/* Copyright 2021 3araht
 *
 * 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
#include "version.h"

//  define which MIDI ch to use.
//  Note that (actual MIDI ch# - 1) -> 0 .. 15 is used for coding.
//  ch1
#define DEFAULT_MAIN_CH_NUMBER 0
//  ch3
#define DEFAULT_SUB_CH_NUMBER  2
//  ch2
#define ALT_MAIN_CH_NUMBER     1
//  ch4
#define ALT_SUB_CH_NUMBER      3
static uint8_t midi_left_ch = DEFAULT_SUB_CH_NUMBER;       //  By default, DEFAULT_SUB_CH_NUMBER is used for left side when separated.

//  By default( when use_alt_ch_gr == false), DEFAULT ch group (DEFAULT_MAIN_CH_NUMBER for entirely, or right side when separated, DEFAULT_SUB_CH_NUMBER for left side) is used.
//  When false, ALT ch group (ALT_MAIN_CH_NUMBER for entirely, or right side when separated, ALT_SUB_CH_NUMBER for left side) is used.
static bool use_alt_ch_gr = false;

// Defines names for use in layer keycodes and the keymap
enum layer_names {
    _BASE,              //  Base layer, shift mode, single channel.
    _SEPALEFTOCT,       //  1st oct channel separated version. Shift mode.
    _SEPAHALF,          //  Half channel separated version. Shift mode.
    _SEPARIGHTOCT,      //  2nd oct channel separated version. Shift mode.
    _TRANS,             //  Transpose feature is enabled instead of shift mode, single channel.
    _FLIPBASE,          //  Horizontal flipped version entirely. single channel.
    _FLIPTRANS,         //  Horizontal flipped version entirely. Transpose is used. single channel.
    _FN                 //  FuNction layer. This must be at the end of the enumurate to use the range from _LS_FN ... _LS_FN_MAX for FN layer LED settings.
};

//  Layer State
#define _LS_BASE           (1UL << _BASE)
#define _LS_SEPALEFTOCT    (1UL << _SEPALEFTOCT)
#define _LS_SEPAHALF       (1UL << _SEPAHALF)
#define _LS_SEPARIGHTOCT   (1UL << _SEPARIGHTOCT)
#define _LS_FLIPBASE       (1UL << _FLIPBASE)

#define _LS_TRANS          (1UL << _BASE         | 1UL << _TRANS)
#define _LS_SEPALEFTOCT_T  (1UL << _SEPALEFTOCT  | 1UL << _TRANS)
#define _LS_SEPAHALF_T     (1UL << _SEPAHALF     | 1UL << _TRANS)
#define _LS_SEPARIGHTOCT_T (1UL << _SEPARIGHTOCT | 1UL << _TRANS)
#define _LS_FLIPTRANS      (1UL << _FLIPBASE     | 1UL << _FLIPTRANS)

#define _LS_FN             (1UL << _FN)
#define _LS_MAX            (_LS_FN << 1)

//  Don't change the DEFAULT_SCALE_COL value below. It must be 0.
#define DEFAULT_SCALE_COL 0
static uint8_t scale_indicator_col = DEFAULT_SCALE_COL;
static bool trans_mode_indicator_loc_sel = true;  // when it is true, the location is _KEY01, _KEY13, ...

//  use led indicator or not.
static bool led_indicator_enable = true;

// Defines the keycodes used by our macros in process_record_user
enum custom_keycodes {
    SHIFT_L = SAFE_RANGE,
    SHIFT_R,
    TGLINDI,  //  ToGgLe INDIcator
    TGLINTR,  //  ToGgLe INdicator location {(_KEY01, _KEY13, _KEY25, _KEY37) or (_KEY02, _KEY14, _KEY26) / (_KEY12, _KEY24, _KEY36)}in TRans mode
    TGLTRNS,  //  ToGgLe TRaNS and shift
    TGLCHGR,  //  ToGgLe CH GRoup
    VERSION,

    B_BASE,            //  border set to the left end.
    B_LEFT,            //  border set to the 1st left octave.
    B_CENTER,          //  border set to the center.
    B_RIGHT,           //  border set to the 1st right octave.
    B_FLIP,            //  border set to the right end.

