<?php
namespace MazlanHalim\IntelliLanz\Graph;

/** Resolve only local, explicit evidence; no discovery, network access or health logic. */
final class RelationshipResolver {
    private KnownEcosystemRelationshipProvider $known;

    public function __construct( ?KnownEcosystemRelationshipProvider $known = null ) {
        $this->known = $known ?? new KnownEcosystemRelationshipProvider();
    }

    /** @return Edge[] New edges, without modifying the supplied graph. */
    public function resolve( Graph $graph ): array {
        $data = $graph->jsonSerialize();
        $nodes = array();
        $plugins = array();
        $seen = array();
        $ids = array();
        $edges = array();
        foreach ( $data['nodes'] as $node ) {
            $nodes[ $node['id'] ] = $node;
            $metadata = (array) $node['metadata'];
            // MU loaders are not valid targets for WordPress.org plugin dependencies.
            if ( $node['type'] === 'plugin' && ( $metadata['kind'] ?? null ) === 'standard' && is_string( $metadata['slug'] ?? null ) ) {
                $plugins[ $metadata['slug'] ][] = $node['id'];
            }
        }
        foreach ( $data['edges'] as $edge ) {
            $seen[ $this->key( $edge['source'], $edge['target'], $edge['relationship'] ) ] = true;
            $ids[ $edge['id'] ] = true;
        }
        $add = function ( string $source, string $target, string $relationship, string $evidence ) use ( &$edges, &$seen, &$ids, $nodes ): void {
            if ( $source === $target || ! isset( $nodes[ $source ], $nodes[ $target ] ) ) { return; }
            $key = $this->key( $source, $target, $relationship );
            if ( isset( $seen[ $key ] ) ) { return; }
            $base = 'edge:resolved:' . hash( 'sha256', $key );
            $id = $base;
            $suffix = 0;
            while ( isset( $ids[ $id ] ) ) { $id = $base . ':' . ++$suffix; }
            $edges[] = new Edge( $id, $source, $target, $relationship, 'high', array( 'evidence' => $evidence ) );
            $seen[ $key ] = true;
            $ids[ $id ] = true;
        };
        foreach ( $nodes as $id => $node ) {
            $metadata = (array) $node['metadata'];
            if ( isset( $nodes['wordpress:installation'] ) && $nodes['wordpress:installation']['type'] === 'wordpress' ) {
                if ( in_array( $node['type'], array( 'plugin', 'theme' ), true ) || ( $id === 'system:cron' && $node['type'] === 'cron' ) ) {
                    $add( 'wordpress:installation', $id, 'contains', 'wordpress_core_structure' );
                }
                if ( ( $id === 'system:php' && $node['type'] === 'php' ) || ( $id === 'system:database' && $node['type'] === 'database' ) ) {
                    $add( 'wordpress:installation', $id, 'uses', 'wordpress_core_structure' );
                }
            }
            if ( $node['type'] === 'theme' && is_string( $metadata['parent_stylesheet'] ?? null ) ) {
                $target = 'theme:' . $metadata['parent_stylesheet'];
                if ( isset( $nodes[ $target ] ) && $nodes[ $target ]['type'] === 'theme' ) {
                    $add( $id, $target, 'child_of', 'theme_parent_metadata' );
                }
            }
            if ( $node['type'] !== 'plugin' ) { continue; }
            $requires = $metadata['requires_plugins'] ?? array();
            foreach ( is_array( $requires ) ? $requires : array() as $slug ) {
                if ( is_string( $slug ) && isset( $plugins[ $slug ] ) && count( $plugins[ $slug ] ) === 1 ) {
                    $add( $id, $plugins[ $slug ][0], 'depends_on', 'wordpress_requires_plugins' );
                }
            }
            // Exact known plugin identities, never display-name or prefix matching.
            if ( $id === 'plugin:elementor-pro/elementor-pro.php' && ( $metadata['kind'] ?? null ) === 'standard' && isset( $plugins['elementor'] ) && $plugins['elementor'] === array( 'plugin:elementor/elementor.php' ) ) {
                $add( $id, 'plugin:elementor/elementor.php', 'extends', 'known_ecosystem_mapping' );
            }
            // Explicit WooCommerce dependency/minimum-version headers provide evidence.
            $wc_minimum = $metadata['wc_requires_at_least'] ?? null;
            $requires_wc = is_array( $requires ) && in_array( 'woocommerce', $requires, true );
            if ( ( $requires_wc || ( is_string( $wc_minimum ) && preg_match( '/^\d+(?:\.\d+){1,3}$/D', $wc_minimum ) ) ) && isset( $plugins['woocommerce'] ) && $plugins['woocommerce'] === array( 'plugin:woocommerce/woocommerce.php' ) ) {
                $add( $id, 'plugin:woocommerce/woocommerce.php', 'extends', $requires_wc ? 'wordpress_requires_plugins' : 'woocommerce_requires_header' );
            }
        }
        foreach ( $this->known->relationships( $graph ) as $rule ) {
            $add( $rule['source'], $rule['target'], $rule['relationship'], $rule['evidence'] );
        }
        return $edges;
    }

    private function key( string $source, string $target, string $relationship ): string {
        return serialize( array( $source, $target, $relationship ) );
    }
}