<?php

namespace Glovario\ImportExport;

defined( 'ABSPATH' ) || exit;

final class ConditionValidator {
	const MAX_SERIALIZED_BYTES = 65535;
	const MAX_DEPTH            = 8;
	const MAX_NODES            = 1000;

	public function validate( $conditions ) {
		if ( ! is_array( $conditions ) || ! $this->within_complexity_limits( $conditions ) ) {
			return new \WP_Error( 'invalid_rule_conditions', __( 'Imported rule conditions are too large, deeply nested, or malformed.', 'glovario' ) );
		}

		$known          = array( 'version', 'date', 'auth', 'roles', 'post_types', 'post_ids', 'locales', 'glovario_translation' );
		$allowed_custom = apply_filters( 'glovario_import_allowed_condition_keys', array(), $conditions );
		$allowed_custom = array_filter( array_map( 'sanitize_key', is_array( $allowed_custom ) ? $allowed_custom : array() ) );
		$unknown        = array_diff( array_keys( $conditions ), $known, $allowed_custom );
		if ( $unknown ) {
			return new \WP_Error( 'unknown_rule_condition', __( 'Imported rule conditions contain unsupported fields.', 'glovario' ) );
		}

		$version = $conditions['version'] ?? 1;
		if ( 1 !== $version && '1' !== $version ) {
			return new \WP_Error( 'invalid_rule_condition_version', __( 'Imported rule conditions use an unsupported schema version.', 'glovario' ) );
		}

		$date = $conditions['date'] ?? array();
		if ( ! is_array( $date ) || array_diff( array_keys( $date ), array( 'from', 'until' ) ) ) {
			return new \WP_Error( 'invalid_rule_date', __( 'Imported rule dates are invalid.', 'glovario' ) );
		}
		$from  = $date['from'] ?? '';
		$until = $date['until'] ?? '';
		if ( ! $this->valid_date( $from ) || ! $this->valid_date( $until ) ) {
			return new \WP_Error( 'invalid_rule_date', __( 'Imported rule dates must use YYYY-MM-DDTHH:MM.', 'glovario' ) );
		}

		$auth = $conditions['auth'] ?? 'everyone';
		if ( ! is_string( $auth ) || ! in_array( $auth, array( 'everyone', 'logged_in', 'logged_out' ), true ) ) {
			return new \WP_Error( 'invalid_rule_auth', __( 'Imported rule authentication conditions are invalid.', 'glovario' ) );
		}

		$roles      = $this->key_list( $conditions['roles'] ?? array(), 100 );
		$post_types = $this->key_list( $conditions['post_types'] ?? array(), 100 );
		$post_ids   = $this->id_list( $conditions['post_ids'] ?? array(), 500 );
		$locales    = $this->locale_list( $conditions['locales'] ?? array(), 100 );
		foreach ( array( $roles, $post_types, $post_ids, $locales ) as $validated ) {
			if ( is_wp_error( $validated ) ) {
				return $validated;
			}
		}

		$normalized = array(
			'version'    => 1,
			'date'       => array(
				'from'  => $from,
				'until' => $until,
			),
			'auth'       => $auth,
			'roles'      => $roles,
			'post_types' => $post_types,
			'post_ids'   => $post_ids,
			'locales'    => $locales,
		);

		if ( isset( $conditions['glovario_translation'] ) ) {
			$marker = $this->translation_marker( $conditions['glovario_translation'] );
			if ( is_wp_error( $marker ) ) {
				return $marker;
			}
			$normalized['glovario_translation'] = $marker;
		}
		foreach ( $allowed_custom as $key ) {
			if ( array_key_exists( $key, $conditions ) ) {
				$normalized[ $key ] = $conditions[ $key ];
			}
		}

