using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

namespace GeoSigmaViewer
{
    public static class ClassExtensions
    {
        /// <summary>
        /// 选中状态：0-未选中， 1-选中，2-部分选中。
        /// </summary>
        /// <param name="node"></param>
        /// <returns></returns>
        public static int GetCheckStatus(this TreeNode node)
        {
            return node.StateImageIndex;
        }
        public static void SetCheckStatus(this TreeNode node, int status)
        {
            node.StateImageIndex=status;
        }
    }
    public partial class TriStateTreeView : TreeView
    {
        private const int STATE_UNCHECKED = 0; //unchecked state
        private const int STATE_CHECKED = 1; //checked state
        private const int STATE_MIXED = 2; //mixed state (indeterminate)
        private bool isMouseOnStatus = false;
        //create a new ThreeStateTreeView
        public int ID { get; set; }
        public TriStateTreeView() : base()
        {
            System.Security.Cryptography.RNGCryptoServiceProvider csp = new System.Security.Cryptography.RNGCryptoServiceProvider();
            byte[] byteCsp = new byte[10];
            csp.GetBytes(byteCsp);
            ID=BitConverter.ToInt32(byteCsp, 0);
        }
        protected override void OnBeforeCollapse(TreeViewCancelEventArgs e)
        {
            if (isMouseOnStatus)
                e.Cancel=true;
        }
        protected override void OnBeforeExpand(TreeViewCancelEventArgs e)
        {
            if (isMouseOnStatus)
                e.Cancel=true;
        }
        /// <summary>
        /// 重新设置所有节点的选中状态
        /// </summary>
        public void UpdateView()
        {
            this.SetNodesState(this.Nodes);
        }

        public void SelectAll()
        {
            this.SetNodesState(this.Nodes, STATE_CHECKED);
        }

        public void UnselectAll()
        {
            this.SetNodesState(this.Nodes, STATE_UNCHECKED);
        }

        public void AntiSelect()
        {
            this.SetNodesToAntiState(this.Nodes);
        }

        //returns a value indicating if all children are checked
        public static bool IsAllChildrenChecked(TreeNode parent)
        {
            return IsAllChildrenSame(parent, STATE_CHECKED);
        }

        //returns a value indicating if all children are unchecked
        public static bool IsAllChildrenUnchecked(TreeNode parent)
        {
            return IsAllChildrenSame(parent, STATE_UNCHECKED);
        }

        //initialize all nodes state image
        private void SetNodesState(TreeNodeCollection nodes, int state)
        {
            foreach (TreeNode node in nodes)
            {
                node.StateImageIndex=state;
                if (state==STATE_CHECKED)
                {
                    node.Checked=true;
                }
                else
                {
                    node.Checked=false;
                }

                if (node.Nodes.Count!=0)
                {
                    SetNodesState(node.Nodes, state);
                }
            }
        }
        private void UpdateStatus(TreeNodeCollection nodes)
        {
            foreach (TreeNode node in nodes)
            {                
                UpdateParent(node);
                if (node.Nodes.Count!=0)
                {
                    UpdateStatus(node.Nodes);
                }
            }
        }
        private void SetNodesState(TreeNodeCollection nodes)
        {
            foreach (TreeNode node in nodes)
            {
                //if (node.Checked)
                //{
                //    node.StateImageIndex=STATE_CHECKED;
                //}
                //else
                //{
                //    node.StateImageIndex=STATE_UNCHECKED;
                //}
                UpdateParent(node);

                if (node.Nodes.Count!=0)
                {
                    SetNodesState(node.Nodes);
                }
            }
        }

        private void SetNodesToAntiState(TreeNodeCollection nodes)
        {
            foreach (TreeNode node in nodes)
            {
                if (node.GetCheckStatus()==STATE_CHECKED)
                {
                    node.SetCheckStatus(STATE_UNCHECKED);
                    //node.Checked=true;
                }
                else if (node.StateImageIndex==STATE_UNCHECKED)
                {
                    node.StateImageIndex=STATE_CHECKED;
                    //node.Checked=false;
                }

                if (node.Nodes.Count!=0)
                {
                    SetNodesToAntiState(node.Nodes);
                }
            }
        }

        //update children state image with the parent value
        private void UpdateChildren(TreeNode parent)
        {
            int state = parent.StateImageIndex;
            foreach (TreeNode node in parent.Nodes)
            {
                node.StateImageIndex=state;
                if (node.Nodes.Count!=0)
                {
                    UpdateChildren(node);
                }
            }
        }

