Snake.cpp

#include "Snake.h"
#include "Game.h"
#include <iostream>

Snake::Snake(Game& _game, Position start): head(new SnakeNode(start)), tail(head), game(_game), cherry(0)
{
    game.snakeMoveTo(start);
}

Snake::~Snake()
{
    for (SnakeNode* p = tail; p != nullptr; ) 
    {
        SnakeNode* nextNode = p->next;
        delete p;
        p = nextNode;
    }
}

vector<Position> Snake::getPositions() const
{
    vector<Position> res;
    for (SnakeNode* p = tail; p != nullptr; p = p->next)
        res.push_back(p->position);
    return res;
}

void Snake::growAtFront(Position newPosition)
{
    head->next = new SnakeNode(newPosition);
    head = head->next;
}

void Snake::slideTo(Position newPosition)
{
    if (tail->next == nullptr) { // snake has only one node
        tail->position = newPosition;
    }
    else {
        SnakeNode* oldTailNode = tail;

        //cut the old tail off the snake
        tail = tail->next;
        oldTailNode->next = nullptr;

        // move it to the head of the snake
        oldTailNode->position = newPosition;
        head->next = oldTailNode;
        head = oldTailNode;
    }
}

void Snake::eatCherry()
{
    cherry++;
}

void Snake::move(Direction direction)
{
    Position newPosition = head->position.move(direction);
    game.snakeMoveTo(newPosition);
    if (game.isGameOver()) return;

    if (cherry > 0) {
        cherry--;
        growAtFront(newPosition);
    }
    else {
        game.snakeLeave(tail->position);
        slideTo(newPosition);
    }
}

bool Snake::checkPosition(Position pos)
{
    return false;
}