#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2012 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using HeuristicLab.Common;
using HeuristicLab.Data;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Views;
using HeuristicLab.MainForm.WindowsForms;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Views {
  public abstract partial class InteractiveSymbolicDataAnalysisSolutionSimplifierView : AsynchronousContentView {
    private Dictionary<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode> replacementNodes;
    private Dictionary<ISymbolicExpressionTreeNode, double> nodeImpacts;
    private Dictionary<ISymbolicExpressionTreeNode, double> originalValues;
    private Dictionary<ISymbolicExpressionTreeNode, string> originalVariableNames;
    private bool updateInProgress = false;
    private ISymbolicExpressionTree model;

    public InteractiveSymbolicDataAnalysisSolutionSimplifierView() {
      InitializeComponent();
      this.replacementNodes = new Dictionary<ISymbolicExpressionTreeNode, ISymbolicExpressionTreeNode>();
      this.nodeImpacts = new Dictionary<ISymbolicExpressionTreeNode, double>();
      this.originalValues = new Dictionary<ISymbolicExpressionTreeNode, double>();
      this.originalVariableNames = new Dictionary<ISymbolicExpressionTreeNode, string>();
      this.Caption = "Interactive Solution Simplifier";
    }

    public new ISymbolicDataAnalysisSolution Content {
      get { return (ISymbolicDataAnalysisSolution)base.Content; }
      set { base.Content = value; }
    }

    protected override void RegisterContentEvents() {
      base.RegisterContentEvents();
      Content.ModelChanged += new EventHandler(Content_ModelChanged);
      Content.ProblemDataChanged += new EventHandler(Content_ProblemDataChanged);
    }
    protected override void DeregisterContentEvents() {
      base.DeregisterContentEvents();
      Content.ModelChanged -= new EventHandler(Content_ModelChanged);
      Content.ProblemDataChanged -= new EventHandler(Content_ProblemDataChanged);
    }

    private void Content_ModelChanged(object sender, EventArgs e) {
      OnModelChanged();
    }
    private void Content_ProblemDataChanged(object sender, EventArgs e) {
      OnProblemDataChanged();
    }

    protected virtual void OnModelChanged() {
      model = (model == null)
                ? (ISymbolicExpressionTree)Content.Model.SymbolicExpressionTree.Clone()
                : Content.Model.SymbolicExpressionTree;
      this.CalculateReplacementNodesAndNodeImpacts(model);
      this.PaintModel();
    }

    protected virtual void OnProblemDataChanged() {
      this.CalculateReplacementNodesAndNodeImpacts();
      this.PaintModel();
    }

    protected override void OnContentChanged() {
      model = (model == null)
          ? (ISymbolicExpressionTree)Content.Model.SymbolicExpressionTree.Clone()
          : Content.Model.SymbolicExpressionTree;
      base.OnContentChanged();
      this.CalculateReplacementNodesAndNodeImpacts(model);
      this.PaintModel();
      this.viewHost.Content = this.Content;
    }

    private void CalculateReplacementNodesAndNodeImpacts() {
      if (Content == null || Content.Model == null || Content.ProblemData == null) return;
      var tree = model;
      var replacementValues = CalculateReplacementValues(tree);
      foreach (var pair in replacementValues.Where(pair => !(pair.Key is ConstantTreeNode))) {
        replacementNodes[pair.Key] = MakeConstantTreeNode(pair.Value);
      }
      nodeImpacts = CalculateImpactValues(tree);

      if (!updateInProgress) {
        // automatically fold all branches with impact = 0
        List<ISymbolicExpressionTreeNode> nodeList = tree.Root.GetSubtree(0).IterateNodesPrefix().ToList();
        foreach (var parent in nodeList) {
          for (int subTreeIndex = 0; subTreeIndex < parent.SubtreeCount; subTreeIndex++) {
            var child = parent.GetSubtree(subTreeIndex);
            if (!(child.Symbol is Constant) && nodeImpacts[child].IsAlmost(0.0)) {
              SwitchNodeWithReplacementNode(parent, subTreeIndex);
            }
          }
        }
      }
      PaintModel();
    }

