text: /* Copyright 2019 Danny Nguyen <danny@keeb.io>
   *
   * 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 2 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 QMK_KEYBOARD_H
  
  
  bool is_alt_tab_active = false;    // ADD this near the begining of keymap.c
  uint16_t alt_tab_timer = 0;        // we will be using them soon.
  
  enum custom_keycodes {             // Make sure have the awesome keycode ready
    ALT_TAB = SAFE_RANGE,
  };
  
  
  const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
      [0] = LAYOUT(
          KC_MS_BTN1, KC_MS_BTN2, KC_MS_BTN3, 
          KC_WH_U, ALT_TAB, KC_WH_L, 
          KC_WH_D, TT(1), KC_WH_R 
      ),
      [1] = LAYOUT(
          RESET,   KC_ACL0, KC_ACL1, 
          KC_VOLU, KC_ACL2, KC_BRIU, 
          KC_VOLD, TO(1),  KC_BRID 
      ),
  };
  
  void encoder_update_user(uint8_t index, bool clockwise) {
      if (index == 0) {
          if (clockwise) {
              tap_code(KC_MS_LEFT);
          } else {
              tap_code(KC_MS_RIGHT);
          }
      }
      else if (index == 1) {
          if (clockwise) {
              tap_code(KC_MS_U);
          } else {
              tap_code(KC_MS_D);
          }
      }
  }
  bool process_record_user(uint16_t keycode, keyrecord_t *record) {
    switch (keycode) {               // This will do most of the grunt work with the keycodes.
      case ALT_TAB:
        if (record->event.pressed) {
          if (!is_alt_tab_active) {
            is_alt_tab_active = true;
            register_code(KC_LALT);
          }
          alt_tab_timer = timer_read();
          register_code(KC_TAB);
        } else {
          unregister_code(KC_TAB);
        }
        break;
    }
    return true;
  }
  
  void matrix_scan_user(void) {     // The very important timer.
    if (is_alt_tab_active) {
      if (timer_elapsed(alt_tab_timer) > 1000) {
        unregister_code(KC_LALT);
        is_alt_tab_active = false;
      }
    }
  }
  