/*
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>

#ifdef PROTOCOL_CHIBIOS
#    if CH_CFG_USE_MEMCORE == FALSE
#        error ChibiOS is configured without a memory allocator. Your keyboard may have set `#define CH_CFG_USE_MEMCORE FALSE`, which is incompatible with this debounce algorithm.
#    endif
#endif

#ifndef DEBOUNCE
#    define DEBOUNCE 5
#endif

#define debounce_counter_t uint8_t
static bool matrix_need_update;

static debounce_counter_t *debounce_counters;
static bool                counters_need_update;

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

static uint8_t wrapping_timer_read(void) {
    static uint16_t time        = 0;
    static uint8_t  last_result = 0;
    uint16_t        new_time    = timer_read();
    uint16_t        diff        = new_time - time;
    time                        = new_time;
    last_result                 = (last_result + diff) % (MAX_DEBOUNCE + 1);
    return last_result;
}

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  = wrapping_timer_read();
    bool    needed_update = counters_need_update;
    if (counters_need_update) {
        update_debounce_counters(num_rows, current_time);
    }

    if (changed || (needed_update && !counters_need_update) || matrix_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) {
    matrix_need_update                   = false;
    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 (existing_row != raw_row) {
            if (*debounce_pointer == DEBOUNCE_ELAPSED) {
                *debounce_pointer    = current_time;
                cooked[row]          = raw_row;
                counters_need_update = true;
            } else {
                matrix_need_update = true;
            }
        }
        debounce_pointer++;
    }
}

bool debounce_active(void) { return true; }