// Copyright (c) 2012-2021 Wojciech Figat. All rights reserved.

namespace FlaxEngine.GUI
{
    /// <summary>
    /// This panel arranges child controls horizontally.
    /// </summary>
    /// <seealso cref="FlaxEngine.GUI.PanelWithMargins" />
    public class HorizontalPanel : PanelWithMargins
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="HorizontalPanel"/> class.
        /// </summary>
        public HorizontalPanel()
        {
        }

        /// <inheritdoc />
        protected override void PerformLayoutBeforeChildren()
        {
            base.PerformLayoutBeforeChildren();

            // Pre-set height of all controls
            float h = Height - _margin.Height;
            for (int i = 0; i < _children.Count; i++)
            {
                Control c = _children[i];
                if (c.Visible && Mathf.IsZero(c.AnchorMin.Y) && Mathf.IsZero(c.AnchorMax.Y))
                {
                    c.Height = h;
                }
            }
        }

        /// <inheritdoc />
        protected override void PerformLayoutAfterChildren()
        {
            // Sort controls horizontally
            float left = _margin.Left;
            float right = _margin.Right;
            float h = Height - _margin.Height;
            bool hasAnyLeft = false, hasAnyRight = false;
            for (int i = 0; i < _children.Count; i++)
            {
                Control c = _children[i];
                if (c.Visible)
                {
                    var w = c.Width;
                    if (Mathf.IsZero(c.AnchorMin.X) && Mathf.IsZero(c.AnchorMax.X))
                    {
                        c.Bounds = new Rectangle(left + _offset.X, _margin.Top + _offset.Y, w, h);
                        left = c.Right + _spacing;
                        hasAnyLeft = true;
                    }
                    else if (Mathf.IsOne(c.AnchorMin.X) && Mathf.IsOne(c.AnchorMax.X))
                    {
                        right += w + _spacing;
                        c.Bounds = new Rectangle(Width - right + _offset.X, _margin.Top + _offset.Y, w, h);
                        hasAnyRight = true;
                    }
                }
            }
            if (hasAnyLeft)
                left -= _spacing;
            if (hasAnyRight)
                right -= _spacing;

            // Update size
            if (_autoSize)
                Width = left + right;
        }
    }
}
