using System;
using System.Collections.Generic;
using System.Windows;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace SketchAssistantWPF
{
    public class MVP_Model
    {
        /// <summary>
        /// The Presenter of the MVP-Model.
        /// </summary>
        MVP_Presenter programPresenter;
        /// <summary>
        /// History of Actions
        /// </summary>
        ActionHistory historyOfActions;
        /// <summary>
        /// The assistant responsible for the redraw mode
        /// </summary>
        //RedrawAssistant redrawAss;


        /***********************/
        /*** CLASS VARIABLES ***/
        /***********************/

        /// <summary>
        /// If the program is in drawing mode.
        /// </summary>
        bool inDrawingMode;
        /// <summary>
        /// Size of deletion area
        /// </summary>
        int deletionRadius = 5;
        /// <summary>
        /// The Position of the Cursor in the right picture box
        /// </summary>
        Point currentCursorPosition;
        /// <summary>
        /// The Previous Cursor Position in the right picture box
        /// </summary>
        Point previousCursorPosition;
        /// <summary>
        /// Queue for the cursorPositions
        /// </summary>
        Queue<Point> cursorPositions = new Queue<Point>();
        /// <summary>
        /// Lookup Matrix for checking postions of lines in the image
        /// </summary>
        bool[,] isFilledMatrix;
        /// <summary>
        /// Lookup Matrix for getting line ids at a certain postions of the image
        /// </summary>
        HashSet<int>[,] linesMatrix;
        /// <summary>
        /// Width of the LeftImageBox.
        /// </summary>
        public int leftImageBoxWidth;
        /// <summary>
        /// Height of the LeftImageBox.
        /// </summary>
        public int leftImageBoxHeight;
        /// <summary>
        /// Width of the RightImageBox.
        /// </summary>
        public int rightImageBoxWidth;
        /// <summary>
        /// Height of the RightImageBox.
        /// </summary>
        public int rightImageBoxHeight;

        public ImageDimension leftImageSize { get; private set; }

        public ImageDimension rightImageSize { get; private set; }
        /// <summary>
        /// Indicates whether or not the canvas on the right side is active.
        /// </summary>
        public bool canvasActive {get; set;}
        /// <summary>
        /// Indicates if there is a graphic loaded in the left canvas.
        /// </summary>
        public bool graphicLoaded { get; set; }
        /// <summary>
        /// Whether or not the mouse is pressed.
        /// </summary>
        private bool mouseDown;

        List<InternalLine> leftLineList;
        
        List<Tuple<bool, InternalLine>> rightLineList;

        List<Point> currentLine = new List<Point>();



        public MVP_Model(MVP_Presenter presenter)
        {
            programPresenter = presenter;
            historyOfActions = new ActionHistory();
            //redrawAss = new RedrawAssistant();
            //overlayItems = new List<Tuple<bool, HashSet<Point>>>();
            rightLineList = new List<Tuple<bool, InternalLine>>();
            canvasActive = false;
            UpdateUI();
            rightImageSize = new ImageDimension(0, 0);
            leftImageSize = new ImageDimension(0, 0);
        }

        /**************************/
        /*** INTERNAL FUNCTIONS ***/
        /**************************/


        /// <summary>
        /// Change the status of whether or not the lines are shown.
        /// </summary>
        /// <param name="lines">The HashSet containing the affected Line IDs.</param>
        /// <param name="shown">True if the lines should be shown, false if they should be hidden.</param>
        private void ChangeLines(HashSet<int> lines, bool shown)
        {
            foreach (int lineId in lines)
            {
                if (lineId <= rightLineList.Count - 1 && lineId >= 0)
                {
                    rightLineList[lineId] = new Tuple<bool, InternalLine>(shown, rightLineList[lineId].Item2);
                }
            }
        }

        /// <summary>
        /// A function that populates the matrixes needed for deletion detection with line data.
        /// </summary>
        private void RepopulateDeletionMatrixes()
        {
            if (canvasActive)
            {
                isFilledMatrix = new bool[rightImageSize.Width, rightImageSize.Height];
                linesMatrix = new HashSet<int>[rightImageSize.Width, rightImageSize.Height];
                foreach (Tuple<bool, InternalLine> lineTuple in rightLineList)
                {
                    if (lineTuple.Item1)
                    {
                        lineTuple.Item2.PopulateMatrixes(isFilledMatrix, linesMatrix);
                    }
                }
            }
        }

        /// <summary>
        /// Tells the Presenter to Update the UI
        /// </summary>
        private void UpdateUI()
        {
            programPresenter.UpdateUIState(inDrawingMode, historyOfActions.CanUndo(), historyOfActions.CanRedo(), canvasActive, graphicLoaded);
        }