    private void CalculateReplacementNodesAndNodeImpacts(ISymbolicExpressionTree tree) {
      var replacementValues = CalculateReplacementValues(tree);
      foreach (var pair in replacementValues.Where(pair => !(pair.Key is ConstantTreeNode))) {
        replacementNodes[pair.Key] = MakeConstantTreeNode(pair.Value);
      }
      nodeImpacts = CalculateImpactValues(tree);

      if (!updateInProgress) {
        // automatically fold all branches with impact = 0
        List<ISymbolicExpressionTreeNode> nodeList = tree.Root.GetSubtree(0).IterateNodesPrefix().ToList();
        foreach (var parent in nodeList) {
          for (int subTreeIndex = 0; subTreeIndex < parent.SubtreeCount; subTreeIndex++) {
            var child = parent.GetSubtree(subTreeIndex);
            if (!(child.Symbol is Constant) && nodeImpacts[child].IsAlmost(0.0)) {
              SwitchNodeWithReplacementNode(parent, subTreeIndex);
            }
          }
        }
      }
      PaintModel();
    }

    private void PaintModel() {
      // show only interesting part of solution 
      this.treeChart.Tree = model.Root.SubtreeCount > 1 ? new SymbolicExpressionTree(model.Root) : new SymbolicExpressionTree(model.Root.GetSubtree(0).GetSubtree(0));
      this.PaintNodeImpacts();
    }

    protected abstract Dictionary<ISymbolicExpressionTreeNode, double> CalculateReplacementValues(ISymbolicExpressionTree tree);
    protected abstract Dictionary<ISymbolicExpressionTreeNode, double> CalculateImpactValues(ISymbolicExpressionTree tree);
    protected abstract void UpdateModel(ISymbolicExpressionTree tree);

    private ConstantTreeNode MakeConstantTreeNode(double value) {
      Constant constant = new Constant();
      constant.MinValue = value - 1;
      constant.MaxValue = value + 1;
      ConstantTreeNode constantTreeNode = (ConstantTreeNode)constant.CreateTreeNode();
      constantTreeNode.Value = value;
      return constantTreeNode;
    }

    private void treeChart_SymbolicExpressionTreeNodeDoubleClicked(object sender, MouseEventArgs e) {
      var visualNode = (VisualSymbolicExpressionTreeNode)sender;
      var symbExprTreeNode = (SymbolicExpressionTreeNode)visualNode.SymbolicExpressionTreeNode;
      if (symbExprTreeNode == null) return;
      var tree = model;
      // check if the node value/weight has been altered
      // if so, the first double click will return the node to its original value/weight/variable name
      // the next double click will replace the ConstantNode with the original SymbolicExpressionTreeNode
      if (originalVariableNames.ContainsKey(symbExprTreeNode)) {
        var variable = (VariableTreeNode)symbExprTreeNode;
        variable.VariableName = originalVariableNames[symbExprTreeNode];
        originalVariableNames.Remove(variable);
        updateInProgress = true;
        UpdateModel(tree);
        updateInProgress = false;
        return;
      }
      if (originalValues.ContainsKey(symbExprTreeNode)) {
        double value = originalValues[symbExprTreeNode];
        if (symbExprTreeNode.Symbol is Constant)
          ((ConstantTreeNode)symbExprTreeNode).Value = value;
        else if (symbExprTreeNode.Symbol is Variable)
          ((VariableTreeNode)symbExprTreeNode).Weight = value;
        originalValues.Remove(symbExprTreeNode);
        updateInProgress = true;
        UpdateModel(tree);
        updateInProgress = false;
        return;
      }
      foreach (SymbolicExpressionTreeNode treeNode in tree.IterateNodesPostfix()) {
        for (int i = 0; i < treeNode.SubtreeCount; i++) {
          ISymbolicExpressionTreeNode subTree = treeNode.GetSubtree(i);
          // only allow to replace nodes for which a replacement value is known (replacement value for ADF nodes are not available)
          if (subTree == symbExprTreeNode && replacementNodes.ContainsKey(subTree)) {
            SwitchNodeWithReplacementNode(treeNode, i);
            // show only interesting part of solution 
            treeChart.Tree = tree.Root.SubtreeCount > 1 ? new SymbolicExpressionTree(tree.Root) : new SymbolicExpressionTree(tree.Root.GetSubtree(0).GetSubtree(0));
            updateInProgress = true;
            UpdateModel(tree);
            updateInProgress = false;
            return; // break all loops
          }
        }
      }
    }