    // MY tone for _FLIPHALF and _FLIPLEFTOCT layers to distinguish the notes to avoid sustain effect, etc.
    // Since they are flipped, their subscripts are not MY_ but YM_, to make them easier to tell.
    YM_TONE_MIN,

    YM_C = YM_TONE_MIN,
    YM_Cs,
    YM_Db = YM_Cs,
    YM_D,
    YM_Ds,
    YM_Eb = YM_Ds,
    YM_E,
    YM_F,
    YM_Fs,
    YM_Gb = YM_Fs,
    YM_G,
    YM_Gs,
    YM_Ab = YM_Gs,
    YM_A,
    YM_As,
    YM_Bb = YM_As,
    YM_B,

    YM_C_1,
    YM_Cs_1,
    YM_Db_1 = YM_Cs_1,
    YM_D_1,
    YM_Ds_1,
    YM_Eb_1 = YM_Ds_1,
    YM_E_1,
    YM_F_1,
    YM_Fs_1,
    YM_Gb_1 = YM_Fs_1,
    YM_G_1,
    YM_Gs_1,
    YM_Ab_1 = YM_Gs_1,
    YM_A_1,
    YM_As_1,
    YM_Bb_1 = YM_As_1,
    YM_B_1,

    YM_C_2,
    YM_Cs_2,
    YM_Db_2 = YM_Cs_2,
    YM_D_2,
    YM_Ds_2,
    YM_Eb_2 = YM_Ds_2,
    YM_E_2,
    YM_F_2,
    YM_Fs_2,
    YM_Gb_2 = YM_Fs_2,
    YM_G_2,
    YM_Gs_2,
    YM_Ab_2 = YM_Gs_2,
    YM_A_2,
    YM_As_2,
    YM_Bb_2 = YM_As_2,
    YM_B_2,

    YM_C_3,
    YM_Cs_3,
    YM_Db_3 = YM_Cs_3,
    YM_D_3,
    YM_Ds_3,
    YM_Eb_3 = YM_Ds_3,
    YM_E_3,
    YM_F_3,
    YM_Fs_3,
    YM_Gb_3 = YM_Fs_3,
    YM_G_3,
    YM_Gs_3,
    YM_Ab_3 = YM_Gs_3,
    YM_A_3,
    YM_As_3,
    YM_Bb_3 = YM_As_3,
    YM_B_3,

    YM_C_4,
    YM_Cs_4,
    YM_Db_4 = YM_Cs_4,
    YM_D_4,
    YM_Ds_4,
    YM_Eb_4 = YM_Ds_4,
    YM_E_4,
    YM_F_4,
    YM_Fs_4,
    YM_Gb_4 = YM_Fs_4,
    YM_G_4,
    YM_Gs_4,
    YM_Ab_4 = YM_Gs_4,
    YM_A_4,
    YM_As_4,
    YM_Bb_4 = YM_As_4,
    YM_B_4,

    YM_C_5,
    YM_Cs_5,
    YM_Db_5 = YM_Cs_5,
    YM_D_5,
    YM_Ds_5,
    YM_Eb_5 = YM_Ds_5,
    YM_E_5,
    YM_F_5,
    YM_Fs_5,
    YM_Gb_5 = YM_Fs_5,
    YM_G_5,
    YM_Gs_5,
    YM_Ab_5 = YM_Gs_5,
    YM_A_5,
    YM_As_5,
    YM_Bb_5 = YM_As_5,
    YM_B_5,

    YM_C_6,
    YM_TONE_MAX = YM_C_6
};

