/**
     * Génère les filtres pour la liste d'appartements
     * @return string
     */
    public static function generateFilters()
    {
        $villeGet = "indifférent";
        $surfaceGet = "indifférent";
        $loyerGet = "indifférent";
        if (isset($_GET['ville'])) {
            $villeGet = $_GET["ville"];
            $surfaceGet = $_GET["surface"];
            $loyerGet = $_GET["loyer"];
        }
        $res = '  <div class="col-sm-1 filters" >

                            <form method="GET" action="./index.php">
                                <input name="a" type=hidden value="search"/>
                                <div class="form-group">
                                    <label for="filter-town">Ville</label>
                                    <select name="ville" id="filter-town" class="form-control">';
        $villes = Adresse::findVilles();
        $res .= '<option>indifférent</option>';
        foreach ($villes as $ville) {
            if ($ville == $villeGet) {
                $res .= '<option selected>' . $ville . '</option>';
            } else {
                $res .= '<option>' . $ville . '</option>';
            }
        }
        $res .= '
                                    </select>
                                </div>
                                <div class="form-group">
                                    <label for="filter-surface">Surface (m²)</label>
                                    <select name="surface" id="filter-surface" class="form-control">';
        $surfaces = AppartementView::generateFiltersSurface();
        foreach ($surfaces as $s) {
            if ($s == $surfaceGet) {
                $res .= '<option selected>' . $s . '</option>';
            } else {
                $res .= '<option>' . $s . '</option>';
            }
        }
        $res .= '</select>
                                </div>
                                <div class="form-group">
                                    <label for="filter-rent">Loyer (€)</label>
                                    <select name="loyer" id="filter-rent" class="form-control">';
        $rents = AppartementView::generateFiltersRent();
        foreach ($rents as $r) {
            if ($r == $loyerGet) {
                $res .= '<option selected>' . $r . '</option>';
            } else {
                $res .= '<option>' . $r . '</option>';
            }
        }
        $res .= '</select>
                                </div>


                                <div class="checkbox" >
                                    <label>
                                        <input type="checkbox" id="filter-type-flat" value="option1"> Appartement
                                    </label>
                                </div>
                                <div class="checkbox" >
                                    <label>
                                        <input type="checkbox" id="filter-type-furniture" value="option2"> Meublé mixte
                                    </label>
                                </div>
                                <div class="checkbox" >
                                    <label>
                                        <input type="checkbox" id="filter-type-holidays" value="option3"> Meublé vacances
                                    </label>
                                </div>

                                <button type="submit" class="btn btn-default"><span class="glyphicon glyphicon-search"></span> Rechercher</button>
                            </form>
                        </div>';
        return $res;
    }