    private void treeChart_SymbolicExpressionTreeNodeClicked(object sender, MouseEventArgs e) {
      // do stuff
      treeChart.Repaint();
    }

    private void treeChart_OnInsertNodeContextMenuItemClicked(object sender, EventArgs e) {
      // display the insert node dialog
    }

    private void treeChart_SymbolicExpressionTreeChanged(object sender, EventArgs e) {
      CalculateReplacementNodesAndNodeImpacts(treeChart.Tree);
      PaintModel();
    }

    private void treeChart_SymbolicExpressionTreeNodeChanged(object sender, EventArgs e) {
      var dialog = (ValueChangeDialog)sender;
      bool flag1 = false, flag2 = false;
      if (dialog.Content is VariableTreeNode) {
        var variable = (VariableTreeNode)dialog.Content;
        var weight = double.Parse(dialog.NewValueTextBox.Text);
        var name = (string)dialog.VariableNameComboBox.SelectedItem;
        if (!variable.Weight.Equals(weight)) {
          flag1 = true;
          originalValues[variable] = variable.Weight;
          variable.Weight = weight;
        }
        if (!variable.VariableName.Equals(name)) {
          flag2 = true;
          originalVariableNames[variable] = variable.VariableName;
          variable.VariableName = name;
        }
      } else if (dialog.Content is ConstantTreeNode) {
        var constant = (ConstantTreeNode)dialog.Content;
        var value = double.Parse(dialog.NewValueTextBox.Text);
        if (!constant.Value.Equals(value)) {
          flag1 = true;
          originalValues[constant] = constant.Value;
          constant.Value = value;

        }
      }
      if (flag1 || flag2) {
        CalculateReplacementNodesAndNodeImpacts();
        PaintModel();
      }
    }

    private void treeChart_SymbolicExpressionTreeNodeInserted(object sender, EventArgs e) {
    }

    private void SwitchNodeWithReplacementNode(ISymbolicExpressionTreeNode parent, int subTreeIndex) {
      ISymbolicExpressionTreeNode subTree = parent.GetSubtree(subTreeIndex);
      parent.RemoveSubtree(subTreeIndex);
      if (replacementNodes.ContainsKey(subTree)) {
        var replacementNode = replacementNodes[subTree];
        parent.InsertSubtree(subTreeIndex, replacementNode);
        // exchange key and value 
        replacementNodes.Remove(subTree);
        replacementNodes.Add(replacementNode, subTree);
      }
    }

    private void PaintNodeImpacts() {
      var impacts = nodeImpacts.Values;
      double max = impacts.Max();
      double min = impacts.Min();
      foreach (ISymbolicExpressionTreeNode treeNode in model.IterateNodesPostfix()) {
        VisualSymbolicExpressionTreeNode visualTree = treeChart.GetVisualSymbolicExpressionTreeNode(treeNode);
        bool flag1 = replacementNodes.ContainsKey(treeNode);
        bool flag2 = originalValues.ContainsKey(treeNode);
        bool flag3 = treeNode is ConstantTreeNode;

        if (flag2) // constant or variable node was changed
          visualTree.ToolTip += Environment.NewLine + "Original value: " + originalValues[treeNode];
        else if (flag1 && flag3) // symbol node was folded to a constant
          visualTree.ToolTip += Environment.NewLine + "Original node: " + replacementNodes[treeNode];

        if (!(treeNode is ConstantTreeNode) && nodeImpacts.ContainsKey(treeNode)) {
          double impact = nodeImpacts[treeNode];

