<?php
/**
 * SchemaTranslator — adapts ability JSON Schemas per provider.
 *
 * Anthropic and OpenAI accept the ability schemas as-is. Gemini's
 * functionDeclarations accept only a restricted OpenAPI-style subset, so
 * unsupported keywords are stripped recursively.
 *
 * @package WPFunnels\AI
 * @since 3.13.0
 */

namespace WPFunnels\AI\Providers;

defined( 'ABSPATH' ) || exit;

/**
 * Class SchemaTranslator
 */
class SchemaTranslator {

	/**
	 * Keys Gemini accepts inside a schema node.
	 */
	private const GEMINI_ALLOWED = [ 'type', 'description', 'properties', 'required', 'items', 'enum', 'nullable', 'format' ];

	/**
	 * Formats Gemini accepts.
	 */
	private const GEMINI_ALLOWED_FORMATS = [ 'enum', 'date-time' ];

	/**
	 * Sanitize a JSON Schema for Gemini functionDeclarations.parameters.
	 *
	 * @param array $schema Ability input schema.
	 * @return array
	 */
	public static function forGemini( $schema ) {
		$clean = [];

		foreach ( (array) $schema as $key => $value ) {
			if ( ! in_array( $key, self::GEMINI_ALLOWED, true ) ) {
				continue;
			}
			if ( 'format' === $key && ! in_array( $value, self::GEMINI_ALLOWED_FORMATS, true ) ) {
				continue;
			}
			if ( 'properties' === $key && is_array( $value ) ) {
				$props = [];
				foreach ( $value as $prop => $prop_schema ) {
					$props[ $prop ] = is_array( $prop_schema ) ? self::forGemini( $prop_schema ) : $prop_schema;
				}
				// Gemini rejects empty properties objects on type:object nodes.
				if ( ! empty( $props ) ) {
					$clean['properties'] = $props;
				}
				continue;
			}
			if ( 'items' === $key && is_array( $value ) ) {
				$clean['items'] = self::forGemini( $value );
				continue;
			}
			$clean[ $key ] = $value;
		}

		// An object schema with no properties confuses Gemini — degrade gracefully.
		if ( isset( $clean['type'] ) && 'object' === $clean['type'] && empty( $clean['properties'] ) ) {
			$clean['properties'] = [
				'_' => [
					'type'        => 'string',
					'description' => 'Unused placeholder.',
				],
			];
		}

		return $clean;
	}
}