<?php
/**
 * @package AgentgateWebMCP
 */

namespace AgentgateWebMCP;

defined( 'ABSPATH' ) || exit;

class Tool_Resolver {

	private const CACHE_NS = 'webmcp_resolved';
	private const MAX_NESTING = 5;

	public function for_current_user(): array {
		$key = 'u_' . get_current_user_id();
		$hit = wp_cache_get( $key, self::CACHE_NS );

		if ( $hit !== false ) {
			return $hit;
		}

		$list = $this->resolve();
		wp_cache_set( $key, $list, self::CACHE_NS, 3600 );
		return $list;
	}

	public function etag(): string {
		return md5( (string) wp_json_encode( $this->for_current_user() ) );
	}

	public function flush(): void {
		wp_cache_flush_group( self::CACHE_NS );
	}

	private function resolve(): array {
		if ( ! function_exists( 'wp_get_abilities' ) ) {
			return [];
		}

		$allowed = Core::TOOLS;
		$out     = [];

		foreach ( wp_get_abilities() as $slug => $ability ) {
			if ( ! in_array( $slug, $allowed, true ) || true !== $ability->check_permissions() ) {
				continue;
			}

			$def = [
				'name'        => $slug,
				'description' => wp_strip_all_tags( $ability->get_description() ),
				'inputSchema' => self::clean_schema( $ability->get_input_schema() ),
			];

			if ( $ability->get_meta_item( 'webmcp_readonly', false ) ) {
				$def['annotations'] = [ 'readOnlyHint' => true ];
			}

			$def = apply_filters( 'webmcp_tool_def', $def, $slug, $ability );

			if ( apply_filters( 'webmcp_show_tool', true, $slug, $ability ) ) {
				$out[] = $def;
			}
		}

		return $out;
	}

	/**
	 * Normalize a JSON Schema for safe transport: reject deep/ref-using schemas
	 * and ensure empty property bags serialize as {} not [].
	 */
	public static function clean_schema( array $s, int $lvl = 0 ): array {
		$blank = [ 'type' => 'object', 'properties' => new \stdClass() ];

		if ( empty( $s ) ) {
			return $blank;
		}

		if ( $lvl > self::MAX_NESTING || isset( $s['$ref'] ) ) {
			return $blank;
		}

		foreach ( [ 'properties', 'items' ] as $branch ) {
			if ( ! isset( $s[ $branch ] ) || ! is_array( $s[ $branch ] ) ) {
				continue;
			}

			if ( $branch === 'properties' && $s[ $branch ] === [] ) {
				$s[ $branch ] = new \stdClass();
				continue;
			}

			foreach ( $s[ $branch ] as $k => $child ) {
				if ( is_array( $child ) ) {
					$cleaned = self::clean_schema( $child, $lvl + 1 );
					if ( $cleaned === $blank && $lvl === 0 ) {
						return $blank;
					}
					$s[ $branch ][ $k ] = $cleaned;
				}
			}
		}

		return $s;
	}
}