/*
Copyright 2019 Alex Ong<the.onga@gmail.com>
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/>.
*/

/*
Basic per-row algorithm. Uses an 8-bit counter per row.
After pressing a key, it immediately changes state, and sets a counter.
No further inputs are accepted until DEBOUNCE milliseconds have occurred.
*/

#include "matrix.h"
#include "timer.h"
#include "quantum.h"
#include <stdlib.h>

#ifndef DEBOUNCE
#  define DEBOUNCE 5
#endif

#define debounce_counter_t uint8_t

static debounce_counter_t *debounce_counters;
static bool                counters_need_update;

#define DEBOUNCE_ELAPSED 251
#define MAX_DEBOUNCE (DEBOUNCE_ELAPSED - 1)

void update_debounce_counters(uint8_t num_rows, uint8_t current_time);
void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t current_time);

// we use num_rows rather than MATRIX_ROWS to support split keyboards
void debounce_init(uint8_t num_rows) {
  debounce_counters = (debounce_counter_t *)malloc(num_rows * sizeof(debounce_counter_t));
  for (uint8_t r = 0; r < num_rows; r++) {
    debounce_counters[r] = DEBOUNCE_ELAPSED;
  }
}

void debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
  uint8_t current_time = timer_read() % MAX_DEBOUNCE;
  bool needed_update = counters_need_update;
  if (counters_need_update) {
    update_debounce_counters(num_rows, current_time);
  }

  if (changed || (needed_update && !counters_need_update)) {
    transfer_matrix_values(raw, cooked, num_rows, current_time);
  }
}

// If the current time is > debounce counter, set the counter to enable input.
void update_debounce_counters(uint8_t num_rows, uint8_t current_time) {
  counters_need_update                 = false;
  debounce_counter_t *debounce_pointer = debounce_counters;
  for (uint8_t row = 0; row < num_rows; row++) {
    if (*debounce_pointer != DEBOUNCE_ELAPSED) {
      if (TIMER_DIFF(current_time, *debounce_pointer, MAX_DEBOUNCE) >= DEBOUNCE) {
        *debounce_pointer = DEBOUNCE_ELAPSED;
      } else {
        counters_need_update = true;
      }
    }
    debounce_pointer++;
  }
}

// upload from raw_matrix to final matrix;
void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t current_time) {
  debounce_counter_t *debounce_pointer = debounce_counters;
  for (uint8_t row = 0; row < num_rows; row++) {
    matrix_row_t existing_row = cooked[row];
    matrix_row_t raw_row      = raw[row];

    // determine new value basd on debounce pointer + raw value
    if (*debounce_pointer == DEBOUNCE_ELAPSED && (existing_row != raw_row)) {
      *debounce_pointer    = current_time;
      cooked[row]          = raw_row;
      counters_need_update = true;
    }

    debounce_pointer++;
  }
}

bool debounce_active(void) { return true; }
