$this->mailer   = $mailer;
	}

	/**
	 * Whether it is switched on (and the Client Monitor it reads from).
	 *
	 * @return bool
	 */
	public function enabled() {
		return (bool) $this->settings->get( 'brief_enabled' ) && $this->monitor->enabled();
	}

	/**
	 * Who gets it: the addresses in Settings, else the site admin email.
	 *
	 * @return string[]
	 */
	public function recipients() {
		$list = array_values( array_unique( array_map( 'strtolower', array_filter( (array) $this->settings->get( 'brief_emails' ), 'is_email' ) ) ) );
		return $list ? $list : array( (string) get_option( 'admin_email' ) );
	}

	/**
	 * The latest send time at or before $now (the chosen weekday and hour, site time zone).
	 *
	 * @param int $now Unix time.
	 * @return int
	 */
	public function last_slot( $now ) {
		$tz    = wp_timezone();
		$local = ( new \DateTimeImmutable( '@' . (int) $now ) )->setTimezone( $tz );
		$day   = min( 7, max( 1, (int) $this->settings->get( 'brief_weekday' ) ) );
		$hour  = min( 23, max( 0, (int) $this->settings->get( 'brief_hour' ) ) );
		$back  = ( (int) $local->format( 'N' ) - $day + 7 ) % 7;
		// Move the date before setting the hour: on a DST change day the hour may not exist.
		$slot = $local->modify( '-' . $back . ' days' )->setTime( $hour, 0 );
		if ( $slot->getTimestamp() > $now ) {
			$slot = $slot->modify( '-7 days' )->setTime( $hour, 0 );
		}
		return $slot->getTimestamp();
	}

	/**
	 * The next send time after $now.
	 *
	 * @param int|null $now Unix time.
	 * @return int
	 */
	public function next_slot( $now = null ) {
		$now  = null === $now ? time() : (int) $now;
		$last = $this->last_slot( $now );
		$sent = (int) get_option( self::SENT, 0 );
		// This week's slot has passed but it hasn't gone yet: the hourly job sends it next.
		if ( $sent < $last && $sent > 0 ) {
			return $last;
		}
		$hour = min( 23, max( 0, (int) $this->settings->get( 'brief_hour' ) ) );
		return ( new \DateTimeImmutable( '@' . $last ) )->setTimezone( wp_timezone() )->modify( '+7 days' )->setTime( $hour, 0 )->getTimestamp();
	}

	/**
	 * Starts the clock when it is switched on, so the first brief goes at the
	 * next chosen time rather than straight away for a time already past.
	 *
	 * @param int|null $now Unix time.
	 * @return void
	 */
	public function start( $now = null ) {
		update_option( self::SENT, null === $now ? time() : (int) $now, false );
	}

	/**
	 * Sends this week's brief if it is due. Called by the hourly job.
	 *
	 * @param int|null $now Unix time.
	 * @return bool Whether at least one message was accepted; normal skips return false.
	 * @throws \Throwable When an attempted send or its outcome storage fails.
	 */
	public function maybe_send( $now = null ) {
		$now = null === $now ? time() : (int) $now;
		if ( ! $this->enabled() ) {
			return false;
		}
		$lock = OptionLock::acquire( 'turtlereport_brief_lock', self::LOCK_TTL );
		if ( null === $lock ) {
			return false;
		}
		$claimed = false;
		try {
			wp_cache_delete( self::SENT, 'options' );
			$sent = (int) get_option( self::SENT, 0 );
			if ( ! $sent ) {
				$this->start( $now );
				return false;
			}
			if ( $sent >= $this->last_slot( $now ) ) {
				return false;
			}
			// Claim before mail: an interrupted attempt must not trigger duplicate mail.
			if ( ! update_option( self::SENT, $now, false ) ) {
				return false;
			}
			$claimed = true;
			$this->record_outcome( 'attempted', $now );
			$result = $this->send( $this->recipients() );
			$sent   = $result['sent'];
			$failed = count( $result['failed'] );
			$this->record_outcome( $failed ? ( $sent ? 'partial' : 'rejected' ) : 'accepted', $now, $sent, $failed );
			return $result['sent'] > 0;
		} catch ( \Throwable $e ) {
			if ( $claimed ) {
				// Some mail may already have been accepted. Preserve the claim; never retry blindly.
				update_option(
					self::OUTCOME,
					array(
						'time'     => $now,
						'status'   => 'unknown',
						'accepted' => null,
						'rejected' => null,
					),
					false
				);
			}
			throw $e;
		} finally {
			$lock->release();
		}
	}

