/*
	Dungeon Warping via Orthographic Projections
	"For my Mother-In-Law, you will be missed..." - javidx9

	License (OLC-3)
	~~~~~~~~~~~~~~~

	Copyright 2018-2020 OneLoneCoder.com

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions
	are met:

	1. Redistributions or derivations of source code must retain the above
	copyright notice, this list of conditions and the following disclaimer.

	2. Redistributions or derivative works in binary form must reproduce
	the above copyright notice. This list of conditions and the following
	disclaimer must be reproduced in the documentation and/or other
	materials provided with the distribution.

	3. Neither the name of the copyright holder nor the names of its
	contributors may be used to endorse or promote products derived
	from this software without specific prior written permission.

	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	Relevant Video: https://youtu.be/Ql5VZGkL23o

	Links
	~~~~~
	YouTube:	https://www.youtube.com/javidx9
				https://www.youtube.com/javidx9extra
	Discord:	https://discord.gg/WhwHUMV
	Twitter:	https://www.twitter.com/javidx9
	Twitch:		https://www.twitch.tv/javidx9
	GitHub:		https://www.github.com/onelonecoder
	Patreon:	https://www.patreon.com/javidx9
	Homepage:	https://www.onelonecoder.com

	Community Blog: https://community.onelonecoder.com

	Author
	~~~~~~
	David Barr, aka javidx9, ŠOneLoneCoder 2018, 2019, 2020
*/

#define OLC_PGE_APPLICATION
#include "olcPixelGameEngine.h"

/*

	NOTE! This program requires a tile spritesheet NOT
	provided in this github. You only need a few tiles,
	see video for details.

*/

class olcDungeon : public olc::PixelGameEngine
{
public:
	olcDungeon()
	{
		sAppName = "Dungeon Explorer";
	}

	struct Renderable
	{
		Renderable() {}

		void Load(const std::string& sFile)
		{
			sprite = new olc::Sprite(sFile);
			decal = new olc::Decal(sprite);
		}

		~Renderable()
		{
			delete decal;
			delete sprite;
		}

		olc::Sprite* sprite = nullptr;
		olc::Decal* decal = nullptr;
	};

	struct vec3d
	{
		float x, y, z;
	};

	struct sQuad
	{
		vec3d points[4];
		olc::vf2d tile;
	};

	struct sCell
	{
		bool wall = false;
		olc::vi2d id[6]{  };
	};

	class World
	{
	public:
		World()
		{

		}

		void Create(int w, int h)
		{
			size = { w, h };
			vCells.resize(w * h);
		}

		sCell& GetCell(const olc::vi2d& v)
		{
			if (v.x >= 0 && v.x < size.x && v.y >= 0 && v.y < size.y)
				return vCells[v.y * size.x + v.x];
			else
				return NullCell;
		}
		
	public:
		olc::vi2d size;

	private:
		std::vector<sCell> vCells;
		sCell NullCell;
	};

	World world;
	Renderable rendSelect;
	Renderable rendAllWalls;
	
	olc::vf2d vCameraPos = { 0.0f, 0.0f };
	float fCameraAngle = 0.0f;
	float fCameraAngleTarget = fCameraAngle;
	float fCameraPitch = 5.5f;
	float fCameraZoom = 16.0f;

	bool bVisible[6];

	olc::vi2d vCursor = { 0, 0 };
	olc::vi2d vTileCursor = { 0,0 };
	olc::vi2d vTileSize = { 32, 32 };

	enum Face
	{
		Floor = 0,
		North = 1,
		East = 2,
		South = 3,
		West = 4,
		Top = 5
	};

public:
	bool OnUserCreate() override
	{
		rendSelect.Load("./gfx/dng_select.png");
		rendAllWalls.Load("./gfx/oldDungeon.png");

		world.Create(64, 64);

		for (int y=0; y<world.size.y; y++)
			for(int x=0; x<world.size.x; x++)
