QMK oneshot layer with tapped mod

/*  https://www.reddit.com/r/olkb/comments/plk4ts/shift_tap_one_shot/
 *  Code to include a macro key that is normally shift, but activates a oneshot layer on tap.
 *  This goes into keymap.c
 *
 *  The macro name used here is SH_LAY2, for SHIFT_LAYER2.  Call it what you want, but update everywhere it is mentioned.
 *  It will press(register_code) and release(unregister_code) KC_LSFT, left shift.  Change this key on lines 31 and 35.
 *  Update the oneshot layer on line 39.
 *  SH_LAY2_timer is specific to SH_LAY2.  Rename it if you rename SH_LAY2 to avoid confusion, and create another timer for each key like this.
 *
 *  If you press another key while SH_LAY2 is held down, this code assumes you're using shift like normal, and will not activate the oneshot layer.
 *  Otherwise, the oneshot will activate if you've held SH_LAY2 for less than TAPPING_TERM.
 *  This defaults to 200ms, and can be changed by defining it in config.h   #define TAPPING_TERM 150
 */

enum custom_keycodes {
    SH_LAY2 = SAFE_RANGE, //normal shift, oneshot layer 2 on tap
    //other macros,
};


bool key_pressed = false;    //variable used to check if a key is pressed while SH_LAY2 is held
uint16_t SH_LAY2_timer = 0;  //declare a timer variable to track hold time for SH_LAY2

bool process_record_user(uint16_t keycode, keyrecord_t *record) {
    if (record->event.pressed)
        key_pressed = true;  //if any key is pressed, set key_pressed to true

    switch (keycode) {
        case SH_LAY2:
            if (record->event.pressed) {       //when SH_LAY2 is pressed
                register_code(KC_LSFT);        //  press left shift
                key_pressed = false;           //  set key_pressed to false
                SH_LAY2_timer = timer_read();  //  mark the time SH_LAY2 was pressed
            } else {                           //when SH_LAY2 is released
                unregister_code(KC_LSFT);      //  release left shift
                if (key_pressed) break;  //  if another key was pressed while shift was held, exit and do not use one shot layer

                if (timer_elapsed(SH_LAY2_timer) < TAPPING_TERM) {  //if SH_LAY2 was held for less than TAPPING_TERM (default 200ms)
                    set_oneshot_layer( 2 , ONESHOT_START);          //  activate oneshot layer 2 (replace '2' with layer name or #)
                    clear_oneshot_layer_state(ONESHOT_PRESSED);     //  necessary for oneshots in macros.  don't touch this line
                }
            }
            break;
    }
    return true;
};