<?php
/**
 * Checks a report before it is delivered.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Delivery;

use TurtleReport\Auth\ApiException;
use TurtleReport\Profiles\Profile;
use TurtleReport\Support\Periods;

defined( 'ABSPATH' ) || exit;

/**
 * Turns a built summary (Reports\Summary::build()) into a verdict:
 *
 * - ready:   every switched-on part loaded, for the right period;
 * - warning: the report can go out, but something deserves a look
 *            (no data yet, configured GA4 events not found, the last days of
 *            the period not available yet, a part switched on without a source);
 * - blocked: a part couldn't be loaded at all (sign-in expired, access denied,
 *            API switched off or temporarily unavailable), or the period is wrong.
 *
 * It distinguishes a real zero from "no data yet", an unconfigured source,
 * denied access, an expired sign-in and a temporary outage, so nothing that
 * failed is ever reported as zero.
 */
final class Readiness {

	const READY   = 'ready';
	const WARNING = 'warning';
	const BLOCKED = 'blocked';

	/** Check level that informs without changing the verdict. */
	const NOTICE = 'notice';
	const OK     = 'ok';

	/**
	 * Checks a summary.
	 *
	 * @param Profile     $site   Site.
	 * @param array       $data   Sections from Summary::build().
	 * @param array       $period Period with s, e, ps and pe.
	 * @param string|null $today  Override for "today" (Y-m-d) in the site's time zone.
	 * @return array{level:string,checks:array[],temporary:bool}
	 */
	public static function check( Profile $site, array $data, array $period, $today = null ) {
		$checks = array();
		$add    = static function ( $section, $level, $code, $message, $temporary = false ) use ( &$checks ) {
			$checks[] = array(
				'section'   => $section,
				'level'     => $level,
				'code'      => $code,
				'message'   => $message,
				'temporary' => (bool) $temporary,
			);
		};

		self::check_period( $period, $today, $add );

		$labels = self::labels();
		$any    = false;
		foreach ( Profile::all_sections() as $section ) {
			if ( ! in_array( $section, $site->sections, true ) ) {
				continue;
			}
			if ( ! $site->wants( $section ) || ( Profile::SECTION_TRAFFIC === $section && ! $site->traffic_metrics ) ) {
				$add(
					$section,
					self::WARNING,
					'not_configured',
					Profile::SECTION_TRAFFIC === $section && $site->wants( $section )
						/* translators: %s: report section name. */
						? sprintf( __( '%s is switched on but no GA4 metrics are chosen, so it is left out.', 'turtlereport' ), $labels[ $section ] )
						/* translators: %s: report section name. */
						: sprintf( __( '%s is switched on but has no data source chosen, so it is left out.', 'turtlereport' ), $labels[ $section ] )
				);
				continue;
			}
			$any = true;
			if ( ! isset( $data[ $section ] ) ) {
				continue;
			}
			$part = $data[ $section ];
			if ( isset( $part['error'] ) ) {
				$reason                   = isset( $part['reason'] ) ? (string) $part['reason'] : ApiException::GOOGLE;
				list( $code, $temporary ) = self::classify( $reason, $section );
				$add( $section, self::BLOCKED, $code, self::error_message( $code, $labels[ $section ], (string) $part['error'] ), $temporary );
				// Kept so problems() can say it once when several sections fail the same way.
				$checks[ count( $checks ) - 1 ] += array(
					'label'  => $labels[ $section ],
					'detail' => (string) $part['error'],
				);
				continue;
			}
			self::check_section( $section, $part, $period, $labels[ $section ], $add );
		}
		if ( ! $any ) {
			$add( '', self::BLOCKED, 'no_sections', __( 'Nothing to report: no section is switched on with a data source.', 'turtlereport' ) );
		}

		$level     = self::READY;
		$temporary = false;
		$blocked   = 0;
		foreach ( $checks as $c ) {
			if ( self::BLOCKED === $c['level'] ) {
				++$blocked;
				$level     = self::BLOCKED;
				$temporary = $temporary || $c['temporary'];
			} elseif ( self::WARNING === $c['level'] && self::READY === $level ) {
				$level = self::WARNING;
			}
		}
		// Only "temporary" when every blocking problem may clear by itself.
		if ( $blocked ) {
			foreach ( $checks as $c ) {
				if ( self::BLOCKED === $c['level'] && ! $c['temporary'] ) {
					$temporary = false;
				}
			}
		}
		return array(
			'level'     => $level,
			'checks'    => $checks,
			'temporary' => $temporary,
		);
	}

