<?php

class View_SmartyPlugin_Form {

    const
        DEFAULT_FORM_SNIPPET_DIRECTORY  = 'Default',
        DEFAULT_FORM_SNIPPET_TEMPLATE   = 'Snippets/Forms/%s/%s.tpl';

    protected
        $forms_stack                = array(),
        $snippet_default_directory  = self::DEFAULT_FORM_SNIPPET_DIRECTORY,
        $snippet_template           = self::DEFAULT_FORM_SNIPPET_TEMPLATE;

    public function setFormSnippetTemplate($sprintf_tpl) {
        $this->snippet_template = $sprintf_tpl ?: self::DEFAULT_FORM_SNIPPET_TEMPLATE;
        return $this;
    }

    public function setDefaultFormSnippetDirectory($directory) {
        $this->snippet_default_directory = $directory ?: self::DEFAULT_FORM_SNIPPET_DIRECTORY;
        return $this;
    }

    public function register($Smarty) {
        $Smarty
            ->registerPlugin('block',    'form',        array($this, 'parseFormBlock'))
            ->registerPlugin('function', 'form_field',  array($this, 'parseFormField'));
    }

    public function parseFormBlock($params, $content, Smarty_Internal_Template $template, &$repeat) {
        if (null === $content) {
            return $this->parseFormOpenTag($params, $template);
        } else {
            return $this->parseFormCloseTag($params, $content, $template);
        }
    }

    protected function parseFormOpenTag($params, Smarty_Internal_Template $template) {
        if (empty($params['src']) || !is_array($params['src'])) {
            throw new SmartyException("Malformed {form} tag: missing 'src' parameter");
        }

        $form_data = $params['src'];
        unset($params['src']);

        $snippet_template = sprintf($this->snippet_template, !empty($params['use']) ? $params['use'] : $this->snippet_default_directory, '%s');
        unset($params['use']);

        $form = Carcass_ArrayTools::filterAssoc($params, function($k) { return !is_int($k); });

        $form['data'] = $form_data;
        $form['snippet_template'] = $snippet_template;

        array_push($this->forms_stack, $form);
    }

    protected function parseFormCloseTag($params, $content, Smarty_Internal_Template $template) {
        $form = array_pop($this->forms_stack);
        if (!$form) {
            throw new SmartyException("Invalid {/form} tag: no matching opening {form} tag");
        }
        return $this->parseFormSnippetTemplate(
            sprintf($form['snippet_template'], 'form'),
            $template,
            array(
                'args' => array_filter($form['data'], 'is_scalar'),
                'content' => $content
            )
        );
    }

    public function parseFormField($params, Smarty_Internal_Template $template) {
        $form = $this->getCurrentForm();
        if (!$form) {
            throw new SmartyException("{form_field} tags must be placed inside a {form} tag");
        }

        foreach (array('name', 'type') as $required_parameter) {
            if (empty($params[$required_parameter]) || !is_scalar($params[$required_parameter])) {
                throw new SmartyException("Malformed {form_field} tag: missing '${required_parameter}' parameter");
            }
            $$required_parameter = $params[$required_parameter];
            unset($params[$required_parameter]);
        }

        $field_params = Carcass_ArrayTools::filterAssoc($params, function($k) { return !is_int($k); });

        if (isset($form['data']['Fields'][$name])) {
            $field_params += $form['data']['Fields'][$name];
        }

        $field_params['args'] = array_filter($field_params, 'is_scalar');

        return $this->parseFormSnippetTemplate(
            sprintf($form['snippet_template'], $type),
            $template,
            $field_params
        );
    }

    protected function getCurrentForm() {
        return end($this->forms_stack);
    }

    protected function parseFormSnippetTemplate($filename, Smarty_Internal_Template $template, array $params = array()) {
        return $template->createTemplate($filename, $params)->fetch();
    }

}