/*
OneLoneCoder.com - Recursive Backtracker Maze Algorithm
"Get lost..." - @Javidx9

License
~~~~~~~
Copyright (C) 2018  Javidx9
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions; See license for details. 
Original works located at:
https://www.github.com/onelonecoder
https://www.onelonecoder.com
https://www.youtube.com/javidx9

GNU GPLv3
https://github.com/OneLoneCoder/videos/blob/master/LICENSE

From Javidx9 :)
~~~~~~~~~~~~~~~
Hello! Ultimately I don't care what you use this for. It's intended to be 
educational, and perhaps to the oddly minded - a little bit of fun. 
Please hack this, change it and use it in any way you see fit. You acknowledge 
that I am not responsible for anything bad that happens as a result of 
your actions. However this code is protected by GNU GPLv3, see the license in the
github repo. This means you must attribute me if you use it. You can view this
license here: https://github.com/OneLoneCoder/videos/blob/master/LICENSE
Cheers!

Background
~~~~~~~~~~
I really like perfect algorithms. This one shows how to generate a maze that guarantees
all cells can reach all other cells, it just may take some time to get there. I introduce
stacks, and show how the algorithm generates the maze visually.

Author
~~~~~~
Twitter: @javidx9
Blog: www.onelonecoder.com

Video:
~~~~~~
https://youtu.be/Y37-gB83HKE

Last Updated: 10/07/2017
*/

#include <iostream>
#include <stack>
using namespace std;

#include "olcConsoleGameEngine.h"

class OneLoneCoder_Maze : public olcConsoleGameEngine
{
public:
	OneLoneCoder_Maze()
	{
		m_sAppName = L"MAZE";
	}

private:	
	int  m_nMazeWidth;
	int  m_nMazeHeight;
	int *m_maze;
	

	// Some bit fields for convenience
	enum
	{
		CELL_PATH_N = 0x01,
		CELL_PATH_E = 0x02,
		CELL_PATH_S = 0x04,
		CELL_PATH_W = 0x08,
		CELL_VISITED = 0x10,
	};
	
	
	// Algorithm variables
	int  m_nVisitedCells;	
	stack<pair<int, int>> m_stack;	// (x, y) coordinate pairs
	int  m_nPathWidth;

	
protected:
	// Called by olcConsoleGameEngine
	virtual bool OnUserCreate()
	{
		// Maze parameters
		m_nMazeWidth = 40;
		m_nMazeHeight = 25;		
		m_maze = new int[m_nMazeWidth * m_nMazeHeight];
		memset(m_maze, 0x00, m_nMazeWidth * m_nMazeHeight * sizeof(int));
		m_nPathWidth = 3;
		
		// Choose a starting cell
		int x = rand() % m_nMazeWidth;
		int y = rand() % m_nMazeHeight;
		m_stack.push(make_pair(x, y));
		m_maze[y * m_nMazeWidth + x] = CELL_VISITED;
		m_nVisitedCells = 1;

		return true;
	}

	// Called by olcConsoleGameEngine
	virtual bool OnUserUpdate(float fElapsedTime)
	{
		// Slow down for animation
		this_thread::sleep_for(10ms);

		// Little lambda function to calculate index in a readable way
		auto offset = [&](int x, int y)
		{
			return (m_stack.top().second + y) * m_nMazeWidth + (m_stack.top().first + x);
		};

		// Do Maze Algorithm
		if (m_nVisitedCells < m_nMazeWidth * m_nMazeHeight)
		{
			// Create a set of unvisted neighbours
			vector<int> neighbours;

			// North neighbour
			if (m_stack.top().second > 0 && (m_maze[offset(0, -1)] & CELL_VISITED) == 0)
				neighbours.push_back(0);
			// East neighbour
			if (m_stack.top().first < m_nMazeWidth - 1 && (m_maze[offset(1, 0)] & CELL_VISITED) == 0)
