<?php
namespace Strikewise\Admin;

use Strikewise\Calculator\Reference;
use Strikewise\Calculator\ReferenceCalculator;
use Strikewise\Calculator\ReferenceService;
use Strikewise\Display\CjeuMode;
use Strikewise\History\Repository;
use Strikewise\Pricing\Perishable;

defined( 'ABSPATH' ) || exit;

/**
 * "Is my shop safe?" in one answer: what Strikewise does for the reduced
 * products right now, and the points that need the shop owner.
 * Shared by the overview page and the dashboard widget.
 */
final class Health {

	const TRANSIENT = 'strikewise_protection';

	/** Reduced products looked at for the figures; enough for nearly every shop. */
	const MAX_PRODUCTS = 2000;

	public static function register(): void {
		foreach ( array( 'strikewise_cjeu_mode', 'strikewise_cjeu_no_history', 'strikewise_show_single', 'strikewise_show_loop' ) as $option ) {
			add_action( 'update_option_' . $option, array( self::class, 'forget' ) );
		}
		add_action( 'strikewise_price_recorded', array( self::class, 'forget' ) );
	}

	public static function forget(): void {
		delete_transient( self::TRANSIENT );
	}

	/**
	 * What happens to the reduced products: shown with the lowest price, strike-through
	 * price corrected, not shown as a reduction, exempt as perishable, earlier price unknown.
	 *
	 * @return array{reduced:int,corrected:int,hidden:int,exempt:int,unknown:int}
	 */
	public static function protection(): array {
		$cached = get_transient( self::TRANSIENT );
		if ( is_array( $cached ) ) {
			return $cached;
		}

		global $wpdb;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery -- cached for 10 minutes below.
		$ids = $wpdb->get_col(
			$wpdb->prepare(
				"SELECT m.post_id FROM %i m INNER JOIN %i p ON p.ID = m.post_id AND p.post_status IN ( 'publish', 'private' ) WHERE m.meta_key = %s AND m.meta_value <> '' LIMIT %d",
				$wpdb->postmeta,
				$wpdb->posts,
				Repository::META_T0,
				self::MAX_PRODUCTS
			)
		);

		$service = new ReferenceService( new Repository(), new ReferenceCalculator() );
		$cjeu    = new CjeuMode( $service );
		$counts  = array(
			'reduced'   => 0,
			'corrected' => 0,
			'hidden'    => 0,
			'exempt'    => 0,
			'unknown'   => 0,
		);

		foreach ( (array) $ids as $id ) {
			$product = wc_get_product( (int) $id );
			if ( ! $product || ! $product->is_on_sale( 'edit' ) ) {
				continue;
			}
			++$counts['reduced'];
			if ( Perishable::applies( $product ) ) {
				++$counts['exempt'];
				continue;
			}
			$decision = $cjeu->decide( $product );
			$action   = $decision['action'];
			if ( CjeuMode::ACTION_REPLACE === $action ) {
				// Only where the strike-through price really changes.
				if ( abs( (float) $decision['regular'] - (float) $product->get_regular_price( 'edit' ) ) > 0.005 ) {
					++$counts['corrected'];
				}
			} elseif ( CjeuMode::ACTION_NO_REDUCTION === $action ) {
				++$counts['hidden'];
			} elseif ( Reference::STATUS_NO_HISTORY === $service->get( $product )->status ) {
				++$counts['unknown'];
			}
		}

		set_transient( self::TRANSIENT, $counts, 10 * MINUTE_IN_SECONDS );
		return $counts;
	}

	/**
	 * Points that need the shop owner, most urgent first.
	 *
	 * @return array<int,array{tone:string,title:string,text:string,url:string,link:string}>
	 */
	public static function issues(): array {
		$settings = AdminPage::settings_url();
		$issues   = array();

		if ( ! Settings::show_single() && ! Settings::show_loop() ) {
			$issues[] = self::issue( 'critical', __( 'The lowest price is not shown anywhere', 'strikewise' ), __( 'Customers do not see the price of the 30 days before a reduction.', 'strikewise' ), $settings, __( 'Turn on', 'strikewise' ) );
		} elseif ( ! Settings::show_single() || ! Settings::show_loop() ) {
			$issues[] = self::issue( 'warning', __( 'The lowest price is only shown in part of the shop', 'strikewise' ), __( 'It belongs wherever a reduced price is shown.', 'strikewise' ), $settings, __( 'Turn on', 'strikewise' ) );
		}

		if ( ! CjeuMode::is_enabled() ) {
			$issues[] = self::issue( 'warning', __( 'Strike-through prices are not corrected', 'strikewise' ), __( 'Since the CJEU ruling, a strike-through price must be the lowest price of the 30 days before.', 'strikewise' ), $settings, __( 'Turn on CJEU mode', 'strikewise' ) );
		}

		$unknown = self::protection()['unknown'];
		if ( $unknown > 0 ) {
			$issues[] = self::issue(
				'warning',
				/* translators: %d: number of products */
				sprintf( _n( '%d reduction without an earlier price', '%d reductions without an earlier price', $unknown, 'strikewise' ), $unknown ),
				__( 'A strike-through price needs the earlier price. Enter it in the product or let Strikewise hide these reductions.', 'strikewise' ),
				$settings,
				__( 'Settings', 'strikewise' )
			);
		}

		if ( null === AdminPage::next_daily_run() ) {
			$issues[] = self::issue( 'warning', __( 'The daily sync is not running', 'strikewise' ), __( 'Deactivate and reactivate Strikewise.', 'strikewise' ), admin_url( 'plugins.php' ), __( 'Plugins', 'strikewise' ) );
		}

		foreach ( array_merge( Compat::discount_plugins(), Compat::currency_plugins() ) as $name ) {
			$issues[] = self::issue(
				'warning',
				/* translators: %s: plugin name */
				sprintf( __( '%s: prices not visible to Strikewise', 'strikewise' ), $name ),
				__( 'Check the lowest price of reductions from this plugin yourself.', 'strikewise' ),
				'',
				''
			);
		}

		/**
		 * Filters the points that need the shop owner (the premium scanner adds its findings).
		 *
		 * @param array<int,array{tone:string,title:string,text:string,url:string,link:string}> $issues
		 */
		$issues = (array) apply_filters( 'strikewise_health_issues', $issues );

		usort(
			$issues,
			static function ( $a, $b ) {
				return ( 'critical' === $b['tone'] ) <=> ( 'critical' === $a['tone'] );
			}
		);

		return $issues;
	}

	/**
	 * @return array{tone:string,title:string,text:string,url:string,link:string}
	 */
	public static function issue( string $tone, string $title, string $text, string $url, string $link ): array {
		return array(
			'tone'  => $tone,
			'title' => $title,
			'text'  => $text,
			'url'   => $url,
			'link'  => $link,
		);
	}

	/**
	 * Overall state: ok, warning or critical.
	 *
	 * @param array<int,array{tone:string}> $issues
	 */
	public static function tone( array $issues ): string {
		if ( ! $issues ) {
			return 'ok';
		}
		return in_array( 'critical', array_column( $issues, 'tone' ), true ) ? 'critical' : 'warning';
	}

	/**
	 * The headline of the status card.
	 *
	 * @param array<int,array{tone:string}> $issues
	 */
	public static function headline( array $issues ): string {
		if ( ! $issues ) {
			return __( 'Your discounts are protected', 'strikewise' );
		}
		/* translators: %d: number of points */
		return sprintf( _n( '%d point needs your attention', '%d points need your attention', count( $issues ), 'strikewise' ), count( $issues ) );
	}
}