Multiple Upload and Resize Images Codeigniter 3.0.4

#CONTROLERS FUNGSI MULTI UPLOAD GAMBAR DAN MULTI RESIZE GAMBAR.


public function proses_tambah()
    {
        $this->_rules(); //manggil fungsi validasi

        $kode = $this->Produk_model->get_kode(); // manggil fungsi id buat id relasi

        $tanggal  = date('Y-m-d'); // tanggal

       if ($this->form_validation->run() == FALSE) {
            $this->tambah(); // kembali ke halaman tambah jika form ada yg kosong
        }
        else
        {

                $user_upload_path = 'media/produk/';
                $config['upload_path'] = './media/produk/ori/';
                $config['allowed_types'] = 'gif|jpg|png';
                $config['max_size']  = 1024 * 4;
                //$config['encrypt_name'] = TRUE;

                $this->load->library('upload', $config);

                $result_array = array();

            for ($i = 1; $i <=4; $i++){

                if (!$this->upload->do_upload('gambar_produk'.$i))
                {
                    $data['upload_error'] = $this->upload->display_errors();
                }
                else
                {
                    array_push($result_array,$this->upload->data());

                    $data_upload = $this->upload->data();

                    $file_name = $data_upload["file_name"];


                    //merubah nama gambar menjadi seperti ini (470x470_nama_gambar.jpg).
                    $file_name_thumb1 = '470x470_'.$data_upload['raw_name'].$data_upload['file_ext'];
                    $file_name_thumb2 = '300x300_'.$data_upload['raw_name'].$data_upload['file_ext'];
                    $file_name_thumb3 = '175x175_'.$data_upload['raw_name'].$data_upload['file_ext'];

                    $this->load->library('image_lib');

                    //resize1
                    $config_resize1['image_library'] = 'gd2';
                    $config_resize1['maintain_ratio'] = TRUE;
                    $config_resize1['master_dim'] = 'height';
                    $config_resize1['quality'] = "100%";
                    $config_resize1['source_image'] = './' . $user_upload_path.'ori/'. $file_name;
                    $config_resize1['new_image'] = './' . $user_upload_path.'detail/' . $file_name_thumb1;
                    $config_resize1['height'] = 470;
                    $config_resize1['width'] = 470;
                    $this->image_lib->initialize($config_resize1);
                    $this->image_lib->resize();
                    $this->image_lib->clear();

                    //resize2
                    $config_resize2['image_library'] = 'gd2';
                    $config_resize2['maintain_ratio'] = TRUE;
                    $config_resize2['master_dim'] = 'height';
                    $config_resize2['quality'] = "100%";
                    $config_resize2['source_image'] = './' . $user_upload_path.'ori/' . $file_name;
                    $config_resize2['new_image'] = './' . $user_upload_path.'medium/' . $file_name_thumb2;
                    $config_resize2['height'] = 300;
                    $config_resize2['width'] = 300;
                    $this->image_lib->initialize($config_resize2);
                    $this->image_lib->resize();
                    $this->image_lib->clear();

                    //resize3
                    $config_resize3['image_library'] = 'gd2';
                    $config_resize3['maintain_ratio'] = TRUE;
                    $config_resize3['master_dim'] = 'height';
                    $config_resize3['quality'] = "100%";
                    $config_resize3['source_image'] = './' . $user_upload_path.'ori/' . $file_name;
                    $config_resize3['new_image'] = './' . $user_upload_path.'small/' . $file_name_thumb3;
                    $config_resize3['height'] = 175;
                    $config_resize3['width'] = 175;
                    $this->image_lib->initialize($config_resize3);
                    $this->image_lib->resize();
                    $this->image_lib->clear();

                }
            }

            $data = array(
                    'sku' => $kode,
                    'nama_produk' => $this->input->post('nama_produk',TRUE),
                    'model_tipe' => $this->input->post('model_tipe',TRUE),
                    'stok' => $this->input->post('stok',TRUE),
                    'harga_jual' => $this->input->post('harga_jual',TRUE),
                    'deskripsi' => $this->input->post('deskripsi',TRUE),
                    'spesifikasi' => $this->input->post('spesifikasi',TRUE),
                    'id_kategori' => $this->input->post('id_kategori',TRUE),
                    'gambar_produk' => $result_array[0]['file_name'], //gambar produk utama
                    'tgl_upload' => $tanggal,
                    'meta_title' => $this->input->post('meta_title',TRUE),
                    'meta_desc' => $this->input->post('meta_desc',TRUE),
                    'meta_keyword' => $this->input->post('meta_keyword',TRUE),
                    'status_tampil' => $this->input->post('status_tampil',TRUE),

                    );

            $data_gambar  = array(
                    'gambar_1' => $result_array[1]['file_name'], //gambar produk galeri
                    'gambar_2' => $result_array[2]['file_name'], //gambar produk galeri
                    'gambar_3' => $result_array[3]['file_name'], //gambar produk galeri
                    'id_produk' => $kode,
                     );

                $this->Produk_model->insert2($data_gambar); // simpan ke tabel galeri produk
                $this->Produk_model->insert1($data); // simpan ke tabel produk
                redirect(site_url('webadmin/produk'));

        }

    }