#include "hardware/gpio.h"
#include "keypad.hpp"

Keypad::Keypad(uint *rows, uint *cols, char chars[4][4]) :
  rows{rows}, cols{cols}
{
  initCharArray(chars);
  init();
}

/*
 * Get pressed key.
 */
char Keypad::getKey() {
  int column_index = pressedColumn();
  int row_index;

  if(column_index < 0)
    return '\0';

  pullPinsDown(cols);
  for(int i = 0; i < KEYPAD_LEN; ++i) {
    gpio_put(rows[i], 1);
    int row_state = gpio_get(rows[i]);
    int column_state = gpio_get(cols[column_index]);

    if(row_state & column_state) {
      row_index = i;

      break;
    }
  }
  restartPins();
  
  return chars[row_index][column_index];
}

/*
 * See if a key is pressed.
 * All columns are pulled up, so if a key is pressed,
 * its corresponding column should be pulled down.
 */
bool Keypad::keyPressed() {
  return pressedColumn() < 0;
}

/*
 * Copy the char matrix passed to the constructor to
 * the object's chars attribute.
 */
void Keypad::initCharArray(char chars[4][4]) {
  for(int i = 0; i < KEYPAD_LEN; ++i) {
    for(int j = 0; j < KEYPAD_LEN; ++j)
      this->chars[i][j] = chars[i][j];
  }
}

/*
 * Initialize the GPIO pins that will be used by the
 * keypad.
 * row pins: pulled low and set as outputs.
 * column pins: pulled high and set as inputs.
 */
void Keypad::init() {
  for (int i = 0; i < KEYPAD_LEN; ++i) {
    gpio_init(rows[i]);
    gpio_init(cols[i]);
    gpio_set_dir(rows[i], OUT);
    gpio_set_dir(cols[i], IN);
    gpio_pull_down(rows[i]);
    gpio_pull_up(cols[i]);
  }
}

/*
 * Get the column that's being pressed.
 * If no column is getting pressed (i.e, no button
 * is getting pressed) return -1, otherwise return
 * the index of the column being pressed.
 */
uint Keypad::pressedColumn() {
  for (int i = 0; i < KEYPAD_LEN; ++i) {
    if(!gpio_get(cols[i]))
      return i;
  }

  return -1;
}

/*
 * Pull every GPIO pin in pins down.
 */
void Keypad::pullPinsDown(uint *pins) {
  for(int i = 0; i < KEYPAD_LEN; ++i)
    gpio_pull_down(pins[i]);
}

/*
 * Leave the state of pins as it was before reading.
 * (Columns pulled up, rows pulled down);
 */
void Keypad::restartPins() {
  for(int i = 0; i < KEYPAD_LEN; ++i) {
    gpio_pull_up(cols[i]);
    gpio_put(rows[i], 0);
  }
}