	/**
	 * Checks that the period is complete and its comparison lines up.
	 *
	 * @param array       $period Period.
	 * @param string|null $today  Today.
	 * @param callable    $add    Adds a check.
	 * @return void
	 */
	private static function check_period( array $period, $today, callable $add ) {
		$valid = static function ( $d ) {
			$x = \DateTimeImmutable::createFromFormat( '!Y-m-d', (string) $d, new \DateTimeZone( 'UTC' ) );
			return $x && $x->format( 'Y-m-d' ) === $d;
		};
		foreach ( array( 's', 'e', 'ps', 'pe' ) as $k ) {
			if ( ! isset( $period[ $k ] ) || ! $valid( $period[ $k ] ) ) {
				$add( '', self::BLOCKED, 'period', __( 'The reporting period is invalid.', 'turtlereport' ) );
				return;
			}
		}
		if ( $period['s'] > $period['e'] || $period['ps'] > $period['pe'] || ( $period['pe'] >= $period['s'] && $period['ps'] <= $period['e'] ) ) {
			$add( '', self::BLOCKED, 'period', __( 'The reporting period or its comparison is invalid (the dates overlap or run backwards).', 'turtlereport' ) );
			return;
		}
		$last = Periods::end_date( $today );
		if ( $period['e'] > $last ) {
			$add(
				'',
				self::BLOCKED,
				'period',
				/* translators: 1: period end date, 2: last date with settled data. */
				sprintf( __( 'The period ends on %1$s, but Google data is only settled up to %2$s. Send it later.', 'turtlereport' ), $period['e'], $last )
			);
		}
	}

	/**
	 * Checks one section that loaded.
	 *
	 * @param string   $section Section key.
	 * @param array    $part    Section data.
	 * @param array    $period  Period.
	 * @param string   $label   Section name.
	 * @param callable $add     Adds a check.
	 * @return void
	 */
	private static function check_section( $section, array $part, array $period, $label, callable $add ) {
		$status = isset( $part['status'] ) ? (string) $part['status'] : 'ok';
		if ( 'no_data' === $status && Profile::SECTION_CONVERSIONS !== $section ) {
			/* translators: %s: report section name. */
			$add( $section, self::WARNING, 'no_data', sprintf( __( '%s returned no data at all for this period or the one before. The property may be new, the wrong one, or not collecting data yet.', 'turtlereport' ), $label ) );
			return;
		}
		if ( 'zero' === $status ) {
			/* translators: %s: report section name. */
			$add( $section, self::OK, 'zero', sprintf( __( '%s is working; this period\'s numbers are genuinely zero.', 'turtlereport' ), $label ) );
		}

		if ( Profile::SECTION_CONVERSIONS === $section ) {
			if ( 'no_events' === $status ) {
				$add( $section, self::WARNING, 'no_events', __( 'No GA4 events are chosen as conversions, so conversions show as none.', 'turtlereport' ) );
				return;
			}
			if ( ! empty( $part['missing_events'] ) ) {
				$add(
					$section,
					self::WARNING,
					'missing_events',
					sprintf(
						/* translators: 1: comma-separated GA4 event names, 2: number of days. */
						_n( 'This conversion event wasn\'t recorded by GA4 in the last %2$d days: %1$s. Check the event name (it is case-sensitive) and that tracking still works.', 'These conversion events weren\'t recorded by GA4 in the last %2$d days: %1$s. Check the event names (they are case-sensitive) and that tracking still works.', count( $part['missing_events'] ), 'turtlereport' ),
						implode( ', ', $part['missing_events'] ),
						\TurtleReport\Reports\Summary::SEEN_DAYS
					)
				);
			}
			if ( ! empty( $part['overlaps'] ) ) {
				$add(
					$section,
					self::NOTICE,
					'overlap',
					sprintf(
						/* translators: %s: comma-separated GA4 event names. */
						__( 'Some events are in more than one conversion group (%s). Each group counts them, but the total counts each event once.', 'turtlereport' ),
						implode( ', ', array_keys( $part['overlaps'] ) )
					)
				);
			}
		}

		$last = isset( $part['last_date'] ) ? (string) $part['last_date'] : '';
		if ( '' !== $last && $last < $period['e'] && in_array( $section, array( Profile::SECTION_SEARCH, Profile::SECTION_BUSINESS ), true ) ) {
			$add(
				$section,
				self::WARNING,
				'incomplete',
				/* translators: 1: report section name, 2: first missing date, 3: period end date. */
				sprintf( __( '%1$s has no data yet for %2$s to %3$s, so the last days of the period may be missing.', 'turtlereport' ), $label, Periods::add_days( $last, 1 ), $period['e'] )
			);
		}
	}

	/**
	 * Check code for an API error reason, and whether it may clear by itself.
	 *
	 * @param string $reason  ApiException reason.
	 * @param string $section Section key.
	 * @return array{0:string,1:bool}
	 */
	public static function classify( $reason, $section = '' ) {
		switch ( $reason ) {
			case ApiException::RECONNECT:
				return array( 'expired', false );
			case ApiException::PERMISSION:
			case ApiException::MISSING_SCOPE:
				return array( 'access_denied', false );
			case ApiException::API_DISABLED:
				return array( 'api_disabled', false );
			case ApiException::QUOTA:
				// For Business Profile a quota error almost always means Google hasn't approved the project.
				return Profile::SECTION_BUSINESS === $section ? array( 'not_approved', false ) : array( 'unavailable', true );
			case ApiException::NETWORK:
			case ApiException::GOOGLE:
				return array( 'unavailable', true );
			default:
				return array( 'not_configured', false );
		}
	}

