using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using Netron.Diagramming.Core.Analysis;
namespace Netron.Diagramming.Core {
  /// <summary>
  /// <para>TreeLayout that computes a tidy layout of a node-link tree
  ///  diagram. This algorithm lays out a rooted tree such that each
  ///  depth level of the tree is on a shared line. The orientation of the
  ///  tree can be set such that the tree goes left-to-right (default),
  ///  right-to-left, top-to-bottom, or bottom-to-top.</para>
  ///  
  ///  <para>The algorithm used is that of Christoph Buchheim, Michael Jünger,
  ///  and Sebastian Leipert from their research paper
  ///  <a href="http://citeseer.ist.psu.edu/buchheim02improving.html">
  ///  Improving Walker's Algorithm to Run in Linear Time</a>, Graph Drawing 2002.
  ///  This algorithm corrects performance issues in Walker's algorithm, which
  ///  generalizes Reingold and Tilford's method for tidy drawings of trees to
  ///  support trees with an arbitrary number of children at any given node.</para>
  /// </summary>
  class StandardTreeLayout : TreeLayoutBase {



    #region Fields
    BackgroundWorker worker;
    private static TreeOrientation mOrientation = TreeOrientation.TopBottom;  // the orientation of the tree
    private static float mBreadth = 50F;   // the spacing between sibling nodes
    private static float mSubTreeSpacing = 50F;  // the spacing between subtrees
    private static float mDepth = 50F;  // the spacing between depth levels
    private float m_offset = 50;  // pixel offset for root node position
    private PointF m_anchor;
    private PointF m_tmpa;
    private float[] m_depths = new float[10];
    private int mMaxDepth = 0;
    private Dictionary<string, Params> Pars;
    private float m_ax, m_ay; // for holding anchor co-ordinates
    #endregion

    #region Properties
    /// <summary>
    /// Gets or sets the orientation of the tree.
    /// </summary>
    /// <value>The orientation.</value>
    public static TreeOrientation Orientation {
      get {
        return mOrientation;
      }
      set {
        mOrientation = value;
      }
    }
    /// <summary>
    /// Gets or sets the depth spacing.
    /// </summary>
    /// <value>The depth spacing.</value>
    public static float DepthSpacing {
      get { return mDepth; }
      set { mDepth = value; }
    }

    /// <summary>
    /// Gets or sets the breadth spacing.
    /// </summary>
    /// <value>The breadth spacing.</value>
    public static float BreadthSpacing {
      get { return mBreadth; }
      set { mBreadth = value; }
    }
    /// <summary>
    /// Gets or sets the spacing between subtrees.
    /// </summary>
    /// <value>The sub tree spacing.</value>
    public static float SubTreeSpacing {
      get { return mSubTreeSpacing; }
      set { mSubTreeSpacing = value; }

    }

    public float RootOffset {
      get { return m_offset; }
      set { m_offset = value; }
    }

    #endregion

    #region Constructor
    public StandardTreeLayout(IController controller)
      : base("Standard TreeLayout", controller) {

      Orientation = TreeOrientation.LeftRight;

    }
    #endregion

    #region Methods

    public override void Run() {
      Run(2000);
    }
    public override void Run(int time) {
      if (worker != null && worker.IsBusy)
        worker.CancelAsync();
      worker = new BackgroundWorker();
      worker.WorkerSupportsCancellation = true;
      worker.DoWork += new DoWorkEventHandler(worker_DoWork);
      worker.RunWorkerAsync(time);
    }

    public override void Stop() {
      if (worker != null && worker.IsBusy)
        worker.CancelAsync();
    }

    private void worker_DoWork(object sender, DoWorkEventArgs e) {
      this.Controller.View.Suspend();
      Init();
      Layout();
      this.Controller.View.Resume();
    }
    /// <summary>
    /// Runs a single step.
    /// </summary>
    private void RunStep() {

    }
    private bool Init() {

      this.Graph = this.Model as IGraph;

      if (Graph == null)
        throw new InconsistencyException("The model has not been set and the Graph property is hence 'null'");

      m_depths = new float[10];
      this.LayoutRoot = this.Controller.Model.LayoutRoot;//could be null if not set in the GUI
      Graph.ClearSpanningTree();
      Graph.MakeSpanningTree(LayoutRoot as INode);

      //Trace.WriteLine((LayoutRoot as INode).ChildCount);

      if (Graph.SpanningTree == null)
        throw new InconsistencyException("The spanning tree is not set (se the root of the tree layout first)");





      Pars = new Dictionary<string, Params>();
      if (Graph.Nodes.Count == 0)
        return false;
      if (Graph.Edges.Count == 0) //this layout is base on embedded springs in the connections
        return false;


