<?php

namespace RoosterLMS\UI;

defined( 'ABSPATH' ) || exit;

final class TableQuery {

	public const SEARCH_MAX = 100;

	public const AFTER_MAX = 512;

	public const MULTI_MAX = 50;

	public const SEARCH_ACTION = 'rooster_lms_table_search';
	public const SEARCH_NONCE  = 'rooster_lms_table_nonce';

	public function __construct(
		public readonly int $page = 1,
		public readonly int $per_page = 50,
		public readonly string $orderby = '',
		public readonly string $order = 'asc',
		public readonly string $search = '',
		public readonly array $filters = array(),
		public readonly string $after = '',
		public readonly array $context = array(),
		public readonly ?int $known_total = null
	) {}

	public static function arg_names( TableDefinition $d ): array {
		$p       = $d->arg_prefix();
		$filters = array();
		foreach ( $d->filters() as $filter ) {
			$filters[ $filter->key ] = $p . $filter->key;
		}
		return array(
			'page'     => '' === $p ? 'paged' : $p . 'page',
			'per_page' => $p . 'per_page',
			'orderby'  => $p . 'orderby',
			'order'    => $p . 'order',
			'search'   => '' === $p ? 's' : $p . 'search',
			'after'    => $p . 'after',
			'filters'  => $filters,
		);
	}

	public static function from_args( TableDefinition $d, array $get, array $body = array() ): self {
		$names   = self::arg_names( $d );
		$filters = array();
		foreach ( $names['filters'] as $key => $arg ) {
			if ( array_key_exists( $arg, $get ) ) {
				$filters[ $key ] = $get[ $arg ];
			}
		}
		$search = 'post' === $d->search_transport() ? ( $body[ $names['search'] ] ?? '' ) : ( $get[ $names['search'] ] ?? ( $body[ $names['search'] ] ?? '' ) );
		return self::build(
			$d,
			array(
				'page'     => $get[ $names['page'] ] ?? 1,
				'per_page' => $get[ $names['per_page'] ] ?? 0,
				'orderby'  => $get[ $names['orderby'] ] ?? null,
				'order'    => $get[ $names['order'] ] ?? null,
				'search'   => $search,
				'filters'  => $filters,
				'after'    => $get[ $names['after'] ] ?? '',
			),
			$d->context(),
			null
		);
	}

	public static function from_state( TableDefinition $d, array $state, array $context, ?int $known_total = null ): self {
		$q    = self::build(
			$d,
			array(
				'page'     => $state['page'] ?? 1,
				'per_page' => $state['per_page'] ?? 0,
				'orderby'  => $state['orderby'] ?? null,
				'order'    => $state['order'] ?? null,
				'search'   => $state['search'] ?? '',
				'filters'  => is_array( $state['filters'] ?? null ) ? $state['filters'] : array(),
				'after'    => $state['after'] ?? '',
			),
			$context,
			null
		);
		$hash = isset( $state['hash'] ) && is_string( $state['hash'] ) ? $state['hash'] : '';
		if ( null !== $known_total && $known_total >= 0 && '' !== $hash && hash_equals( $q->hash(), $hash ) ) {
			return $q->with( array( 'known_total' => $known_total ) );
		}
		return $q;
	}

	public static function from_request( TableDefinition $d ): self {
		return self::from_args( $d, TableRequest::args( $d ), TableRequest::posted_search( $d ) );
	}

	private static function build( TableDefinition $d, array $raw, array $context, ?int $known_total ): self {
		$options  = array_values( array_filter( array_map( 'intval', $d->per_page_options() ), static fn( int $n ): bool => $n > 0 ) );
		$default  = in_array( 50, $options, true ) || array() === $options ? 50 : $options[0];
		$per_page = is_scalar( $raw['per_page'] ) && is_numeric( $raw['per_page'] ) ? (int) $raw['per_page'] : 0;
		$per_page = in_array( $per_page, $options, true ) ? $per_page : $default;

		$page = is_scalar( $raw['page'] ) && is_numeric( $raw['page'] ) ? (int) $raw['page'] : 1;
		$page = max( 1, min( 1000000, $page ) );

		list( $default_by, $default_order ) = $d->default_order();
		$default_order                      = 'desc' === $default_order ? 'desc' : 'asc';
		$sortable                           = array();
		foreach ( $d->columns() as $column ) {
			if ( $column->sortable ) {
				$sortable[] = $column->key;
			}
		}
		$orderby = is_string( $raw['orderby'] ) ? sanitize_key( $raw['orderby'] ) : '';
		$order   = is_string( $raw['order'] ) ? strtolower( $raw['order'] ) : '';
		if ( ! in_array( $orderby, $sortable, true ) ) {
			$orderby = (string) $default_by;
		}
		if ( ! in_array( $order, array( 'asc', 'desc' ), true ) ) {
			$order = $default_order;
		}

		$search = is_scalar( $raw['search'] ) ? trim( sanitize_text_field( (string) $raw['search'] ) ) : '';
		$search = '' === $d->search_label() ? '' : mb_substr( $search, 0, self::SEARCH_MAX );

		$filters = array();
		foreach ( $d->filters() as $filter ) {
			if ( ! array_key_exists( $filter->key, $raw['filters'] ) ) {
				continue;
			}
			$value = $raw['filters'][ $filter->key ];
			if ( Filter::MULTI === $filter->type ) {
				$values = array();
				foreach ( is_array( $value ) ? $value : array( $value ) as $one ) {
					$one = is_scalar( $one ) ? (string) $one : '';
					if ( $filter->allows( $one ) && ! in_array( $one, $values, true ) && count( $values ) < self::MULTI_MAX ) {
						$values[] = $one;
					}
				}
				if ( array() !== $values ) {
					$filters[ $filter->key ] = $values;
				}
				continue;
			}
			$value = is_scalar( $value ) ? (string) $value : '';
			if ( $filter->allows( $value ) ) {
				$filters[ $filter->key ] = $value;
			}
		}

