// subtitleeditor -- a tool to create or edit subtitle
//
// https://subtitleeditor.github.io/subtitleeditor/
// https://github.com/subtitleeditor/subtitleeditor/
//
// Copyright @ 2005-2018, kitone
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

#include <debug.h>
#include <extension/action.h>
#include <i18n.h>

class ExtendLengthPlugin : public Action {
  public:
   ExtendLengthPlugin() {
      activate();
      update_ui();
   }

   ~ExtendLengthPlugin() {
      deactivate();
   }

   void activate() {
      se_dbg(SE_DBG_PLUGINS);

      // actions
      action_group = Gtk::ActionGroup::create("ExtendLengthPlugin");

      action_group->add(Gtk::Action::create("extend-length",
                                            _("_Extend Length Forward"),
                                            _("Extend the length of the selected subtitles to the "
                                              "start time of the next subtitle (while respecting minimum gap "
                                              "between subtitles)")),
                        sigc::mem_fun(*this, &ExtendLengthPlugin::on_extend_length_fwd));

      action_group->add(Gtk::Action::create("extend-length-bwd",
                                            _("E_xtend Length Backwards"),
                                            _("Extend the length of selected selected subtitles "
                                              "backwards to the end time of the previous subtitle (while "
                                              "respecting minimum gap between subtitles)")),
                        sigc::mem_fun(*this, &ExtendLengthPlugin::on_extend_length_bwd));
      // ui
      Glib::RefPtr<Gtk::UIManager> ui = get_ui_manager();

      ui_id = ui->new_merge_id();

      ui->insert_action_group(action_group);

      ui->add_ui(ui_id, "/menubar/menu-timings/extend-length", "extend-length", "extend-length");
      ui->add_ui(ui_id, "/menubar/menu-timings/extend-length-bwd", "extend-length-bwd", "extend-length-bwd");
   }

   void deactivate() {
      se_dbg(SE_DBG_PLUGINS);

      Glib::RefPtr<Gtk::UIManager> ui = get_ui_manager();

      ui->remove_ui(ui_id);
      ui->remove_action_group(action_group);
   }

   void update_ui() {
      se_dbg(SE_DBG_PLUGINS);

      bool visible = (get_current_document() != NULL);

      action_group->get_action("extend-length")->set_sensitive(visible);
      action_group->get_action("extend-length-bwd")->set_sensitive(visible);
   }

  protected:
   void on_extend_length_fwd() {
      se_dbg(SE_DBG_PLUGINS);

      execute(true);
   }

   void on_extend_length_bwd() {
      se_dbg(SE_DBG_PLUGINS);

      execute(false);
   }

   bool execute(bool forward) {
      se_dbg(SE_DBG_PLUGINS);

      Document* doc = get_current_document();

      g_return_val_if_fail(doc, false);

      Subtitles subtitles = doc->subtitles();

      std::vector<Subtitle> selection = subtitles.get_selection();

      if (selection.empty()) {
         doc->flash_message(_("Please select at least 1 subtitle."));
         return false;
      }

      SubtitleTime gap(cfg::get_int("timing", "min-gap-between-subtitles"));

      doc->start_command(_("Extend lenght"));

      if (forward) {  // extend length forward, i.e. keep start and move end
         for (auto& sub : selection) {
            Subtitle next = subtitles.get_next(sub);
            if (next) {
               SubtitleTime time = next.get_start() - gap;
               sub.set_end(time);
            }
         }
      } else {  // extend length backwards, i.e. keep end and move start
         for (int i = selection.size() - 1; i >= 0; --i) {
            Subtitle& sub = selection[i];
            Subtitle prev = subtitles.get_previous(sub);
            if (prev) {
               SubtitleTime endtime = sub.get_end();
               SubtitleTime starttime = prev.get_end() + gap;
               // NOTE: we cannot just call sub.set_start() because it automatically
               // shifts the end to preserve duration
               sub.set_start_and_end(starttime, endtime);
            }
         }
      }
      doc->emit_signal("subtitle-time-changed");
      doc->finish_command();

      return true;
   }

  protected:
   Gtk::UIManager::ui_merge_id ui_id;
   Glib::RefPtr<Gtk::ActionGroup> action_group;
};

REGISTER_EXTENSION(ExtendLengthPlugin)