        /// <summary>
        /// A function that checks the deletion matrixes at a certain point 
        /// and returns all Line ids at that point and in a square around it in a certain range.
        /// </summary>
        /// <param name="p">The point around which to check.</param>
        /// <param name="range">The range around the point. If range is 0, only the point is checked.</param>
        /// <returns>A List of all lines.</returns>
        private HashSet<int> CheckDeletionMatrixesAroundPoint(Point p, int range)
        {
            HashSet<int> returnSet = new HashSet<int>();

            foreach (Point pnt in GeometryCalculator.FilledCircleAlgorithm(p, (int)range))
            {
                if (pnt.X >= 0 && pnt.Y >= 0 && pnt.X < rightImageSize.Width && pnt.Y < rightImageSize.Height)
                {
                    if (isFilledMatrix[(int)pnt.X, (int)pnt.Y])
                    {
                        returnSet.UnionWith(linesMatrix[(int)pnt.X, (int)pnt.Y]);
                    }
                }
            }
            return returnSet;
        }

        /********************************************/
        /*** FUNCTIONS TO INTERACT WITH PRESENTER ***/
        /********************************************/

        /// <summary>
        /// A function to update the dimensions of the left and right canvas when the window is resized.
        /// </summary>
        /// <param name="LeftCanvas">The size of the left canvas.</param>
        /// <param name="RightCanvas">The size of the right canvas.</param>
        public void ResizeEvent(ImageDimension LeftCanvas, ImageDimension RightCanvas)
        {
            if(LeftCanvas.Height >= 0 && LeftCanvas.Width>= 0) { leftImageSize = LeftCanvas; }
            if(RightCanvas.Height >= 0 && RightCanvas.Width >= 0) { rightImageSize = RightCanvas; }
            RepopulateDeletionMatrixes();
        }

        /// <summary>
        /// A function to reset the right image.
        /// </summary>
        public void ResetRightImage()
        {
            rightLineList.Clear();
            programPresenter.PassLastActionTaken(historyOfActions.Reset());
            programPresenter.ClearRightLines();
        }

        /// <summary>
        /// The function to set the left image.
        /// </summary>
        /// <param name="width">The width of the left image.</param>
        /// <param name="height">The height of the left image.</param>
        /// <param name="listOfLines">The List of Lines to be displayed in the left image.</param>
        public void SetLeftLineList(int width, int height, List<InternalLine> listOfLines)
        {
            leftImageSize = new ImageDimension(width, height);
            rightImageSize = new ImageDimension(width, height);
            leftLineList = listOfLines;
            graphicLoaded = true;
            programPresenter.UpdateLeftLines(leftLineList);
            CanvasActivated();
        }

        /// <summary>
        /// A function to tell the model a new canvas was activated.
        /// </summary>
        public void CanvasActivated()
        {
            canvasActive = true;
            RepopulateDeletionMatrixes();
            UpdateUI();
        }

        /// <summary>
        /// Will undo the last action taken, if the action history allows it.
        /// </summary>
        public void Undo()
        {
            if (historyOfActions.CanUndo())
            {
                HashSet<int> affectedLines = historyOfActions.GetCurrentAction().GetLineIDs();
                SketchAction.ActionType undoAction = historyOfActions.GetCurrentAction().GetActionType();
                switch (undoAction)
                {
                    case SketchAction.ActionType.Delete:
                        //Deleted Lines need to be shown
                        ChangeLines(affectedLines, true);
                        break;
                    case SketchAction.ActionType.Draw:
                        //Drawn lines need to be hidden
                        ChangeLines(affectedLines, false);
                        break;
                    default:
                        break;
                }
                programPresenter.UpdateRightLines(rightLineList);
            }
            RepopulateDeletionMatrixes();
            programPresenter.PassLastActionTaken(historyOfActions.MoveAction(true));
            UpdateUI();
        }

        /// <summary>
        /// Will redo the last action undone, if the action history allows it.
        /// </summary>
        public void Redo()
        {
            if (historyOfActions.CanRedo())
            {
                programPresenter.PassLastActionTaken(historyOfActions.MoveAction(false));
                HashSet<int> affectedLines = historyOfActions.GetCurrentAction().GetLineIDs();
                SketchAction.ActionType redoAction = historyOfActions.GetCurrentAction().GetActionType();
                switch (redoAction)
                {
                    case SketchAction.ActionType.Delete:
                        //Deleted Lines need to be redeleted
                        ChangeLines(affectedLines, false);
                        break;
                    case SketchAction.ActionType.Draw:
                        //Drawn lines need to be redrawn
                        ChangeLines(affectedLines, true);
                        break;
                    default:
                        break;
                }
                //TODO: For the person implementing overlay: Add check if overlay needs to be added
                programPresenter.UpdateRightLines(rightLineList);
                RepopulateDeletionMatrixes();
            }
            UpdateUI();
        }