		$after = is_string( $raw['after'] ) ? $raw['after'] : '';
		$after = 'keyset' === $d->paging() && null !== self::decode_after( $after ) ? $after : '';

		return new self( $page, $per_page, $orderby, $order, $search, $filters, $after, $context, $known_total );
	}

	public function with( array $change ): self {
		$filters = $this->filters;
		if ( isset( $change['filters'] ) && is_array( $change['filters'] ) ) {
			foreach ( $change['filters'] as $key => $value ) {
				if ( null === $value || '' === $value || array() === $value ) {
					unset( $filters[ $key ] );
				} else {
					$filters[ $key ] = $value;
				}
			}
		}
		return new self(
			(int) ( $change['page'] ?? $this->page ),
			(int) ( $change['per_page'] ?? $this->per_page ),
			(string) ( $change['orderby'] ?? $this->orderby ),
			(string) ( $change['order'] ?? $this->order ),
			array_key_exists( 'search', $change ) ? (string) $change['search'] : $this->search,
			$filters,
			array_key_exists( 'after', $change ) ? (string) $change['after'] : $this->after,
			$this->context,
			array_key_exists( 'known_total', $change ) ? ( null === $change['known_total'] ? null : (int) $change['known_total'] ) : $this->known_total
		);
	}

	public function args( TableDefinition $d, array $change = array() ): array {
		$q                                  = array() === $change ? $this : $this->with( $change );
		$names                              = self::arg_names( $d );
		list( $default_by, $default_order ) = $d->default_order();
		$default_order                      = 'desc' === $default_order ? 'desc' : 'asc';
		$options                            = array_map( 'intval', $d->per_page_options() );
		$default_size                       = in_array( 50, $options, true ) || array() === $options ? 50 : (int) $options[0];
		$out                                = array();
		if ( $q->page > 1 ) {
			$out[ $names['page'] ] = (string) $q->page;
		}
		if ( $q->per_page !== $default_size ) {
			$out[ $names['per_page'] ] = (string) $q->per_page;
		}
		if ( $q->orderby !== (string) $default_by || $q->order !== $default_order ) {
			$out[ $names['orderby'] ] = $q->orderby;
			$out[ $names['order'] ]   = $q->order;
		}
		foreach ( $q->filters as $key => $value ) {
			if ( isset( $names['filters'][ $key ] ) ) {
				$out[ $names['filters'][ $key ] ] = is_array( $value ) ? array_values( array_map( 'strval', $value ) ) : (string) $value;
			}
		}
		if ( '' !== $q->after ) {
			$out[ $names['after'] ] = $q->after;
		}
		return $out;
	}

	public function url( TableDefinition $d, array $change = array() ): string {
		$args = array();
		foreach ( $this->args( $d, $change ) as $name => $value ) {
			$args[ $name ] = is_array( $value ) ? array_map( 'rawurlencode', $value ) : rawurlencode( $value );
		}
		return \RoosterLMS\Admin\View::link( add_query_arg( $args, self::strip( $d, $d->base_url() ) ) );
	}

	public static function strip( TableDefinition $d, string $url ): string {
		$names = self::arg_names( $d );
		$keys  = array_merge( array( $names['page'], $names['per_page'], $names['orderby'], $names['order'], $names['search'], $names['after'] ), array_values( $names['filters'] ) );
		return remove_query_arg( $keys, $url );
	}

	public function hash(): string {
		$filters = $this->filters;
		ksort( $filters );
		foreach ( $filters as $key => $value ) {
			if ( is_array( $value ) ) {
				sort( $value, SORT_STRING );
				$filters[ $key ] = $value;
			}
		}
		return substr( hash( 'sha256', (string) wp_json_encode( array( $filters, $this->search, $this->context ) ) ), 0, 16 );
	}

	public function filtered(): bool {
		return '' !== $this->search || array() !== $this->filters;
	}

	public function offset(): int {
		return ( $this->page - 1 ) * $this->per_page;
	}

	public function filter( string $key ): string|array {
		return $this->filters[ $key ] ?? '';
	}

	public function values( string $key ): array {
		$value = $this->filters[ $key ] ?? '';
		return array_values( array_filter( array_map( 'strval', (array) $value ), static fn( string $v ): bool => '' !== $v ) );
	}

	public function ints( string $key ): array {
		return array_values( array_unique( array_filter( array_map( 'intval', $this->values( $key ) ), static fn( int $n ): bool => $n > 0 ) ) );
	}

	public function after_key(): ?array {
		return '' === $this->after ? null : self::decode_after( $this->after );
	}

	public static function encode_after( array $key ): string {
		return rtrim( strtr( base64_encode( (string) wp_json_encode( $key ) ), '+/', '-_' ), '=' ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode -- an opaque URL-safe cursor, not obfuscation.
	}

	public static function decode_after( string $after ): ?array {
		if ( '' === $after || strlen( $after ) > self::AFTER_MAX || 1 !== preg_match( '/^[A-Za-z0-9_-]+$/', $after ) ) {
			return null;
		}
		$json = base64_decode( strtr( $after, '-_', '+/' ), true ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode -- decodes the URL-safe cursor encode_after() made (not obfuscation).
		$data = is_string( $json ) ? json_decode( $json, true ) : null;
		if ( ! is_array( $data ) || array() === $data || array_is_list( $data ) ) {
			return null;
		}
		foreach ( $data as $value ) {
			if ( ! is_scalar( $value ) && null !== $value ) {
				return null;
			}
		}
		return $data;
	}
}