      Params par;

      foreach (INode node in Graph.Nodes) {
        par = new Params();
        par.init(node);
        Pars.Add(node.Uid.ToString(), par);
      }
      return true;
    }
    public PointF LayoutAnchor {
      get {
        //if (m_anchor != null)
        //{
        //    return m_anchor;
        //}

        m_tmpa = PointF.Empty;
        if (Graph != null) {
          Rectangle b = Bounds;

          switch (mOrientation) {
            case TreeOrientation.LeftRight:
              m_tmpa = new PointF(m_offset, b.Height / 2F);
              break;
            case TreeOrientation.RightLeft:
              m_tmpa = new PointF(b.Width - m_offset, b.Height / 2F);
              break;
            case TreeOrientation.TopBottom:
              m_tmpa = new PointF(b.Width / 2F, m_offset);
              break;
            case TreeOrientation.BottomTop:
              m_tmpa = new PointF(b.Width / 2F, b.Height - m_offset);
              break;
            case TreeOrientation.Center:
              m_tmpa = new PointF(b.Width / 2F, b.Height / 2F);
              break;
            default:
              break;
          }
          //TODO: set the center of the layout here on the view
          //d.getInverseTransform().transform(m_tmpa, m_tmpa);
        }
        return m_tmpa;
      }
      set {
        m_anchor = value;
      }
    }

    /// <summary>
    /// Returns the location of halfway the two given nodes
    /// </summary>
    /// <param name="l"></param>
    /// <param name="r"></param>
    /// <param name="siblings"></param>
    /// <returns></returns>
    private double spacing(INode l, INode r, bool siblings) {
      bool w = (mOrientation == TreeOrientation.TopBottom || mOrientation == TreeOrientation.BottomTop);
      return (siblings ? mBreadth : mSubTreeSpacing) + 0.5 * (w ? l.Rectangle.Width + r.Rectangle.Width : l.Rectangle.Height + r.Rectangle.Height);
    }
    private void updateDepths(int depth, INode item) {
      bool v = (mOrientation == TreeOrientation.TopBottom || mOrientation == TreeOrientation.BottomTop);
      double d = (v ? item.Rectangle.Height : item.Rectangle.Width);
      if (m_depths.Length <= depth)
        Array.Resize<float>(ref m_depths, (int)(3 * depth / 2));
      m_depths[depth] = (float)Math.Max(m_depths[depth], d);
      mMaxDepth = (int)Math.Max(mMaxDepth, depth);
    }

    private void determineDepths() {
      for (int i = 1; i < mMaxDepth; ++i)
        m_depths[i] += m_depths[i - 1] + mDepth;
    }

    public void Layout() {
      m_depths.Initialize();

      mMaxDepth = 0;

      PointF a = LayoutAnchor;
      m_ax = a.X;
      m_ay = a.Y;

      INode root = LayoutRoot as INode;
      Params rp = Pars[root.Uid.ToString()];

      // do first pass - compute breadth information, collect depth info
      firstWalk(root, 0, 1);

      // sum up the depth info
      determineDepths();

      // do second pass - assign layout positions
      secondWalk(root, null, -rp.prelim, 0);
    }

    private void firstWalk(INode n, int num, int depth) {
      //Trace.WriteLine("depthj: " + depth);
      Params np = Pars[n.Uid.ToString()];

      np.number = num;
      updateDepths(depth, n);

      bool expanded = n.IsExpanded;
      if (n.ChildCount == 0 || !expanded) // is leaf
            {
        INode l = (INode)n.PreviousSibling;
        if (l == null) {
          np.prelim = 0;
        } else {
          np.prelim = Pars[l.Uid.ToString()].prelim + spacing(l, n, true);
        }
      } else if (expanded) {
        INode leftMost = n.FirstChild;
        INode rightMost = n.LastChild;
        INode defaultAncestor = leftMost;
        INode c = leftMost;
        for (int i = 0; c != null; ++i, c = c.NextSibling) {
          firstWalk(c, i, depth + 1);
          defaultAncestor = apportion(c, defaultAncestor);
        }

        executeShifts(n);

        double midpoint = 0.5 *
            (Pars[leftMost.Uid.ToString()].prelim + Pars[rightMost.Uid.ToString()].prelim);

        INode left = (INode)n.PreviousSibling;
        if (left != null) {
          np.prelim = Pars[left.Uid.ToString()].prelim + spacing(left, n, true);
          np.mod = np.prelim - midpoint;
        } else {
          np.prelim = midpoint;
        }
      }
    }
    private INode apportion(INode v, INode a) {
      INode w = (INode)v.PreviousSibling;
      if (w != null) {
        INode vip, vim, vop, vom;
        double sip, sim, sop, som;

        vip = vop = v;
        vim = w;
        vom = (INode)vip.ParentNode.FirstChild;