#define MY_TONE_COUNT (YM_TONE_MAX - YM_TONE_MIN + 1)
static uint8_t my_tone_status[MY_TONE_COUNT];

// Long press: go to _FN layer, tap: MUTE
#define FN_MUTE LT(_FN, KC_MUTE)

// Used to set octave to 0
extern midi_config_t midi_config;
static bool is_trans_mode = false;     //  By default, shift mode is chosen.

static uint8_t key_separator_col = _KEY01;  //  (_KEY01 .. _KEY37).     By default, _KEY01 (= _BASE layer) is chosen. _KEY13 = *LEFT, _KEY19 = *HALF, _KEY25 = *RIGHT, _KEY37 = _FLIPBASE and _FLIPTRANS.

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    /* Base */
    [_BASE] = LAYOUT(
            FN_MUTE,         MI_SUST,
            MI_BNDU,
        SHIFT_L, SHIFT_R,    MI_C2, MI_D2, MI_E2,  MI_Fs2, MI_Ab2, MI_Bb2, MI_C3, MI_D3, MI_E3, MI_Fs3, MI_Ab3, MI_Bb3, MI_C4,  MI_D4,  MI_E4, MI_Fs4, MI_Ab4, MI_Bb4, MI_C5,
            MI_BNDD,            MI_Db2, MI_Eb2, MI_F2,  MI_G2,  MI_A2,  MI_B2, MI_Db3, MI_Eb3, MI_F3,  MI_G3, MI_A3,  MI_B3, MI_Db4, MI_Eb4, MI_F4,  MI_G4,  MI_A4,  MI_B4
    ),

    /* 1 octave on the left side is ch2, others are ch1 (normal) */
    [_SEPALEFTOCT] = LAYOUT(
            _______,          _______,
            _______,
        SHIFT_L, SHIFT_R,     YM_C_2, YM_D_2, YM_E_2,  YM_Fs_2, YM_Ab_2, YM_Bb_2,     MI_C3, MI_D3, MI_E3, MI_Fs3, MI_Ab3, MI_Bb3, MI_C4,  MI_D4,  MI_E4, MI_Fs4, MI_Ab4, MI_Bb4, MI_C5,
            _______,             YM_Db_2, YM_Eb_2, YM_F_2,  YM_G_2,  YM_A_2,  YM_B_2,     MI_Db3, MI_Eb3, MI_F3,  MI_G3, MI_A3,  MI_B3, MI_Db4, MI_Eb4, MI_F4,  MI_G4,  MI_A4,  MI_B4
    ),

    /* Half ch2, half ch1 (normal) */
    [_SEPAHALF] = LAYOUT(
            _______,           _______,
            _______,
        SHIFT_L, SHIFT_R,      YM_C_2, YM_D_2, YM_E_2,  YM_Fs_2, YM_Ab_2, YM_Bb_2, YM_C_3, YM_D_3, YM_E_3,       MI_Fs3, MI_Ab3, MI_Bb3, MI_C4,  MI_D4,  MI_E4, MI_Fs4, MI_Ab4, MI_Bb4, MI_C5,
            _______,               YM_Db_2, YM_Eb_2, YM_F_2,  YM_G_2,  YM_A_2,  YM_B_2, YM_Db_3, YM_Eb_3, YM_F_3,    MI_G3, MI_A3,  MI_B3, MI_Db4, MI_Eb4, MI_F4,  MI_G4,  MI_A4,  MI_B4
    ),

    /* 2 octave on the left side is ch2, others are ch1 (normal) */
    [_SEPARIGHTOCT] = LAYOUT(
            _______,           _______,
            _______,
        SHIFT_L, SHIFT_R,      YM_C_2, YM_D_2, YM_E_2,  YM_Fs_2, YM_Ab_2, YM_Bb_2, YM_C_3, YM_D_3, YM_E_3, YM_Fs_3, YM_Ab_3, YM_Bb_3,      MI_C4,  MI_D4,  MI_E4, MI_Fs4, MI_Ab4, MI_Bb4, MI_C5,
            _______,               YM_Db_2, YM_Eb_2, YM_F_2,  YM_G_2,  YM_A_2,  YM_B_2, YM_Db_3, YM_Eb_3, YM_F_3,  YM_G_3, YM_A_3,  YM_B_3,     MI_Db4, MI_Eb4, MI_F4,  MI_G4,  MI_A4,  MI_B4
    ),

