namespace Digger
{
    public class Terrain : ICreature
    {
        public CreatureCommand Act(int x, int y) => new CreatureCommand {DeltaX = 0, DeltaY = 0};

        public bool DeadInConflict(ICreature conflictedObject) => true;

        public int GetDrawingPriority() => 2;

        public string GetImageFileName() => "Terrain.png";
    }

    public class Player : ICreature
    {
        public CreatureCommand Act(int x, int y)
        {
            switch (Game.KeyPressed)
            {
                case System.Windows.Forms.Keys.Left:
                    if (IsStepPossible(x - 1, y))
                        return new CreatureCommand {DeltaX = -1, DeltaY = 0};
                    break;

                case System.Windows.Forms.Keys.Up:
                    if (IsStepPossible(x, y - 1))
                        return new CreatureCommand {DeltaX = 0, DeltaY = -1};
                    break;

                case System.Windows.Forms.Keys.Right:
                    if (IsStepPossible(x, y + 1))
                        return new CreatureCommand {DeltaX = 0, DeltaY = 1};
                    break;

                case System.Windows.Forms.Keys.Down:
                    if (IsStepPossible(x + 1, y))
                        return new CreatureCommand {DeltaX = 1, DeltaY = 0};
                    break;
            }

            return new CreatureCommand();
        }

        public bool DeadInConflict(ICreature conflictedObject)
        {
            if (conflictedObject is Gold)
            {
                Game.Scores += 10;
                return false;
            }

            return conflictedObject is Sack || conflictedObject is Monster;
        }

        public int GetDrawingPriority() => 1;

        public string GetImageFileName() => "Digger.png";

        private bool IsStepPossible(int x, int y)
        {
            if (!(x >= 0 && x < Game.MapWidth && y >= 0 && y < Game.MapHeight))
                return false;

            return Game.Map[x, y] == null || !(Game.Map[x, y] is Sack);
        }
    }

    public class Sack : ICreature
    {
        private int counter;

        public CreatureCommand Act(int x, int y)
        {
            if (y < Game.MapHeight - 1)
            {
                var map = Game.Map[x, y + 1];

                if (map == null || counter > 0 && (map is Player || map is Monster))
                {
                    counter++;
                    return new CreatureCommand {DeltaX = 0, DeltaY = 1};
                }
            }

            if (counter > 1)
                return new CreatureCommand {DeltaX = 0, DeltaY = 0, TransformTo = new Gold()};

            counter = 0;
            return new CreatureCommand {DeltaX = 0, DeltaY = 0};
        }

        public bool DeadInConflict(ICreature conflictedObject) => false;

        public int GetDrawingPriority() => 5;

        public string GetImageFileName() => "Sack.png";
    }

    public class Gold : ICreature
    {
        public CreatureCommand Act(int x, int y) => new CreatureCommand {DeltaX = 0, DeltaY = 0};

        public bool DeadInConflict(ICreature conflictedObject) =>
            conflictedObject is Player || conflictedObject is Monster;

        public int GetDrawingPriority() => 3;

        public string GetImageFileName() => "Gold.png";
    }

    public class Monster : ICreature
    {
        public CreatureCommand Act(int x, int y)
        {
            var directionToPlayer = GetDirectionToPlayer(x, y);

            if (IsStepPossible(x + directionToPlayer.DX, y + directionToPlayer.DY))
                return new CreatureCommand {DeltaX = directionToPlayer.DX, DeltaY = directionToPlayer.DY};

            return new CreatureCommand();
        }

        public bool DeadInConflict(ICreature conflictedObject) =>
            conflictedObject is Sack || conflictedObject is Monster;

        public int GetDrawingPriority() => 0;

        public string GetImageFileName() => "Monster.png";

        private (int DX, int DY) GetDirectionToPlayer(int x, int y)
        {
            var dx = 0;
            var dy = 0;

            var playerPosition = GetPlayerPosition();

            if (playerPosition.X == x)
            {
                if (playerPosition.Y < y) dy = -1;
                else if (playerPosition.Y > y) dy = 1;
            }
            else if (playerPosition.Y == y)
            {
                if (playerPosition.X < x) dx = -1;
                else if (playerPosition.X > x) dx = 1;
            }
            else
            {
                if (playerPosition.X < x) dx = -1;
                else if (playerPosition.X > x) dx = 1;
            }

            return (dx, dy);
        }

        private (int X, int Y) GetPlayerPosition()
        {
            for (var x = 0; x < Game.MapWidth; x++)
            for (var y = 0; y < Game.MapHeight; y++)
            {
                if (Game.Map[x, y] is Player)
                    return (x, y);
            }

            return (-1, -1);
        }

        private bool IsStepPossible(int x, int y)
        {
            if (!(x >= 0 && x < Game.MapWidth && y >= 0 && y < Game.MapHeight))
                return false;

            var block = Game.Map[x, y];
            return block == null || block is Player || block is Gold;
        }
    }
}