#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() % 7) {
        case 0: // I-tetromino
          cur_trmno.colour = CYAN;
          for (i = 0; i < 4; i++) {
            cur_trmno.pos[i].x = WIDTH / 2;
            cur_trmno.pos[i].y = i;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          break;

        case 1: // O-tetromino
          cur_trmno.colour = YELLOW;
          for (i = 0; i < 4; i += 2) {
            cur_trmno.pos[i].x = WIDTH / 2;
            cur_trmno.pos[i].y = 1 - i / 2;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;

            cur_trmno.pos[i+1].x = WIDTH / 2 + 1;
            cur_trmno.pos[i+1].y = 1 - i / 2;
            grid[cur_trmno.pos[i+1].x][cur_trmno.pos[i+1].y] =
              cur_trmno.colour;
          }
          break;

        case 2: // L-tetromino
          cur_trmno.colour = ORANGE;
          for (i = 0; i < 3; i++) {
            cur_trmno.pos[i].x = WIDTH / 2;
            cur_trmno.pos[i].y = i;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          cur_trmno.pos[3].x = WIDTH / 2 + 1;
          cur_trmno.pos[3].y = 2;
          grid[cur_trmno.pos[3].x][cur_trmno.pos[3].y] = cur_trmno.colour;
          break;

        case 3: // J-tetromino
          cur_trmno.colour = DARKBLUE;
          for (i = 0; i < 3; i++) {
            cur_trmno.pos[i].x = WIDTH / 2;
            cur_trmno.pos[i].y = i;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          cur_trmno.pos[3].x = WIDTH / 2 - 1;
          cur_trmno.pos[3].y = 2;
          grid[cur_trmno.pos[3].x][cur_trmno.pos[3].y] = cur_trmno.colour;
          break;

        case 4: // T-tetromino
          cur_trmno.colour = PURPLE;
          for (i = 0; i < 3; i++) {
            cur_trmno.pos[i].x = WIDTH / 2 - 1 + i;
            cur_trmno.pos[i].y = 1;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          cur_trmno.pos[3].x = WIDTH / 2;
          cur_trmno.pos[3].y = 0;
          grid[cur_trmno.pos[3].x][cur_trmno.pos[3].y] = cur_trmno.colour;
          break;

        case 5: // S-tetromino
          cur_trmno.colour = GREEN;
          for (i = 0; i < 4; i++) {
            cur_trmno.pos[i].x = WIDTH / 2 + (i < 2 ? i - 1 : i - 2);
            cur_trmno.pos[i].y = i < 2 ? 1 : 0;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          break;

        case 6: // Z-tetromino
          cur_trmno.colour = RED;
          for (i = 0; i < 4; i++) {
            cur_trmno.pos[i].x = WIDTH / 2 + (i < 2 ? i : 2 - i);
            cur_trmno.pos[i].y = i < 2 ? 1 : 0;
            grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
          }
          break;
      }
      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;
      for (i = 0; i < 4; i++) {
        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;

      for (i = 0; i < 4; i++) {
        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;

      for (i = 0; i < 4; i++) {
        cur_trmno.pos[i].x--;
        grid[cur_trmno.pos[i].x][cur_trmno.pos[i].y] = cur_trmno.colour;
      }
    }

    if (IsKeyPressed(KEY_G))
      gen_trmno = true;

    BeginDrawing();
      Draw2DGrid(grid);
#ifdef DEBUG
      char *str1, *str2;
      asprintf(&str1, "block0: x: %d y: %d", cur_trmno.pos[0].x,
          cur_trmno.pos[0].y);
      for (i = 1; i < 4; i++) {
        asprintf(&str2, "%s\nblock%d: x: %d y: %d", str1, i,
            cur_trmno.pos[i].x, cur_trmno.pos[i].y);
        free(str1);
        str1 = str2;
      }
      DrawText(str2, 0, 20, 16, BLACK);
      free(str2);
#endif
    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);
}