#include "terminal-game-utils.hpp"
#include <algorithm>
#include <chrono>
#include <cstdint>
#include <future>
#include <iostream>
#include <ostream>
#include <poll.h>
#include <queue>
#include <string>
#include <termios.h>
#include <thread>
#include <tuple>
#include <unistd.h>

struct termios orig_termios;

class Snake {
  private:
	struct mSnakeUnit {
		int x;
		int y;
		std::string appearance;
	};

	struct mCell {
		int x;
		int y;

		bool operator==(const mCell &other) const {
			return (x == other.x) && (y == other.y);
		}
	};

	const std::map<char, std::string> HEAD_ARROWS = {
		{'l', "◁"}, {'d', "▽"}, {'u', "△"}, {'r', "▷"}};

	const int GRACE_FRAMES = 3;
	const int BOARD_OFFSET_X = 2;
	const int BOARD_OFFSET_Y = 1;
	const int WIDTH, HEIGHT, STARTING_DELAY, MAX_SPEED;
	const double ACCELERATION = 0;

	mSnakeUnit mLastDequeued;
	mSnakeUnit mApple;

	std::deque<mSnakeUnit> mSnake;
	std::queue<tgu::GameKey> mKeyQueue;

	std::vector<mCell> mUnoccupied;
	std::vector<mCell> mOccupied;

	int mGraceFrames = GRACE_FRAMES;
	char mSnakeDirection = 'r';
	int mApplesAte = 0;

	bool mRunning = true;

	std::string mRepeat(int times, std::string str) {
		std::string returned;
		for (int i = 0; i < times; i++)
			returned += str;
		return returned;
	}

	std::uint8_t mGetDirectionByte(mSnakeUnit pos, mSnakeUnit goal) {
		if (pos.x > goal.x)
			return 0b0001;
		if (pos.x < goal.x)
			return 0b1000;
		if (pos.y > goal.y)
			return 0b0100;
		if (pos.y < goal.y)
			return 0b0010;
		return 0b0000;
	}

	mSnakeUnit mPopSnake() {
		mSnakeUnit tr = mSnake.front();
		mCell val(tr.x, tr.y);

		mUnoccupy(val);
		mSnake.pop_front();
		return tr;
	}

	void mPushSnake(mSnakeUnit input) {
		mCell val(input.x, input.y);

		mOccupy(val);
		mSnake.push_back(input);
	}

	void mOccupy(int x, int y) {
		mCell val(x, y);

		std::erase(mUnoccupied, val);
		mOccupied.push_back(val);
	}

	void mOccupy(mCell val) {
		std::erase(mUnoccupied, val);
		mOccupied.push_back(val);
	}

	void mUnoccupy(int x, int y) {
		mCell val(x, y);

		std::erase(mOccupied, val);
		mUnoccupied.push_back(val);
	}

	void mUnoccupy(mCell val) {
		std::erase(mOccupied, val);
		mUnoccupied.push_back(val);
	}

	std::string mGetTurningCharacter(mSnakeUnit Before, mSnakeUnit Current,
									 mSnakeUnit After) {
		std::uint8_t BeforeDirection = mGetDirectionByte(Current, Before);
		std::uint8_t AfterDirection = mGetDirectionByte(Current, After);

		std::uint8_t CharacterBytes = BeforeDirection + AfterDirection;

		if (CharacterBytes == 0b1001)
			return "═";
		if (CharacterBytes == 0b0110)
			return "║";
		if (CharacterBytes == 0b1010)
			return "╔";
		if (CharacterBytes == 0b0011)
			return "╗";
		if (CharacterBytes == 0b1100)
			return "╚";
		if (CharacterBytes == 0b0101)
			return "╝";

		return "";
	}

	void mDrawBoardOutlines() {
		tgu::MoveCursor(0, 0);
		tgu::ClearTerminal();
		tgu::ClearTerminal();
		tgu::MoveCursor(0, 0);

		std::string horizontalLine = mRepeat(WIDTH * 2 + 1, "═");
		std::string horizontalSpaces = std::string(WIDTH * 2 - 1, ' ');

		std::cout << "╔" << horizontalLine + "╗\n\r";

		for (int i = 0; i < HEIGHT; i++) {
			std::cout << "║ " + horizontalSpaces << " ║\n\r";
		}

		std::cout << "╚" << horizontalLine + "╝";
	}

	char mFlipDirection(char c) {
		if (c == 'l')
			return 'r';
		else if (c == 'd')
			return 'u';
		else if (c == 'u')
			return 'd';
		else if (c == 'r')
			return 'l';
		else
			return ' ';
	}

