using System;
using System.Collections.Generic;
using System.Drawing;
using JD.Collections;
using JD.Collections.Interfaces;
using JD.Kernel.StaticHelpers;
using JD.Sequencers.Times;
using JD.Sequencers.Windowlesses;

namespace JD.Sequencers.Controls
{
    /// <summary>
    /// A single track in the track view.
    /// </summary>
    public class Track : WindowlessControl
    {
        #region Variables

        private readonly TrackItemCollection m_children;
        private TrackView m_trackView;

        private System.Drawing.Color m_color = SystemColors.AppWorkspace;

        #endregion

        #region Constructor

        public Track()
        {
            m_children = new TrackItemCollection(Controls);
            m_children.CollectionChanged += c_children_CollectionChanged;
        }

        #endregion

        #region Properties

        public bool IsActiveTrack
        {
            get { return TrackView != null && TrackView.ActiveTrack == this; }
        }

        public System.Drawing.Color Color
        {
            get { return m_color; }
            set 
            {
                if (m_color != value)
                {
                    m_color = value;
                    Invalidate();
                }
            }
        }

        public IObservableList<TrackItem> Children
        {
            get { return m_children; }
        }

        public TrackView TrackView
        {
            get { return m_trackView; }
            internal set
            {
                Throw.InvalidOperationIf(m_trackView != null && value != null, "Track is already owned by another track view");
                m_trackView = value;
            }
        }

        public Timeline Timeline
        {
            get { return TrackView != null ? TrackView.Timeline : null; }
        }

        /// <summary>
        /// True if the track is always on top and does not scroll.
        /// </summary>
        public bool Fixed
        {
            get; 
            set;
        }

        #endregion

        #region Methods

        public virtual void Initialize()
        {
        }

        #region Painting

        protected override void OnPaintSelf(System.Windows.Forms.PaintEventArgs e)
        {
            base.OnPaintSelf(e);

            OnPaintBackground(e);
            OnPaintBorder(e);
        }

        protected virtual void OnPaintBackground(System.Windows.Forms.PaintEventArgs e)
        {
            using (Brush backgroundBrush = new SolidBrush(IsActiveTrack ? System.Drawing.Color.FromArgb(50, SystemColors.Highlight) : Color))
            {
                e.Graphics.FillRectangle(backgroundBrush, Bounds);
            }
        }

        protected virtual void OnPaintBorder(System.Windows.Forms.PaintEventArgs e)
        {
            using (var pen = new Pen(System.Drawing.Color.FromArgb(50, 0, 0, 0)))
            {
                e.Graphics.DrawLine(pen, Bounds.Left, Bounds.Bottom - 1, Bounds.Right, Bounds.Bottom - 1);
            }
        }

        #endregion

        #region Layout

        /// <summary>
        /// Allows to automatically resize child bounds when painting
        /// </summary>
        public virtual void ComputeChildBounds(Graphics graphics)
        {
        }

        /// <summary>
        /// Called after all track size have been computed, allows to bake final position in track items.
        /// </summary>
        public virtual void FinalizeChildBounds(Graphics graphics)
        {
        }

        private void RefreshChildrenBounds()
        {
            foreach (TrackItem item in Children)
            {
                RefreshTrackItemBounds(item);
            }
        }

        private void RefreshTrackItemBounds(TrackItem item)
        {
            if (TrackView != null)
            {
                AlignTrackItemBounds(item);
            }
            else
            {
                item.Height = 0;
                item.Location = new Point(item.Location.X, Bounds.Top);
            }
        }

        protected virtual void AlignTrackItemBounds(TrackItem item)
        {
            switch (TrackView.TrackItemAlignment)
            {
                case TrackView.VerticalAlignment.Bottom:
                    item.Height = Height - TrackView.InnerTrackSpacing;
                    item.Location = new Point(item.Location.X, Bounds.Top + TrackView.InnerTrackSpacing);
                    break;

                case TrackView.VerticalAlignment.Middle:
                    item.Height = Height - TrackView.InnerTrackSpacing - 1;
                    item.Location = new Point(item.Location.X, Bounds.Top + TrackView.InnerTrackSpacing / 2);
                    break;

                case TrackView.VerticalAlignment.Top:
                    item.Height = Height - TrackView.InnerTrackSpacing;
                    item.Location = new Point(item.Location.X, Bounds.Top);
                    break;

                default:
                    throw new NotImplementedException();
            }
        }

        protected override void OnBoundsChanged(EventArgs e)
        {
            base.OnBoundsChanged(e);
            RefreshChildrenBounds();
        }

        public void OnTimeScaleChanged()
        {
            OnVisibleRangeChanged();
        }

        public void OnTimeOffsetChanged()
        {
            OnVisibleRangeChanged();
        }

        protected virtual void OnVisibleRangeChanged()
        {
            foreach (TrackItem item in Children)
            {
                item.OnVisibleRangeChanged();
            }
        }

        #endregion

        #endregion

        #region Event Handlers

        private void c_children_CollectionChanged(object sender, CollectionChangedEventArgs<TrackItem> e)
        {
            m_children.Synchronize(e, RegisterTrackItem, UnregisterTrackItem);
        }

        private void RegisterTrackItem(TrackItem item)
        {
            item.Track = this;
            item.Initialize();
            RefreshTrackItemBounds(item);
            item.SelectedChanged += item_SelectedChanged;
        }

        private void UnregisterTrackItem(TrackItem item)
        {
            item.SelectedChanged -= item_SelectedChanged;
            item.Track = null;
        }

        private void item_SelectedChanged(object sender, EventArgs e)
        {
            // We sort items so that the selected item is always on top (easier to see)
            TrackItem selectedItem = (TrackItem)sender;

            if (selectedItem.Selected)
            {
                Controls.Sort(new SelectedItemComparer<WindowlessControl>(selectedItem));
            }
        }

        #region Sorting

        private class SelectedItemComparer<T> : IComparer<T>
        {
            #region Variables

            private readonly T m_selectedItem;

            #endregion

            #region Constructor

            public SelectedItemComparer(T selectedItem)
            {
                m_selectedItem = selectedItem;
            }

            #endregion

            #region Implementation of IComparer<TrackItem>

            public int Compare(T x, T y)
            {
                bool xIsSelected = Equals(x, m_selectedItem);
                bool yIsSelected = Equals(y, m_selectedItem);

                if (xIsSelected)
                {
                    return yIsSelected ? 0 : 1;
                }

                return yIsSelected ? -1 : 0;
            }

            #endregion
        }

        #endregion

        #endregion

        #region Inner Types

        private class TrackItemCollection : AttachedControlCollection<TrackItem>
        {
            public TrackItemCollection(IObservableList<WindowlessControl> originalCollection)
                : base(originalCollection)
            {
            }
        }

        #endregion
    }
}