		$filtered = apply_filters( 'glovario_validated_imported_rule_conditions', $normalized, $conditions );
		if ( is_wp_error( $filtered ) ) {
			return $filtered;
		}
		return is_array( $filtered ) && $this->within_complexity_limits( $filtered ) ? $filtered : new \WP_Error( 'invalid_filtered_rule_conditions', __( 'Imported rule conditions were rejected by an integration.', 'glovario' ) );
	}

	private function key_list( $values, $maximum ) {
		if ( ! is_array( $values ) || count( $values ) > $maximum || array_values( $values ) !== $values ) {
			return new \WP_Error( 'invalid_rule_key_list', __( 'Imported rule role or post-type conditions are invalid.', 'glovario' ) );
		}
		$clean = array();
		foreach ( $values as $value ) {
			if ( ! is_string( $value ) || '' === $value || strlen( $value ) > 64 || sanitize_key( $value ) !== $value ) {
				return new \WP_Error( 'invalid_rule_key_list', __( 'Imported rule role or post-type conditions are invalid.', 'glovario' ) );
			}
			$clean[] = $value;
		}
		return array_values( array_unique( $clean ) );
	}

	private function id_list( $values, $maximum ) {
		if ( ! is_array( $values ) || count( $values ) > $maximum || array_values( $values ) !== $values ) {
			return new \WP_Error( 'invalid_rule_post_ids', __( 'Imported rule post IDs are invalid.', 'glovario' ) );
		}
		$clean = array();
		foreach ( $values as $value ) {
			if ( ( ! is_int( $value ) && ! ctype_digit( (string) $value ) ) || absint( $value ) < 1 ) {
				return new \WP_Error( 'invalid_rule_post_ids', __( 'Imported rule post IDs are invalid.', 'glovario' ) );
			}
			$clean[] = absint( $value );
		}
		return array_values( array_unique( $clean ) );
	}

	private function locale_list( $values, $maximum ) {
		if ( ! is_array( $values ) || count( $values ) > $maximum || array_values( $values ) !== $values ) {
			return new \WP_Error( 'invalid_rule_locales', __( 'Imported rule locales are invalid.', 'glovario' ) );
		}
		$clean = array();
		foreach ( $values as $value ) {
			if ( ! is_string( $value ) || '' === $value || strlen( $value ) > 64 || sanitize_locale_name( $value ) !== $value ) {
				return new \WP_Error( 'invalid_rule_locales', __( 'Imported rule locales are invalid.', 'glovario' ) );
			}
			$clean[] = $value;
		}
		return array_values( array_unique( $clean ) );
	}

	private function translation_marker( $marker ) {
		if ( ! is_array( $marker ) || array_diff( array_keys( $marker ), array( 'managed', 'source_locale', 'provider' ) ) ) {
			return new \WP_Error( 'invalid_translation_marker', __( 'Imported managed-translation metadata is invalid.', 'glovario' ) );
		}
		$managed = $marker['managed'] ?? false;
		$source  = $marker['source_locale'] ?? '';
		$provider = $marker['provider'] ?? '';
		if ( ! is_bool( $managed ) || ! is_string( $source ) || '' === $source || strlen( $source ) > 64 || sanitize_locale_name( $source ) !== $source || ! is_string( $provider ) || '' === $provider || strlen( $provider ) > 64 || sanitize_key( $provider ) !== $provider ) {
			return new \WP_Error( 'invalid_translation_marker', __( 'Imported managed-translation metadata is invalid.', 'glovario' ) );
		}
		return array(
			'managed'       => $managed,
			'source_locale' => $source,
			'provider'      => $provider,
		);
	}

	private function valid_date( $value ) {
		if ( ! is_string( $value ) || ( '' !== $value && 1 !== preg_match( '/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}$/', $value ) ) ) {
			return false;
		}
		if ( '' === $value ) {
			return true;
		}
		$date   = \DateTimeImmutable::createFromFormat( '!Y-m-d\TH:i', $value, wp_timezone() );
		$errors = \DateTimeImmutable::getLastErrors();
		return false !== $date && ( false === $errors || ( 0 === $errors['warning_count'] && 0 === $errors['error_count'] ) ) && $date->format( 'Y-m-d\TH:i' ) === $value;
	}

	private function within_complexity_limits( $conditions ) {
		$encoded = wp_json_encode( $conditions );
		if ( false === $encoded || strlen( $encoded ) > self::MAX_SERIALIZED_BYTES ) {
			return false;
		}
		$nodes = 0;
		return $this->measure( $conditions, 1, $nodes );
	}

	private function measure( $value, $depth, &$nodes ) {
		++$nodes;
		if ( $depth > self::MAX_DEPTH || $nodes > self::MAX_NODES ) {
			return false;
		}
		if ( is_array( $value ) ) {
			foreach ( $value as $child ) {
				if ( ! $this->measure( $child, $depth + 1, $nodes ) ) {
					return false;
				}
			}
		}
		return true;
	}
}