<?php
namespace MazlanHalim\IntelliLanz\Graph;

/** Short-lived, validated graph snapshots. */
final class SnapshotCache {
    private const KEY = 'intellilanz_snapshot_v1';
    private const TTL = 300;

    /** @return array{graph: Graph, generated_at: int}|null */
    public function get(): ?array {
        $payload = get_transient( $this->key() );
        $generated_at = $payload['generated_at'] ?? null;
        if ( ! is_array( $payload ) || ( $payload['schema'] ?? null ) !== 1 || ! is_int( $generated_at ) || $generated_at < time() - self::TTL - 60 || $generated_at > time() + 60 || ! is_array( $payload['graph'] ?? null ) ) {
            if ( $payload !== false ) { $this->invalidate(); }
            return null;
        }
        try {
            $graph = new Graph();
            $data = $payload['graph'];
            if ( ! is_array( $data['nodes'] ?? null ) || ! is_array( $data['edges'] ?? null ) ) { throw new \UnexpectedValueException(); }
            foreach ( $data['nodes'] as $node ) {
                if ( ! is_array( $node ) || array_diff( array( 'id', 'type', 'category', 'label', 'status', 'severity', 'metadata' ), array_keys( $node ) ) || ( ! is_array( $node['metadata'] ) && ! is_object( $node['metadata'] ) ) ) {
                    throw new \UnexpectedValueException();
                }
                $graph->addNode( new Node( $node['id'], $node['type'], $node['category'], $node['label'], $node['status'], $node['severity'], (array) $node['metadata'] ) );
            }
            foreach ( $data['edges'] as $edge ) {
                if ( ! is_array( $edge ) || array_diff( array( 'id', 'source', 'target', 'relationship', 'confidence' ), array_keys( $edge ) ) ) { throw new \UnexpectedValueException(); }
                $graph->addEdge( new Edge( $edge['id'], $edge['source'], $edge['target'], $edge['relationship'], $edge['confidence'], (array) ( $edge['metadata'] ?? array() ) ) );
            }
            return array( 'graph' => $graph, 'generated_at' => $payload['generated_at'] );
        } catch ( \Throwable $error ) {
            $this->invalidate();
            return null;
        }
    }

    public function set( Graph $graph ): int {
        $generated_at = time();
        set_transient( $this->key(), array( 'schema' => 1, 'generated_at' => $generated_at, 'graph' => $graph->jsonSerialize() ), self::TTL );
        return $generated_at;
    }

    public function invalidate( ...$unused ): void {
        delete_transient( $this->key() );
    }

    public function registerInvalidationHooks(): void {
        foreach ( array( 'activated_plugin', 'deactivated_plugin', 'switch_theme', 'upgrader_process_complete', 'update_option_active_plugins', 'update_site_option_active_sitewide_plugins' ) as $hook ) {
            add_action( $hook, array( $this, 'invalidate' ) );
        }
    }

    private function key(): string {
        if ( ! is_multisite() ) { return self::KEY; }
        $network_plugins = get_site_option( 'active_sitewide_plugins', array() );
        $network_plugins = is_array( $network_plugins ) ? $network_plugins : array();
        ksort( $network_plugins );
        return self::KEY . '_' . md5( wp_json_encode( $network_plugins ) );
    }
}