using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace GraphingCalculator
{
    /// <summary>
    /// Interaction logic for GraphingCanvas.xaml
    /// </summary>
    public partial class GraphingCanvas : Canvas
    {
        #region Settings
        private double PlotPrecision 
        {
            get { return GraphingCalculator.Properties.Settings.Default.PlotPrecision; }
            set { GraphingCalculator.Properties.Settings.Default.PlotPrecision = value; }
        }

        private double GridDensity
        {
            get { return GraphingCalculator.Properties.Settings.Default.GridDensity; }
            set { GraphingCalculator.Properties.Settings.Default.GridDensity = value; }
        }

        private int RoundDoublesGraph
        {
            get { return GraphingCalculator.Properties.Settings.Default.RoundDoublesGraph; }
            set { GraphingCalculator.Properties.Settings.Default.RoundDoublesGraph = value; }
        }

        private double NavigationSens
        {
            get { return GraphingCalculator.Properties.Settings.Default.NavigationSensitivity; }
            set { GraphingCalculator.Properties.Settings.Default.NavigationSensitivity = value; }
        }

        private double ZoomSens
        {
            get { return GraphingCalculator.Properties.Settings.Default.ZoomSensitivity; }
            set { GraphingCalculator.Properties.Settings.Default.ZoomSensitivity = value; }
        }

        #endregion

        #region Constants
        private Point specialSeparator = new Point(double.MaxValue, double.MaxValue);
        private Point specialVisibleTrue = new Point(0, double.MaxValue);
        private Point specialVisibleFalse = new Point(0, double.MinValue);
        #endregion

        #region Expressions
        private List<VisualExpression> expressions = new List<VisualExpression>();
        public List<VisualExpression> Expressions { get { return expressions; } }

        /// <summary>
        /// Adds an expression to be plotted
        /// </summary>
        public void AddExpression(VisualExpression ex)
        {
            this.Expressions.Add(ex);
            EvaluateExpression(ex);
            Redraw();

            #region Log
            Log.LogEvent("Plotted expression '{0}'", ex.ExpressionString);
            #endregion
        }

        public void SetExpressionVisibility(int index, bool visibility)
        {
            if (Expressions[index].IsVisible == visibility) return;

            if (queuedPoints.Count != 0) {
                int i, ci;
                for (i = 0, ci = -1; i < queuedPoints.Count && ci < index; i++)
                    if (queuedPoints[i] == specialSeparator) ci++;

                queuedPoints[i] = (visibility) ? specialVisibleTrue : specialVisibleFalse;
            }

            Expressions[index].IsVisible = visibility;
            Redraw();
        }
        #endregion

        #region Canvas and screen bounds
        public Bounds CanvasBounds { get; set; }
        public Bounds ScreenBounds { get; set; }

        public double CoordXToCanvas(double x)
        {
            double scrX = x - ScreenBounds.Left;
            return CanvasBounds.Left + (CanvasBounds.Width * (scrX / ScreenBounds.Width));
        }

        public double CoordXToScreen(double x)
        {
            double canX = x - CanvasBounds.Left;
            return ScreenBounds.Left + (ScreenBounds.Width * (canX / CanvasBounds.Width));
        }

        public double CoordYToCanvas(double y)
        {
            double scrY = y - ScreenBounds.Bottom;
            return CanvasBounds.Bottom + (CanvasBounds.Height * (scrY / ScreenBounds.Height));
        }

        public double CoordYToScreen(double y)
        {
            double canY = y - CanvasBounds.Bottom;
            return ScreenBounds.Bottom + (ScreenBounds.Height * (canY / CanvasBounds.Height));
        }

        public Point CoordToCanvas(double x, double y)
        {
            return new Point(CoordXToCanvas(x), CoordYToCanvas(y));
        }

        public Point CoordToCanvas(Point p)
        {
            return new Point(CoordXToCanvas(p.X), CoordYToCanvas(p.Y));
        }

        public Point CoordToScreen(double x, double y)
        {
            return new Point(CoordXToScreen(x), CoordYToScreen(y));
        }

        public Point CoordToScreen(Point p)
        {
            return new Point(CoordXToScreen(p.X), CoordYToScreen(p.Y));
        }

        public void SetCanvasBounds(Bounds b)
        {
            if (b.Width <= 0 || b.Height <= 0) return;

            CanvasBounds.Top = b.Top;
            CanvasBounds.Bottom = b.Bottom;
            CanvasBounds.Left = b.Left;
            CanvasBounds.Right = b.Right;

            EvaluateExpressions();
            Redraw();
        }
        #endregion

        #region Constructor
        public GraphingCanvas()
        {
            InitializeComponent();

            CanvasBounds = new Bounds(-5, 5, 5, -5);
            ScreenBounds = new Bounds(0, 0, this.ActualWidth, this.ActualHeight);
        }
        #endregion

