String translation support, closes #33

* polylang support using {{ Template tags }}

Author: k1sul1

classes/class-wplf-polylang.php

@@ -0,0 +1,78 @@
+<?php
+if ( !class_exists( 'WPLF_Polylang' ) ) {
+  class WPLF_Polylang {
+    /**
+     * CPT for the forms
+     */
+    public static $instance;
+    protected $regular_expression = "/{{\s*.+\s*}}/";
+    protected $strings = array();
+
+    public static function init() {
+      if ( is_null( self::$instance ) ) {
+        self::$instance = new WPLF_Polylang();
+      }
+      return self::$instance;
+    }
+
+    /**
+     * Hook our actions, filters and such
+     */
+    private function __construct() {
+      add_filter( 'wplf_form', array( $this, 'render_form' ) );
+      add_filter( 'save_post_wplf-form', array( $this, 'save_form' ), 10, 3);
+      add_action( 'after_setup_theme', array ( $this, 'register_strings') );
+
+      $this->strings = get_option( 'wplf-translation-strings', array() );
+      $this->register_strings();
+    }
+
+    public function render_form ( $form_content ) {
+      // Get all strings inside double curly braces.
+      preg_match_all( $this->regular_expression, $form_content, $matches );
+      foreach( $matches[0] as $match ){
+        // match contains the braces, get rid of them.
+        $string = trim( str_replace( array( "{" , "}" ), array( "", "" ), $match ) );
+        $form_content = str_replace( $match, $this->translate_string ( $string ), $form_content );
+      }
+
+      return $form_content;
+    }
+
+    function save_form ( $post_id, $post, $update ) {
+      preg_match_all( $this->regular_expression, $post->post_content, $matches );
+      if( !empty( $matches ) ) {
+        foreach( $matches[0] as $match ){
+          // match contains the braces, get rid of them.
+          $string = trim( str_replace( array( "{" , "}" ), array( "", "" ), $match ) );
+          $this->strings[$string] = null;
+          // By storing the string as the array key, we don't need to use array_unique.
+        }
+      }
+
+      update_option( 'wplf-translation-strings', $this->strings ); // Let's be optimistic.
+    }
+
+    public function register_strings () {
+      foreach( $this->strings as $string => $value ) {
+        $this->register_string( $string );
+      }
+    }
+
+    public function register_string ( $string  ) {
+      if( function_exists( 'pll_register_string' ) ) {
+        pll_register_string( $string, $string, 'WP Libre Form' );
+      } else {
+        // Don't kill anything.
+      }
+    }
+
+    public function translate_string ( $string ) {
+      if( function_exists( 'pll__' ) ) {
+        return pll__( $string );
+      } else {
+        return $string; // Don't kill anything.
+      }
+    }
+  }
+}

readme.md

@@ -185,3 +185,20 @@ function wplf_recaptcha( $return ) {
   return $return;
 }
 ```
+
+### Multilingual
+
+You can create multilingual forms using Polylang. WPLF will register and automatically fetch the translation when you use special template tags.
+
+Example:
+```html
+<input type="text" placeholder="{{ Test string  }}" name="test">
+```
+
+You can also disable this feature, and create your own middleware for WPML, if you'd like.
+
+```php
+add_filter( 'wplf_load_polylang' , function() {
+  return false;
+} );
+```

wp-libre-form.php

@@ -56,6 +56,13 @@ private function __construct() {
     CPT_WPLF_Form::init();
     CPT_WPLF_Submission::init();
 
+    add_action( 'after_setup_theme', function() {
+      if ( apply_filters( 'wplf_load_polylang', true ) ) {
+        require_once 'classes/class-wplf-polylang.php';
+        WPLF_Polylang::init();
+      }
+    } );
+
     add_action( 'plugins_loaded', array( $this, 'load_our_textdomain' ) );
 
     // flush rewrites on activation since we have slugs for our cpts