        //update parent state image base on the children state
        private void UpdateParent(TreeNode child)
        {
            TreeNode parent = child.Parent;
            if (parent==null)
            {
                return;
            }

            if (child.StateImageIndex==STATE_MIXED)
            {
                parent.StateImageIndex=STATE_MIXED;
            }
            else if (IsAllChildrenChecked(parent))
            {
                parent.StateImageIndex=STATE_CHECKED;
            }
            else if (IsAllChildrenUnchecked(parent))
            {
                parent.StateImageIndex=STATE_UNCHECKED;
            }
            else
            {
                parent.StateImageIndex=STATE_MIXED;
            }
            UpdateParent(parent);
        }

        //returns a value indicating if all children are in the same state
        private static bool IsAllChildrenSame(TreeNode parent, int state)
        {
            foreach (TreeNode node in parent.Nodes)
            {
                if (node.StateImageIndex!=state)
                {
                    return false;
                }
                if (node.Nodes.Count!=0&&!IsAllChildrenSame(node, state))
                {
                    return false;
                }
            }
            return true;
        }

        //build the checked, unchecked and indeterminate images
        private static Image GetStateImage(CheckBoxState state, Size imageSize)
        {
            Bitmap bmp = new Bitmap(16, 16);
            using (Graphics g = Graphics.FromImage(bmp))
            {
                Point pt = new Point((16-imageSize.Width)/2, (16-imageSize.Height)/2);
                CheckBoxRenderer.DrawCheckBox(g, pt, state);
            }
            return bmp;
        }


        protected override void OnHandleCreated(EventArgs e)
        {
            base.OnHandleCreated(e);
            this.StateImageList=new ImageList();
            using (Graphics g = base.CreateGraphics())
            {
                Size glyphSize = CheckBoxRenderer.GetGlyphSize(g, CheckBoxState.UncheckedNormal);
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.UncheckedNormal, glyphSize));
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.CheckedNormal, glyphSize));
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.MixedNormal, glyphSize));
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.UncheckedDisabled, glyphSize));
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.CheckedDisabled, glyphSize));
                this.StateImageList.Images.Add(GetStateImage(CheckBoxState.MixedDisabled, glyphSize));
            }
        }

        protected override void OnMouseDown(MouseEventArgs e)
        {
            MouseEventArgs ee = e as MouseEventArgs;
            if (ee.Button==MouseButtons.Left)
            {
                TreeViewHitTestInfo info = base.HitTest(ee.Location);
                if (info.Node!=null&&info.Location==TreeViewHitTestLocations.StateImage)
                {
                    isMouseOnStatus=true;
                    TreeNode node = info.Node;
                    switch (node.StateImageIndex)
                    {
                        case STATE_UNCHECKED:
                        case STATE_MIXED:
                            node.StateImageIndex=STATE_CHECKED;
                            break;
                        case STATE_CHECKED:
                            node.StateImageIndex=STATE_UNCHECKED;
                            break;
                    }
                    UpdateChildren(node);
                    UpdateParent(node);
                    return;
                }
                else
                {
                    isMouseOnStatus=false;
                }
            }
            base.OnMouseDown(e);
        }

        protected override void OnClick(EventArgs e)
        {
            base.OnClick(e);
        }
        protected override void OnMouseDoubleClick(MouseEventArgs e)
        {
            base.OnMouseDoubleClick(e);
        }
        protected override void OnMouseClick(MouseEventArgs e)
        {
            base.OnMouseClick(e);           
        }

        //check if user press the space key
        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);
            if (e.KeyCode==Keys.Space)
            {
                if (base.SelectedNode!=null)
                {
                    TreeNode node = base.SelectedNode;
                    switch (node.StateImageIndex)
                    {
                        case STATE_UNCHECKED:
                        case STATE_MIXED:
                            node.StateImageIndex=STATE_CHECKED;
                            break;
                        case STATE_CHECKED:
                            node.StateImageIndex=STATE_UNCHECKED;
                            break;
                    }
                    UpdateChildren(node);
                    UpdateParent(node);
                }
            }
        }

        //swap between enabled and disabled images
        protected override void OnEnabledChanged(EventArgs e)
        {
            base.OnEnabledChanged(e);

            for (int i = 0; i<3; i++)
            {
                Image img = this.StateImageList.Images[0];
                this.StateImageList.Images.RemoveAt(0);
                this.StateImageList.Images.Add(img);
            }
        }
    }
}