	/**
	 * Whether the last scheduled attempt stopped before recording its outcome
	 * (a fatal error, timeout or killed process). Some mail may have gone out.
	 *
	 * @param int|null $now Unix time.
	 * @return bool
	 */
	public function interrupted( $now = null ) {
		$now     = null === $now ? time() : (int) $now;
		$outcome = $this->last_outcome();
		return 'attempted' === $outcome['status'] && $outcome['time'] < $now - self::LOCK_TTL;
	}

	/**
	 * Last attempt, preserved through ordinary disabled/not-due/busy skips.
	 *
	 * @return array{time:int,status:string,accepted:int|null,rejected:int|null}
	 */
	public function last_outcome() {
		$value = get_option( self::OUTCOME, array() );
		$value = is_array( $value ) ? $value : array();
		return array(
			'time'     => isset( $value['time'] ) ? max( 0, (int) $value['time'] ) : 0,
			'status'   => isset( $value['status'] ) && in_array( $value['status'], array( 'attempted', 'accepted', 'rejected', 'partial', 'unknown' ), true ) ? $value['status'] : '',
			'accepted' => isset( $value['accepted'] ) ? max( 0, (int) $value['accepted'] ) : null,
			'rejected' => isset( $value['rejected'] ) ? max( 0, (int) $value['rejected'] ) : null,
		);
	}

	/**
	 * Persists only safe state and counts before/after an external side effect.
	 *
	 * @param string   $status   Attempt state.
	 * @param int      $now      Attempt start.
	 * @param int|null $accepted Accepted count when known.
	 * @param int|null $rejected Rejected count when known.
	 * @return void
	 * @throws \RuntimeException When the outcome cannot be persisted.
	 */
	private function record_outcome( $status, $now, $accepted = null, $rejected = null ) {
		$value = array(
			'time'     => $now,
			'status'   => $status,
			'accepted' => $accepted,
			'rejected' => $rejected,
		);
		if ( ! update_option( self::OUTCOME, $value, false ) && get_option( self::OUTCOME ) !== $value ) {
			throw new \RuntimeException( 'Weekly brief outcome storage failed.' );
		}
	}

	/**
	 * What the brief says, grouped so it reads in half a minute: the verdict,
	 * then each client that needs attention with its most important issues,
	 * then the clients with nothing open.
	 *
	 * @return array{total:int,attention:int,issues:int,top:array[],groups:array[],quiet:string[],unavailable:string[],period:array,checked:int,monitor_url:string,lead:string}
	 */
	public function build() {
		$all     = array_values( $this->sites->all() );
		$payload = $this->monitor->payload( $all );
		$active  = array_values(
			array_filter(
				$payload['alerts'],
				static function ( $a ) {
					return AlertStore::ACTIVE === $a['state'];
				}
			)
		);
		usort( $active, array( __CLASS__, 'compare' ) );
		$open = array();
		foreach ( $active as $a ) {
			$open[ $a['site'] ] = isset( $open[ $a['site'] ] ) ? $open[ $a['site'] ] + 1 : 1;
		}
		// The most important issue of each client first, so three clients aren't crowded out by one.
		$top  = array();
		$seen = array();
		foreach ( array( true, false ) as $first_only ) {
			foreach ( $active as $a ) {
				if ( count( $top ) >= self::TOP ) {
					break 2;
				}
				$key = $a['site'] . '|' . $a['id'];
				if ( isset( $seen[ $key ] ) || ( $first_only && isset( $seen[ $a['site'] ] ) ) ) {
					continue;
				}
				$seen[ $key ]       = true;
				$seen[ $a['site'] ] = true;
				$top[]              = array(
					'site'     => (string) $a['site'],
					'client'   => (string) $a['siteName'],
					'title'    => (string) $a['title'],
					'summary'  => self::short_summary( (string) $a['summary'] ),
					'basis'    => (string) $a['basis'],
					'severity' => 'high' === $a['severity'] ? 'high' : 'medium',
					'priority' => ! empty( $a['priority']['level'] ) ? (string) $a['priority']['label'] : '',
					'action'   => ! empty( $a['next'] ) ? (string) $a['next'] : ( ! empty( $a['checks'] ) ? (string) $a['checks'][0] : '' ),
					'url'      => (string) $a['reportUrl'],
				);
			}
		}
		// The same items, one block per client, in the order they first appear.
		$groups = array();
		foreach ( $top as $t ) {
			if ( ! isset( $groups[ $t['site'] ] ) ) {
				$groups[ $t['site'] ] = array(
					'client' => $t['client'],
					'url'    => $t['url'],
					'open'   => $open[ $t['site'] ],
					'items'  => array(),
				);
			}
			$groups[ $t['site'] ]['items'][] = $t;
		}
		foreach ( $groups as $id => $g ) {
			$groups[ $id ]['more'] = max( 0, $g['open'] - count( $g['items'] ) );
		}
		$quiet       = array();
		$unavailable = array();
		$records     = array_column( $payload['sites'], null, 'id' );
		foreach ( $all as $site ) {
			if ( ! Monitor::checkable( $site ) ) {
				continue;
			}
			$record = isset( $records[ $site->id ] ) ? $records[ $site->id ] : array(
				'checked' => 0,
				'errors'  => array(),
			);
			if ( ! $record['checked'] || $record['errors'] ) {
				$unavailable[] = $site->display_name();
				continue;
			}
			if ( ! isset( $open[ $site->id ] ) ) {
				$quiet[] = $site->display_name();
			}
		}
		natcasesort( $quiet );
		natcasesort( $unavailable );
		return array(
			'total'       => count( $all ),
			'attention'   => count( $open ),
			'issues'      => count( $active ),
			'top'         => $top,
			'groups'      => array_values( $groups ),
			'quiet'       => array_values( $quiet ),
			'unavailable' => array_values( $unavailable ),
			'period'      => Periods::last_days( 28 ),
			'checked'     => (int) $payload['checked'],
			'monitor_url' => AdminLinks::url( AdminLinks::OVERVIEW ),
			'lead'        => $top ? $top[0]['client'] : '',
		);
	}

