using System;
using System.Drawing;
using System.Windows.Forms;
using System.IO;

public class UI : Form
{
    private Label inputFileLabel;
    private Label outputFileLabel;
    private Label statusLabel;

    private Button inputFileButton;
    private Button outputFileButton;
    private Button convertButton;

    public FileStream inputFileStream;
    public FileStream outputFileStream;

    public UI()
    {
        Size = new Size(380,170);

        Text = "File Converter";

        inputFileLabel = new Label();
        inputFileLabel.Text = "(none chosen)";
        inputFileLabel.Location = new Point(24,16);
        inputFileLabel.Size = new Size(190,30);

        outputFileLabel = new Label();
        outputFileLabel.Text = "(none chosen)";
        outputFileLabel.Location = new Point(24,56);
        outputFileLabel.Size = new Size(190,30);

        statusLabel = new Label();
        statusLabel.Location = new Point(24,96);
        statusLabel.Size = new Size(190,60);

        inputFileButton = new Button();
        inputFileButton.Text = "Select input file";
        inputFileButton.Location = new Point(230,16);
        inputFileButton.Size = new Size(130,20);
        inputFileButton.Click += new EventHandler(inputFileButtonClicked);

        outputFileButton = new Button();
        outputFileButton.Text = "Select ouput file";
        outputFileButton.Location = new Point(230,56);
        outputFileButton.Size = new Size(130,20);
        outputFileButton.Click += new EventHandler(outputFileButtonClicked);

        convertButton = new Button();
        convertButton.Text = "Convert";
        convertButton.Location = new Point(230,96);
        convertButton.Size = new Size(100,20);
        convertButton.Click += new EventHandler(convert);
        convertButton.Hide();

        this.Controls.Add(inputFileLabel);
        this.Controls.Add(inputFileButton);
        this.Controls.Add(outputFileLabel);
        this.Controls.Add(outputFileButton);
        this.Controls.Add(convertButton);
        this.Controls.Add(statusLabel);

        validate();
    }

    private void validate()
    {
        if (null!=inputFileStream && null!=outputFileStream)
        {
            convertButton.Show();
            statusLabel.Text = "Ready to convert";
        } else {
            convertButton.Hide();
            statusLabel.Text = "Choose files";
        }
    }

    private void convert(object o, EventArgs e)
    {
        statusLabel.Text = "Converting...";
        convertButton.Hide();

        // call real convert

        inputFileStream.Close();
        outputFileStream.Close();
        convertButton.Show();
        statusLabel.Text = "Done converting.";
    }

    private void inputFileButtonClicked(object o, EventArgs e)
    {
        OpenFileDialog fd = new OpenFileDialog();
        if (fd.ShowDialog() == DialogResult.OK)
        {
            if (outputFileLabel.Text == fd.FileName)
            {
                statusLabel.Text = "Input file and output file must be different";
            } else {
                inputFileLabel.Text = fd.FileName;
                inputFileStream = (FileStream)fd.OpenFile();
                validate();
            }
        }
    }

    private void outputFileButtonClicked(object o, EventArgs e)
    {
        SaveFileDialog fd = new SaveFileDialog();
        if (fd.ShowDialog() == DialogResult.OK)
        {
            if (inputFileLabel.Text == fd.FileName)
            {
                statusLabel.Text = "Input file and output file must be different";
            } else {
                outputFileLabel.Text = fd.FileName;
                outputFileStream = (FileStream)fd.OpenFile();
                validate();
            }
        }
    }

    public static void Main()
    {
        Application.Run(new UI());
    }
}