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.Shapes;

namespace GraphingCalculator
{
    /// <summary>
    /// Interaction logic for EvaluateWindow.xaml
    /// </summary>
    public partial class EvaluateWindow : Window
    {
        private Dictionary<string, double> variables = new Dictionary<string, double>();

        #region Properties
        public string InputExpression
        {
            get { return inputExpression.Text; }
            set { inputExpression.Text = value; }
        }
        #endregion

        #region Constructors
        public EvaluateWindow()
        {
            InitializeComponent();
        }
        
        public EvaluateWindow(string txt)
        {
            InitializeComponent();
            InputExpression = txt;

            // Convenience: evaluate already
            buttonEval_Click(this, new RoutedEventArgs());
        }
        #endregion

        #region User input
        private void buttonAdd_Click(object sender, RoutedEventArgs e)
        {
            string errorMessage = "";
            double val = 0;

            outputResult.Clear();

            // Verify boxes are not empty
            if (inputVarName.Text == "" || inputVarValue.Text == "")
                errorMessage = "Name or value cannot be empty!";
            
            // Get number
            if (errorMessage == "" && !double.TryParse(inputVarValue.Text, out val))
            {
                try {
                    Expression expr = new Expression(inputVarValue.Text);
                    val = expr.Evaluate();
                }

                catch { errorMessage = "Value must be a number!"; }
            }

            // Verify name is unique
            if (errorMessage == "" && variables.ContainsKey(inputVarName.Text))
            {
                var res = MessageBox.Show("A variable with the same name already exists. Replace it with the new value?", "Warning", MessageBoxButton.YesNo);
                if (res != MessageBoxResult.Yes) errorMessage = "A variable with the same name already exists!";
            }

            // Verify name doesn't contain forbidden characters
            if (errorMessage == "")
            {
                bool ok = char.IsLetter (inputVarName.Text.First());
                foreach (var i in inputVarName.Text)
                    if (!char.IsLetterOrDigit(i)) ok = false;

                if (!ok) errorMessage = "Forbidden variable name, it can only contain letters or digits!";
            }

            // Add variable
            if (errorMessage == "")
            {
                variables[inputVarName.Text] = val;
                
                // Remove if it exists already
                for (int i = 0; i < listVars.Items.Count; i++)
                {
                    string str = listVars.Items[i] as string;
                    if (str != null && str.StartsWith(inputVarName.Text + " = ")) listVars.Items.RemoveAt(i);
                }

                // Add variable
                listVars.Items.Add(inputVarName.Text + " = " + inputVarValue.Text);

                // Clear text boxes
                inputVarName.Clear();
                inputVarValue.Clear();
            }

            else
            {
                outputResult.Foreground = Brushes.DarkRed;
                outputResult.Text = "Error adding variable: " + errorMessage;
            }
        }

        private void buttonEval_Click(object sender, RoutedEventArgs e)
        {
            // Create expression
            Expression expression = new Expression(inputExpression.Text);
            double result = 0;

            // Add variables
            foreach (var i in variables)
                expression.Variables.Add(i.Key, i.Value);

            // Try to evaluate
            try {
                result = expression.Evaluate();
            }

            catch (Exception ex) {
                outputResult.Text = "Error evaluating: " + ex.Message;
                outputResult.Foreground = Brushes.DarkRed;

                #region Log
                Log.LogEvent("Failed to evaluate expression '{0}'. Message: {1}", inputExpression.Text, ex.Message);
                Log.LogEvent("> Stack trace: {0}", ex.StackTrace);

                if (listVars.Items.Count > 0) Log.LogEvent("> Variables: ");

                foreach (var i in listVars.Items)
                    Log.LogEvent(">> {0}", i.ToString());
                #endregion

                return;
            }

            // Output results
            outputResult.Text = Math.Round(result, 15).ToString();
            outputResult.Foreground = Brushes.Black;

            #region Log
            // Log what happened here
            Log.LogEvent("Evaluated expression '{0}' result={1}", inputExpression.Text, outputResult.Text);
            if (listVars.Items.Count > 0) Log.LogEvent("> WHERE: ");

            foreach (var i in listVars.Items)
                Log.LogEvent(">> {0}", i.ToString());
            #endregion
        }

        private void buttonClose_Click(object sender, RoutedEventArgs e)
        {
            this.Close();
        }

        private void contextEdit_Click(object sender, RoutedEventArgs e)
        {
            // Make sure we have 1 selected item
            if (listVars.SelectedItems.Count != 1) return;

            // Get key
            var item = listVars.SelectedItem as string;
            if (item == null) return;
            string key = item.Substring(0, item.IndexOf(" = "));

            // Place in input boxes
            inputVarName.Text = key;
            inputVarValue.Text = variables[key].ToString();

            // Remove item
            listVars.Items.Remove(listVars.SelectedItem);
            variables.Remove(key);
        }

        private void contextDelete_Click(object sender, RoutedEventArgs e)
        {
            // Make sure we have 1 selected item
            if (listVars.SelectedItems.Count != 1) return;

            // Get key
            var item = listVars.SelectedItem as string;
            if (item == null) return;
            string key = item.Substring(0, item.IndexOf(" = "));

            // Remove
            listVars.Items.Remove(listVars.SelectedItem);
            variables.Remove(key);
        }

        private void contextClear_Click(object sender, RoutedEventArgs e)
        {
            listVars.Items.Clear();
            variables.Clear();
        }

        private void Window_KeyUp(object sender, KeyEventArgs e)
        {
            e.Handled = true;
            if (e.Key == Key.Escape) buttonClose_Click(this, new RoutedEventArgs());
            else if (e.Key == Key.Enter) buttonEval_Click(this, new RoutedEventArgs());
            else if (e.Key == Key.Insert) buttonAdd_Click(this, new RoutedEventArgs());

            else e.Handled = false;
        }
        #endregion
    }
}