using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace GraphingCalculator.IO
{
    public class ExpressionFile
    {
        private List<VisualExpression> expressions = new List<VisualExpression>();
        public List<VisualExpression> Expressions { get { return expressions; } }

        public void SaveToFile(string filename)
        {
            System.Xml.XmlWriter writer = System.Xml.XmlWriter.Create(filename, new System.Xml.XmlWriterSettings() { Indent = true });
            writer.WriteStartDocument();
            writer.WriteStartElement("Document");

            // Write expressions
            writer.WriteStartElement("ExpressionList");
            foreach (var i in Expressions)
            {
                writer.WriteStartElement("Expression");
                writer.WriteAttributeString("String", i.ExpressionString);
                writer.WriteAttributeString("IsVisible", i.IsVisible.ToString());
                writer.WriteAttributeString("Color", i.Color.ToString());

                foreach (var j in i.Variables)
                {
                    writer.WriteStartElement("Variable");
                    writer.WriteAttributeString("Key", j.Key);
                    writer.WriteAttributeString("Value", j.Value.ToString());
                    writer.WriteEndElement();
                }

                writer.WriteEndElement();
            }

            writer.WriteEndElement();

            // Finish
            writer.WriteEndElement();
            writer.WriteEndDocument();
            writer.Close();
        }

        public void LoadFromFile(string filename)
        {
            System.Xml.XmlReader reader = System.Xml.XmlReader.Create(filename);
            string varKey = "", varVal = "";
            VisualExpression expr;
            
            while (reader.Read())
                switch (reader.NodeType)
                {
                    case System.Xml.XmlNodeType.Element:
                        // Read an expression
                        if (reader.Name == "Expression")
                        {
                            expr = new VisualExpression();
                            while (reader.MoveToNextAttribute()) {
                                if (reader.Name == "String") expr.ExpressionString = reader.Value;
                                else if (reader.Name == "IsVisible") expr.IsVisible = bool.Parse(reader.Value);
                                else if (reader.Name == "Color") expr.Color = (System.Windows.Media.Color) System.Windows.Media.ColorConverter.ConvertFromString(reader.Value);
                            }

                            this.Expressions.Add(expr);
                        }

                        // A variable
                        else if (reader.Name == "Variable") 
                        {
                            while (reader.MoveToNextAttribute()) {
                                if (reader.Name == "Key") varKey = reader.Value;
                                else if (reader.Name == "Value") varVal = reader.Value; 
                            }

                            if (varKey != "") 
                                this.Expressions.Last().Variables[varKey] = double.Parse(varVal);
                        }

                        break;
                }

            reader.Close();
        }
    }
}