using System;
using System.Diagnostics;
using System.Linq;
using Godot;
using Array = Godot.Collections.Array;

public class HexCell : Resource
{
    public static readonly Vector2 size = new Vector2(1, Mathf.Sqrt(3) / 2);
    public static readonly Vector3 DIR_N = new Vector3(0, 1, -1);
    public static readonly Vector3 DIR_NE = new Vector3(1, 0, -1);
    public static readonly Vector3 DIR_SE = new Vector3(1, -1, 0);
    public static readonly Vector3 DIR_S = new Vector3(0, -1, 1);
    public static readonly Vector3 DIR_SW = new Vector3(-1, 0, 1);
    public static readonly Vector3 DIR_NW = new Vector3(-1, 1, 0);

    public static readonly Array DIR_ALL = new Array()
        { DIR_N, DIR_NE, DIR_SE, DIR_S, DIR_SW, DIR_NW };

    public HexCell()
    {
    }

    public HexCell(float cubeX, float cubeY, float cubeZ)
    {
        CubeCoords = RoundCoords(new Vector3(cubeX, cubeY, cubeZ));
    }

    public static bool operator==(HexCell cellA, HexCell cellB)
    {
        return cellA.AxialCoords == cellB.AxialCoords;
    }
    
    public static bool operator!=(HexCell cellA, HexCell cellB)
    {
        return cellA.AxialCoords != cellB.AxialCoords;
    }
    
    public HexCell(Vector3 cubeCoords)
    {
        CubeCoords = cubeCoords;
    }

    public HexCell(float axialX, float axialY)
    {
        AxialCoords = new Vector2(axialX, axialY);
    }

    public HexCell(Vector2 axialCoords)
    {
        AxialCoords = axialCoords;
    }

    public HexCell(HexCell other)
    {
        CubeCoords = other.CubeCoords;
    }

    public static HexCell FromOffsetCoords(Vector2 offsetCoords)
    {
        HexCell result = new HexCell();
        result.OffsetCoords = offsetCoords;

        return result;
    }

    private Vector3 _cubeCoords;

    public Vector3 CubeCoords
    {
        get { return _cubeCoords; }
        set
        {
            if (Mathf.Abs(value.x + value.y + value.z) > 0.0001)
            {
                GD.Print("Warning: Invalid cube coordinates for hex (x + y + z != 0): ", value.ToString());
            }

            _cubeCoords = RoundCoords(value);
        }
    }

    public Vector2 AxialCoords
    {
        get => new Vector2(CubeCoords.x, CubeCoords.y);

        set { CubeCoords = AxialToCubeCoords(value); }
    }

    public Vector2 OffsetCoords
    {
        get
        {
            int x = (int)CubeCoords.x;
            int y = (int)CubeCoords.y;
            int off_y = y + (x - (x & 1)) / 2;
            return new Vector2(x, off_y);
        }

        set
        {
            int x = (int)value.x;
            int y = (int)value.y;
            int cube_y = y - (x - (x & 1)) / 2;
            AxialCoords = new Vector2(x, cube_y);
        }
    }

    public Vector3 AxialToCubeCoords(Vector2 axialCoords)
    {
        return new Vector3(axialCoords.x, axialCoords.y, -axialCoords.x - axialCoords.y);
    }

    public Vector3 RoundCoords(Vector2 coords)
    {
        Vector3 cubeCoords = AxialToCubeCoords(coords);

        return RoundCoords(cubeCoords);
    }

    public Vector3 RoundCoords(Vector3 cubeCoords)
    {
        Vector3 rounded = new Vector3(
            Mathf.Round(cubeCoords.x),
            Mathf.Round(cubeCoords.y),
            Mathf.Round(cubeCoords.z));

        Vector3 diffs = (rounded - cubeCoords).Abs();
        if (diffs.x > diffs.y && diffs.x > diffs.z)
        {
            rounded.x = -rounded.y - rounded.z;
        }
        else if (diffs.y > diffs.z)
        {
            rounded.y = -rounded.x - rounded.z;
        }
        else
        {
            rounded.z = -rounded.x - rounded.y;
        }

        return rounded;
    }

    public HexCell GetAdjacent(Vector3 dir)
    {
        return new HexCell(this.CubeCoords + dir);
    }

    public HexCell[] GetAllAdjacent()
    {
        return new[]
        {
            GetAdjacent(DIR_NE), 
            GetAdjacent(DIR_SE), 
            GetAdjacent(DIR_S), 
            GetAdjacent(DIR_SW), 
            GetAdjacent(DIR_NW),
            GetAdjacent(DIR_N)
        };
    }

    public int DistanceTo(HexCell target)
    {
        return (int)(
            Mathf.Abs(_cubeCoords.x - target.CubeCoords.x)
            + Mathf.Abs(_cubeCoords.y - target.CubeCoords.y)
            + Mathf.Abs(_cubeCoords.z - target.CubeCoords.z)
        ) / 2;
    }

    public HexCell[] LineTo(HexCell target)
    {
        HexCell nudgedTarget = new HexCell();
        nudgedTarget.CubeCoords = target.CubeCoords + new Vector3(1.0e-6f, 2.0e-6f, -3.0e-6f);
        int steps = DistanceTo(target);

        HexCell[] path = new HexCell[steps + 1];

        foreach (int dist in Enumerable.Range(0, steps))
        {
            path[dist] = new HexCell();
            path[dist].CubeCoords = CubeCoords.LinearInterpolate(nudgedTarget.CubeCoords, (float)dist / steps);
        }

        path[steps] = target;

        return path;
    }
}