	void mSetSnakeDirection() {
		tgu::GameKey popped = mKeyQueue.front();
		mKeyQueue.pop();

		char PotentialSnakeDirection;

		if (popped == tgu::GameKey::W || popped == tgu::GameKey::UPARROW)
			PotentialSnakeDirection = 'u';
		else if (popped == tgu::GameKey::A || popped == tgu::GameKey::LEFTARROW)
			PotentialSnakeDirection = 'l';
		else if (popped == tgu::GameKey::S || popped == tgu::GameKey::DOWNARROW)
			PotentialSnakeDirection = 'd';
		else if (popped == tgu::GameKey::D ||
				 popped == tgu::GameKey::RIGHTARROW) {
			PotentialSnakeDirection = 'r';
		} else if (popped == tgu::GameKey::Q) {
			tgu::ClearTerminal();
			tgu::MoveCursor(0, 0);
			exit(0);
		} else
			return;

		if (PotentialSnakeDirection == mFlipDirection(mSnakeDirection))
			return;
		else
			mSnakeDirection = PotentialSnakeDirection;
	}

	std::tuple<int, int> mGetDirectionOffset(char c) {
		tgu::MoveCursor(30, 30);
		if (c == 'l')
			return std::tuple<int, int>(-1, 0);
		if (c == 'd')
			return std::tuple<int, int>(0, 1);
		if (c == 'u')
			return std::tuple<int, int>(0, -1);
		if (c == 'r') {
			return std::tuple<int, int>(1, 0);
		}

		std::cout << "Some ting wong. Direction is " << c;
		return std::tuple<int, int>(0, 0);
	}

	void mDie() {
		std::cout << "Die about it";
		tgu::ClearTerminal();
		tgu::MoveCursor(0, 0);
		exit(0);
	}

	bool mProcessApple(int &PotentialX, int &PotentialY) {
		if (mApple.x == PotentialX && mApple.y == PotentialY) {
			mAddApple();
			return true;
		} else {
			return false;
		}
	}

	void mAdvanceSnake(int &PotentialX, int &PotentialY) {
		mPushSnake({PotentialX, PotentialY, HEAD_ARROWS.at(mSnakeDirection)});
		mSnake[mSnake.size() - 2].appearance = mGetTurningCharacter(
			mSnake[mSnake.size() - 3], mSnake[mSnake.size() - 2],
			mSnake[mSnake.size() - 1]);
	}

	bool IsInSnake(int x, int y) {
		for (mSnakeUnit &u : mSnake) {
			if (u.x == x && u.y == y)
				return true;
		}
		return false;
	}

	bool mCheckDeathTick(int &PotentialX, int &PotentialY) {
		if (PotentialX <= -1 || PotentialY <= -1 || PotentialX >= WIDTH ||
			PotentialY >= HEIGHT || IsInSnake(PotentialX, PotentialY)) {
			if (mGraceFrames <= 0) {
				mRunning = false;
				mDie();
			} else {
				mGraceFrames = 0;
			}
			return true;
		} else {
			return false;
		}
	}

	void mSnakeStep() {
		std::tuple<int, int> Offset = mGetDirectionOffset(mSnakeDirection);

		int PotentialX = mSnake.back().x + std::get<0>(Offset);
		int PotentialY = mSnake.back().y + std::get<1>(Offset);

		bool AteApple = mProcessApple(PotentialX, PotentialY);

		bool DeathTicked = mCheckDeathTick(PotentialX, PotentialY);

		if (!DeathTicked) {
			mGraceFrames = mGraceFrames + 1 >= GRACE_FRAMES ? GRACE_FRAMES
															: mGraceFrames + 1;
			mAdvanceSnake(PotentialX, PotentialY);

			if (!AteApple) {
				mLastDequeued = mPopSnake();
			}
		} else {
			mSnake.back().appearance = HEAD_ARROWS.at(mSnakeDirection);
			mLastDequeued = mSnakeUnit(-1, -1, " ");
		}
	}

	void mGameTick() {
		if (mKeyQueue.size() != 0) {
			mSetSnakeDirection();
		}

		mSnakeStep();
	}

	void mInputLoop() {
		tgu::GameKey key;
		while (mRunning) {
			key = tgu::GetKeyPress();
			if (mKeyQueue.size() <= 2)
				mKeyQueue.push(key);
		}
	}