			{
				world.GetCell({ x, y }).wall = false;
				world.GetCell({ x, y }).id[Face::Floor] = olc::vi2d{ 3, 0 } * vTileSize;
				world.GetCell({ x, y }).id[Face::Top] = olc::vi2d{ 1, 0 } * vTileSize;
				world.GetCell({ x, y }).id[Face::North] = olc::vi2d{ 0, 6 } * vTileSize;
				world.GetCell({ x, y }).id[Face::South] = olc::vi2d{ 0, 6 } * vTileSize;
				world.GetCell({ x, y }).id[Face::West] = olc::vi2d{ 0, 6 } * vTileSize;
				world.GetCell({ x, y }).id[Face::East] = olc::vi2d{ 0, 6 } * vTileSize;
			}
		return true;
	}

	std::array<vec3d, 8> CreateCube(const olc::vi2d& vCell, const float fAngle, const float fPitch, const float fScale, const vec3d& vCamera)
	{
		// Unit Cube
		std::array<vec3d, 8> unitCube, rotCube, worldCube, projCube;
		unitCube[0] = { 0.0f, 0.0f, 0.0f };
		unitCube[1] = { fScale, 0.0f, 0.0f };
		unitCube[2] = { fScale, -fScale, 0.0f };
		unitCube[3] = { 0.0f, -fScale, 0.0f };
		unitCube[4] = { 0.0f, 0.0f, fScale };
		unitCube[5] = { fScale, 0.0f, fScale };
		unitCube[6] = { fScale, -fScale, fScale };
		unitCube[7] = { 0.0f, -fScale, fScale };

		// Translate Cube in X-Z Plane
		for (int i = 0; i < 8; i++)
		{
			unitCube[i].x += (vCell.x * fScale - vCamera.x);
			unitCube[i].y += -vCamera.y;
			unitCube[i].z += (vCell.y * fScale - vCamera.z);
		}

		// Rotate Cube in Y-Axis around origin
		float s = sin(fAngle);
		float c = cos(fAngle);
		for (int i = 0; i < 8; i++)
		{
			rotCube[i].x = unitCube[i].x * c + unitCube[i].z * s;
			rotCube[i].y = unitCube[i].y;
			rotCube[i].z = unitCube[i].x * -s + unitCube[i].z * c;
		}

		// Rotate Cube in X-Axis around origin (tilt slighly overhead)
		s = sin(fPitch);
		c = cos(fPitch);
		for (int i = 0; i < 8; i++)
		{
			worldCube[i].x = rotCube[i].x;
			worldCube[i].y = rotCube[i].y * c - rotCube[i].z * s;
			worldCube[i].z = rotCube[i].y * s + rotCube[i].z * c;
		}

		// Project Cube Orthographically - Unit Cube Viewport
		//float fLeft = -ScreenWidth() * 0.5f;
		//float fRight = ScreenWidth() * 0.5f;
		//float fTop = ScreenHeight() * 0.5f;
		//float fBottom = -ScreenHeight() * 0.5f;
		//float fNear = 0.1f;
		//float fFar = 100.0f;*/
		//for (int i = 0; i < 8; i++)
		//{
		//	projCube[i].x = (2.0f / (fRight - fLeft)) * worldCube[i].x - ((fRight + fLeft) / (fRight - fLeft));
		//	projCube[i].y = (2.0f / (fTop - fBottom)) * worldCube[i].y - ((fTop + fBottom) / (fTop - fBottom));
		//	projCube[i].z = (2.0f / (fFar - fNear)) * worldCube[i].z - ((fFar + fNear) / (fFar - fNear));
		//  projCube[i].x *= -fRight;
		//  projCube[i].y *= -fTop;
		//  projCube[i].x += fRight;
		//  projCube[i].y += fTop;
		//}

		// Project Cube Orthographically - Full Screen Centered
		for (int i = 0; i < 8; i++)
		{
			projCube[i].x = worldCube[i].x + ScreenWidth() * 0.5f;
			projCube[i].y = worldCube[i].y + ScreenHeight() * 0.5f;
			projCube[i].z = worldCube[i].z;
		}

		return projCube;
	}



	void CalculateVisibleFaces(std::array<vec3d, 8>& cube)
	{
		auto CheckNormal = [&](int v1, int v2, int v3)
		{
			olc::vf2d a = { cube[v1].x, cube[v1].y };
			olc::vf2d b = { cube[v2].x, cube[v2].y };
			olc::vf2d c = { cube[v3].x, cube[v3].y };
			return  (b - a).cross(c - a) > 0;
		};

		bVisible[Face::Floor] = CheckNormal(4, 0, 1);
