/***************************************************************************
 *   Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO,                    *
 *                         Niccolò Izzo IU2KIN                             *
 *                         Silvano Seva IU2KWO                             *
 *                                                                         *
 *   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 3 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/>   *
 ***************************************************************************/

#ifndef KEYBOARD_H
#define KEYBOARD_H

#include <stdint.h>
#include <stdbool.h>
#include <os_cfg_app.h>

/**
 * The following enum provides a set of flags to be used to check which buttons
 * are pressed by bit-masking the uint32_t value returned by kbd_getKeys().
 */
enum key
{
    KEY_0     = (1 << 0),   /* Keypad digit "0"                  */
    KEY_1     = (1 << 1),   /* Keypad digit "1"                  */
    KEY_2     = (1 << 2),   /* Keypad digit "2"                  */
    KEY_3     = (1 << 3),   /* Keypad digit "3"                  */
    KEY_4     = (1 << 4),   /* Keypad digit "4"                  */
    KEY_5     = (1 << 5),   /* Keypad digit "5"                  */
    KEY_6     = (1 << 6),   /* Keypad digit "6"                  */
    KEY_7     = (1 << 7),   /* Keypad digit "7"                  */
    KEY_8     = (1 << 8),   /* Keypad digit "8"                  */
    KEY_9     = (1 << 9),   /* Keypad digit "9"                  */
    KEY_STAR  = (1 << 10),  /* Keypad digit "*"                  */
    KEY_HASH  = (1 << 11),  /* Keypad digit "#"                  */
    KEY_ENTER = (1 << 12),  /* Keypad green button/enter         */
    KEY_ESC   = (1 << 13),  /* Keypad red button/esc             */
    KEY_UP    = (1 << 14),  /* Keypad upward arrow               */
    KEY_DOWN  = (1 << 15),  /* Keypad downward arrow             */
    KEY_LEFT  = (1 << 16),  /* Keypad leftward arrow             */
    KEY_RIGHT = (1 << 17),  /* Keypad rightward arrow            */
    KEY_MONI  = (1 << 18),  /* Monitor button                    */
    KEY_F1    = (1 << 19),  /* Function button                   */
    KEY_F2    = (1 << 20),  /* Function button (device specific) */
    KEY_F3    = (1 << 21),  /* Function button (device specific) */
    KEY_F4    = (1 << 22),  /* Function button (device specific) */
    KEY_F5    = (1 << 23),  /* Function button (device specific) */
    KEY_F6    = (1 << 24),  /* Function button (device specific) */
    KEY_F7    = (1 << 25),  /* Function button (device specific) */
    KEY_F8    = (1 << 26),  /* Function button (device specific) */
    KEY_F9    = (1 << 27),  /* Function button (device specific) */
    KEY_F10   = (1 << 28),  /* Function button (device specific) */
};

/**
 * Number of supported keys
 */
static const uint8_t kbd_num_keys = 29;

/**
 * Time interval in ticks after which a keypress is considered a long-press
 */
static const uint16_t kbd_long_interval = OS_CFG_TICK_RATE_HZ * 0.7;

/**
 * Structure that represents a keyboard event payload
 * The maximum size of an event payload is 30 bits
 * For a keyboard event we use 1 bit to signal a short or long press
 * And the remaining 29 bits to communicate currently pressed keys.
 */
typedef union
{
    struct
    {
        uint32_t _padding   : 2,
                 long_press : 1,
                 keys       : 29;
    };

    uint32_t value;
} kbd_msg_t;

/**
 * We encode the status of all the keys with a uint32_t value
 * To check which buttons are pressed one can bit-mask the 
 * keys value with one of the enum values defined in key.
 * Example:
 * keyboard_t keys = kbd_getKeys();
 * if(keys & KEY_ENTER) do_stuff();
 */
typedef uint32_t keyboard_t;

/**
 * This function initialises the keyboard subsystem, configuring the GPIOs as
 * needed.
 */
void kbd_init();

/**
 * When called, this function terminates the keyboard driver.
 */
void kbd_terminate();

/**
 * When called, this function takes a snapshot of the current configuration of
 * all the keyboard buttons and returns it as a 32-bit variable.
 * 
 * @return an uint32_t representing the current keyboard configuration.
 */
keyboard_t kbd_getKeys();

#endif /* KEYBOARD_H */