<?php

/**

 * I18N: WP_Translation_File class.

 *

 * @package WordPress

 * @subpackage I18N

 * @since 6.5.0

 */

/**

 * Class WP_Translation_File.

 *

 * @since 6.5.0

 */

abstract class WP_Translation_File {

	/**

	 * List of headers.

	 *

	 * @since 6.5.0

	 * @var array<string, string>

	 */

	protected $headers = array();

	/**

	 * Whether file has been parsed.

	 *

	 * @since 6.5.0

	 * @var bool

	 */

	protected $parsed = false;

	/**

	 * Error information.

	 *

	 * @since 6.5.0

	 * @var string|null Error message or null if no error.

	 */

	protected $error;

	/**

	 * File name.

	 *

	 * @since 6.5.0

	 * @var string

	 */

	protected $file = '';

	/**

	 * Translation entries.

	 *

	 * @since 6.5.0

	 * @var array<string, string>

	 */

	protected $entries = array();

	/**

	 * Plural forms function.

	 *

	 * @since 6.5.0

	 * @var callable|null Plural forms.

	 */

	protected $plural_forms = null;

	/**

	 * Constructor.

	 *

	 * @since 6.5.0

	 *

	 * @param string $file File to load.

	 */

	protected function __construct( string $file ) {

		$this->file = $file;

	}

	/**

	 * Creates a new WP_Translation_File instance for a given file.

	 *

	 * @since 6.5.0

	 *

	 * @param string      $file     File name.

	 * @param string|null $filetype Optional. File type. Default inferred from file name.

	 * @return false|WP_Translation_File

	 */

	public static function create( string $file, ?string $filetype = null ) {

		if ( ! is_readable( $file ) ) {

			return false;

		}

		if ( null === $filetype ) {

			$pos = strrpos( $file, '.' );

			if ( false !== $pos ) {

				$filetype = substr( $file, $pos + 1 );

			}

		}

		switch ( $filetype ) {

			case 'mo':

				return new WP_Translation_File_MO( $file );

			case 'php':

				return new WP_Translation_File_PHP( $file );

			default:

				return false;

		}

	}

	/**

	 * Creates a new WP_Translation_File instance for a given file.

	 *

	 * @since 6.5.0

	 *

	 * @param string $file     Source file name.

	 * @param string $filetype Desired target file type.

	 * @return string|false Transformed translation file contents on success, false otherwise.

	 */

	public static function transform( string $file, string $filetype ) {

		$source = self::create( $file );

		if ( false === $source ) {

			return false;

		}

		switch ( $filetype ) {

			case 'mo':

				$destination = new WP_Translation_File_MO( '' );

				break;

			case 'php':

				$destination = new WP_Translation_File_PHP( '' );

				break;

			default:

				return false;

		}

		$success = $destination->import( $source );

		if ( ! $success ) {

			return false;

		}

		return $destination->export();

	}

	/**

	 * Returns all headers.

	 *

	 * @since 6.5.0

	 *

	 * @return array<string, string> Headers.

	 */

	public function headers(): array {

		if ( ! $this->parsed ) {

			$this->parse_file();

		}

		return $this->headers;

	}

	/**

	 * Returns all entries.

	 *

	 * @since 6.5.0

	 *

	 * @return array<string, string[]> Entries.

	 */

	public function entries(): array {

		if ( ! $this->parsed ) {

			$this->parse_file();

		}

		return $this->entries;

	}

	/**

	 * Returns the current error information.

	 *

	 * @since 6.5.0

	 *

	 * @return string|null Error message or null if no error.

	 */

	public function error() {

		return $this->error;

	}

	/**

	 * Returns the file name.

	 *

	 * @since 6.5.0

	 *

	 * @return string File name.

	 */

	public function get_file(): string {

		return $this->file;

	}

	/**

	 * Translates a given string.

	 *

	 * @since 6.5.0

	 *

	 * @param string $text String to translate.

	 * @return false|string Translation(s) on success, false otherwise.

	 */

	public function translate( string $text ) {

		if ( ! $this->parsed ) {

			$this->parse_file();

		}

		return $this->entries[ $text ] ?? false;

	}

	/**

	 * Returns the plural form for a given number.

	 *

	 * @since 6.5.0

	 *

	 * @param int $number Count.

	 * @return int Plural form.

	 */

	public function get_plural_form( int $number ): int {

		if ( ! $this->parsed ) {

			$this->parse_file();

		}

		if ( null === $this->plural_forms && isset( $this->headers['plural-forms'] ) ) {

			$expression         = $this->get_plural_expression_from_header( $this->headers['plural-forms'] );

			$this->plural_forms = $this->make_plural_form_function( $expression );

		}

		if ( is_callable( $this->plural_forms ) ) {

			/**

			 * Plural form.

			 *

			 * @var int $result Plural form.

			 */

			$result = call_user_func( $this->plural_forms, $number );

			return $result;

		}

		// Default plural form matches English, only "One" is considered singular.

		return ( 1 === $number ? 0 : 1 );

	}

	/**

	 * Returns the plural forms expression as a tuple.

	 *

	 * @since 6.5.0

	 *

	 * @param string $header Plural-Forms header string.

	 * @return string Plural forms expression.

	 */

	protected function get_plural_expression_from_header( string $header ): string {

		if ( preg_match( '/^\s*nplurals\s*=\s*(\d+)\s*;\s+plural\s*=\s*(.+)$/', $header, $matches ) ) {

			return trim( $matches[2] );

		}

		return 'n != 1';

	}

	/**

	 * Makes a function, which will return the right translation index, according to the

	 * plural forms header.

	 *

	 * @since 6.5.0

	 *

	 * @param string $expression Plural form expression.

	 * @return callable(int $num): int Plural forms function.

	 */

	protected function make_plural_form_function( string $expression ): callable {

		try {

			$handler = new Plural_Forms( rtrim( $expression, ';' ) );

			return array( $handler, 'get' );

		} catch ( Exception $e ) {

			// Fall back to default plural-form function.

			return $this->make_plural_form_function( 'n != 1' );

		}

	}

	/**

	 * Imports translations from another file.

	 *

	 * @since 6.5.0

	 *

	 * @param WP_Translation_File $source Source file.

	 * @return bool True on success, false otherwise.

	 */

	protected function import( WP_Translation_File $source ): bool {

		if ( null !== $source->error() ) {

			return false;

		}

		$this->headers = $source->headers();

		$this->entries = $source->entries();

		$this->error   = $source->error();

		return null === $this->error;

	}

	/**

	 * Parses the file.

	 *

	 * @since 6.5.0

	 */

	abstract protected function parse_file();

	/**

	 * Exports translation contents as a string.

	 *

	 * @since 6.5.0

	 *

	 * @return string Translation file contents.

	 */

	abstract public function export();

}