using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading;
using GraphVizWrapper;
using GraphVizWrapper.Commands;
using GraphVizWrapper.Queries;
using HeuristicLab.Algorithms.Bandits;
using HeuristicLab.Algorithms.GrammaticalOptimization;
using HeuristicLab.Algorithms.MonteCarloTreeSearch.Base;
using HeuristicLab.Algorithms.MonteCarloTreeSearch.Simulation;
using HeuristicLab.Common;
using HeuristicLab.Problems.GrammaticalOptimization;

namespace HeuristicLab.Algorithms.MonteCarloTreeSearch
{
    public class MonteCarloTreeSearch : SolverBase
    {
        protected readonly int maxLen;
        protected readonly ISymbolicExpressionTreeProblem problem;
        protected readonly IGrammar grammar;
        protected readonly Random random;
        protected readonly IBanditPolicy behaviourPolicy;
        protected readonly ISimulation simulation;
        protected TreeNode rootNode;
        protected int goodSelections;

        public MonteCarloTreeSearch(ISymbolicExpressionTreeProblem problem, int maxLen, Random random, IBanditPolicy behaviourPolicy,
            ISimulation simulationPolicy)
        {
            this.problem = problem;
            this.grammar = problem.Grammar;
            this.maxLen = maxLen;
            this.random = random;
            this.behaviourPolicy = behaviourPolicy;
            this.simulation = simulationPolicy;

            this.problem.GenerateProblemSolutions(maxLen);
        }

        public event Action<int, int> IterationFinished;

        protected virtual void OnIterationFinishedChanged(int value, int selections)
        {
            RaiseIterationFinishedChanged(value, selections);
        }

        private void RaiseIterationFinishedChanged(int value, int selections)
        {
            var handler = IterationFinished;
            if (handler != null) handler(value, selections);
        }

        public bool StopRequested { get; set; }
        
        public int GoodSelections { get { return this.goodSelections; } }

        protected void CheckSelection(TreeNode node, int selections)
        {
            if (problem.IsParentOfProblemSolution(node.phrase, maxLen))
            {
                goodSelections++;
            }
        }

        public override void Run(int maxIterations)
        {
            Reset();
            int selections = 0;
            TreeNode currentNode;
            string phrase;
            string simulatedPhrase;
            double quality;

            for (int i = 0; !StopRequested && i < maxIterations; i++)
            {
                currentNode = rootNode;

                while (!currentNode.IsLeaf())
                {
                    int currentActionIndex = behaviourPolicy.SelectAction(random,
                        currentNode.GetChildActionInfos());
                    currentNode = currentNode.children[currentActionIndex];
                    selections++;
                    CheckSelection(currentNode, selections);
                }

                phrase = currentNode.phrase;

                if (!grammar.IsTerminal(phrase) && phrase.Length <= maxLen)
                {
                    ExpandTreeNode(currentNode);
                    currentNode =
                        currentNode.children[behaviourPolicy.SelectAction(random, currentNode.GetChildActionInfos())
                            ];
                    selections++;
                    CheckSelection(currentNode, selections);
                }
                if (currentNode.phrase.Length <= maxLen)
                {
                    quality = simulation.Simulate(currentNode, out simulatedPhrase);
                    OnSolutionEvaluated(simulatedPhrase, quality);

                    OnIterationFinishedChanged(goodSelections, selections);
                    Propagate(currentNode, quality);
                }
            }
        }

        protected void ExpandTreeNode(TreeNode treeNode)
        {
            // create children on the first visit
            Sequence newSequence;
            TreeNode childNode;
            if (treeNode.children == null)
            {
                List<TreeNode> newChildren = new List<TreeNode>();

