<?php
/**
 * Using this factory you can create new Template objects.
 *
 * @copyright 2008 Marcus Lunzenauer <mlunzena@uos.de>
 * @author Marcus Lunzenauer <mlunzena@uos.de>
 * @license MIT
 */

namespace Flexi;

class Factory
{
    /**
     * mapping of file extensions to supported template classes
     */
    protected array $handlers = [
        'php' => [PhpTemplate::class, []],
    ];

    /**
     * Constructor of TemplateFactory.
     *
     * @param string $path the template include path
     */
    public function __construct(protected string $path)
    {
        $this->set_path($path);
    }

    /**
     * Sets a new include path for the factory and returns the old one.
     *
     * @param string $path the new path
     *
     * @return string the old path
     */
    public function set_path(string $path): string
    {
        $old_path = $this->get_path();

        if (!str_ends_with($path, '/')) {
            $path .= '/';
        }

        $this->path = $path;

        return $old_path;
    }

    /**
     * Returns the include path of the factory
     *
     * @return string the current include path
     */
    public function get_path(): string
    {
        return $this->path;
    }

    /**
     * Open a template of the given name using the factory method pattern.
     * If a string was given, the path of the factory is searched for a matching
     * template.
     * If this string starts with a slash or with /\w+:\/\//, the string is
     * interpreted as an absolute path. Otherwise the path of the factory will be
     * prepended.
     * After that the factory searches for a file extension in this string. If
     * there is none, the directory where the template is supposed to live is
     * searched for a file starting with the template string and a supported
     * file extension.
     * At last the factory instantiates a template object of the matching template
     * class.
     *
     * Examples:
     *
     *   $factory->open('/path/to/template')
     *     does not prepend the factory's path but searches for "template.*" in
     *     "/path/to"
     *
     *   $factory->open('template')
     *     prepends the factory's path and searches there for "template.*"
     *
     *  $factory->open('template.php')
     *     prepends the factory's path but does not search and instantiates a
     *     PHPTemplate instead
     *
     * This method returns it's parameter, if it is not a string. This
     * functionality is useful for helper methods like #render_partial
     *
     * @param Template|string $template A name of a template.
     * @return Template the factored object
     * @throws TemplateNotFoundException if the template could not be found
     */
    public function open(Template|string $template): Template
    {
        # if it is not a string, this method behaves like identity
        if ($template instanceof Template) {
            return $template;
        }

        # get file
        $file = $this->get_template_file($template);

        # retrieve handler
        [$class, $options] = $this->get_template_handler($file);

        return new $class($file, $this, $options);
    }

    /**
     * This method returns the absolute filename of the template
     *
     * @param string $template0 a template string
     *
     * @return string     an absolute filename
     *
     * @throws TemplateNotFoundException  if the template could not be found
     */
    public function get_template_file(string $template0): string
    {
        $template = $this->get_absolute_path($template0);
        $extension = $this->get_extension($template);

        # extension defined, is there a matching template class?
        if ($extension !== null) {
            if (file_exists($template)) {
                return $template;
            }
        } # no extension defined, find it
        else {
            $file = $this->find_template($template);
            if ($file !== null) {
                return $file;
            }
        }

        # falling through to throw exception
        throw new TemplateNotFoundException(sprintf(
            'Missing template "%s" in "%s".',
            $template0,
            $this->path
        ));
    }

    /**
     * Matches an extension to a template handler.
     *
     * @param string $template the template
     *
     * @return array|null an array containing the class name and an array of
     *                    options of the matched extension;
     *                    or NULL if the extension did not match
     */
    public function get_template_handler(string $template): ?array
    {
        $extension = $this->get_extension($template);
        return $this->handlers[$extension] ?? null;
    }

    /**
     * Registers a handler for templates with a matching extension.
     *
     * @param string $extension the extension of the templates to handle
     * @param class-string<Template> $class the name of the already loaded class
     * @param array $options optional; an array of options which is used
     *                       when constructing a new instance
     */
    public function add_handler(
        string $extension,
        string $class,
        array $options = []
    ): void {
        $this->handlers[$extension] = [$class, $options];
    }

    /**
     * Returns the absolute path to the template. If the given argument starts
     * with a slash or with a protocoll, this method just returns its arguments.
     *
     * @param string $template an incomplete template name
     *
     * @return string an absolute path to the incomplete template name
     */
    public function get_absolute_path(string $template): string
    {
        return preg_match('#^(/|\w+://)#', $template)
            ? $template
            : $this->get_path() . $template;
    }


    /**
     * Find template given w/o extension.
     *
     * @param string $template the template's filename w/o extension
     * @return string|null null if there no such file could be found, a string
     *                     containing the complete file name otherwise
     */
    public function find_template(string $template): ?string
    {
        foreach ($this->handlers as $ext => $handler) {
            $file = "$template.$ext";
            if (file_exists($file)) {
                return $file;
            }
        }
        return null;
    }

    /**
     * Returns the file extension if there is one.
     *
     * @param string $file an possibly incomplete template file name
     * @return string|null a string containing the file extension if there is one,
     *                     NULL otherwise
     */
    public function get_extension(string $file): ?string
    {
        return pathinfo($file, PATHINFO_EXTENSION) ?: null;
    }

    /**
     * Class method to parse, render and return the presentation of a
     * template.
     *
     * @param Template|string      $template   A name of a template or a template
     * @param array                $attributes An associative array of attributes and their
     *                                         associated values.
     * @param Template|string|null $layout     A name of a layout template or a template.
     *
     * @return string A string representing the rendered presentation.
     *
     * @throws TemplateNotFoundException
     */
    public function render(
        Template|string $template,
        array $attributes = [],
        Template|string|null $layout = null
    ): string {
        return $this->open($template)->render($attributes, $layout);
    }
}