#include <raylib.h>

#define SevenHundredAndNine (709)

#define BoardLimit (4)
#define StartState (7)

static int BoardState [BoardLimit] [BoardLimit] = { 0 };

static bool IsPrimeNumber (int Number) {
	if (Number     <= 1) return (false);
	if (Number     <= 3) return (true);
	if (Number % 2 == 0) return (false);

	for (int Iterator = 3; Iterator < Number / 2; ++Iterator) {
		if (Number % Iterator == 0) {
			return (false);
		}
	}

	return (true);
}

static bool IsGameOver (void) {
	for (int Vertical = 0; Vertical < BoardLimit; ++Vertical) {
		for (int Horizontal = 0; Horizontal < BoardLimit; ++Horizontal) {
			if (BoardState [Vertical] [Horizontal] == 0) {
				return (false);
			}
		}
	}

	return (true);
}

static void SetRandomField (void) {
	int Spawner [] = { 2, 3, 5, 7 };

	int X = 0, Y = 0;

	Repeat:

	X = GetRandomValue (0, BoardLimit - 1);
	Y = GetRandomValue (0, BoardLimit - 1);

	if (BoardState [Y] [X] == 0) {
		BoardState [Y] [X] = Spawner [GetRandomValue (0, (int) (sizeof (Spawner) / sizeof (* Spawner)) - 1)];
	} else {
		goto Repeat;
	}
}

static void SetRandomBoard (void) {
	for (int Index = 0; Index < StartState; ++Index) {
		SetRandomField ();
	}
}

static void DrawState (void) {
	int Margin   = 7;
	int Width    = (GetScreenWidth  () - BoardLimit * Margin) / BoardLimit - Margin;
	int Height   = (GetScreenHeight () - BoardLimit * Margin) / BoardLimit - Margin;
	int FontSize = Height - 2 * Margin;

	ClearBackground ((Color) { 23, 23, 23, 255 });

	for (int Vertical = 0; Vertical < BoardLimit; ++Vertical) {
		for (int Horizontal = 0; Horizontal < BoardLimit; ++Horizontal) {
			int Number = BoardState [Vertical] [Horizontal];
			int X      = Margin + Horizontal * (Margin + Width);
			int Y      = Margin + Vertical   * (Margin + Height);

			Rectangle Data = { X, Y, Width, Height };

			Color Tint = { 63, 63, 63, 255 };

			//~Color Tint = {
				//~(unsigned char) (0.9 * (float) ((Number * 255) / SevenHundredAndNine)),
				//~(unsigned char) (0.6 * (float) ((Number * 255) / SevenHundredAndNine)),
				//~(unsigned char) (0.3 * (float) ((Number * 255) / SevenHundredAndNine)),
				//~255
			//~};

			DrawRectangleRounded (Data, 0.3, 3, Tint);

			DrawText (TextFormat ("%i", Number), X + Margin, Y + Margin, FontSize, (Color) { 255, 255, 255, 255 });
		}
	}
}

static void DrawScore (void) {
	int TotalScore = 0;

	for (int Horizontal = 0; Horizontal < BoardLimit; ++Horizontal) {
		for (int Vertical = 0; Vertical < BoardLimit; ++Vertical) {
			TotalScore += BoardState [Vertical] [Horizontal];
		}
	}

	DrawText (TextFormat ("%i", TotalScore), 0, 0, GetScreenHeight () / 3, (Color) { 255, 0, 0, 255 });
}

static int SumVertically (int Horizontal, int From, int To) {
	int Sum = 0;

	for (int Index = From; Index < To; ++Index) {
		Sum += BoardState [Index] [Horizontal];
	}

	return (Sum);
}

static int SumHorizontally (int Vertical, int From, int To) {
	int Sum = 0;

	for (int Index = From; Index < To; ++Index) {
		Sum += BoardState [Vertical] [Index];
	}