                var phrase = new Sequence(treeNode.phrase);
                // create subnodes for each nt-symbol in phrase
                for (int i = 0; i < phrase.Length; i++)
                {
                    char symbol = phrase[i];
                    if (grammar.IsNonTerminal(symbol))
                    {
                        // create subnode for each alternative of symbol
                        foreach (Sequence alternative in grammar.GetAlternatives(symbol))
                        {
                            newSequence = new Sequence(phrase);
                            newSequence.ReplaceAt(i, 1, alternative);
                            if (newSequence.Length <= maxLen)
                            {
                                childNode = new TreeNode(treeNode, newSequence.ToString(),
                                    behaviourPolicy.CreateActionInfo(), (ushort) (treeNode.level + 1));
                                newChildren.Add(childNode);
                            }
                        }
                    }
                }
                treeNode.children = newChildren.ToArray();
            }
        }

        protected void Reset()
        {
            goodSelections = 0;
            StopRequested = false;
            bestQuality = 0.0;
            rootNode = new TreeNode(null, grammar.SentenceSymbol.ToString(), behaviourPolicy.CreateActionInfo(), 0);
        }

        protected void Propagate(TreeNode node, double quality)
        {
            var currentNode = node;
            do
            {
                currentNode.actionInfo.UpdateReward(quality);
                currentNode = currentNode.parent;
            } while (currentNode != null);
        }

        private void GetTreeInfosRek(TreeInfos treeInfos, TreeNode[] children)
        {
            treeInfos.TotalNodes += children.Length;
            foreach (TreeNode child in children)
            {
                if (child.children != null)
                {
                    treeInfos.ExpandedNodes++;
                    if (treeInfos.DeepestLevel <= child.level)
                    {
                        treeInfos.DeepestLevel = child.level + 1;
                    }
                    GetTreeInfosRek(treeInfos, child.children);
                }
                else
                {
                    if (grammar.IsTerminal(child.phrase))
                    {
                        treeInfos.LeaveNodes++;
                    }
                    else
                    {
                        treeInfos.UnexpandedNodes++;
                    }
                }
            }
        }

        public TreeInfos GetTreeInfos()
        {
            TreeInfos treeInfos = new TreeInfos();

            if (rootNode != null)
            {
                treeInfos.TotalNodes++;
                if (rootNode.children != null)
                {
                    treeInfos.ExpandedNodes++;
                    treeInfos.DeepestLevel = rootNode.level + 1;
                    GetTreeInfosRek(treeInfos, rootNode.children);
                }
                else
                {
                    treeInfos.DeepestLevel = rootNode.level;
                    if (grammar.IsTerminal(rootNode.phrase))
                    {
                        treeInfos.LeaveNodes++;
                    }
                    else
                    {
                        treeInfos.UnexpandedNodes++;
                    }
                }
            }
            return treeInfos;
        }

        public byte[] GenerateSvg()
        {
            if (GetTreeInfos().TotalNodes < 1000)
            {
                IGetStartProcessQuery getStartProcessQuery = new GetStartProcessQuery();
                IGetProcessStartInfoQuery getProcessStartInfoQuery = new GetProcessStartInfoQuery();
                IRegisterLayoutPluginCommand registerLayoutPluginCommand =
                    new RegisterLayoutPluginCommand(getProcessStartInfoQuery, getStartProcessQuery);

                GraphGeneration wrapper = new GraphGeneration(getStartProcessQuery,
                    getProcessStartInfoQuery,
                    registerLayoutPluginCommand);
                wrapper.GraphvizPath = @"../../../Graphviz2.38/bin";
                StringBuilder dotFile = new StringBuilder("digraph {");
                dotFile.AppendLine();
                dotFile.AppendLine("splines=ortho;");
                dotFile.AppendLine("concentrate=true;");
                dotFile.AppendLine("ranksep=1.2;");

                List<TreeNode> toDoNodes = new List<TreeNode>();
                if (rootNode != null)
                {
                    toDoNodes.Add(rootNode);
                    // declare node
                    string hexColor = GetHexNodeColor(Color.White, Color.OrangeRed, rootNode.actionInfo.Value);

                    dotFile.AppendLine(
                        string.Format("{0} [label=\"{1}\\n{2:0.00}/{3}\", style=filled, fillcolor=\"{4}\"]",
                            rootNode.GetHashCode(),
                            rootNode.phrase, rootNode.actionInfo.Value, rootNode.actionInfo.Tries, hexColor));
                }