        #region UI Events
        private void Canvas_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            ScreenBounds.Right = e.NewSize.Width;
            ScreenBounds.Bottom = e.NewSize.Height;

            Redraw();
        }

        private void buttonReset_Click(object sender, RoutedEventArgs e)
        {
            CanvasBounds.Left = -5;
            CanvasBounds.Right = 5;
            CanvasBounds.Bottom = -5;
            CanvasBounds.Top = 5;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonUp_Click(object sender, RoutedEventArgs e)
        {
            double h = CanvasBounds.Height * NavigationSens;
            CanvasBounds.Top += h;
            CanvasBounds.Bottom += h;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonLeft_Click(object sender, RoutedEventArgs e)
        {
            double w = CanvasBounds.Width * NavigationSens;
            CanvasBounds.Left -= w;
            CanvasBounds.Right -= w;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonRight_Click(object sender, RoutedEventArgs e)
        {
            double w = CanvasBounds.Width * NavigationSens;
            CanvasBounds.Left += w;
            CanvasBounds.Right += w;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonBottom_Click(object sender, RoutedEventArgs e)
        {
            double h = CanvasBounds.Height * NavigationSens;
            CanvasBounds.Top -= h;
            CanvasBounds.Bottom -= h;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonZoomIn_Click(object sender, RoutedEventArgs e)
        {
            double new_w = CanvasBounds.Width / ZoomSens;
            double new_h = CanvasBounds.Height / ZoomSens;
            double diff_w = (CanvasBounds.Width - new_w) / 2 ;
            double diff_h = (CanvasBounds.Height - new_h) / 2;

            CanvasBounds.Left += diff_w;
            CanvasBounds.Right -= diff_w;
            CanvasBounds.Bottom += diff_h;
            CanvasBounds.Top -= diff_h;

            EvaluateExpressions();
            Redraw();
        }

        private void buttonZoomOut_Click(object sender, RoutedEventArgs e)
        {
            double new_w = CanvasBounds.Width * ZoomSens;
            double new_h = CanvasBounds.Height * ZoomSens;
            double diff_w = (CanvasBounds.Width - new_w) / 2;
            double diff_h = (CanvasBounds.Height - new_h) / 2;

            CanvasBounds.Left += diff_w;
            CanvasBounds.Right -= diff_w;
            CanvasBounds.Bottom += diff_h;
            CanvasBounds.Top -= diff_h;

            EvaluateExpressions();
            Redraw();
        }
        #endregion

        #region Expression evaluation
        List<Point> queuedPoints = new List<Point>();

        public void EvaluateExpression(VisualExpression expr)
        {
            queuedPoints.Add(specialSeparator);
            queuedPoints.Add((expr.IsVisible) ? specialVisibleTrue : specialVisibleFalse);

            for (double x = CanvasBounds.Left; x <= CanvasBounds.Right; x += CanvasBounds.Width / PlotPrecision)
            {
                expr.Variables["x"] = expr.Variables["X"] = x;
                queuedPoints.Add(new Point(x, expr.Evaluate()));
            }
        }

        public void EvaluateExpressions()
        {
            queuedPoints.Clear();
            foreach (var expr in Expressions)
                EvaluateExpression(expr);
        }
        #endregion

        #region Rendering
        public void Redraw()
        {
            this.InvalidateVisual();
        }

        private void RenderDouble(DrawingContext dc, double n, Point pos, bool center)
        {
            FormattedText text = new FormattedText(Math.Round(n, RoundDoublesGraph).ToString(),
                new System.Globalization.CultureInfo("en-US"), FlowDirection.LeftToRight, 
                new Typeface("Arial"), 8.0, Brushes.Black);

            if (center) dc.DrawText(text, new Point(pos.X - (text.Width / 2), pos.Y + 10));
            else dc.DrawText(text, new Point(pos.X + 2, pos.Y));
        }

        private void RenderGridVertical(DrawingContext dc, Pen pen, double from, double to, double interv)
        {
            if (from > to) interv *= -1;

            // Draw vertical grid
            for (double i = from; (from < to && i < to) || (from > to && i > to); i += interv)
            {
                Point text = CoordToScreen(i, 0);
                Point f = CoordToScreen(i, CanvasBounds.Bottom);
                Point t = CoordToScreen(i, CanvasBounds.Top);

                dc.DrawLine(pen, f, t);
                RenderDouble(dc, i, text, true);
            }
        }

        private void RenderGridHorizontal(DrawingContext dc, Pen pen, double from, double to, double interv)
        {
            if (from > to) interv *= -1;

