using System;
using System.Windows;
using System.Windows.Controls;

namespace Tango.Hive
{
    /// <summary>
    /// Hexagonal panel
    /// </summary>
    public class HexGrid: Panel
    {
        #region Orientation
        public static readonly DependencyProperty OrientationProperty =
            DependencyProperty.RegisterAttached("Orientation", typeof(Orientation), typeof(HexGrid),
                new FrameworkPropertyMetadata(Orientation.Horizontal,
                    FrameworkPropertyMetadataOptions.AffectsMeasure | 
                    FrameworkPropertyMetadataOptions.AffectsArrange |
                    FrameworkPropertyMetadataOptions.Inherits));

        public static void SetOrientation(DependencyObject element, Orientation value)
        {
            element.SetValue(OrientationProperty, value);
        }

        public static Orientation GetOrientation(DependencyObject element)
        {
            return (Orientation)element.GetValue(OrientationProperty);
        }

        public Orientation Orientation
        {
            get { return (Orientation) GetValue(OrientationProperty); }
            set { SetValue(OrientationProperty, value); }
        }
        #endregion

        public static readonly DependencyProperty RowCountProperty = 
            DependencyProperty.Register("RowCount", typeof (int), typeof (HexGrid),
            new FrameworkPropertyMetadata(1, FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsArrange), 
            ValidateCountCallback);


        public int RowCount
        {
            get { return (int) GetValue(RowCountProperty); }
            set { SetValue(RowCountProperty, value); }
        }

        public static readonly DependencyProperty ColumnCountProperty = 
            DependencyProperty.Register("ColumnCount", typeof (int), typeof (HexGrid),
            new FrameworkPropertyMetadata(1, FrameworkPropertyMetadataOptions.AffectsMeasure | FrameworkPropertyMetadataOptions.AffectsArrange),
            ValidateCountCallback);
        
        public int ColumnCount
        {
            get { return (int) GetValue(ColumnCountProperty); }
            set { SetValue(ColumnCountProperty, value); }
        }

        private static bool ValidateCountCallback(object value)
        {
            if (value is int)
            {
                int count = (int)value;
                return count > 0;
            }

            return false;
        }

        private int GetRow(UIElement e)
        {
            int row = (int)e.GetValue(Grid.RowProperty);
            if (row >= RowCount)
                row = RowCount - 1;
            return row;
        }

        private int GetColumn(UIElement e)
        {
            int column = (int)e.GetValue(Grid.ColumnProperty);
            if (column >= ColumnCount)
                column = ColumnCount - 1;
            return column;
        }

        protected override Size MeasureOverride(Size availableSize)
        {
            double w = availableSize.Width;
            double h = availableSize.Height;            

            // if there is Infinity size dimension
            if (Double.IsInfinity(w) || Double.IsInfinity(h))
            {
                // determine maximum desired size
                h = 0;
                w = 0;
                foreach (UIElement e in InternalChildren)
                {
                    e.Measure(availableSize);
                    var s = e.DesiredSize;
                    if (s.Height > h)
                        h = s.Height;
                    if (s.Width > w)
                        w = s.Width;
                }                

                // multiply maximum size to RowCount and ColumnCount to get total size
                if (Orientation == Orientation.Horizontal)
                    return new Size(w*(ColumnCount * 3 + 1)/4, h*(RowCount * 2 + 1)/2);

                return new Size(w*(ColumnCount * 2 + 1)/2, h*(RowCount * 3 + 1)/4);
            }            

            return availableSize;
        }

        #region HasShift
        private void HasShift(out bool first, out bool last)
        {
            if (Orientation == Orientation.Horizontal)
                HasRowShift(out first, out last);
            else
                HasColumnShift(out first, out last);
        }

        private void HasRowShift(out bool firstRow, out bool lastRow)
        {
            firstRow = lastRow = true;

            UIElementCollection elements = base.InternalChildren;
            for (int i = 0; i < elements.Count && (firstRow || lastRow); i++)
            {
                var e = elements[i];
                if (e.Visibility == Visibility.Collapsed)
                    continue;

                int row = GetRow(e);
                int column = GetColumn(e);

                int mod = column % 2;

                if (row == 0 && mod == 0)
                    firstRow = false;

                if (row == RowCount - 1 && mod == 1)
                    lastRow = false;
            }
        }

        private void HasColumnShift(out bool firstColumn, out bool lastColumn)
        {
            firstColumn = lastColumn = true;

