using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace EncrySMS
{
    public partial class ViewEncryptedForm : Form
    {
        public ViewEncryptedForm()
        {
            InitializeComponent();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            timer1.Enabled = false;
            Close();
        }
        public static void ShowDecryptContent(string EncryptedContent,ref bool bAutoClose) 
        {
            ViewEncryptedForm form = new ViewEncryptedForm();
            form.edtEncrypt.Text = EncryptedContent;
            form.chbAutoClose.Checked = bAutoClose;
            form.ShowDialog();
            bAutoClose = form.chbAutoClose.Checked;
            form = null;
        }

        private void ViewEncryptedForm_Activated(object sender, EventArgs e)
        {
            if (chbAutoClose.Checked)
            {
                timer1.Enabled = true;
                btnPin.Text = "釘住";
            }
            else
                btnPin.Text = "關閉";


        }
        private string Decrypt(string content)
        {
            if (content.Substring(0, 4) != "zzzz")
                return content;
            char[] tmp = content.Substring(4).ToCharArray();
            byte[] encryptedbyte = new byte[2];
            char[] encrypedchars = new char[tmp.Length];
            for (int i = 0; i < tmp.Length; i++)
            {
                byte[] charbyte = BitConverter.GetBytes(tmp[i]);
                if (charbyte[1] == 0)
                {
                    encryptedbyte[1] = 0;
                    if (charbyte[0] >= 0x20 && charbyte[0] <= 0x7e)//visible char
                    {
                        encryptedbyte[0] = (byte)(charbyte[0] - (byte)0x5);
                        if (encryptedbyte[0] < 0x20)
                            encryptedbyte[0] = (byte)(encryptedbyte[0] - 0x20 - (0xff - 0x7e));
                    }
                    else
                        encryptedbyte[0] = charbyte[0];

                }
                else
                {
                    encryptedbyte[0] = (byte)((charbyte[0] - 0x7) );
                    encryptedbyte[1] = (byte)((charbyte[1] - 0x7) );

                }
                encrypedchars[i] = BitConverter.ToChar(encryptedbyte, 0);

            }
            return new string(encrypedchars);

        }

        private void edtEncrypt_TextChanged(object sender, EventArgs e)
        {
            edtDecrypt.Text = Decrypt(edtEncrypt.Text);
        }

        private void btnPin_Click(object sender, EventArgs e)
        {
            if (btnPin.Text=="釘住")
            {
                timer1.Enabled = false;
                btnPin.Text = "關閉";

            }
            else
            {
                Close();

            }
        }

        private void ViewEncryptedForm_Closing(object sender, CancelEventArgs e)
        {
            timer1.Enabled = false;

        }

    }
}