	/**
	 * An issue's numbers; its actual measurement period is shown separately.
	 *
	 * @param string $summary Summary.
	 * @return string
	 */
	public static function short_summary( $summary ) {
		$tail = __( ', last 28 days vs the 28 days before.', 'turtlereport' );
		$s    = trim( (string) $summary );
		if ( '' !== $tail && substr( $s, -strlen( $tail ) ) === $tail ) {
			$s = substr( $s, 0, -strlen( $tail ) ) . '.';
		}
		return $s;
	}

	/**
	 * A short date range, e.g. "17 Sep – 14 Oct".
	 *
	 * @param string $s Start (Y-m-d).
	 * @param string $e End (Y-m-d).
	 * @return string
	 */
	public static function short_range( $s, $e ) {
		$utc = new \DateTimeZone( 'UTC' );
		$day = static function ( $ymd ) use ( $utc ) {
			return wp_date( 'j M', (int) strtotime( $ymd . ' 12:00:00 UTC' ), $utc );
		};
		return $day( $s ) . ' – ' . $day( $e );
	}

	/**
	 * The one-line verdict at the top of the brief and in the inbox preview.
	 *
	 * @param array $data Result of build().
	 * @return string
	 */
	public static function verdict( array $data ) {
		if ( ! $data['attention'] ) {
			if ( ! empty( $data['unavailable'] ) ) {
				return __( 'Some client checks are incomplete. Review the Client Monitor before drawing conclusions.', 'turtlereport' );
			}
			/* translators: %d: number of checked clients. */
			return sprintf( _n( 'No active issues recorded for %d client.', 'No active issues recorded for %d clients.', $data['total'], 'turtlereport' ), $data['total'] );
		}
		return sprintf(
			/* translators: 1: clients that need attention, 2: all clients, 3: client to start with. */
			_n( '%1$d of %2$d clients needs attention. Start with %3$s.', '%1$d of %2$d clients need attention. Start with %3$s.', $data['attention'], 'turtlereport' ),
			$data['attention'],
			$data['total'],
			$data['lead']
		);
	}

	/**
	 * Most important first: the client's own priorities, then business impact, then severity.
	 *
	 * @param array $a Presented alert.
	 * @param array $b Presented alert.
	 * @return int
	 */
	public static function compare( array $a, array $b ) {
		$la = isset( $a['priority']['level'] ) ? (int) $a['priority']['level'] : 0;
		$lb = isset( $b['priority']['level'] ) ? (int) $b['priority']['level'] : 0;
		$ia = isset( self::IMPACT[ $a['type'] ] ) ? self::IMPACT[ $a['type'] ] : 9;
		$ib = isset( self::IMPACT[ $b['type'] ] ) ? self::IMPACT[ $b['type'] ] : 9;
		foreach ( array( $lb <=> $la, $ia <=> $ib, ( 'high' === $b['severity'] ) <=> ( 'high' === $a['severity'] ) ) as $order ) {
			if ( 0 !== $order ) {
				return $order;
			}
		}
		return strnatcasecmp( (string) $a['siteName'], (string) $b['siteName'] );
	}

