using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
// DllImportに必要
using System.Runtime.InteropServices;

namespace Explorer
{
    public partial class Form1 : Form
    {
        /// <summary>
        /// ファイル情報を取得
        /// </summary>
        /// <param name="pszPath"></param>
        /// <param name="dwFileAttributes"></param>
        /// <param name="psfi"></param>
        /// <param name="cbFileInfo"></param>
        /// <param name="uFlags"></param>
        /// <returns></returns>
        [DllImport("shell32.dll", CharSet = CharSet.Auto)]
        private static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, out SHFILEINFO psfi, uint cbFileInfo, uint uFlags);

        /// <summary>
        /// イメージリストを登録
        /// </summary>
        /// <param name="hWnd"></param>
        /// <param name="Msg"></param>
        /// <param name="wParam"></param>
        /// <param name="lParam"></param>
        /// <returns></returns>
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        /// <summary>
        /// SHGetFileInfo関数で使用する構造体
        /// </summary>
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        private struct SHFILEINFO
        {
            public IntPtr hIcon;
            public int iIcon;
            public uint dwAttributes;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
            public string szDisplayName;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
            public string szTypeName;
        };

        // ファイル情報用
        private const int SHGFI_LARGEICON = 0x00000000;
        private const int SHGFI_SMALLICON = 0x00000001;
        private const int SHGFI_USEFILEATTRIBUTES = 0x00000010;
        private const int SHGFI_OVERLAYINDEX = 0x00000040;
        private const int SHGFI_ICON = 0x00000100;
        private const int SHGFI_SYSICONINDEX = 0x00004000;
        private const int SHGFI_TYPENAME = 0x000000400;

        // TreeView用
        private const int TVSIL_NORMAL = 0x0000;
        private const int TVSIL_STATE = 0x0002;
        private const int TVM_SETIMAGELIST = 0x1109;

        // ListView用
        private const int LVSIL_NORMAL = 0;
        private const int LVSIL_SMALL = 1;
        private const int LVM_SETIMAGELIST = 0x1003;

        // 選択された項目を保持
        private String selectedItem = "";

        public Form1()
        {
            InitializeComponent();

            // イメージリストの設定
            SHFILEINFO shFileInfo = new SHFILEINFO();
            IntPtr imageListHandle = SHGetFileInfo(String.Empty, 0, out shFileInfo, (uint)Marshal.SizeOf(shFileInfo), SHGFI_SMALLICON | SHGFI_SYSICONINDEX);
            // TreeView
            SendMessage(treeView1.Handle, TVM_SETIMAGELIST, new IntPtr(TVSIL_NORMAL), imageListHandle);
            // ListView
            SendMessage(listView1.Handle, LVM_SETIMAGELIST, new IntPtr(LVSIL_SMALL), imageListHandle);

            // ドライブ一覧を走査してツリーに追加
            foreach (String drive in Environment.GetLogicalDrives())
            {
                // アイコンの取得
                int iconIndex = 0;
                IntPtr hSuccess = SHGetFileInfo(drive, 0, out shFileInfo, (uint)Marshal.SizeOf(shFileInfo), SHGFI_SYSICONINDEX);
                if (hSuccess != IntPtr.Zero)
                {
                    iconIndex = shFileInfo.iIcon;
                }

                // 新規ノード作成
                // プラスボタンを表示するため空のノードを追加しておく
                TreeNode node = new TreeNode(drive, iconIndex, iconIndex);
                node.Nodes.Add(new TreeNode());
                treeView1.Nodes.Add(node);
            }

            // 初期選択ドライブの内容を表示
            setListItem(Environment.GetLogicalDrives().First());
        }

        /// <summary>
        /// ファイルサイズを単位付きに変換して返します.
        /// </summary>
        /// <param name="fileSize"></param>
        /// <returns></returns>
        private String getFileSize(long fileSize)
        {
            String ret = fileSize + " バイト";
            if (fileSize > (1024f * 1024f * 1024f))
            {
                ret = Math.Round((fileSize / 1024f / 1024f / 1024f), 2).ToString() + " GB";
            }
            else if (fileSize > (1024f * 1024f))
            {
                ret = Math.Round((fileSize / 1024f / 1024f), 2).ToString() + " MB";
            }
            else if (fileSize > 1024f)
            {
                ret = Math.Round((fileSize / 1024f)).ToString() + " KB";
            }

            return ret;
        }

        /// <summary>
        /// リストビューの項目を設定します.
        /// </summary>
        private void setListItem(String filePath)
        {
            // リストビューのヘッダーを設定
            listView1.View = View.Details;
            listView1.Clear();
            listView1.Columns.Add("名前");
            listView1.Columns.Add("種類");
            listView1.Columns.Add("更新日時");
            listView1.Columns.Add("サイズ");

            try
            {
                // フォルダ一覧
                DirectoryInfo dirList = new DirectoryInfo(filePath);
                foreach (DirectoryInfo di in dirList.GetDirectories())
                {
                    ListViewItem item = new ListViewItem(di.Name);

