/* ----------------------------------------------------------------------------
 * main()
 * ----------------------------------------------------------------------------
 * Copyright (c) 2012 Ben Blazak <benblazak.dev@gmail.com>
 * Released under The MIT License (MIT) (see "license.md")
 * Project located at <https://github.com/benblazak/ergodox-firmware>
 * ------------------------------------------------------------------------- */

#include <stdbool.h>
#include <stdint.h>
#include "./keyboard/controller.c"
#include "./keyboard/keyboard.h"

// --------------------------------------------------------------------
// types and forward declarations
// --------------------------------------------------------------------

typedef void (*void_funptr_t)(void);

typedef enum StickyState {
  StickyNone,
  StickyOnceDown,
  StickyOnceUp,
  StickyLock,
} StickyState;

#include "./main.h"

// ----------------------------------------------------------------------------
// layout data
// ----------------------------------------------------------------------------

#include "./keyboard/layout.c"
// defines:
// #define KB_Layers #{Layers.size}
// static const uint8_t      	PROGMEM _kb_layout[KB_LAYERS][KB_ROWS][KB_COLUMNS];
// static const void_funptr_t	PROGMEM _kb_layout_press[KB_LAYERS][KB_ROWS][KB_COLUMNS];
// static const void_funptr_t	PROGMEM _kb_layout_release[KB_LAYERS][KB_ROWS][KB_COLUMNS];

// ----------------------------------------------------------------------------
// globals
// ----------------------------------------------------------------------------
static bool	_kb_is_pressed[KB_ROWS][KB_COLUMNS];
static bool	(*kb_is_pressed)[KB_ROWS][KB_COLUMNS] = &_kb_is_pressed;

static bool	_kb_was_pressed[KB_ROWS][KB_COLUMNS];
static bool	(*kb_was_pressed)[KB_ROWS][KB_COLUMNS] = &_kb_was_pressed;

static bool   	kb_was_transparent[KB_ROWS][KB_COLUMNS];
static uint8_t	layers_pressed[KB_ROWS][KB_COLUMNS];

static uint8_t	current_layer;
static uint8_t	layer_offset;
static uint8_t	current_row;
static uint8_t	current_col;
static bool   	current_is_pressed;
static bool   	non_trans_key_pressed;
static bool   	trans_key_pressed;

static bool       	layers_active[KB_LAYERS];
static StickyState	layers_sticky[KB_LAYERS];
static uint8_t    	layers_top = 0;

// ----------------------------------------------------------------------------

/*
 * main()
 */
int main(void) {
  kb_init(); // does controller initialization too

  usb_init();
  while (!usb_configured());

  // initialize layers
  main_init_layers();

  // never return
  main_key_loop();
  return 0;
}


// ----------------------------------------------------------------------------
// layer functions
// ----------------------------------------------------------------------------

void main_init_layers() {
  for (uint8_t layer=0; layer < KB_LAYERS; layer++) {
    layers_active[layer] = false;
    layers_sticky[layer] = StickyNone;
  }
  layers_active[0] = true;
}


// find highest active layer
uint8_t _highest_active_layer(uint8_t offset) {
  if (offset < layers_top) {
    for (uint8_t l = layers_top - offset; l > 0 && l < KB_LAYERS; l--) {
      if (layers_active[l]) { return l; }
    }
  }

  // the base layer is always active
  return 0;
}

// return the highest active layer
uint8_t main_layers_top_layer() {
  return layers_top;
}

// return if highest active layer is sticky
StickyState main_layers_top_sticky() {
  return main_layers_sticky(layers_top);
}

// return if layer is sticky
StickyState main_layers_sticky(uint8_t layer) {
  if (layer < KB_LAYERS) {
    return layers_sticky[layer];
  }
  return StickyNone;
}