          // impact = 0 if no change
          // impact < 0 if new solution is better
          // impact > 0 if new solution is worse
          if (impact < 0.0) {
            // min is guaranteed to be < 0
            visualTree.FillColor = Color.FromArgb((int)(impact / min * 255), Color.Red);
          } else if (impact.IsAlmost(0.0)) {
            visualTree.FillColor = Color.White;
          } else {
            // max is guaranteed to be > 0
            visualTree.FillColor = Color.FromArgb((int)(impact / max * 255), Color.Green);
          }
          visualTree.ToolTip += Environment.NewLine + "Node impact: " + impact;
          var constantReplacementNode = replacementNodes[treeNode] as ConstantTreeNode;
          if (constantReplacementNode != null) {
            visualTree.ToolTip += Environment.NewLine + "Replacement value: " + constantReplacementNode.Value;
          }
        }
      }
      this.PaintCollapsedNodes();
      this.treeChart.Repaint();
    }

    private void PaintCollapsedNodes() {
      foreach (ISymbolicExpressionTreeNode treeNode in model.IterateNodesPostfix()) {
        bool flag1 = replacementNodes.ContainsKey(treeNode);
        bool flag2 = originalValues.ContainsKey(treeNode);
        if (flag1 && treeNode is ConstantTreeNode) {
          this.treeChart.GetVisualSymbolicExpressionTreeNode(treeNode).LineColor = flag2 ? Color.DarkViolet : Color.DarkOrange;
        } else if (flag2) {
          this.treeChart.GetVisualSymbolicExpressionTreeNode(treeNode).LineColor = Color.DodgerBlue;
        }
      }
    }

    private void btnSimplify_Click(object sender, EventArgs e) {
      var simplifier = new SymbolicDataAnalysisExpressionTreeSimplifier();
      var simplifiedExpressionTree = simplifier.Simplify(model);
      UpdateModel(simplifiedExpressionTree);
    }

    protected abstract void btnOptimizeConstants_Click(object sender, EventArgs e);

    private void btnPrune_Click(object sender, EventArgs e) {
      btnPrune.Enabled = false;
      backgroundWorker1.RunWorkerAsync();
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) {
      var worker = sender as BackgroundWorker;
      PruneTree(worker);
    }

    private void PruneTree(BackgroundWorker worker) {
      var tree = model;
      // get all tree nodes starting from depth 2 (below the root and start nodes) 
      foreach (var node in GetNodesAtDepth(tree, new IntRange(2, tree.Depth))) {
        if (worker.CancellationPending)
          break; // pruning cancelled
        if (!(node.Symbol is Constant) && nodeImpacts.ContainsKey(node) && nodeImpacts[node] < 0.001) {
          SwitchNodeWithReplacementNode(node.Parent, node.Parent.IndexOfSubtree(node));
          nodeImpacts = CalculateImpactValues(tree);
          // we do not refresh the replacementValues because they won't change when folding nodes with such low impacts (<0.001)
        }
      }
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) {
      if (e.Cancelled) {
        // The user canceled the operation.
      } else if (e.Error != null) {
        // There was an error during the operation.
        // Error-handling
      } else {
        // The operation completed normally. We can update the model
        UpdateModel(model);
      }
      btnPrune.Enabled = true;
    }

    #region helpers
    private static IEnumerable<ISymbolicExpressionTreeNode> GetNodesAtDepth(ISymbolicExpressionTree tree, IntRange depthRange) {
      var treeDepth = tree.Root.GetDepth();
      return from node in tree.Root.IterateNodesPostfix()
             let depth = treeDepth - node.GetDepth()
             where depthRange.Start <= depth
             where depth <= depthRange.End
             select node;
    }
    #endregion
  }
}