/* Copyright 2021 tiltowait
 *
 * 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

enum custom_layers {
    _BASE,
    _SECOND,
    _NUMPAD,
};

enum custom_keycodes {
  NUM_SCRL = SAFE_RANGE /* Dual-purpose Scroll Lock / Numlock button as on original hardware */
};

void toggle_numlock_layer(int set_state);

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
  [_BASE] = LAYOUT( /* Base layer */
    KC_ESC,                KC_F1,  KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   KC_F7,   KC_F8,   KC_MUTE, KC_F10,  KC_VOLD, KC_VOLU,   S(G(KC_4)), NUM_SCRL, KC_PAUS,

    KC_GRV,       KC_1,    KC_2,   KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    KC_MINS, KC_EQL,  KC_BSLS,   KC_INS,  KC_HOME,  KC_PGUP,
    LT(_SECOND,KC_TAB), KC_Q,    KC_W,   KC_E,    KC_R,    KC_T,    KC_Y,    KC_U,    KC_I,    KC_O,    KC_P,    KC_LBRC, KC_RBRC, KC_BSPC,   KC_DEL,  KC_END,   KC_PGDN,
    KC_LCTL,      KC_A,    KC_S,   KC_D,    KC_F,    KC_G,    KC_H,    KC_J,    KC_K,    KC_L,    KC_SCLN, KC_QUOT, KC_NUHS, KC_ENT,
    KC_LSFT,      KC_NUBS, KC_Z,   KC_X,    KC_C,    KC_V,    KC_B,    KC_N,    KC_M,    KC_COMM, KC_DOT,  KC_SLSH,          KC_RSFT,            KC_UP,
    KC_LALT,               LGUI_T(KC_ENT),                    KC_SPC,                                      KC_RALT,          KC_RCTL,   KC_LEFT, KC_DOWN,  KC_RGHT
  ),
  [_SECOND] = LAYOUT( /* Layer 1 */
     KC_TRNS,          KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,    KC_TRNS,       KC_TRNS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,

     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,    KC_TRNS,    KC_TRNS, KC_TRNS,    S(A(KC_MINS)), KC_TRNS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, C(KC_LEFT), C(KC_RGHT), KC_TRNS, KC_TRNS,    KC_TRNS,       KC_TRNS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_LEFT, KC_DOWN,    KC_UP,      KC_RGHT, S(A(KC_M)), KC_TRNS,       KC_TRNS, KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,    KC_ENT,     KC_TRNS, KC_TRNS,    KC_TRNS,                KC_TRNS,            KC_TRNS,
     KC_TRNS,          KC_TRNS,                            C(KC_SPC),                                            KC_TRNS,                KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS
  ),
  [_NUMPAD] = LAYOUT( /* Numpad Layer */
     KC_TRNS,          KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,        KC_TRNS,     KC_TRNS,    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,

     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_KP_7, KC_KP_8, KC_KP_9, KC_TRNS,        KC_KP_MINUS, KC_KP_PLUS, KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_KP_4, KC_KP_5, KC_KP_6, KC_TRNS,        KC_TRNS,     KC_TRNS,    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_KP_1, KC_KP_2, KC_KP_3, KC_KP_ASTERISK, KC_TRNS,     KC_TRNS,    KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_KP_0, KC_TRNS, KC_KP_DOT,      KC_KP_SLASH,             KC_TRNS,            KC_TRNS,
     KC_TRNS,          KC_TRNS,                            KC_TRNS,                                            KC_TRNS,                 KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS
  ),
};

bool process_record_user(uint16_t keycode, keyrecord_t *record) {
  static uint16_t last_num_scroll = 0; /* For unregistering the proper key */

  switch (keycode) {
    case NUM_SCRL:
    if (record->event.pressed) {
      if (get_mods() & MOD_MASK_SHIFT) {
        /* Remove the shift modifiers */
        uint8_t shift_mods = get_mods() & (MOD_BIT(KC_LSFT) | MOD_BIT(KC_RSFT));
        set_mods(get_mods() & ~(MOD_BIT(KC_LSFT) | MOD_BIT(KC_RSFT)) );

        last_num_scroll = KC_NUM_LOCK;
        register_code(last_num_scroll);
        toggle_numlock_layer(-1);

        /* Reset the shift modifiers */
        set_mods(shift_mods);
      } else {
        last_num_scroll = KC_SCROLL_LOCK;
        register_code(last_num_scroll);
      }
    } else {
      unregister_code(last_num_scroll);
    }
    break;
  }
  return true;
}

void toggle_numlock_layer(int set_state) {
  static uint8_t numlock_enabled = 0;

  /* set_state allows us to explicitly change the numlock state
     rather than merely toggling it. */
  if (set_state == -1) {
    numlock_enabled = !numlock_enabled;
  } else {
    numlock_enabled = set_state;
  }

  if (numlock_enabled) {
    layer_on(_NUMPAD);
  }
  else {
    layer_off(_NUMPAD);
  }
}

bool led_update_kb(led_t led_state) {
  static int8_t numlock_state = -1;

  if (led_state.num_lock != numlock_state) {
    numlock_state = led_state.num_lock;
    toggle_numlock_layer(led_state.num_lock);
  }
  return true;
}