				neighbours.push_back(1);
			// South neighbour
			if (m_stack.top().second < m_nMazeHeight - 1 && (m_maze[offset(0, 1)] & CELL_VISITED) == 0)
				neighbours.push_back(2);
			// West neighbour
			if (m_stack.top().first > 0 && (m_maze[offset(-1, 0)] & CELL_VISITED) == 0)
				neighbours.push_back(3);

			// Are there any neighbours available?
			if (!neighbours.empty())
			{
				// Choose one available neighbour at random
				int next_cell_dir = neighbours[rand() % neighbours.size()];

				// Create a path between the neighbour and the current cell
				switch (next_cell_dir)
				{
				case 0: // North
					m_maze[offset(0, -1)] |= CELL_VISITED | CELL_PATH_S;
					m_maze[offset(0,  0)] |= CELL_PATH_N;
					m_stack.push(make_pair((m_stack.top().first + 0), (m_stack.top().second - 1)));
					break;

				case 1: // East
					m_maze[offset(+1, 0)] |= CELL_VISITED | CELL_PATH_W;
					m_maze[offset( 0, 0)] |= CELL_PATH_E;
					m_stack.push(make_pair((m_stack.top().first + 1), (m_stack.top().second + 0)));
					break;

				case 2: // South
					m_maze[offset(0, +1)] |= CELL_VISITED | CELL_PATH_N;
					m_maze[offset(0,  0)] |= CELL_PATH_S;
					m_stack.push(make_pair((m_stack.top().first + 0), (m_stack.top().second + 1)));
					break;

				case 3: // West
					m_maze[offset(-1, 0)] |= CELL_VISITED | CELL_PATH_E;
					m_maze[offset( 0, 0)] |= CELL_PATH_W;
					m_stack.push(make_pair((m_stack.top().first - 1), (m_stack.top().second + 0)));
					break;

				}

				m_nVisitedCells++;
			}
			else
			{
				// No available neighbours so backtrack!
				m_stack.pop();
			}
		}


		// === DRAWING STUFF ===

		// Clear Screen by drawing 'spaces' everywhere
		Fill(0, 0, ScreenWidth(), ScreenHeight(), L' ');

		// Draw Maze
		for (int x = 0; x < m_nMazeWidth; x++)
		{
			for (int y = 0; y < m_nMazeHeight; y++)
			{
				// Each cell is inflated by m_nPathWidth, so fill it in
				for (int py = 0; py < m_nPathWidth; py++)
					for (int px = 0; px < m_nPathWidth; px++)
					{
						if (m_maze[y * m_nMazeWidth + x] & CELL_VISITED)
							Draw(x * (m_nPathWidth + 1) + px, y * (m_nPathWidth + 1) + py, PIXEL_SOLID, FG_WHITE); // Draw Cell
						else
							Draw(x * (m_nPathWidth + 1) + px, y * (m_nPathWidth + 1) + py, PIXEL_SOLID, FG_BLUE); // Draw Cell
					}

				// Draw passageways between cells
				for (int p = 0; p < m_nPathWidth; p++)
				{
					if (m_maze[y * m_nMazeWidth + x] & CELL_PATH_S)
						Draw(x * (m_nPathWidth + 1) + p, y * (m_nPathWidth + 1) + m_nPathWidth); // Draw South Passage

					if (m_maze[y * m_nMazeWidth + x] & CELL_PATH_E)
						Draw(x * (m_nPathWidth + 1) + m_nPathWidth, y * (m_nPathWidth + 1) + p); // Draw East Passage
				}
			}
		}

		// Draw Unit - the top of the stack
		for (int py = 0; py < m_nPathWidth; py++)
			for (int px = 0; px < m_nPathWidth; px++)
				Draw(m_stack.top().first * (m_nPathWidth + 1) + px, m_stack.top().second * (m_nPathWidth + 1) + py, 0x2588, FG_GREEN); // Draw Cell
		
		
		return true;
	}
};


int main()
{
	// Seed random number generator
	srand(clock());

	// Use olcConsoleGameEngine derived app
	OneLoneCoder_Maze game;
	game.ConstructConsole(160, 100, 8, 8);
	game.Start();

	return 0;
}