		bVisible[Face::South] = CheckNormal(3, 0, 1);
		bVisible[Face::North] = CheckNormal(6, 5, 4);
		bVisible[Face::East] = CheckNormal(7, 4, 0);
		bVisible[Face::West] = CheckNormal(2, 1, 5);
		bVisible[Face::Top] = CheckNormal(7, 3, 2);		
	}

	void GetFaceQuads(const olc::vi2d& vCell, const float fAngle, const float fPitch, const float fScale, const vec3d& vCamera, std::vector<sQuad> &render)
	{
		std::array<vec3d, 8> projCube = CreateCube(vCell, fAngle, fPitch, fScale, vCamera);

		auto& cell = world.GetCell(vCell);

		auto MakeFace = [&](int v1, int v2, int v3, int v4, Face f)
		{
			render.push_back({ projCube[v1], projCube[v2], projCube[v3], projCube[v4], cell.id[f] });
		};

		if (!cell.wall)
		{
			if(bVisible[Face::Floor]) MakeFace(4, 0, 1, 5, Face::Floor);
		}
		else
		{
			if (bVisible[Face::South]) MakeFace(3, 0, 1, 2, Face::South);
			if (bVisible[Face::North]) MakeFace(6, 5, 4, 7, Face::North);
			if (bVisible[Face::East]) MakeFace(7, 4, 0, 3, Face::East);
			if (bVisible[Face::West]) MakeFace(2, 1, 5, 6, Face::West);
			if (bVisible[Face::Top]) MakeFace(7, 3, 2, 6, Face::Top);
		}
	}


	bool OnUserUpdate(float fElapsedTime) override
	{
		// Grab mouse for convenience
		olc::vi2d vMouse = { GetMouseX(), GetMouseY() };

		// Edit mode - Selection from tile sprite sheet
		if (GetKey(olc::Key::TAB).bHeld)
		{
			DrawSprite({ 0, 0 }, rendAllWalls.sprite);
			DrawRect(vTileCursor * vTileSize, vTileSize);
			if (GetMouse(0).bPressed) vTileCursor = vMouse / vTileSize;
			return true;
		}

		// WS keys to tilt camera
		if (GetKey(olc::Key::W).bHeld) fCameraPitch += 1.0f * fElapsedTime;
		if (GetKey(olc::Key::S).bHeld) fCameraPitch -= 1.0f * fElapsedTime;

		// DA Keys to manually rotate camera
		if (GetKey(olc::Key::D).bHeld) fCameraAngleTarget += 1.0f * fElapsedTime;
		if (GetKey(olc::Key::A).bHeld) fCameraAngleTarget -= 1.0f * fElapsedTime;

		// QZ Keys to zoom in or out
		if (GetKey(olc::Key::Q).bHeld) fCameraZoom += 5.0f * fElapsedTime;
		if (GetKey(olc::Key::Z).bHeld) fCameraZoom -= 5.0f * fElapsedTime;

		// Numpad keys used to rotate camera to fixed angles
		if (GetKey(olc::Key::NP2).bPressed) fCameraAngleTarget = 3.14159f * 0.0f;
		if (GetKey(olc::Key::NP1).bPressed) fCameraAngleTarget = 3.14159f * 0.25f;
		if (GetKey(olc::Key::NP4).bPressed) fCameraAngleTarget = 3.14159f * 0.5f;
		if (GetKey(olc::Key::NP7).bPressed) fCameraAngleTarget = 3.14159f * 0.75f;
		if (GetKey(olc::Key::NP8).bPressed) fCameraAngleTarget = 3.14159f * 1.0f;
		if (GetKey(olc::Key::NP9).bPressed) fCameraAngleTarget = 3.14159f * 1.25f;
		if (GetKey(olc::Key::NP6).bPressed) fCameraAngleTarget = 3.14159f * 1.5f;
		if (GetKey(olc::Key::NP3).bPressed) fCameraAngleTarget = 3.14159f * 1.75f;

		// Numeric keys apply selected tile to specific face
		if (GetKey(olc::Key::K1).bPressed) world.GetCell(vCursor).id[Face::North] = vTileCursor * vTileSize;
		if (GetKey(olc::Key::K2).bPressed) world.GetCell(vCursor).id[Face::East] = vTileCursor * vTileSize;
		if (GetKey(olc::Key::K3).bPressed) world.GetCell(vCursor).id[Face::South] = vTileCursor * vTileSize;
		if (GetKey(olc::Key::K4).bPressed) world.GetCell(vCursor).id[Face::West] = vTileCursor * vTileSize;
		if (GetKey(olc::Key::K5).bPressed) world.GetCell(vCursor).id[Face::Floor] = vTileCursor * vTileSize;
