model

using System;
using System.Collections.Generic;
using System.Linq;

namespace Game2048
{
  public class Model
  {
    private int score = 0;
    private Map map;
    private Random random = new Random();
    private bool isGameOver;
    private bool moved;

    public int Score => this.score;

    public int size => this.map.size;

    public Model(int size) => this.map = new Map(size);

    public void Start()
    {
      this.score = 0;
      this.isGameOver = false;
      for (int x = 0; x < this.size; ++x)
      {
        for (int y = 0; y < this.size; ++y)
          this.map.Set(x, y, 0);
      }
      this.AddRandomNumber();
      this.AddRandomNumber();
    }

    private void AddRandomNumber()
    {
      if (this.isGameOver)
        return;
      List<int[]> source = new List<int[]>();
      for (int x = 0; x < this.size; ++x)
      {
        for (int y = 0; y < this.size; ++y)
        {
          if (this.GetMap(x, y) == 0)
            source.Add(new int[2]{ x, y });
        }
      }
      int index = this.random.Next(0, source.Count<int[]>());
      int number = this.random.Next(1, 3) * 2;
      this.map.Set(source[index][0], source[index][1], number);
    }

    private void Join(int x, int y, int sx, int sy)
    {
      if (this.map.Get(x, y) <= 0 || this.map.Get(x + sx, y + sy) != this.map.Get(x, y))
        return;
      this.map.Set(x + sx, y + sy, this.map.Get(x, y) * 2);
      this.score += this.map.Get(x, y) * this.map.Get(x, y);
      for (; this.map.Get(x - sx, y - sy) > 0; y -= sy)
      {
        this.map.Set(x, y, this.map.Get(x - sx, y - sy));
        x -= sx;
      }
      this.map.Set(x, y, 0);
      this.moved = true;
    }

    private void Lift(int x, int y, int sx, int sy)
    {
      if (this.map.Get(x, y) <= 0)
        return;
      while (this.map.Get(x + sx, y + sy) == 0)
      {
        this.map.Set(x + sx, y + sy, this.map.Get(x, y));
        this.map.Set(x, y, 0);
        x += sx;
        y += sy;
        this.moved = true;
      }
    }

    public void Left()
    {
      this.moved = false;
      for (int y = 0; y < this.map.size; ++y)
      {
        for (int x = 1; x < this.map.size; ++x)
          this.Lift(x, y, -1, 0);
      }
      for (int y = 0; y < this.map.size; ++y)
      {
        for (int x = 1; x < this.map.size; ++x)
          this.Join(x, y, -1, 0);
      }
      if (!this.moved)
        return;
      this.AddRandomNumber();
    }

    public void Right()
    {
      this.moved = false;
      for (int y = 0; y < this.map.size; ++y)
      {
        for (int x = this.map.size - 2; x >= 0; --x)
          this.Lift(x, y, 1, 0);
        for (int x = this.map.size - 2; x >= 0; --x)
          this.Join(x, y, 1, 0);
      }
      if (!this.moved)
        return;
      this.AddRandomNumber();
    }

    public void Up()
    {
      this.moved = false;
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = 1; y < this.map.size; ++y)
          this.Lift(x, y, 0, -1);
      }
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = 1; y < this.map.size; ++y)
          this.Join(x, y, 0, -1);
      }
      if (!this.moved)
        return;
      this.AddRandomNumber();
    }

    public void Down()
    {
      this.moved = false;
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = this.map.size - 2; y >= 0; --y)
          this.Lift(x, y, 0, 1);
      }
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = this.map.size - 2; y >= 0; --y)
          this.Join(x, y, 0, 1);
      }
      if (!this.moved)
        return;
      this.AddRandomNumber();
    }

    public int GetMap(int x, int y) => this.map.Get(x, y);

    public bool IsGameOver()
    {
      if (this.isGameOver)
        return this.isGameOver;
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = 0; y < this.map.size; ++y)
        {
          if (this.map.Get(x, y) == 0)
            return false;
        }
      }
      for (int x = 0; x < this.map.size; ++x)
      {
        for (int y = 0; y < this.map.size; ++y)
        {
          if (this.map.Get(x, y) == this.map.Get(x + 1, y) || this.map.Get(x, y) == this.map.Get(x, y + 1))
            return false;
        }
      }
      this.isGameOver = true;
      return this.isGameOver;
    }
  }
}