	/**
	 * Message for a blocking error.
	 *
	 * @param string $code   Check code.
	 * @param string $label  Section name.
	 * @param string $detail Message from Google or the plugin.
	 * @return string
	 */
	private static function error_message( $code, $label, $detail ) {
		switch ( $code ) {
			case 'expired':
				if ( '' !== trim( $detail ) ) {
					// The plugin's own message already says what expired and how to fix it.
					/* translators: 1: report section name, 2: what expired and how to reconnect. */
					$text = __( '%1$s couldn\'t load. %2$s', 'turtlereport' );
					break;
				}
				/* translators: 1: report section name, 2: details (empty). */
				$text = __( '%1$s couldn\'t load: the Google sign-in expired or was revoked. Reconnect it on the Connections screen.%2$s', 'turtlereport' );
				break;
			case 'access_denied':
				/* translators: 1: report section name, 2: details. */
				$text = __( '%1$s couldn\'t load: Google denied access to this property. (%2$s)', 'turtlereport' );
				break;
			case 'api_disabled':
				/* translators: 1: report section name, 2: details. */
				$text = __( '%1$s couldn\'t load: an API is switched off in the Google Cloud project. (%2$s)', 'turtlereport' );
				break;
			case 'not_approved':
				/* translators: 1: report section name, 2: details. */
				$text = __( '%1$s couldn\'t load: Google hasn\'t approved Business Profile API access for this Cloud project yet. (%2$s)', 'turtlereport' );
				break;
			case 'unavailable':
				/* translators: 1: report section name, 2: details. */
				$text = __( '%1$s couldn\'t load: Google was temporarily unavailable. (%2$s)', 'turtlereport' );
				break;
			default:
				/* translators: 1: report section name, 2: details. */
				$text = __( '%1$s couldn\'t load: it isn\'t set up correctly. (%2$s)', 'turtlereport' );
		}
		return sprintf( $text, $label, $detail );
	}

	/**
	 * Section names for messages.
	 *
	 * @return array<string,string>
	 */
	public static function labels() {
		return array(
			Profile::SECTION_SEARCH      => __( 'Search Console', 'turtlereport' ),
			Profile::SECTION_CONVERSIONS => __( 'GA4 conversions', 'turtlereport' ),
			Profile::SECTION_AI          => __( 'AI assistant traffic', 'turtlereport' ),
			Profile::SECTION_TRAFFIC     => __( 'GA4 website traffic', 'turtlereport' ),
			Profile::SECTION_BUSINESS    => __( 'Business Profile', 'turtlereport' ),
		);
	}

	/**
	 * Human label for a verdict.
	 *
	 * @param string $level Verdict.
	 * @return string
	 */
	public static function label( $level ) {
		switch ( $level ) {
			case self::READY:
				return __( 'Ready', 'turtlereport' );
			case self::WARNING:
				return __( 'Warning', 'turtlereport' );
			default:
				return __( 'Blocked', 'turtlereport' );
		}
	}

	/**
	 * The checks a reader needs to see: problems first, without "all fine" lines.
	 *
	 * @param array $result Result of check().
	 * @return array[]
	 */
	public static function problems( array $result ) {
		$order = array(
			self::BLOCKED => 0,
			self::WARNING => 1,
			self::NOTICE  => 2,
		);
		$rows  = array_values(
			array_filter(
				isset( $result['checks'] ) ? (array) $result['checks'] : array(),
				static function ( $c ) use ( $order ) {
					return isset( $order[ $c['level'] ] );
				}
			)
		);
		usort(
			$rows,
			static function ( $a, $b ) use ( $order ) {
				return $order[ $a['level'] ] <=> $order[ $b['level'] ];
			}
		);
		// One line per cause: four sections failing on the same expired sign-in read as one problem.
		$merged = array();
		$groups = array();
		foreach ( $rows as $row ) {
			if ( self::BLOCKED !== $row['level'] || ! isset( $row['label'], $row['detail'] ) ) {
				$merged[] = $row;
				continue;
			}
			$key = $row['code'] . '|' . $row['detail'];
			if ( ! isset( $groups[ $key ] ) ) {
				$groups[ $key ] = count( $merged );
				$merged[]       = $row + array( 'labels' => array() );
			}
			$merged[ $groups[ $key ] ]['labels'][] = $row['label'];
		}
		foreach ( $groups as $i ) {
			$labels = $merged[ $i ]['labels'];
			if ( count( $labels ) > 1 ) {
				$merged[ $i ]['message']  = self::error_message( $merged[ $i ]['code'], wp_sprintf( '%l', $labels ), $merged[ $i ]['detail'] );
				$merged[ $i ]['sections'] = count( $labels );
			}
			unset( $merged[ $i ]['labels'] );
		}
		return $merged;
	}
}