    /* TRANS   This layer must locate 1 layer below _FN layer. */
    [_TRANS] = LAYOUT(
            _______,           _______,
            _______,
        MI_TRSD,  MI_TRSU,    _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,
            _______,               _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______
    ),

    /* Flip Base    SFIFTUP and SHIFT_L are swapped. */
    [_FLIPBASE] = LAYOUT(
            FN_MUTE,          MI_SUST,
            MI_BNDU,
        SHIFT_L, SHIFT_R,     MI_C5, MI_Bb4, MI_Ab4,  MI_Fs4, MI_E4, MI_D4, MI_C4, MI_Bb3, MI_Ab3, MI_Fs3, MI_E3, MI_D3, MI_C3,  MI_Bb2,  MI_Ab2, MI_Fs2, MI_E2, MI_D2, MI_C2,
            MI_BNDD,            MI_B4, MI_A4, MI_G4,  MI_F4,  MI_Eb4,  MI_Db4, MI_B3, MI_A3, MI_G3,  MI_F3, MI_Eb3,  MI_Db3, MI_B2, MI_A2, MI_G2,  MI_F2,  MI_Eb2,  MI_Db2
    ),

    /* Flip Trans   This layer must locate 1 layer above _FLIPBASE layer.  MI_TRSU and MI_TRSD are swapped. */
    [_FLIPTRANS] = LAYOUT(
            _______,          _______,
            _______,
        MI_TRSU,  MI_TRSD,    _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,
            _______,               _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______
    ),

    [_FN] =  LAYOUT(
            _______,          XXXXXXX,
            MI_VELU,
        MI_OCTD, MI_OCTU,     B_BASE,  XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, XXXXXXX, B_LEFT, XXXXXXX, XXXXXXX, B_CENTER, XXXXXXX, XXXXXXX, B_RIGHT, XXXXXXX, XXXXXXX, XXXXXXX, VERSION, XXXXXXX, B_FLIP,
            MI_VELD,               TGLINTR, TGLTRNS, TGLCHGR, XXXXXXX, XXXXXXX, RGB_SAD, RGB_SAI, RGB_HUD, RGB_HUI, RGB_SPD, RGB_SPI, RGB_VAD, RGB_VAI, RGB_RMOD, RGB_MOD, EE_CLR, TGLINDI, RGB_TOG
    )
};

#if defined(ENCODER_MAP_ENABLE)
const uint16_t PROGMEM encoder_map[][NUM_ENCODERS][2] = {
    [_BASE]         = { ENCODER_CCW_CW(KC_VOLD, KC_VOLU)  },
    [_SEPALEFTOCT]  = { ENCODER_CCW_CW(_______, _______)  },
    [_SEPAHALF]     = { ENCODER_CCW_CW(_______, _______)  },
    [_SEPARIGHTOCT] = { ENCODER_CCW_CW(_______, _______)  },
    [_TRANS]        = { ENCODER_CCW_CW(_______, _______)  },
    [_FLIPBASE]     = { ENCODER_CCW_CW(KC_VOLD, KC_VOLU)  },
    [_FLIPTRANS]    = { ENCODER_CCW_CW(_______, _______)  },
    [_FN]           = { ENCODER_CCW_CW(RGB_RMOD, RGB_MOD) },
};
#endif