// enable a layer
void main_layers_enable(uint8_t layer, StickyState sticky) {
  if (layer >= KB_LAYERS) { return; }

  layers_active[layer] = true;
  layers_sticky[layer] = sticky;

  if (layer > layers_top) {
    layers_top = layer;
  }
}

// disable a layer
void main_layers_disable(uint8_t layer) {
  // base layer stays always on
  if (layer >= KB_LAYERS || layer == 0) { return; }

  layers_active[layer] = false;
  layers_sticky[layer] = StickyNone;

  if (layer == layers_top) {
    layers_top = _highest_active_layer(1);
  }
}

// disable the highest active layer
void main_layers_disable_top() {
  main_layers_disable(layers_top);
}

// return layer offset elements below the top
uint8_t main_layers_peek(uint8_t offset) {
  return _highest_active_layer(offset);
}

// execute the keypress or keyrelease function (if it exists) of the key at the current possition
void main_exec_key(void) {
  void (*key_function)(void) =
    ( (current_is_pressed)
      ? kb_layout_press_get(current_layer, current_row, current_col)
      : kb_layout_release_get(current_layer, current_row, current_col) );

  if (key_function) {
    (*key_function)();
  }

  // If the current layer is in the sticky once up state and a key defined
  //  for this layer (a non-transparent key) was pressed, pop the layer
  if (main_layers_top_sticky() == StickyOnceUp && non_trans_key_pressed) {
    main_layers_disable_top();
  }
}

// ----------------------------------------------------------------------------

uint8_t kb_layout_get(uint8_t layer, uint8_t row, uint8_t column) {
  return (uint8_t) pgm_read_byte(&(_kb_layout[layer][row][column] ));
}

void_funptr_t kb_layout_press_get(uint8_t layer, uint8_t row, uint8_t column) {
  return (void_funptr_t) pgm_read_word(&(_kb_layout_press[layer][row][column] ));
}

void_funptr_t kb_layout_release_get(uint8_t layer, uint8_t row, uint8_t column) {
  return (void_funptr_t) pgm_read_word(&(_kb_layout_release[layer][row][column]));
}

/*
 * Generate a normal keypress or keyrelease
 *
 * Arguments
 * - press: whether to generate a keypress (true) or keyrelease (false)
 * - keycode: the keycode to use
 *
 * Note
 * - Because of the way USB does things, what this actually does is either add
 *   or remove 'keycode' from the list of currently pressed keys, to be sent at
 *   the end of the current cycle (see main.c)
 */
void _kbfun_press_release(bool press, uint8_t keycode) {
// no-op
  if (keycode == 0) {
    return;
  }

// modifier keys
  switch (keycode) {
  case KEY_LeftControl: 	(press)	? (keyboard_modifier_keys |= (1<<0))	: (keyboard_modifier_keys &= ~(1<<0));	return;
  case KEY_LeftShift:   	(press)	? (keyboard_modifier_keys |= (1<<1))	: (keyboard_modifier_keys &= ~(1<<1));	return;
  case KEY_LeftAlt:     	(press)	? (keyboard_modifier_keys |= (1<<2))	: (keyboard_modifier_keys &= ~(1<<2));	return;
  case KEY_LeftGUI:     	(press)	? (keyboard_modifier_keys |= (1<<3))	: (keyboard_modifier_keys &= ~(1<<3));	return;
  case KEY_RightControl:	(press)	? (keyboard_modifier_keys |= (1<<4))	: (keyboard_modifier_keys &= ~(1<<4));	return;
  case KEY_RightShift:  	(press)	? (keyboard_modifier_keys |= (1<<5))	: (keyboard_modifier_keys &= ~(1<<5));	return;
  case KEY_RightAlt:    	(press)	? (keyboard_modifier_keys |= (1<<6))	: (keyboard_modifier_keys &= ~(1<<6));	return;
  case KEY_RightGUI:    	(press)	? (keyboard_modifier_keys |= (1<<7))	: (keyboard_modifier_keys &= ~(1<<7));	return;
  }

// all others
  for (uint8_t i=0; i<6; i++) {
    if (press) {
      if (keyboard_keys[i] == 0) {
        keyboard_keys[i] = keycode;
        return;
      }
    } else {
      if (keyboard_keys[i] == keycode) {
        keyboard_keys[i] = 0;
        return;
      }
    }
  }
}

