#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include "raylib.h"

/*
 * each cube is 1 unit, so FACT is used as a scale factor for the size of the
 * screen
 */
#define WIDTH 10
#define HEIGHT 22
#define VIS_HEIGHT 20
#define FACT 40
/* since the game only moves on a block per block basis, no smoothness is
 * necessary, so the only thing FPS controls is how fast the blocks move left
 * and right, due to how often it polls */
#define FPS 30

#define CYAN CLITERAL(Color){ 0, 255, 255, 255 }

typedef struct Vector2Int {
  int x, y;
} Vector2Int;

typedef struct Tetromino {
  Color colour;
  Vector2Int pos[4]; // position of 4 cubes making the tetromino
} Tetromino;

void Draw2DGrid(Color grid[WIDTH][HEIGHT]);

int
main(void){
  int const width = WIDTH * FACT, height = HEIGHT * FACT,
    vis_height = VIS_HEIGHT * FACT;
  Color grid[WIDTH][HEIGHT]; // if colour is WHITE, the position is empty
  int interval = FPS, count, i, j;
  Tetromino cur_trmno; // trnmo is faster and easier to write than tetromino
  bool gen_trmno = true;

  srand(time(NULL));

  for (i = 0; i < WIDTH; i++)
    for (j = 0; j < HEIGHT; j++)
      grid[i][j] = WHITE;

  InitWindow(width, height, "retris");
  SetTargetFPS(FPS);
  for (count = 0; !WindowShouldClose(); count++) {
    if (gen_trmno) {
      switch (rand() % 1) {
        case 0:
          cur_trmno.colour = CYAN;
          for (i = 0; i < 4; i++) {
            cur_trmno.pos[i].x = WIDTH / 2;
            // 3 - i so that tetrominoes are listed from bottom up; if drawn
            // from top to bottom on line 69, then they will overlap and just
            // be 1 cube
            cur_trmno.pos[i].y = 3 - i;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] =
              cur_trmno.colour;
          }
      }
      gen_trmno = false;
    }

    if (count >= (IsKeyDown(KEY_DOWN) ? FPS/30 : interval)) {
      count = 0;
      for (i = 0; i < 4; i++) {
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = WHITE;
        cur_trmno.pos[i].y++;
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
      }
    }

    if (IsKeyDown(KEY_RIGHT)) {
      for (i = 0; i < 4; i++) {
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = WHITE;
        cur_trmno.pos[i].x++;
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
      }
    }
    else if (IsKeyDown(KEY_LEFT)) {
      for (i = 0; i < 4; i++) {
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = WHITE;
        cur_trmno.pos[i].x--;
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
      }
    }

    if (IsKeyDown(KEY_G))
      gen_trmno = true;

    BeginDrawing();
      Draw2DGrid(grid);
    EndDrawing();
  }

  CloseWindow();
  return 0;
}

void
Draw2DGrid(Color grid[WIDTH][HEIGHT]){
  int i, j;

  for (i = 0; i < WIDTH; i++) {
    for (j = 0; j < HEIGHT; j++) {
      DrawRectangle(i*FACT, j*FACT, FACT, FACT, grid[i][j]);
    }
  }

  for (i = 0; i <= WIDTH; i++)
    DrawLine(i*FACT, 0, i*FACT, HEIGHT*FACT, LIGHTGRAY);
  for (i = 0; i <= HEIGHT; i++)
    DrawLine(0, i*FACT, WIDTH*FACT, i*FACT, LIGHTGRAY);
}