// commom codes called from eeconfig_init_user() and keyboard_post_init_user().
void my_init(void){
    //  Set octave to 0
    midi_config.octave = QK_MIDI_OCTAVE_0 - MIDI_OCTAVE_MIN;
    // avoid using 127 since it is used as a special number in some sound sources.
    midi_config.velocity = MIDI_INITIAL_VELOCITY;
    default_layer_set(_LS_BASE);
    layer_state_set(_LS_BASE);

#ifdef RGB_MATRIX_ENABLE
    rgb_matrix_sethsv(HSV_BLUE);
    //  party mode (for LED soldering test. Enable rainbow color effect, and disable led_indicator to check all LEDs)
    rgb_matrix_mode(RGB_MATRIX_RAINBOW_MOVING_CHEVRON);
    led_indicator_enable = false;
#endif  // RGB_MATRIX_ENABLE
}

void eeconfig_init_user(void) {  // EEPROM is getting reset!
    midi_init();

#ifdef RGB_MATRIX_ENABLE
    rgb_matrix_enable();
    rgb_matrix_set_speed(RGB_MATRIX_DEFAULT_SPD);
#endif  // RGB_MATRIX_ENABLE
    my_init(); // commom codes called from eeconfig_init_user() and keyboard_post_init_user().
}

void keyboard_post_init_user(void) {
    for (uint8_t i = 0; i < MY_TONE_COUNT; i++) {
        my_tone_status[i] = MIDI_INVALID_NOTE;
    }
    my_init(); // commom codes called from eeconfig_init_user() and keyboard_post_init_user().
}

void reset_scale_indicator(void) {
    //  reset transpose value and scale_indicator_col to default.
    midi_config.transpose = 0;
    scale_indicator_col = DEFAULT_SCALE_COL;
    trans_mode_indicator_loc_sel = true;
}

void reset_all(void) {
    reset_scale_indicator();
    is_trans_mode = false;      //  trans mode is disabled by default.
}

void my_process_midi4single_note(uint8_t channel, uint16_t keycode, keyrecord_t *record, uint8_t *my_tone_status) {
    uint8_t  mytone    = keycode - YM_TONE_MIN;
    uint16_t mykeycode = mytone + MIDI_TONE_MIN;
    // uint16_t mykeycode = keycode - YM_TONE_MIN;
    // uint8_t  mytone    = mykeycode - MIDI_TONE_MIN;
    uint8_t  velocity  = midi_config.velocity;
    // uprintf("keycode=%u,mykeycode=%u,mytone =%u,velo = %u\n", keycode, mykeycode, mytone, velocity);
    if (record->event.pressed) {
        if (my_tone_status[mytone] == MIDI_INVALID_NOTE) {
            uint8_t note = midi_compute_note(mykeycode);
            midi_send_noteon(&midi_device, channel, note, velocity);
            dprintf("midi noteon channel:%d note:%d mytone:%d velocity:%d\n", channel, note, mytone, velocity);
            // uprintf("midi noteon channel:%d note:%d mytone:%d velocity:%d\n", channel, note, mytone, velocity);
            my_tone_status[mytone] = note;  // store root_note status.
        }
    } else {
        uint8_t note = my_tone_status[mytone];
        if (note != MIDI_INVALID_NOTE) {
            midi_send_noteoff(&midi_device, channel, note, velocity);
            dprintf("midi noteoff channel:%d note:%d velocity:%d\n", channel, note, velocity);
            // uprintf("midi noteoff channel:%d note:%d velocity:%d\n", channel, note, velocity);
        }
        my_tone_status[mytone] = MIDI_INVALID_NOTE;
    }
}

void select_layer_state_set(void) {
    switch (key_separator_col) {
        case _KEY01:
            if (is_trans_mode) {
                layer_state_set(_LS_TRANS);
            } else {
                layer_state_set(_LS_BASE);
            }
            break;

        case _KEY13:
            if (is_trans_mode) {
                layer_state_set(_LS_SEPALEFTOCT_T);
            } else {
                layer_state_set(_LS_SEPALEFTOCT);
            }
            break;