            // Draw vertical grid
            for (double i = from; (from < to && i < to) || (from > to && i > to); i += interv)
            {
                Point text = CoordToScreen(0, i);
                Point f = CoordToScreen(CanvasBounds.Left, i);
                Point t = CoordToScreen(CanvasBounds.Right, i);

                dc.DrawLine(pen, f, t);
                RenderDouble(dc, i, text, false);
            }
        }

        private void RenderGrid(DrawingContext dc)
        {
            Pen pen = new Pen(new SolidColorBrush(Color.FromRgb(0xa6, 0xdd, 0xe2)), 1);
            pen.DashStyle = DashStyles.Dash;

            double w_div = Math.Truncate(this.ActualWidth / GridDensity);
            double h_div = Math.Truncate(this.ActualHeight / GridDensity);
            if (Convert.ToInt32(w_div) % 2 == 1) w_div += 1;
            if (Convert.ToInt32(h_div) % 2 == 1) h_div += 1;

            double w_int = CanvasBounds.Width / w_div;
            double h_int = CanvasBounds.Height / h_div;

            RenderGridVertical(dc, pen, 0, CanvasBounds.Right, w_int);
            RenderGridVertical(dc, pen, 0, CanvasBounds.Left, w_int);
            RenderGridHorizontal(dc, pen, 0, CanvasBounds.Top, h_int);
            RenderGridHorizontal(dc, pen, 0, CanvasBounds.Bottom, h_int);
        }

        private void RenderAxis(DrawingContext dc)
        {
            Point dst;
            Pen lines = new Pen(Brushes.Coral, 1.5);

            // Draw X axis
            dst = CoordToScreen(CanvasBounds.Right, 0);
            dc.DrawLine(lines, CoordToScreen(CanvasBounds.Left, 0), dst);
            dc.DrawLine(lines, dst, new Point(dst.X - 5, dst.Y + 2));
            dc.DrawLine(lines, dst, new Point(dst.X - 5, dst.Y - 2));

            // Draw Y axis
            dst = CoordToScreen(0, CanvasBounds.Top);
            dc.DrawLine(lines, CoordToScreen(0, CanvasBounds.Bottom), dst);
            dc.DrawLine(lines, dst, new Point(dst.X - 2, dst.Y + 5));
            dc.DrawLine(lines, dst, new Point(dst.X + 2, dst.Y + 5));
        }

        private void RenderFunctions(DrawingContext dc)
        {
            if (Expressions.Count == 0) return;

            int exprIndex = -1;
            bool visible = true;
            Pen pen = new Pen();

            for (int i = 0; i < queuedPoints.Count - 1; i++)
            {
                if (queuedPoints[i] == specialSeparator)
                {
                    exprIndex++; i++;
                    pen = new Pen(new SolidColorBrush(Expressions[exprIndex].Color), Expressions[exprIndex].Thickness);
                    visible = (queuedPoints[i] == specialVisibleTrue);
                }

                else if (visible && queuedPoints[i + 1] != specialSeparator)
                {
                    Point src = CoordToScreen(queuedPoints[i]);
                    Point dst = CoordToScreen(queuedPoints[i + 1]);

                    if (ScreenBounds.IsInBounds(src) || ScreenBounds.IsInBounds(dst)) 
                        dc.DrawLine(pen, src, dst);
                }
            }
        }

        protected override void OnRender(DrawingContext dc)
        {
            // Reduce garbage collector intrusions
            var latency = System.Runtime.GCSettings.LatencyMode;
            System.Runtime.GCSettings.LatencyMode = System.Runtime.GCLatencyMode.LowLatency;

            // Draw grid
            RenderGrid(dc);
            RenderAxis(dc);

            // Render functions
            RenderFunctions(dc);

            // Base render
            base.OnRender(dc);

            // Restore previous garbage collector setting
            System.Runtime.GCSettings.LatencyMode = latency;
        } 
        #endregion

        private void Canvas_MouseWheel(object sender, MouseWheelEventArgs e)
        {
            if (e.Delta > 0) buttonZoomIn_Click(this, new RoutedEventArgs());
            else buttonZoomOut_Click(this, new RoutedEventArgs());
        }

        #region Navigation control
        public void PeformMouseWheelChange(MouseWheelEventArgs e)
        {
            Canvas_MouseWheel(this, e);
        }

        public void PerformMoveLeft() 
        {
            buttonLeft_Click(this, new RoutedEventArgs());
        }

        public void PerformMoveRight()
        {
            buttonRight_Click(this, new RoutedEventArgs());
        }

        public void PerformMoveUp()
        {
            buttonUp_Click(this, new RoutedEventArgs());
        }

        public void PerformMoveDown()
        {
            buttonBottom_Click(this, new RoutedEventArgs());
        }

        public void PerformReset()
        {
            buttonReset_Click(this, new RoutedEventArgs());
        }

        public void PerformZoomIn()
        {
            buttonZoomIn_Click(this, new RoutedEventArgs());
        }

        public void PerformZoomOut()
        {
            buttonZoomOut_Click(this, new RoutedEventArgs());
        }
        #endregion
    }
}