                // to put nodes on the same level in graph
                Dictionary<int, List<TreeNode>> levelMap = new Dictionary<int, List<TreeNode>>();

                List<TreeNode> sameLevelNodes;

                while (toDoNodes.Any())
                {
                    TreeNode currentNode = toDoNodes[0];
                    toDoNodes.RemoveAt(0);
                    // put currentNode into levelMap
                    if (levelMap.TryGetValue(currentNode.level, out sameLevelNodes))
                    {
                        sameLevelNodes.Add(currentNode);
                    }
                    else
                    {
                        sameLevelNodes = new List<TreeNode>();
                        sameLevelNodes.Add(currentNode);
                        levelMap.Add(currentNode.level, sameLevelNodes);
                    }

                    // draw line from current node to all its children
                    if (currentNode.children != null)
                    {
                        foreach (TreeNode childNode in currentNode.children)
                        {
                            toDoNodes.Add(childNode);
                            // declare node

                            string hexColor = GetHexNodeColor(Color.White, Color.OrangeRed, childNode.actionInfo.Value);
                            dotFile.AppendLine(
                                string.Format("{0} [label=\"{1}\\n{2:0.00}/{3}\", style=filled, fillcolor=\"{4}\"]",
                                    childNode.GetHashCode(),
                                    childNode.phrase, childNode.actionInfo.Value, childNode.actionInfo.Tries, hexColor));
                            // add edge
                            dotFile.AppendLine(string.Format("{0} -> {1}", currentNode.GetHashCode(),
                                childNode.GetHashCode()));
                        }
                    }
                }

                // set same level ranks..
                foreach (KeyValuePair<int, List<TreeNode>> entry in levelMap)
                {
                    dotFile.Append("{rank = same;");
                    foreach (TreeNode node in entry.Value)
                    {
                        dotFile.Append(string.Format(" {0};", node.GetHashCode()));
                    }
                    dotFile.AppendLine("}");
                }

                dotFile.Append(" }");
                byte[] output = wrapper.GenerateGraph(dotFile.ToString(), Enums.GraphReturnType.Svg);
                return output;
            }
            return null;
        }

        protected String HexConverter(Color c)
        {
            return "#" + c.R.ToString("X2") + c.G.ToString("X2") + c.B.ToString("X2");
        }

        protected String GetHexNodeColor(Color weakColor, Color strongColor, double quality)
        {
            // convert quality to value between 0 and 1
            double bestKnownQuality = problem.BestKnownQuality(this.maxLen);
            double q = quality / bestKnownQuality;

            // calculate difference between colors
            byte rDiff = (byte)Math.Abs(weakColor.R - strongColor.R);
            byte bDiff = (byte)Math.Abs(weakColor.B - strongColor.B);
            byte gDiff = (byte)Math.Abs(weakColor.G - strongColor.G);

            byte newR = weakColor.R > strongColor.R
                ? Convert.ToByte(weakColor.R - Math.Round(rDiff * q))
                : Convert.ToByte(weakColor.R + Math.Round(rDiff * q));

            byte newB = weakColor.B > strongColor.B
                ? Convert.ToByte(weakColor.B - Math.Round(bDiff * q))
                : Convert.ToByte(weakColor.B + Math.Round(bDiff * q));

            byte newG = weakColor.G > strongColor.G
                ? Convert.ToByte(weakColor.G - Math.Round(gDiff * q))
                : Convert.ToByte(weakColor.G + Math.Round(gDiff * q));

            return HexConverter(Color.FromArgb(newR, newG, newB));
        }

        public void FreeAll()
        {
            rootNode = null;
            GC.Collect();
        }
    }
}