	bool mHorizontalConnectors(mSnakeUnit a, mSnakeUnit b) {
		std::string horizontals = "╔╗╚╝◁▷";
		if (a.y != b.y)
			return false;

		if (horizontals.find(a.appearance) != std::string::npos &&
			horizontals.find(b.appearance) != std::string::npos)
			return true;

		return false;
	}

	void mDrawSnake() {
		tgu::TextRGB(0, 255, 0);
		if (mLastDequeued.x != -1) {
			tgu::MoveCursor(mLastDequeued.y + BOARD_OFFSET_Y,
							(mLastDequeued.x * 2) + BOARD_OFFSET_X - 1);
			std::cout << "   ";
		}

		for (int i = 0; i < mSnake.size(); i++) {
			mSnakeUnit &s = mSnake[i];

			if (s.appearance == "═") {
				tgu::MoveCursor(s.y + BOARD_OFFSET_Y,
								(s.x * 2) + BOARD_OFFSET_X - 1);
				std::cout << mRepeat(3, s.appearance);
			} else {
				tgu::MoveCursor(s.y + BOARD_OFFSET_Y,
								(s.x * 2) + BOARD_OFFSET_X);
				std::cout << s.appearance;
			}

			if (i != 0 && mHorizontalConnectors(s, mSnake[i - 1])) {
				int x = std::max(s.x, mSnake[i - 1].x) * 2 + BOARD_OFFSET_X - 1;
				tgu::MoveCursor(s.y + BOARD_OFFSET_Y, x);
				std::cout << "═";
			}
		}

		tgu::TextRed();
		tgu::MoveCursor(mApple.y + BOARD_OFFSET_Y,
						mApple.x * 2 + BOARD_OFFSET_X);
		std::cout << mApple.appearance;

		tgu::TerminalColorReset();
		std::cout << std::flush;
	}

	void mInitializeApple() {
		int iPos = rand() % mUnoccupied.size();
		mCell apple(mUnoccupied[iPos].x, mUnoccupied[iPos].y);

		mOccupy(apple.x, apple.y);

		mApple = {apple.x, apple.y, "■"};
	}

	void mAddApple() {
		mApplesAte++;
		int iPos = rand() % mUnoccupied.size();
		mCell apple(mUnoccupied[iPos].x, mUnoccupied[iPos].y);

		mUnoccupy(mApple.x, mApple.y);
		mOccupy(apple.x, apple.y);

		mApple = {mUnoccupied[iPos].x, mUnoccupied[iPos].y, mApple.appearance};
	}

	void mGameLoop() {
		while (mRunning) {
			int CalculatedDelay = STARTING_DELAY - (mApplesAte * ACCELERATION);
			int TickDelay =
				CalculatedDelay >= MAX_SPEED ? CalculatedDelay : MAX_SPEED;
			std::this_thread::sleep_for(std::chrono::milliseconds(TickDelay));
			mGameTick();

			mDrawSnake();
		}
	}

  public:
	struct GameSettings {
		int width = 14;
		int height = 14;
		int startingdelay = 400;
		int maxspeed = 200;
		int acceleration = 10;
	};

	Snake(const GameSettings &settings)
		: WIDTH(settings.width), HEIGHT(settings.height),
		  STARTING_DELAY(settings.startingdelay),
		  ACCELERATION(settings.acceleration), MAX_SPEED(settings.maxspeed) {
		if (WIDTH < 5 || HEIGHT < 5) {
			std::cout << "Minimum board size of 5x5 not met.";
			return;
		}
	}

	void mFillUnoccupied() {
		for (int i = 0; i < WIDTH; i++) {
			for (int j = 0; j < HEIGHT; j++) {
				mUnoccupied.push_back({i, j});
			}
		}
	}

	void StartGame() {
		tgu::EnableRawMode();
		tgu::MakeCursorInvisible();
		tgu::EnterGameBuffer();
		tgu::ClearTerminal();
		std::cout << std::flush;

		mDrawBoardOutlines();

		mFillUnoccupied();
		mPushSnake({1, 2, "═"});
		mPushSnake({2, 2, "═"});
		mPushSnake({3, 2, "═"});
		mPushSnake({4, 2, "⇒"});
		mSnakeDirection = 'r';

		mInitializeApple();

		mDrawSnake();

		auto InputLoopResponse =
			std::async(std::launch::async, [this] { mInputLoop(); });

		mGameLoop();
	}
};

int main() {
	Snake hi({.startingdelay = 100});
	hi.StartGame();
}