	/**
	 * The email.
	 *
	 * @param array $data Result of build().
	 * @param bool  $test Test send.
	 * @return array Message for ReportMailer::deliver().
	 */
	public function compose( array $data, $test = false ) {
		$args = array(
			'data'   => $data,
			'test'   => (bool) $test,
			'brand'  => $this->settings->brand_name(),
			'color'  => $this->settings->brand_color(),
			'logo'   => $this->settings->logo_url(),
			'footer' => (string) $this->settings->get( 'footer_text' ),
			'credit' => $this->settings->show_credit(),
			'week'   => wp_date( 'j M Y' ),
		);
		ob_start();
		View::render( 'email/brief', $args );
		$html    = (string) ob_get_clean();
		$subject = ( $test ? '[' . __( 'Test', 'turtlereport' ) . '] ' : '' ) . ( $data['attention']
			/* translators: 1: number of clients, 2: client to start with. */
			? sprintf( _n( 'Weekly summary: %1$d client needs attention · start with %2$s', 'Weekly summary: %1$d clients need attention · start with %2$s', $data['attention'], 'turtlereport' ), $data['attention'], $data['lead'] )
			: ( ! empty( $data['unavailable'] )
				? __( 'Weekly summary: client checks need attention', 'turtlereport' )
				/* translators: %d: number of clients. */
				: sprintf( _n( 'Weekly summary: no active issues for %d client', 'Weekly summary: no active issues for %d clients', $data['total'], 'turtlereport' ), $data['total'] ) ) );
		$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'        => self::plain( $data ),
			'headers'     => $headers,
			'attachments' => array(),
			'tmp'         => '',
		);
	}

	/**
	 * Builds and sends it.
	 *
	 * @param string[] $to   Addresses.
	 * @param bool     $test Test send.
	 * @return array{sent:int,failed:string[],errors:array<string,string>}
	 */
	public function send( array $to, $test = false ) {
		$message = $this->compose( $this->build(), $test );
		$sent    = 0;
		$failed  = array();
		$errors  = array();
		foreach ( $to as $address ) {
			$ok = $this->mailer->deliver( $message, (string) $address );
			if ( true === $ok ) {
				++$sent;
			} else {
				$failed[]                    = (string) $address;
				$errors[ (string) $address ] = $ok->get_error_message();
			}
		}
		return array(
			'sent'   => $sent,
			'failed' => $failed,
			'errors' => $errors,
		);
	}

	/**
	 * Plain-text version.
	 *
	 * @param array $data Result of build().
	 * @return string
	 */
	public static function plain( array $data ) {
		$lines = array(
			self::verdict( $data ),
			__( 'From the latest Client Monitor checks', 'turtlereport' ),
		);
		foreach ( $data['groups'] as $g ) {
			$lines[] = '';
			/* translators: %d: number of open issues. */
			$lines[] = strtoupper( $g['client'] ) . ' · ' . sprintf( _n( '%d open issue', '%d open issues', $g['open'], 'turtlereport' ), $g['open'] );
			foreach ( $g['items'] as $t ) {
				$lines[] = '- ' . ( 'high' === $t['severity'] ? __( 'High', 'turtlereport' ) : __( 'Medium', 'turtlereport' ) ) . ': ' . $t['title'] . ( '' !== $t['priority'] ? ' [' . $t['priority'] . ']' : '' );
				$lines[] = '  ' . $t['summary'];
				if ( ! empty( $t['basis'] ) ) {
					$lines[] = '  ' . $t['basis'];
				}
				if ( '' !== $t['action'] ) {
					/* translators: %s: recommended next step. */
					$lines[] = '  ' . sprintf( __( 'Next step: %s', 'turtlereport' ), $t['action'] );
				}
			}
			$lines[] = '  ' . $g['url'];
		}
		if ( $data['quiet'] ) {
			$lines[] = '';
			/* translators: %s: client names. */
			$lines[] = sprintf( __( 'No active issues: %s', 'turtlereport' ), implode( ', ', $data['quiet'] ) );
		}
		if ( ! empty( $data['unavailable'] ) ) {
			/* translators: %s: names of clients whose checks failed or have not run. */
			$lines[] = sprintf( __( 'Checks incomplete: %s. Earlier issues may still be listed.', 'turtlereport' ), implode( ', ', $data['unavailable'] ) );
		}
		$lines[] = '';
		/* translators: %s: Client Monitor address. */
		$lines[] = sprintf( __( 'Open the Client Monitor: %s', 'turtlereport' ), $data['monitor_url'] );
		return implode( "\n", $lines );
	}
}