        sip = Pars[vip.Uid.ToString()].mod;
        sop = Pars[vop.Uid.ToString()].mod;
        sim = Pars[vim.Uid.ToString()].mod;
        som = Pars[vom.Uid.ToString()].mod;
        Params parms;
        INode nr = nextRight(vim);
        INode nl = nextLeft(vip);
        while (nr != null && nl != null) {
          vim = nr;
          vip = nl;
          vom = nextLeft(vom);
          vop = nextRight(vop);
          parms = Pars[vop.Uid.ToString()];
          parms.ancestor = v;
          double shift = (Pars[vim.Uid.ToString()].prelim + sim) -
              (Pars[vip.Uid.ToString()].prelim + sip) + spacing(vim, vip, false);
          if (shift > 0) {
            moveSubtree(ancestor(vim, v, a), v, shift);
            sip += shift;
            sop += shift;
          }
          sim += Pars[vim.Uid.ToString()].mod;
          sip += Pars[vip.Uid.ToString()].mod;
          som += Pars[vom.Uid.ToString()].mod;
          sop += Pars[vop.Uid.ToString()].mod;

          nr = nextRight(vim);
          nl = nextLeft(vip);
        }
        if (nr != null && nextRight(vop) == null) {
          Params vopp = Pars[vop.Uid.ToString()];
          vopp.thread = nr;
          vopp.mod += sim - sop;
        }
        if (nl != null && nextLeft(vom) == null) {
          Params vomp = Pars[vom.Uid.ToString()];
          vomp.thread = nl;
          vomp.mod += sip - som;
          a = v;
        }
      }
      return a;
    }
    private INode nextLeft(INode n) {
      INode c = null;
      if (n.IsExpanded) c = n.FirstChild;
      return (c != null ? c : Pars[n.Uid.ToString()].thread);
    }

    private INode nextRight(INode n) {
      INode c = null;
      if (n.IsExpanded) c = n.LastChild;
      return (c != null ? c : Pars[n.Uid.ToString()].thread);
    }

    private void moveSubtree(INode wm, INode wp, double shift) {
      Params wmp = Pars[wm.Uid.ToString()];
      Params wpp = Pars[wp.Uid.ToString()];
      double subtrees = wpp.number - wmp.number;
      wpp.change -= shift / subtrees;
      wpp.shift += shift;
      wmp.change += shift / subtrees;
      wpp.prelim += shift;
      wpp.mod += shift;
    }

    private void executeShifts(INode n) {
      double shift = 0, change = 0;
      for (INode c = n.LastChild; c != null; c = c.PreviousSibling) {
        Params cp = Pars[c.Uid.ToString()];
        cp.prelim += shift;
        cp.mod += shift;
        change += cp.change;
        shift += cp.shift + change;
      }
    }

    private INode ancestor(INode vim, INode v, INode a) {
      INode p = (INode)v.ParentNode;
      Params vimp = Pars[vim.Uid.ToString()];
      if (vimp.ancestor != null && vimp.ancestor.ParentNode == p) {
        return vimp.ancestor;
      } else {
        return a;
      }
    }

    private void secondWalk(INode n, INode p, double m, int depth) {
      Params np = Pars[n.Uid.ToString()];
      setBreadth(n, p, np.prelim + m);
      setDepth(n, p, m_depths[depth]);

      if (n.IsExpanded) {
        depth += 1;
        for (INode c = n.FirstChild; c != null; c = c.NextSibling) {
          if (worker.CancellationPending)
            break;
          secondWalk(c, n, m + np.mod, depth);
        }
      }

      np.clear();
    }

    private void setBreadth(INode n, INode p, double b) {
      switch (mOrientation) {
        case TreeOrientation.LeftRight:
        case TreeOrientation.RightLeft:
          setY(n, p, m_ay + b);
          break;
        case TreeOrientation.TopBottom:
        case TreeOrientation.BottomTop:
          setX(n, p, m_ax + b);
          break;
        default:
          throw new InconsistencyException();
      }
    }

    private void setDepth(INode n, INode p, double d) {
      switch (mOrientation) {
        case TreeOrientation.LeftRight:
          setX(n, p, m_ax + d);
          break;
        case TreeOrientation.RightLeft:
          setX(n, p, m_ax - d);
          break;
        case TreeOrientation.TopBottom:
          setY(n, p, m_ay + d);
          break;
        case TreeOrientation.BottomTop:
          setY(n, p, m_ay - d);
          break;
        default:
          throw new InconsistencyException();
      }
    }


    #endregion

    /// <summary>
    /// Paramter blob to temporarily keep working data of one node.
    /// </summary>
    class Params {
      public double prelim;
      public double mod;
      public double shift;
      public double change;
      public int number;
      public INode ancestor;
      public INode thread;

      public void init(INode item) {
        ancestor = item;
        number = -1;
        ancestor = thread = null;
      }

      public void clear() {
        number = -2;
        prelim = mod = shift = change = 0;
        ancestor = thread = null;
      }
    }
  }

  public enum TreeOrientation {
    LeftRight,
    RightLeft,
    TopBottom,
    BottomTop,
    Center
  }
}