<?php
namespace Strikewise\History;

use Strikewise\Calculator\ReferenceService;
use Strikewise\Pricing\PriceResolver;

defined( 'ABSPATH' ) || exit;

/**
 * Writes a history row whenever the consumer price of a product changes.
 *
 * Hooks into the WooCommerce CRUD layer, which covers the product editor,
 * quick/bulk edit, the REST API, scheduled sales and every importer that uses
 * WC_Product::save(). Direct database writes are caught by the Reconciler.
 */
final class Recorder {

	/** @var Repository */
	private $repository;

	/** @var ReferenceService */
	private $references;

	public function __construct( Repository $repository, ReferenceService $references ) {
		$this->repository = $repository;
		$this->references = $references;
	}

	public function register(): void {
		add_action( 'woocommerce_after_product_object_save', array( $this, 'on_save' ), 20 );
		add_action( 'woocommerce_after_product_variation_object_save', array( $this, 'on_save' ), 20 );
	}

	/**
	 * @param mixed $product
	 */
	public function on_save( $product ): void {
		if ( $product instanceof \WC_Product ) {
			$this->record( $product, self::detect_source() );
		}
	}

	/**
	 * Records the current price if it differs from the open history row.
	 *
	 * @return bool Whether a new row was written.
	 */
	public function record( \WC_Product $product, string $source ): bool {
		if ( ! $product->get_id() || ! PriceResolver::is_trackable( $product ) ) {
			return false;
		}

		$snapshot = PriceResolver::snapshot( $product );
		if ( null === $snapshot ) {
			return false;
		}

		$currency = PriceResolver::currency();
		$open     = $this->repository->get_open( $product->get_id(), $currency );

		if ( null !== $open && self::unchanged( $open, $snapshot ) ) {
			return false;
		}

		$change                = new Change();
		$change->product_id    = $product->get_id();
		$change->parent_id     = $product->get_parent_id();
		$change->currency      = $currency;
		$change->price         = $snapshot['price'];
		$change->regular_price = $snapshot['regular'];
		$change->reduced       = $snapshot['reduced'];
		$change->valid_from    = Repository::to_datetime( $this->valid_from( $product, $source, $open, $snapshot['reduced'] ) );
		$change->source        = $source;
		$change->user_id       = self::responsible_user( $source );

		$this->repository->insert_change( $change );
		$this->references->refresh( $product );

		/**
		 * Fires after Strikewise recorded a price change.
		 *
		 * @param Change      $change
		 * @param \WC_Product $product
		 */
		do_action( 'strikewise_price_recorded', $change, $product );

		return true;
	}

	/**
	 * When did the new price start to apply?
	 *
	 * Usually "now". For a scheduled sale the start date set in WooCommerce is
	 * used, because the WooCommerce cron may run hours later.
	 *
	 * @param \WC_Product              $product
	 * @param string                   $source
	 * @param array<string,mixed>|null $open
	 * @param bool                     $reduced
	 */
	private function valid_from( \WC_Product $product, string $source, ?array $open, bool $reduced ): int {
		$now  = time();
		$from = $now;

		if ( $reduced ) {
			$sale_start = $product->get_date_on_sale_from( 'edit' );
			if ( $sale_start instanceof \WC_DateTime && $sale_start->getTimestamp() <= $now ) {
				$from = $sale_start->getTimestamp();
			} elseif ( 'schedule' === $source ) {
				// The WooCommerce cron clears the start date; scheduled sales start at midnight shop time.
				$from = ( new \DateTimeImmutable( 'today', wp_timezone() ) )->getTimestamp();
			}
		}

		// Never reach back before the price that applied until now.
		if ( null !== $open ) {
			$from = max( $from, Repository::to_timestamp( $open['valid_from'] ) );
		}

		return min( $from, $now );
	}

	/**
	 * @param array<string,mixed>                                     $open
	 * @param array{price: float, regular: float|null, reduced: bool} $snapshot
	 */
	public static function unchanged( array $open, array $snapshot ): bool {
		$regular = null === $open['regular_price'] ? null : (float) $open['regular_price'];

		return abs( (float) $open['price'] - $snapshot['price'] ) < 0.00005
			&& (bool) $open['is_reduced'] === $snapshot['reduced']
			&& ( null === $regular ? null === $snapshot['regular'] : null !== $snapshot['regular'] && abs( $regular - $snapshot['regular'] ) < 0.00005 );
	}

	/**
	 * Only changes made by a person get a user; automatic ones (cron, sync,
	 * storefront self-healing) would otherwise log whoever happened to be logged in.
	 */
	private static function responsible_user( string $source ): ?int {
		if ( ! in_array( $source, array( 'editor', 'rest', 'cli' ), true ) ) {
			return null;
		}
		$user_id = get_current_user_id();
		return $user_id ? $user_id : null;
	}

	private static function detect_source(): string {
		if ( doing_action( 'woocommerce_scheduled_sales' ) ) {
			return 'schedule';
		}
		if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
			return 'rest';
		}
		if ( defined( 'WP_CLI' ) && WP_CLI ) {
			return 'cli';
		}
		if ( wp_doing_cron() ) {
			return 'cron';
		}
		if ( is_admin() ) {
			return 'editor';
		}
		return 'other';
	}
}