/*
 * Is the given keycode pressed?
 */
bool _kbfun_is_pressed(uint8_t keycode) {
// modifier keys
  switch (keycode) {
  case KEY_LeftControl: 	if (keyboard_modifier_keys & (1<<0))	{ return true; }
  case KEY_LeftShift:   	if (keyboard_modifier_keys & (1<<1))	{ return true; }
  case KEY_LeftAlt:     	if (keyboard_modifier_keys & (1<<2))	{ return true; }
  case KEY_LeftGUI:     	if (keyboard_modifier_keys & (1<<3))	{ return true; }
  case KEY_RightControl:	if (keyboard_modifier_keys & (1<<4))	{ return true; }
  case KEY_RightShift:  	if (keyboard_modifier_keys & (1<<5))	{ return true; }
  case KEY_RightAlt:    	if (keyboard_modifier_keys & (1<<6))	{ return true; }
  case KEY_RightGUI:    	if (keyboard_modifier_keys & (1<<7))	{ return true; }
  }

// all others
  for (uint8_t i=0; i<6; i++)
    if (keyboard_keys[i] == keycode) {
      return true;
    }

  return false;
}

void _kbfun_mediakey_press_release(bool press, uint8_t keycode) {
  uint16_t mediakey_code = _media_code_lookup_table[keycode];
  if (press) {
    consumer_key = mediakey_code;
  } else {
// Only one key can be pressed at a time so only clear the keypress for
//  active key (most recently pressed)
    if (mediakey_code == consumer_key) {
      consumer_key = 0;
    }
  }
}

uint8_t _kbfun_get_keycode() {
  return kb_layout_get(current_layer, current_row, current_col);
}

// ----------------------------------------------------------------------------
// basic
// ----------------------------------------------------------------------------

void kbfun_press_release() {
  if (!trans_key_pressed) {
    non_trans_key_pressed = true;
  }
  kbfun_press_release_preserve_sticky();
}

/*
 * Generate a normal keypress or keyrelease
 * While basing the sticky key state transition on whether
 *  kbfun_press_release() was called after kbfun_transparent() generally
 *  works in practice, it is not always the desired behavior. One of the
 *  benefits of sticky keys is avoiding key chording, so we want to make sure
 *  that standard modifiers do not interrupt the sticky key cycle. Use
 *  kbfun_press_release_preserve_sticky() if you want to define a standard
 *  modifier key (shift, control, alt, gui) on the sticky layer instead of
 *  defining the key to be transparent for the layer.
 */
void kbfun_press_release_preserve_sticky() {
  uint8_t keycode = _kbfun_get_keycode();
  _kbfun_press_release(current_is_pressed, keycode);
}

/*
 * Toggle the key pressed or unpressed
 */
void kbfun_toggle(void) {
  uint8_t keycode	= _kbfun_get_keycode();
  bool is_pressed	= _kbfun_is_pressed(keycode);
  _kbfun_press_release(!is_pressed, keycode);
}

/*
 * Execute the key that would have been executed if the current layer was not
 * active
 */
void kbfun_transparent(void) {
  // TODO maybe re-implement this cleaner?
  trans_key_pressed = true;
  layer_offset++;
  current_layer = main_layers_peek(layer_offset);
  layers_pressed[current_row][current_col] = current_layer;
  main_exec_key();
}


// ----------------------------------------------------------------------------
// layer helper functions
// ----------------------------------------------------------------------------

static bool is_layer_enable(void_funptr_t f) {
  if (f == &kbfun_layer_enable || f == &kbfun_layer_sticky) {
    return true;
  }
  return false;
}

static bool is_layer_disable(void_funptr_t f) {
  if (f == &kbfun_layer_disable || f == &kbfun_layer_sticky) {
    return true;
  }
  return false;
}

static void layer_enable_upto(uint8_t max_layer) {
  // FIXME clean this up

  // pressing a key implicitly activates all lower layers as well
  for (uint8_t layer=0; layer <= KB_LAYERS; layer++) {
    void (*key_function)(void) = kb_layout_press_get(layer, current_row, current_col);

    if (is_layer_enable(key_function)) {
      uint8_t enable_layer = kb_layout_get(layer, current_row, current_col);
      if (enable_layer <= max_layer) {
        main_layers_enable(enable_layer, StickyNone);
      }
    }
  }
}