        case _KEY19:
            if (is_trans_mode) {
                layer_state_set(_LS_SEPAHALF_T);
            } else {
                layer_state_set(_LS_SEPAHALF);
            }
            break;

        case _KEY25:
            if (is_trans_mode) {
                layer_state_set(_LS_SEPARIGHTOCT_T);
            } else {
                layer_state_set(_LS_SEPARIGHTOCT);
            }
            break;

        case _KEY37:
            if (is_trans_mode) {
                layer_state_set(_LS_FLIPTRANS);
            } else {
                layer_state_set(_LS_FLIPBASE);
            }
            break;
    }
}


bool process_record_user(uint16_t keycode, keyrecord_t *record) {
    // uprintf("keycode=%u, YM_C_3=%u, YM_Db_2 =%u, YM_MIN = %u, YM_MAX = %u\n", keycode, YM_C_3, YM_Db_2, YM_TONE_MIN, YM_TONE_MAX);
    switch (keycode) {
        case VERSION: // Output firmware info.
            if (record->event.pressed) {
                SEND_STRING(QMK_KEYBOARD ":" QMK_KEYMAP " @ " QMK_VERSION " | " QMK_BUILDDATE);
            }
            break;

        //  Layer-related settings.
        //  reset_scale_indicator() first, followed by each modification, and then change the default layer.

        //  1, separator column modification
        case B_BASE:
            if (record->event.pressed) {
                reset_all();
                key_separator_col = _KEY01;
                select_layer_state_set();
            }
            break;

        case B_LEFT:
            if (record->event.pressed) {
                reset_all();
                key_separator_col = _KEY13;
                select_layer_state_set();
            }
            break;

        case B_CENTER:
            if (record->event.pressed) {
                reset_all();
                key_separator_col = _KEY19;
                select_layer_state_set();
            }
            break;

        case B_RIGHT:
            if (record->event.pressed) {
                reset_all();
                key_separator_col = _KEY25;
                select_layer_state_set();
            }
            break;

        case B_FLIP:
            if (record->event.pressed) {
                reset_all();
                key_separator_col = _KEY37;
                select_layer_state_set();
            }
            break;

        //  2, Toggle scale shift mode and transpose mode
        case TGLTRNS:
            if (record->event.pressed) {
                reset_scale_indicator();
                is_trans_mode = !is_trans_mode;
                select_layer_state_set();
            }
            break;

        //  SHIFT_L and SHIFT_R can be pressed only when layer is either _BASE, _FLIPBASE.
        case SHIFT_L:
            if (record->event.pressed) {
                switch (layer_state) {
                    case _LS_BASE:
                    case _LS_SEPALEFTOCT:
                    case _LS_SEPAHALF:
                    case _LS_SEPARIGHTOCT:
                    case _LS_FLIPBASE:
                        scale_indicator_col = shift_led_indicator_left(scale_indicator_col);
                        break;
                }
            }
            break;

        case SHIFT_R:
            if (record->event.pressed) {
                switch (layer_state) {
                    case _LS_BASE:
                    case _LS_SEPALEFTOCT:
                    case _LS_SEPAHALF:
                    case _LS_SEPARIGHTOCT:
                    case _LS_FLIPBASE:
                        scale_indicator_col = shift_led_indicator_right(scale_indicator_col);
                        break;
                }
            }
            break;

        case TGLINDI:
            if (record->event.pressed) {
                led_indicator_enable = !led_indicator_enable;
            }
            break;

        case TGLINTR:
            if (record->event.pressed) {
                switch (layer_state) {
                    //  main function of the TGLINTR part 1. alternate the status of trans_mode_indicator_loc_sel.
                    case _LS_TRANS          | (1UL << _FN):
                    case _LS_SEPALEFTOCT_T  | (1UL << _FN):
                    case _LS_SEPAHALF_T     | (1UL << _FN):
                    case _LS_SEPARIGHTOCT_T | (1UL << _FN):
                        trans_mode_indicator_loc_sel = !trans_mode_indicator_loc_sel;

