#include "SynEngine.hpp"
#include <time.h>

enum CellState
{
    EmptyCell,
    PointCell,
    SnakeCell
};

enum PlayerSprite
{
    Empty,
    Point,
    Straight,
    Curved,
    Back,
    Head,
    PointGot,
    GameOver
};

struct SnakePart
{
    sf::Vector2i cellPosition;
    unsigned direction;
};

class Snake : public IBehaviour
{
    private:
        std::vector<SnakePart> snake;
        unsigned int lenght;
        SnakePart *backSecond;
        SnakePart *back;
        SnakePart *headSecond;
        SnakePart *head;
        Timer *timer;
        Grid *grid;
        sf::Vector2i gridSize;
        float timeCountdown;
        float timeResetValue;
        unsigned TickPerSec;
        GameConfiguration *config;

        sf::Vector2i pointPosition;

        void Move();
        void Grow();
        void ResetPointPosition();
        int GetRandom(int, int);
        unsigned GetDirection(sf::Vector2i, sf::Vector2i);
        unsigned GetBackDirection();
        unsigned GetMoveDirection();
        sf::Vector2i GetDirectionVector(unsigned);
        PlayerSprite GetNewSprite(unsigned &);
        CellState NextCellState();
    public:
        Snake();
        void Update();
        ~Snake();
};

Snake::Snake()
{
    pointPosition = { 0, 0 }; // TEST
    lenght = 2;
    snake.reserve(lenght);

    for (unsigned i = 0; i < lenght; i++)
        snake.push_back({ sf::Vector2i(1 - i, 0), 0});
    
    timer = &GameManager::timer;
    head = backSecond = &snake[0];
    back = headSecond = &snake[1];
    config = GameManager::GetConfig();
    grid = &GameManager::GetGrid();
    gridSize = config -> GetGridSize();
    TickPerSec = config -> GetTickPerSec();
    timeResetValue = 1.0 / (float)TickPerSec;
    timeCountdown = timeResetValue;

    grid -> UpdateCell(snake[0].cellPosition.x, snake[0].cellPosition.y, PlayerSprite::Head, 0);
    grid -> UpdateCell(snake[1].cellPosition.x, snake[1].cellPosition.y, PlayerSprite::Back, 0);

    ResetPointPosition();
}


int Snake::GetRandom(int min, int max)
{
    int result;
    static float value = 0.0;
    value += GameManager::timer.GetTimePassed();
    srand(value);
    result = rand() % (max - min);
    result += min;
    return result;
}

void Snake::ResetPointPosition()
{
    bool isInside = false;
    int i;
    do
    {
        isInside = false;
        pointPosition = sf::Vector2i(GetRandom(0, gridSize.x), GetRandom(0, gridSize.y));

        for (i = 0; i < lenght; i++)
            if(snake[i].cellPosition == pointPosition)
            {
                isInside = true;
                break;
            }
    } while (isInside);

    grid -> UpdateCell(pointPosition.x, pointPosition.y, PlayerSprite::Point, 0);
}

void Snake::Grow()
{
    sf::Vector2i secondPosition;
    sf::Vector2i headPosition = head -> cellPosition;
    unsigned previousDirection;
    unsigned headDirection;
    PlayerSprite sprite;

    headDirection = GetMoveDirection();
    headPosition += GetDirectionVector(headDirection);
    grid -> ApplyGridLimitsToVector2i(headPosition);
    snake.insert(snake.begin(), { headPosition, headDirection });
    lenght = snake.size();
    
    previousDirection = snake[1].direction;
    sprite = GetNewSprite(previousDirection);

    head = &snake[0]; headSecond = &snake[1];
    back = &snake[lenght - 1]; backSecond = &snake[lenght - 2];

    grid -> UpdateCell(headPosition.x, headPosition.y, PlayerSprite::Head, headDirection);
    grid -> UpdateCell(headSecond -> cellPosition.x, headSecond -> cellPosition.y, sprite, (int)previousDirection); 
}

void Snake::Move()
{
    grid -> UpdateCell(back -> cellPosition.x, back -> cellPosition.y, PlayerSprite::Empty);
    snake.pop_back();
    Grow();
    grid -> UpdateCell(back -> cellPosition.x, back -> cellPosition.y, PlayerSprite::Back, GetBackDirection()); 
}

void Snake::Update()
{
    if(timeCountdown > 0.0)
    {
        timeCountdown -= timer -> GetDeltaTime();
        return;
    }
    
    switch (NextCellState())
    {
        case CellState::EmptyCell: Move(); break;
        case CellState::PointCell: Grow(); ResetPointPosition(); break;
        // case CellState::SnakeCell: GameOver(); break;
    }
    timeCountdown = timeResetValue;
}

unsigned Snake::GetMoveDirection()
{
    // Check if the new direction is opposite to the head's direction
    unsigned direction = head -> direction;
    unsigned inputDirection = GameManager::GetInputDirection();

    if((inputDirection + 2) % 4 != direction)
        return inputDirection;

    return direction;
}

sf::Vector2i Snake::GetDirectionVector(unsigned direction)
{
    switch (direction)
    {
        case 0: return sf::Vector2i(1, 0);
        case 1: return sf::Vector2i(0, -1);
        case 2: return sf::Vector2i(-1, 0);
        case 3: return sf::Vector2i(0, 1);
        default: return sf::Vector2i(1, 0);
    }
}

CellState Snake::NextCellState()
{
    sf::Vector2i cellPosition = head -> cellPosition + GetDirectionVector(GetMoveDirection());
    grid -> ApplyGridLimitsToVector2i(cellPosition);
    
    for (int i = 0; i < lenght; i++)
        if(snake[i].cellPosition == cellPosition)
            return CellState::SnakeCell;
    
    if(cellPosition == pointPosition)
        return CellState::PointCell;
    
    return CellState::EmptyCell;
}

PlayerSprite Snake::GetNewSprite(unsigned &direction)
{
    SnakePart *third = &snake[2];
    SnakePart *second = headSecond;
    sf::Vector2i vector = third -> cellPosition - head -> cellPosition;
    unsigned newDirection = GameManager::GetInputDirection();

    // I need to update this. It look so bad
    if(vector.x != 0 && vector.y != 0)
    {
        direction += 2;
        direction %= 4;
        if(direction > newDirection)
        {
            unsigned temp;
            temp = direction;
            direction = newDirection;
            newDirection = temp;
        }
        
        // 0 - 1 -> 0
        // 1 - 2 -> 1
        // 2 - 3 -> 2
        // 0 - 3 -> 3
        if(direction == 0 && newDirection == 3)
            direction = 3;

        return PlayerSprite::Curved;
    }
    
    direction = GetDirection(head -> cellPosition, second -> cellPosition);
    return PlayerSprite::Straight;
}

unsigned Snake::GetDirection(sf::Vector2i first, sf::Vector2i second)
{
    first -= second;

    if(first.x > 0) return 0;
    if(first.y < 0) return 1;
    if(first.x < 0) return 2;
    if(first.y > 0) return 3;
    return 0;
}

unsigned Snake::GetBackDirection()
{
    
    return GetDirection(snake[lenght - 2].cellPosition, snake[lenght - 1].cellPosition);
}

Snake::~Snake()
{
}