<?php
/** Generic rule pack composer. @package Leanmerce\CommerceCompliance */
namespace Leanmerce\CommerceCompliance\Domain\Rules;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

use Leanmerce\CommerceCompliance\Domain\Compliance\CommerceContext;
final class RulesEngine {
	/** @param RulePackInterface[] $packs */
	public function compose( CommerceContext $context, array $packs ): EffectiveRuleSet {
		$obligations = array();
		$pack_ids    = array();
		$conflicts   = array();
		$overrides   = array();
		foreach ( $packs as $pack ) {
			if ( ! $pack instanceof RulePackInterface || ! $pack->supports( $context ) || ! $this->is_effective( $pack->get_manifest(), $context ) ) {
				continue; }
			$pack_id    = $pack->get_manifest()->get_id();
			$pack_ids[] = $pack_id;
			foreach ( $pack->get_obligations( $context ) as $obligation ) {
				if ( ! $obligation instanceof Obligation ) {
					continue; }
				$id = $obligation->get_id();
				if ( isset( $obligations[ $id ] ) && $obligations[ $id ]->get_value() !== $obligation->get_value() ) {
					$conflicts[ $id ] = $id;
					continue; }
				$obligations[ $id ] = $obligation;
			}
			foreach ( $pack->get_overrides( $context ) as $target => $value ) {
				$overrides[ $target ] = array(
					'value'  => $value,
					'source' => $pack_id,
				); }
		}
		foreach ( $overrides as $target => $override ) {
			if ( isset( $obligations[ $target ] ) ) {
				$obligations[ $target ] = $obligations[ $target ]->with_value( $override['value'], $override['source'] );
				unset( $conflicts[ $target ] ); }
		}
		return new EffectiveRuleSet( $obligations, array_values( array_unique( $pack_ids ) ), array_values( $conflicts ) );
	}

	private function is_effective( RulePackManifest $manifest, CommerceContext $context ): bool {
		$occurred_at = $context->temporal()->get_occurred_at();
		try {
			$occurred_at = $occurred_at->setTimezone( new \DateTimeZone( $context->temporal()->get_timezone() ) );
		} catch ( \Throwable $exception ) {
			unset( $exception );
		}
		$date  = $occurred_at->format( 'Y-m-d' );
		$from  = trim( $manifest->get_effective_from() );
		$until = trim( (string) $manifest->get_effective_until() );
		return ( '' === $from || $date >= $from ) && ( '' === $until || $date <= $until );
	}
}