#include <Arduino.h>
#include <TFT_eSPI.h>
#include <SPI.h>

// We assume the size of the screen 120x160
#define GRID_WIDTH   12
#define GRID_HEIGHT  16
#define BLOCK_SIZE   10
#define BLOCK_MARGIN  2

const int BTN1_PIN = 25;
volatile bool btn1_pressed = false;
const int BTN2_PIN = 33;
volatile bool btn2_pressed = false;

// I am using ST7735S, a very cheap display from aliexpress
TFT_eSPI tft = TFT_eSPI();
// pins are defined un User_Setup.h


// forward declarations
void IRAM_ATTR isr1();
void IRAM_ATTR isr2();

// the main board and the offboard, to check for dirty squares
uint32_t main_board[GRID_WIDTH][GRID_HEIGHT], offboard[GRID_WIDTH][GRID_HEIGHT];
/* 
   The value (i,j) on the board is given by main_board[i][j].
   if board(i,j) = 0, then the space there is empty
   otherwise board(i,j)'s first bit determines whether the block is "old" or not, and the rest denotes a color
 */


/* Blocks are defined in grids of 4x4:

  0    1   2   3
  4    5   6   7
  8    9  10  11
  12  13  14  15

*/
#define BLOCKS_COUNT 2
uint8_t blocks[BLOCKS_COUNT][4] =
  {
   {0,1,2,3},{0,1,4,5}
  };

#define COLORS_SIZE  6
uint32_t block_colors[COLORS_SIZE] = { TFT_NAVY, TFT_DARKGREEN, TFT_RED, TFT_YELLOW, TFT_GREEN, TFT_PINK };

// Graphics-related functions
void
init_board()
{
  tft.fillScreen(TFT_BLACK);

  for(int i = 0; i < GRID_WIDTH; i++)
    for(int j = 0; j < GRID_HEIGHT; j++)
      {
        main_board[i][j] = 0;
        offboard[i][j]  = 0;
      }
}

void
set_board(int i, int j, int color, bool old)
{
 int v = color<<1;
 if (old)
   {
     v = v|1;
   }
 main_board[i][j] = v;
}

void
draw_board()
{
  for(int i = 0; i < GRID_WIDTH; i++)
    for(int j = 0; j < GRID_HEIGHT; j++)
      {
        if (main_board[i][j] == offboard[i][j]) continue; // no need to redraw
        offboard[i][j] = main_board[i][j];
        int color = main_board[i][j]>>1;
        tft.fillRect(i*BLOCK_SIZE+BLOCK_MARGIN,j*BLOCK_SIZE+BLOCK_MARGIN,
                     BLOCK_SIZE-BLOCK_MARGIN,BLOCK_SIZE-BLOCK_MARGIN,
                     color);
      }
}

// Draw a block of type TYPE with color COLOR, starting at coordinates X, Y.
// Updates the main_board directly
void
draw_block(int x, int y, int type, int color, bool old)
{
  for (int i = 0; i < 4; i++)
    {
      int v = blocks[type][i];
      int dx = v%4;
      int dy = v/4;
      set_board(x+dx, y+dy, color, old);
    }
}


// Game logic

// Current and previous positions of the active block
int px = 0, cx = 0;
int py = 0, cy = 0;
// Type of the active block. Should be 0 <= cblokc_ty < BLOCKS_COUNT
int cblock_ty = 0;
// Color of the current block
int cblock_color = TFT_RED;

void
new_block()
{
  px = 0; cx = 0;
  py = 0; cy = 0;
  cblock_ty = 0;
  cblock_color = TFT_RED;
}

bool
check_collision()
{
  for (int i = 0; i < 4; i++)
    {
      int v = blocks[cblock_ty][i];
      int dx = v%4;
      int dy = v/4;
      if (cy+dy >= GRID_HEIGHT)
        {
          return true;
        }
      int is_old = main_board[cx+dx][cy+dy]&1;
      if (is_old)
        {
          return true;
        }
    }

  return false;
}

// Setup
void setup() {
  tft.init();   // initialize a ST7735S chip

  Serial.begin(115200);

  // set up the buttons and the interrupts
  pinMode(BTN1_PIN, INPUT_PULLUP);
  attachInterrupt(BTN1_PIN, isr1, FALLING);
  pinMode(BTN2_PIN, INPUT_PULLUP);
  attachInterrupt(BTN2_PIN, isr2, FALLING);

  init_board();
  new_block();

  delay(100);
}

void loop() {

  if (check_collision ())
    {
      // designate the block as "old" and leave it there
      draw_block(px, py, cblock_ty, cblock_color, true);
      new_block();
      return;
    }

  // clear the previous block
  if (cy != py || cx != px)
    {
      draw_block(px, py, cblock_ty, TFT_BLACK, false);
    }
  draw_block(cx, cy, cblock_ty, cblock_color, false);

  draw_board();

  px = cx;
  py = cy;

  if (btn1_pressed)
    {
      btn1_pressed = false;
      cx--;
    }
  if (btn2_pressed)
    {
      btn2_pressed = false;
      cx++;
    }

  cy++;

  delay(350);
}

void IRAM_ATTR
isr1()
{
  btn1_pressed = true;
}

void IRAM_ATTR
isr2()
{
  btn2_pressed = true;
}