// ----------------------------------------------------------------------------
// layer functions
// ----------------------------------------------------------------------------

// enable given layer
void kbfun_layer_enable() {
  uint8_t layer = _kbfun_get_keycode();

  // FIXME useful for anything?
  // Only the topmost layer on the stack should be in sticky once state, pop
  // the top layer if it is in sticky once state
  /* uint8_t topSticky = main_layers_top_sticky(); */
  /* if (topSticky == StickyOnceDown || topSticky == StickyOnceUp) { */
  /*   main_layers_disable_top(); */
  /* } */

  layer_enable_upto(layer);
}

// disable given layer
void kbfun_layer_disable() {
  /* uint8_t layer = _kbfun_get_keycode(); */
  // FIXME clean this up

  // letting go off a key releases *all* layers on that key
  for (uint8_t layer=0; layer <= KB_LAYERS; layer++) {
    void (*key_function)(void) = kb_layout_release_get(layer, current_row, current_col);

    if (is_layer_disable(key_function)) {
      uint8_t disable_layer = kb_layout_get(layer, current_row, current_col);
      main_layers_disable(disable_layer);
    }
  }
}

/*
 * This function gives similar behavior to sticky keys for modifiers available
 *  on most operating systems.
 * 1) One time down (set on key press) - The layer was not active and the key
 *     has been pressed but not yet released. The layer is pushed in the one
 *     time down state.
 * 2) One time up (set on key release) - The layer was active when the layer
 *     sticky key was released. If a key on this layer (not set to
 *     transparent) was pressed before the key was released, the layer will be
 *     popped. If a non-transparent key was not pressed, the layer is popped
 *     and pushed again in the one time up state.
 * 3) Locked (set on key press) - The layer was active and in the one time up
 *     state when the layer sticky key was pressed again. The layer will be
 *     popped if the function is invoked on a subsequent keypress.
 */
void kbfun_layer_sticky() {
  uint8_t    	layer    	= _kbfun_get_keycode();
  uint8_t    	topLayer 	= main_layers_top_layer();
  StickyState	topSticky	= main_layers_top_sticky();

  if (current_is_pressed) {
    if (topLayer == layer) {
      // FIXME
      /* if (topSticky == StickyOnceUp) { */
      /*   main_layers_enable(layer, StickyLock); */
      /* } */
    } else {
      // only the topmost layer on the stack should be in sticky once state
      if (topSticky == StickyOnceDown || topSticky == StickyOnceUp) {
        main_layers_disable_top();
      }
      main_layers_enable(layer, StickyOnceDown);

      // this should be the only place we care about this flag being cleared
      non_trans_key_pressed = false;
    }
  } else {
    if (main_layers_sticky(layer) == StickyOnceDown) {
      // When releasing this sticky key, pop the layer always
      main_layers_disable(layer);

      if (!non_trans_key_pressed) {
        // If no key defined for this layer (a non-transparent key)
        //  was pressed, push the layer again, but in the
        //  StickyOnceUp state
        main_layers_enable(layer, StickyOnceUp);
      }
    }
  }
}

// ----------------------------------------------------------------------------
// special
// ----------------------------------------------------------------------------

/*
 * Generate a 'shift' press or release before the normal keypress or release
 */
void kbfun_shift_press_release(void) {
  _kbfun_press_release(current_is_pressed, KEY_LeftShift);
  kbfun_press_release();
}

/*
 * Generate a 'control' press or release before the normal keypress or release
 */
void kbfun_control_press_release(void) {
  _kbfun_press_release(current_is_pressed, KEY_LeftControl);
  kbfun_press_release();
}

