using UnityEngine;
using System.Collections;

using System.Collections.Generic;
public class SquareGrid
{
    // Implementation notes: I made the fields public for convenience,
    // but in a real project you'll probably want to follow standard
    // style and make them private.
    public static readonly Direction[] DIRS = new[]
        {
            new Direction(1, 0),
            new Direction(1, 1),
            new Direction(1, -1),
            new Direction(-1, 1),
            new Direction(-1, -1),
            new Direction(0, -1),
            new Direction(-1, 0),
            new Direction(0, 1)
        };

    public int width, height;
    public NodeElement[,] nodes;
    public SquareGrid(int width, int height)
    {
        Instance = this;
        nodes = new NodeElement[width, height];
        for (int x = 0; x < width; x++)
        {
            for (int y = 0; y < height; y++)
            {
                nodes[x, y] = new NodeElement(x, y, 1, true);
            }
        }
        this.width = width;
        this.height = height;
    }
    public static NodeElement GetNodeAt(int x, int y)
    {
        if (InBounds(x, y))
            return Instance.nodes[x, y];
        else
        {
            return null;
        }
    }
    public static bool InBounds(NodeElement id)
    {
        return 0 <= id.x && id.x < Instance.width
            && 0 <= id.y && id.y < Instance.height;
    }
    public static bool InBounds(int x, int y)
    {
        return 0 <= x && x < Instance.width
            && 0 <= y && y < Instance.height;
    }

    public double Cost(NodeElement a, NodeElement b)
    {
        double c = b.item2;
        if (a.x != b.x && a.y != b.y)
            c += 0.1f;
        return c;
    }
    public static SquareGrid Instance;
    public static IEnumerable<NodeElement> Neighbors(NodeElement id, Seeker seeker)
    {
        Direction curDir;
        if (seeker._start == id)
        {
            curDir = new Direction(Mathf.Clamp(seeker.LastDestination.x - id.x, -1, 1), Mathf.Clamp(seeker.LastDestination.y - id.y, -1, 1));
        }
        else
        {
            curDir = new Direction(Mathf.Clamp(-seeker.camefrom[id].x + id.x, -1, 1), Mathf.Clamp(-seeker.camefrom[id].y + id.y, -1, 1));
        }
        if (Mathf.Abs(curDir.x) == 1 && curDir.y == 0)
        {
            //horizontal
            NodeElement middleForward = GetNodeAt(id.x + curDir.x, id.y);
            NodeElement right = GetNodeAt(id.x, id.y + 1);
            NodeElement left = GetNodeAt(id.x, id.y - 1);
            if (middleForward != null)
            {
                if (middleForward.Passable())
                {
                    yield return middleForward;
                }
            }
            if (!right.Passable())
            {
                NodeElement rightForward = GetNodeAt(id.x + curDir.x, id.y + 1);
                if (rightForward != null)
                {
                    if (rightForward.Passable())
                    {
                        yield return rightForward;
                    }
                }
            }
            if (!left.Passable())
            {
                NodeElement leftForward = GetNodeAt(id.x + curDir.x, id.y - 1);
                if (leftForward != null)
                {
                    if (leftForward.Passable())
                    {
                        yield return leftForward;
                    }
                }
            }
        }
        else
        if (Mathf.Abs(curDir.y) == 1 && curDir.x == 0)
        {
            //vertical
            NodeElement middleForward = GetNodeAt(id.x, id.y + curDir.y);
            NodeElement right = GetNodeAt(id.x + 1, id.y);
            NodeElement left = GetNodeAt(id.x - 1, id.y);
            if (middleForward != null)
            {
                if (middleForward.Passable())
                {
                    yield return middleForward;
                }
            }
            if (!right.Passable())
            {
                NodeElement rightForward = GetNodeAt(id.x + 1, id.y + curDir.y);
                if (rightForward != null)
                {
                    if (rightForward.Passable())
                    {
                        yield return rightForward;
                    }
                }
            }
            if (!left.Passable())
            {
                NodeElement leftForward = GetNodeAt(id.x - 1, id.y + curDir.y);
                if (leftForward != null)
                {
                    if (leftForward.Passable())
                    {
                        yield return leftForward;
                    }
                }
            }
        }
        else
        if (Mathf.Abs(curDir.x) == Mathf.Abs(curDir.y))
        {
            //diagonal
            NodeElement middleForward = GetNodeAt(id.x + curDir.x, id.y + curDir.y);
            if (middleForward == null)
            {
               // Debug.LogError(id.x + " " + curDir.x + " " + id.y + " " + curDir.y + " " + seeker.name);
            }
            else
            {
                NodeElement right = GetNodeAt(middleForward.x - curDir.x, middleForward.y);
                NodeElement left = GetNodeAt(middleForward.x, middleForward.y - curDir.y);
                if (middleForward.Passable())
                {
                    yield return middleForward;
                }
                if (right != null)
                {
                    if (right.Passable())
                    {
                        yield return right;
                    }
                }
                if (left != null)
                {
                    if (left.Passable())
                    {
                        yield return left;
                    }

                }
            }
        }
    }
}