                        //  when trans_mode_indicator_loc_sel == false, change the scale indicator and transpose.
                        scale_indicator_col = trans_mode_indicator_loc_sel ? 0:1;
                        // when TGLINTR is pressed, it also change the initial transpose setting to follow the scale indicator.
                        if (scale_indicator_col == 1) {
                            midi_config.transpose = -1;
                        } else {
                            midi_config.transpose = 0;
                        }
                        break;

                    //  main function of the TGLINTR part 2. alternate the status of trans_mode_indicator_loc_sel.
                    case _LS_FLIPTRANS      | (1UL << _FN):
                        trans_mode_indicator_loc_sel = !trans_mode_indicator_loc_sel;

                        //  when trans_mode_indicator_loc_sel == false, change the scale indicator and transpose.
                        scale_indicator_col = trans_mode_indicator_loc_sel ? 0:11;
                        // when TGLINTR is pressed, it also change the initial transpose setting to follow the scale indicator.
                        if (scale_indicator_col == 11) {
                            midi_config.transpose = -1;
                        } else {
                            midi_config.transpose = 0;
                        }
                        break;

                    //  special treatment when TGLINTR is pressed in _LS_FLIPBASE layer.
                    case _LS_FLIPBASE       | (1UL << _FN):   // when in FLIPBASE layer && non-Trans mode, change it to Trans mode.
                        trans_mode_indicator_loc_sel = false;
                        scale_indicator_col = 11;
                        midi_config.transpose = -1;
                        is_trans_mode = true;
                        select_layer_state_set();
                        break;


                    //  special treatment when TGLINTR is pressed in other non-Trans layer.
                    default :  // when other layers = non-Trans mode, change it to Trans mode.
                        trans_mode_indicator_loc_sel = false;
                        scale_indicator_col = 1;
                        midi_config.transpose = -1;
                        is_trans_mode = true;
                        select_layer_state_set();
                }
            }
            break;

        case TGLCHGR:
            if (record->event.pressed) {
                use_alt_ch_gr = !use_alt_ch_gr;
                if (use_alt_ch_gr) {
                    midi_config.channel = ALT_MAIN_CH_NUMBER;
                    midi_left_ch = ALT_SUB_CH_NUMBER;
                } else {  //  default
                    midi_config.channel = DEFAULT_MAIN_CH_NUMBER;
                    midi_left_ch = DEFAULT_SUB_CH_NUMBER;
                }
            }
            break;

        case  YM_TONE_MIN ... YM_TONE_MAX:  // MY tone
            // uprintf("keycode=%u, YM_C_3=%u, YM_Db_2 =%u, YM_MIN = %u, YM_MAX = %u\n", keycode, YM_C_3, YM_Db_2, YM_TONE_MIN, YM_TONE_MAX);
            //  DO NOT THROW BELOW into 'if (record->event.pressed) {}' STATEMENT SINCE IT IS USED IN THE FUNCTION BELOW.
            my_process_midi4single_note(midi_left_ch, keycode, record, my_tone_status);
            break;
    }
    return true;
}

#ifdef RGB_MATRIX_ENABLE
void set_led_scale_indicator(uint8_t r, uint8_t g, uint8_t b) {
    uint8_t max_scale_indicator_led_loop;
    uint8_t i;
    if (led_indicator_enable) {  //  turn on indicators when enabled.
        max_scale_indicator_led_loop = ( scale_indicator_col == DEFAULT_SCALE_COL ) ? 12 : 9;
        for (i = 0; i < max_scale_indicator_led_loop; i++) {
            rgb_matrix_set_color(led_scale_indicator[scale_indicator_col][i], r, g, b);
        }
    }
}

bool rgb_matrix_indicators_user(void) {
    // uint32_t mode = rgblight_get_mode();

    if (rgb_matrix_is_enabled()) {  // turn the lights on when it is enabled.