                    // フォルダ種類、アイコンの取得
                    String type = "";
                    int iconIndex = 0;
                    SHFILEINFO shFileInfo = new SHFILEINFO();
                    IntPtr hSuccess = SHGetFileInfo(di.FullName, 0, out shFileInfo, (uint)Marshal.SizeOf(shFileInfo),
                        SHGFI_ICON | SHGFI_LARGEICON | SHGFI_SMALLICON | SHGFI_SYSICONINDEX | SHGFI_TYPENAME);
                    if (hSuccess != IntPtr.Zero)
                    {
                        type = shFileInfo.szTypeName;
                        iconIndex = shFileInfo.iIcon;
                    }

                    // 各列の内容を設定
                    item.ImageIndex = iconIndex;
                    item.SubItems.Add(type);
                    item.SubItems.Add(String.Format("{0:yyyy/MM/dd HH:mm:ss}", di.LastAccessTime));
                    item.SubItems.Add("");

                    // リストに追加
                    listView1.Items.Add(item);

                }

                // ファイル一覧
                List<String> files = Directory.GetFiles(filePath).ToList<String>();
                foreach (String file in files)
                {
                    FileInfo info = new FileInfo(file);
                    ListViewItem item = new ListViewItem(info.Name);

                    // ファイル種類、アイコンの取得
                    String type = "";
                    int iconIndex = 0;
                    SHFILEINFO shinfo = new SHFILEINFO();
                    IntPtr hSuccess = SHGetFileInfo(info.FullName, 0, out shinfo, (uint)Marshal.SizeOf(shinfo), SHGFI_ICON | SHGFI_LARGEICON | SHGFI_SMALLICON | SHGFI_SYSICONINDEX | SHGFI_TYPENAME);
                    if (hSuccess != IntPtr.Zero)
                    {
                        type = shinfo.szTypeName;
                        iconIndex = shinfo.iIcon;
                    }

                    // 各列の内容を設定
                    item.ImageIndex = iconIndex;
                    item.SubItems.Add(type);
                    item.SubItems.Add(String.Format("{0:yyyy/MM/dd HH:mm:ss}", info.LastAccessTime));
                    item.SubItems.Add(getFileSize(info.Length));
                    listView1.Items.Add(item);
                }
            }
            catch (IOException ie)
            {
                MessageBox.Show(ie.Message, "選択エラー");
            }

            // 列幅を自動調整
            listView1.AutoResizeColumns(ColumnHeaderAutoResizeStyle.HeaderSize);
        }

        /// <summary>
        /// ツリービュー項目展開時（前）のイベントハンドラ.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void treeView1_BeforeExpand(object sender, TreeViewCancelEventArgs e)
        {
            TreeNode node = e.Node;
            node.Nodes.Clear();

            try
            {
                DirectoryInfo dirList = new DirectoryInfo(node.FullPath);
                foreach (DirectoryInfo di in dirList.GetDirectories())
                {
                    // フォルダのアイコンを取得
                    SHFILEINFO shinfo = new SHFILEINFO();
                    int iconIndex = 0;
                    IntPtr hSuccess = SHGetFileInfo(di.FullName, 0, out shinfo, (uint)Marshal.SizeOf(shinfo), SHGFI_ICON | SHGFI_LARGEICON | SHGFI_SMALLICON | SHGFI_SYSICONINDEX | SHGFI_TYPENAME);
                    if (hSuccess != IntPtr.Zero)
                    {
                        iconIndex = shinfo.iIcon;
                    }

                    // 子を追加してノードを展開
                    TreeNode child = new TreeNode(di.Name, shinfo.iIcon, shinfo.iIcon);
                    child.ImageIndex = iconIndex;
                    child.Nodes.Add(new TreeNode());
                    node.Nodes.Add(child);
                }
            }
            catch (IOException ie)
            {
                MessageBox.Show(ie.Message, "選択エラー");
            }
        }

        /// <summary>
        /// ツリービュー項目選択時（前）のイベントハンドラ.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            setListItem(e.Node.FullPath);
        }
    }
}