        /// <summary>
        /// The function called by the Presenter to change the drawing state of the program.
        /// </summary>
        /// <param name="nowDrawing">The new drawingstate of the program</param>
        public void ChangeState(bool nowDrawing)
        {
            inDrawingMode = nowDrawing;
            UpdateUI();
        }
        
        /// <summary>
        /// Updates the current cursor position of the model.
        /// </summary>
        /// <param name="p">The new cursor position</param>
        public void SetCurrentCursorPosition(Point p)
        {
            currentCursorPosition = p;
            mouseDown = programPresenter.IsMousePressed();
        }

        /// <summary>
        /// Start a new Line, when the Mouse is pressed down.
        /// </summary>
        public void MouseDown()
        {
            mouseDown = true;
            if (inDrawingMode && mouseDown)
            {
                currentLine.Clear();
                currentLine.Add(currentCursorPosition);
            }
        }

        /// <summary>
        /// Finish the current Line, when the pressed Mouse is released.
        /// </summary>
        /// <param name="valid">Whether the up event is valid or not</param>
        public void MouseUp(bool valid)
        {
            mouseDown = false;
            if (valid)
            {
                if (inDrawingMode && currentLine.Count > 0)
                {
                    InternalLine newLine = new InternalLine(currentLine, rightLineList.Count);
                    rightLineList.Add(new Tuple<bool, InternalLine>(true, newLine));
                    newLine.PopulateMatrixes(isFilledMatrix, linesMatrix);
                    programPresenter.PassLastActionTaken(historyOfActions.AddNewAction(new SketchAction(SketchAction.ActionType.Draw, newLine.GetID())));
                    programPresenter.UpdateRightLines(rightLineList);
                    currentLine.Clear();
                }
            }
            else
            {
                currentLine.Clear();
            }
            UpdateUI();
        }

        /// <summary>
        /// Finish the current Line, when the pressed Mouse is released.
        /// Overload that is used to pass a list of points to be used when one is available.
        /// </summary>
        /// <param name="p">The list of points</param>
        public void MouseUp(List<Point> p)
        {
            mouseDown = false;
            if (inDrawingMode && currentLine.Count > 0)
            {
                InternalLine newLine = new InternalLine(p, rightLineList.Count);
                rightLineList.Add(new Tuple<bool, InternalLine>(true, newLine));
                newLine.PopulateMatrixes(isFilledMatrix, linesMatrix);
                programPresenter.PassLastActionTaken(historyOfActions.AddNewAction(new SketchAction(SketchAction.ActionType.Draw, newLine.GetID())));
                programPresenter.UpdateRightLines(rightLineList);
                currentLine.Clear();
            }
            UpdateUI();
        }

        /// <summary>
        /// Method to be called every tick. Updates the current Line, or checks for Lines to delete, depending on the drawing mode.
        /// </summary>
        public void Tick()
        {
            if (cursorPositions.Count > 0) { previousCursorPosition = cursorPositions.Dequeue(); }
            else { previousCursorPosition = currentCursorPosition; }
            cursorPositions.Enqueue(currentCursorPosition);
            //Drawing
            if (inDrawingMode && programPresenter.IsMousePressed())
            {
                currentLine.Add(currentCursorPosition);
                //programPresenter.UpdateCurrentLine(currentLine);
            }
            //Deleting
            if (!inDrawingMode && programPresenter.IsMousePressed())
            {
                List<Point> uncheckedPoints = GeometryCalculator.BresenhamLineAlgorithm(previousCursorPosition, currentCursorPosition);
                foreach (Point currPoint in uncheckedPoints)
                {
                    HashSet<int> linesToDelete = CheckDeletionMatrixesAroundPoint(currPoint, deletionRadius);
                    if (linesToDelete.Count > 0)
                    {
                        programPresenter.PassLastActionTaken(historyOfActions.AddNewAction(new SketchAction(SketchAction.ActionType.Delete, linesToDelete)));
                        foreach (int lineID in linesToDelete)
                        {
                            rightLineList[lineID] = new Tuple<bool, InternalLine>(false, rightLineList[lineID].Item2);
                        }
                        RepopulateDeletionMatrixes();
                        //TODO: For the person implementing overlay: Add check if overlay needs to be added
                        programPresenter.UpdateRightLines(rightLineList);
                    }
                }
            }
        }

        /// <summary>
        /// If there is unsaved progress.
        /// </summary>
        /// <returns>True if there is progress that has not been saved.</returns>
        public bool HasUnsavedProgress()
        {
            return !historyOfActions.IsEmpty();
        }
    }
}