        // uint8_t max_scale_indicator_led_loop;
        uint8_t i;

        switch (layer_state) {
            case _LS_BASE:
                set_led_scale_indicator(BASE_LAYER_COLOR);
                break;

            case _LS_FLIPBASE:
                set_led_scale_indicator(FLIPB_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY37][i], FLIP_BORDER_COLOR);    //  right end
                }
                break;

            case _LS_TRANS:
                set_led_scale_indicator(TRANS_LAYER_COLOR);
                break;

            case _LS_SEPALEFTOCT_T:
                set_led_scale_indicator(SEPALEFT_T_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY13][i], FLIP_BORDER_COLOR);    //  Left
                }
                break;

            case _LS_SEPAHALF_T:
                set_led_scale_indicator(SEPAHALF_T_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY19][i], FLIP_BORDER_COLOR);    //  Center
                }
                break;

            case _LS_SEPARIGHTOCT_T:
                set_led_scale_indicator(SEPARIGHT_T_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY25][i], FLIP_BORDER_COLOR);    //  Right
                }
                break;

            case _LS_FLIPTRANS:
                set_led_scale_indicator(FLIPT_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY37][i], FLIP_BORDER_COLOR);    //  right end
                }
                break;

            case _LS_SEPALEFTOCT:
                set_led_scale_indicator(SEPALEFT_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY13][i], FLIP_BORDER_COLOR);    //  Left
                }
                break;

            case _LS_SEPAHALF:
                set_led_scale_indicator(SEPAHALF_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY19][i], FLIP_BORDER_COLOR);    //  Center
                }
                break;

            case _LS_SEPARIGHTOCT:
                set_led_scale_indicator(SEPARIGHT_LAYER_COLOR);
                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY25][i], FLIP_BORDER_COLOR);    //  Right
                }
                break;

            case _LS_FN ... _LS_MAX:  //  When Mute Button is long-pressed, the previous layers are still active.
                for (i = 1; i < 5; i++) {
                    rgb_matrix_set_color(i, RGB_DARKSPRINGGREEN);  //  up(1) down(4) left(3) right(2)  keys
                }
                rgb_matrix_set_color(led_single_col_indicator[_KEY02][0], RGB_DARKSPRINGGREEN);   //  TGLTRNS
                rgb_matrix_set_color(led_single_col_indicator[_KEY04][0], RGB_DARKSPRINGGREEN);   //  TGLINTR
                rgb_matrix_set_color(led_single_col_indicator[_KEY06][0], RGB_DARKSPRINGGREEN);   //  TGLCHGR

                for (i = 0; i < 3; i++) {
                    rgb_matrix_set_color(led_single_col_indicator[_KEY01][i], BASE_LAYER_COLOR);   //  B_BASE

                    rgb_matrix_set_color(led_single_col_indicator[_KEY13][i], SEPALEFT_LAYER_COLOR);   //  B_LEFT

                    rgb_matrix_set_color(led_single_col_indicator[_KEY19][i], SEPAHALF_LAYER_COLOR);   //  B_CENTER

                    rgb_matrix_set_color(led_single_col_indicator[_KEY25][i], SEPARIGHT_LAYER_COLOR);   //  B_RIGHT

                    rgb_matrix_set_color(led_single_col_indicator[_KEY37][i], FLIPB_LAYER_COLOR);   //  B_FLIP
                }

                for (i = _KEY12; i < _KEY37; i+=2){  //  even numbers from _KEY12 to _KEY36 are LED related settings.
                    // turn on the bottom row only to keep the visibility of the RGB MATRIX effects.
                    rgb_matrix_set_color(led_single_col_indicator[i][0], RGB_DARKSPRINGGREEN);  //       //  LED related settings.
                }
                break;
        }
    }
    return false;
}
#endif  // RGB_MATRIX_ENABLE