/*
 * When assigned to two keys (e.g. the physical left and right shift keys)
 * (in both the press and release matrices), pressing and holding down one of
 * the keys will make the second key toggle capslock
 *
 * If either of the shifts are pressed when the second key is pressed, they
 * wil be released so that capslock will register properly when pressed.
 * Capslock will then be pressed and released, and the original state of the
 * shifts will be restored
 */
void kbfun_2_keys_capslock_press_release(void) {
  static uint8_t keys_pressed;
  static bool lshift_pressed;
  static bool rshift_pressed;

  uint8_t keycode = _kbfun_get_keycode();

  if (!current_is_pressed) { keys_pressed--; }

// take care of the key that was actually pressed
  _kbfun_press_release(current_is_pressed, keycode);

// take care of capslock (only on the press of the 2nd key)
  if (keys_pressed == 1 && current_is_pressed) {
// save the state of left and right shift
    lshift_pressed = _kbfun_is_pressed(KEY_LeftShift);
    rshift_pressed = _kbfun_is_pressed(KEY_RightShift);
// disable both
    _kbfun_press_release(false, KEY_LeftShift);
    _kbfun_press_release(false, KEY_RightShift);

// press capslock, then release it
    _kbfun_press_release(true, KEY_CapsLock); 	usb_keyboard_send();
    _kbfun_press_release(false, KEY_CapsLock);	usb_keyboard_send();

// restore the state of left and right shift
    if (lshift_pressed)	{ _kbfun_press_release(true, KEY_LeftShift); 	}
    if (rshift_pressed)	{ _kbfun_press_release(true, KEY_RightShift);	}
  }

  if (current_is_pressed) { keys_pressed++; }
}

/*
 * Generate a keypress for a media key
 */
void kbfun_mediakey_press_release(void) {
  uint8_t keycode = _kbfun_get_keycode();
  _kbfun_mediakey_press_release(current_is_pressed, keycode);
}

// --------------------------------------------------------------------------------------

void main_key_loop() {
  for (;;) {
    // swap `kb_is_pressed` and `kb_was_pressed`, then update
    bool (*temp)[KB_ROWS][KB_COLUMNS]	= kb_was_pressed;
    kb_was_pressed                   	= kb_is_pressed;
    kb_is_pressed                    	= temp;

    kb_update_matrix(*kb_is_pressed);

    // this loop is responsible to
    // - "execute" keys when they change state
    // - keep track of which layers the keys were on when they were pressed
    //   (so they can be released using the function from that layer)
    //
    // note
    // - everything else is the key function's responsibility
    //   - see the keyboard layout file ("keyboard/layout/*.c") for
    //     which key is assigned which function (per layer)
    //   - see "lib/key-functions/public/*.c" for the function definitions
    for (uint8_t row=0; row<KB_ROWS; row++) {
      for (uint8_t col=0; col<KB_COLUMNS; col++) {
        current_is_pressed	= (*kb_is_pressed)[row][col];
        bool was_pressed  	= (*kb_was_pressed)[row][col];

        if (current_is_pressed != was_pressed) {
          if (current_is_pressed) {
            current_layer           	= main_layers_top_layer();
            layers_pressed[row][col]	= current_layer;
            trans_key_pressed       	= false;
          } else {
            current_layer    	= layers_pressed[row][col];
            trans_key_pressed	= kb_was_transparent[row][col];
          }

          // set remaining vars, and "execute" key
          current_row 	= row;
          current_col 	= col;
          layer_offset	= 0;
          main_exec_key();
          kb_was_transparent[row][col] = trans_key_pressed;
        }
      }
    }

    // send the USB report (even if nothing's changed)
    usb_keyboard_send();
    usb_extra_consumer_send();

    // debounce in ms; see keyswitch spec for necessary value
    _delay_ms(5);
  }
}

// ---------------------------------------------------------------------------------
// generated keyboard layout
// ---------------------------------------------------------------------------------