            UIElementCollection elements = base.InternalChildren;
            for (int i = 0; i < elements.Count && (firstColumn || lastColumn); i++)
            {
                var e = elements[i];
                if (e.Visibility == Visibility.Collapsed)
                    continue;

                int row = GetRow(e);
                int column = GetColumn(e);

                int mod = row % 2;

                if (column == 0 && mod == 0)
                    firstColumn = false;

                if (column == ColumnCount - 1 && mod == 1)
                    lastColumn = false;
            }
        }
        #endregion

        #region GetHexSize
        private Size GetHexSize(Size gridSize)
        {
            double minH = 0;
            double minW = 0;

            foreach (UIElement e in InternalChildren)
            {
                var f = e as FrameworkElement;
                if (f != null)
                {
                    if (f.MinHeight > minH)
                        minH = f.MinHeight;
                    if (f.MinWidth > minW)
                        minW = f.MinWidth;
                }
            }

            bool first, last;
            HasShift(out first, out last);

            var possibleSize = GetPossibleSize(gridSize);
            double possibleW = possibleSize.Width;
            double possibleH = possibleSize.Height;

            var w = Math.Max(minW, possibleW);
            var h = Math.Max(minH, possibleH);

            return new Size(w, h);
        }

        private Size GetPossibleSize(Size gridSize)
        {
            bool first, last;
            HasShift(out first, out last);

            if (Orientation == Orientation.Horizontal)
                return GetPossibleSizeHorizontal(gridSize, first, last);

            return GetPossibleSizeVertical(gridSize, first, last);
        }

        private Size GetPossibleSizeVertical(Size gridSize, bool first, bool last)
        {
            int columns = ((first ? 0 : 1) + 2*ColumnCount - (last ? 1 : 0));
            double w = 2 * (gridSize.Width / columns);

            int rows = 1 + 3*RowCount;
            double h = 4 * (gridSize.Height / rows);

            return new Size(w, h);
        }

        private Size GetPossibleSizeHorizontal(Size gridSize, bool first, bool last)
        {
            int columns = 1 + 3*ColumnCount;
            double w = 4 * (gridSize.Width / columns);

            int rows = (first ? 0 : 1) + 2 * RowCount - (last ? 1 : 0);
            double h = 2 * (gridSize.Height / rows);

            return new Size(w, h);
        }
        #endregion

        protected override Size ArrangeOverride(Size finalSize)
        {            
            // determine if there is empty space at grid borders
            bool first, last;
            HasShift(out first, out last);

            // compute final hex size
            Size hexSize = GetHexSize(finalSize);
            
            // compute arrange line sizes
            double columnWidth, rowHeight;
            if (Orientation == Orientation.Horizontal)
            {
                rowHeight   = 0.50 * hexSize.Height;
                columnWidth = 0.25 * hexSize.Width;
            }
            else
            {
                rowHeight   = 0.25 * hexSize.Height;
                columnWidth = 0.50 * hexSize.Width;
            }            

            // arrange elements
            UIElementCollection elements = base.InternalChildren;
            for (int i = 0; i < elements.Count; i++)
            {
                if (elements[i].Visibility == Visibility.Collapsed)
                    continue;
                ArrangeElement(elements[i], hexSize, columnWidth, rowHeight, first);
            }
                        
            return finalSize;
        }

        private void ArrangeElement(UIElement e, Size hexSize, double columnWidth, double rowHeight, bool shift)
        {
            int row = GetRow(e);
            int column = GetColumn(e);

            double x;
            double y;

            if (Orientation == Orientation.Horizontal)
            {
                x = 3 * columnWidth * column;
                y = rowHeight * (2 * row + (column % 2 == 1 ? 1 : 0) + (shift ? -1 : 0));
            }
            else
            {
                x = columnWidth * (2 * column + (row % 2 == 1 ? 1 : 0) + (shift ? -1 : 0));
                y = 3 * rowHeight * row;
            }

            e.Arrange(new Rect(x, y, hexSize.Width, hexSize.Height));
        }
    }
}