	return (Sum);
}

static void SumToTop (void) {
	for (int Horizontal = 0; Horizontal < BoardLimit; ++Horizontal) {
		for (int Vertical = 0; Vertical < BoardLimit; ++Vertical) {
			for (int Index = BoardLimit; Index >= Vertical; --Index) {
				int Sum = SumVertically (Horizontal, Vertical, Index);

				if ((IsPrimeNumber (Sum)) && (Sum <= SevenHundredAndNine)) {
					BoardState [Vertical] [Horizontal] = Sum;

					for (int Replace = Vertical + 1; Replace < Index; ++Replace) {
						BoardState [Replace] [Horizontal] = 0;
					}

					break;
				}
			}
		}
	}
}

static void SumToBottom (void) {
	for (int Horizontal = BoardLimit - 1; Horizontal >= 0; --Horizontal) {
		for (int Vertical = BoardLimit - 1; Vertical >= 0; --Vertical) {
			for (int Index = 0; Index <= Vertical; ++Index) {
				int Sum = SumVertically (Horizontal, Index, Vertical + 1);

				if ((IsPrimeNumber (Sum)) && (Sum <= SevenHundredAndNine)) {
					BoardState [Vertical] [Horizontal] = Sum;

					for (int Replace = Vertical - 1; Replace >= Index; --Replace) {
						BoardState [Replace] [Horizontal] = 0;
					}

					break;
				}
			}
		}
	}
}

static void SumToLeft (void) {
	for (int Vertical = 0; Vertical < BoardLimit; ++Vertical) {
		for (int Horizontal = 0; Horizontal < BoardLimit; ++Horizontal) {
			for (int Index = BoardLimit; Index >= Horizontal; --Index) {
				int Sum = SumHorizontally (Vertical, Horizontal, Index);

				if ((IsPrimeNumber (Sum)) && (Sum <= SevenHundredAndNine)) {
					BoardState [Vertical] [Horizontal] = Sum;

					for (int Replace = Horizontal + 1; Replace < Index; ++Replace) {
						BoardState [Vertical] [Replace] = 0;
					}

					break;
				}
			}
		}
	}
}

static void SumToRight (void) {
	for (int Vertical = BoardLimit - 1; Vertical >= 0; --Vertical) {
		for (int Horizontal = BoardLimit - 1; Horizontal >= 0; --Horizontal) {
			for (int Index = 0; Index <= Horizontal; ++Index) {
				int Sum = SumHorizontally (Vertical, Index, Horizontal + 1);

				if ((IsPrimeNumber (Sum)) && (Sum <= SevenHundredAndNine)) {
					BoardState [Vertical] [Horizontal] = Sum;

					for (int Replace = Horizontal - 1; Replace >= Index; --Replace) {
						BoardState [Vertical] [Replace] = 0;
					}

					break;
				}
			}
		}
	}
}

int main (void) {
	SetTraceLogLevel (LOG_NONE);

	InitWindow (960, 480, "x709 --- Raylib");

	SetRandomSeed  ((unsigned int) GetTime ());
	SetRandomBoard ();

	SetTargetFPS (60);
	SetExitKey   (KEY_Q);

	while (! WindowShouldClose ()) {
		BeginDrawing ();

		DrawState ();

		if (IsGameOver ()) {
			DrawScore  ();
			EndDrawing ();

			continue;
		}

		if (IsKeyPressed (KEY_W) || IsKeyPressed (KEY_UP)) {
			SumToTop       ();
			SetRandomField ();
		} else if (IsKeyPressed (KEY_S) || IsKeyPressed (KEY_DOWN)) {
			SumToBottom    ();
			SetRandomField ();
		} else if (IsKeyPressed (KEY_A) || IsKeyPressed (KEY_LEFT)) {
			SumToLeft      ();
			SetRandomField ();
		} else if (IsKeyPressed (KEY_D) || IsKeyPressed (KEY_RIGHT)) {
			SumToRight     ();
			SetRandomField ();
		}

		EndDrawing ();
	}

	CloseWindow ();

	return (0);
}