		if (GetKey(olc::Key::K6).bPressed) world.GetCell(vCursor).id[Face::Top] = vTileCursor * vTileSize;
		
		// Smooth camera
		fCameraAngle += (fCameraAngleTarget - fCameraAngle) * 10.0f * fElapsedTime;

		// Arrow keys to move the selection cursor around map (boundary checked)
		if (GetKey(olc::Key::LEFT).bPressed) vCursor.x--;
		if (GetKey(olc::Key::RIGHT).bPressed) vCursor.x++;
		if (GetKey(olc::Key::UP).bPressed) vCursor.y--;
		if (GetKey(olc::Key::DOWN).bPressed) vCursor.y++;
		if (vCursor.x < 0) vCursor.x = 0;
		if (vCursor.y < 0) vCursor.y = 0;
		if (vCursor.x >= world.size.x) vCursor.x = world.size.x - 1;
		if (vCursor.y >= world.size.y) vCursor.y = world.size.y - 1;

		// Place block with space
		if (GetKey(olc::Key::SPACE).bPressed)
		{
			world.GetCell(vCursor).wall = !world.GetCell(vCursor).wall;				
		}

		// Position camera in world		
		vCameraPos = { vCursor.x + 0.5f, vCursor.y + 0.5f };
		vCameraPos *= fCameraZoom;

		// Rendering

		// 1) Create dummy cube to extract visible face information
		// Cull faces that cannot be seen
		std::array<vec3d, 8> cullCube = CreateCube({ 0, 0 }, fCameraAngle, fCameraPitch, fCameraZoom, { vCameraPos.x, 0.0f, vCameraPos.y });
		CalculateVisibleFaces(cullCube);

		// 2) Get all visible sides of all visible "tile cubes"
		std::vector<sQuad> vQuads;
		for(int y = 0; y<world.size.y; y++)
			for(int x=0; x<world.size.x; x++)
				GetFaceQuads({ x, y }, fCameraAngle, fCameraPitch, fCameraZoom, { vCameraPos.x, 0.0f, vCameraPos.y }, vQuads);

		// 3) Sort in order of depth, from farthest away to closest
		std::sort(vQuads.begin(), vQuads.end(), [](const sQuad& q1, const sQuad& q2)
			{
				float z1 = (q1.points[0].z + q1.points[1].z + q1.points[2].z + q1.points[3].z) * 0.25f;
				float z2 = (q2.points[0].z + q2.points[1].z + q2.points[2].z + q2.points[3].z) * 0.25f;
				return z1 < z2;
			});
				
		// 4) Iterate through all "tile cubes" and draw their visible faces
		Clear(olc::BLACK);
		for (auto& q : vQuads)
			DrawPartialWarpedDecal
			(
				rendAllWalls.decal, 
				{ {q.points[0].x, q.points[0].y}, {q.points[1].x, q.points[1].y}, {q.points[2].x, q.points[2].y}, {q.points[3].x, q.points[3].y} }, 
				q.tile, 
				vTileSize
			);
	
		// 5) Draw current tile selection
		DrawPartialDecal({ 10,10 }, rendAllWalls.decal, vTileCursor * vTileSize, vTileSize);

		// 6) Draw selection "tile cube"	
		vQuads.clear();
		GetFaceQuads(vCursor, fCameraAngle, fCameraPitch, fCameraZoom, { vCameraPos.x, 0.0f, vCameraPos.y }, vQuads);
		for (auto& q : vQuads)
			DrawWarpedDecal(rendSelect.decal, { {q.points[0].x, q.points[0].y}, {q.points[1].x, q.points[1].y}, {q.points[2].x, q.points[2].y}, {q.points[3].x, q.points[3].y} });
		
		// 7) Draw some debug info
		DrawStringDecal({ 0,0 }, "Cursor: " + std::to_string(vCursor.x) + ", " + std::to_string(vCursor.y), olc::YELLOW, { 0.5f, 0.5f });
		DrawStringDecal({ 0,8 }, "Angle: " + std::to_string(fCameraAngle) + ", " + std::to_string(fCameraPitch), olc::YELLOW, { 0.5f, 0.5f });

		// Graceful exit if user is in full screen mode
		return !GetKey(olc::Key::ESCAPE).bPressed;
	}
};

int main()
{
	olcDungeon demo;
	if (demo.Construct(640, 480, 2, 2, false))
		demo.Start();
	return 0;
}