using System;
using System.Collections;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32;
using System.Drawing;

namespace DTS.Common.Utilities
{
    public class PersistWindowState : System.ComponentModel.Component
    {
        // event info that allows form to persist extra window state data
        public delegate void WindowStateDelegate(object sender, RegistryKey key);
        public event WindowStateDelegate LoadStateEvent;
        public event WindowStateDelegate SaveStateEvent;

        private Form m_parent;
        private string m_regPath;
        private int m_normalLeft;
        private int m_normalTop;
        private int m_normalWidth;
        private int m_normalHeight;
        private FormWindowState m_windowState;
        private bool m_allowSaveMinimized = false;
        private bool m_startMaximized = false;

        public PersistWindowState()
        {
        }

        public Form Parent
        {
            set
            {
                m_parent = value;

                // subscribe to parent form's events
                m_parent.Closing += new System.ComponentModel.CancelEventHandler(OnClosing);
                m_parent.Resize += new System.EventHandler(OnResize);
                m_parent.Move += new System.EventHandler(OnMove);
                m_parent.Load += new System.EventHandler(OnLoad);

                // get initial width and height in case form is never resized
                m_normalWidth = m_parent.Width;
                m_normalHeight = m_parent.Height;
            }
            get => m_parent;
        }

        // registry key should be set in parent form's constructor
        public string RegistryPath
        {
            set => m_regPath = value;
            get => m_regPath;
        }

        public bool AllowSaveMinimized
        {
            set => m_allowSaveMinimized = value;
        }

        public bool StartMaximized
        {
            set => m_startMaximized = value;
        }

        private void OnResize(object sender, System.EventArgs e)
        {
            // save width and height
            if (m_parent.WindowState == FormWindowState.Normal)
            {
                m_normalWidth = m_parent.Width;
                m_normalHeight = m_parent.Height;
            }
        }

        private void OnMove(object sender, System.EventArgs e)
        {
            // save position
            if (m_parent.WindowState == FormWindowState.Normal)
            {
                m_normalLeft = m_parent.Left;
                m_normalTop = m_parent.Top;
            }
            // save state
            m_windowState = m_parent.WindowState;
        }

        private void OnClosing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            // save position, size and state
            var key = Registry.CurrentUser.CreateSubKey(m_regPath);
            key.SetValue("Left", m_normalLeft);
            key.SetValue("Top", m_normalTop);
            key.SetValue("Width", m_normalWidth);
            key.SetValue("Height", m_normalHeight);

            // check if we are allowed to save the state as minimized (not normally)
            if (!m_allowSaveMinimized)
            {
                if (m_windowState == FormWindowState.Minimized)
                    m_windowState = FormWindowState.Normal;
            }

            key.SetValue("WindowState", (int)m_windowState);

            // fire SaveState event
            if (SaveStateEvent != null)
                SaveStateEvent(this, key);
        }

        private void OnLoad(object sender, System.EventArgs e)
        {
            // attempt to read state from registry
            var key = Registry.CurrentUser.OpenSubKey(m_regPath);
            if (key != null)
            {
                var left = (int)key.GetValue("Left", m_parent.Left);
                var top = (int)key.GetValue("Top", m_parent.Top);
                var width = (int)key.GetValue("Width", m_parent.Width);
                var height = (int)key.GetValue("Height", m_parent.Height);
                var windowState = new FormWindowState();
                if (m_startMaximized == true)
                {
                    windowState = FormWindowState.Maximized;
                }
                else
                {
                    windowState = (FormWindowState)key.GetValue("WindowState", (int)m_parent.WindowState);
                }
                if (Screen.AllScreens.Length == 1)
                {
                    //There is only 1 monitor, so disregard what was in the registry
                    //to ensure that the window is not displayed on a non-existent monitor
                    m_parent.Location = new Point(100, 100);
                }
                else
                {
                    m_parent.Location = new Point(left, top);
                }
                m_parent.Size = new Size(width, height);
                m_parent.WindowState = windowState;

                // fire LoadState event
                if (LoadStateEvent != null)
                    LoadStateEvent(this, key);
            }
        }
    }
}