using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
//using System.IO;
//using System.Runtime.InteropServices;

namespace Biff8Excel.COM
{
    public sealed class Storage : IDisposable
    {
        private bool disposed;
        private IStorage storage;

        public Storage(IStorage storage)
        {
            this.storage = storage;
        }

        ~Storage()
        {
            this.Dispose();
        }

        public static Storage CreateDocFile(string storageFile, StorageMode mode)
        {
            IStorage storage = NativeMethods.StgCreateDocfile(storageFile, (int)mode, 0);

            return new Storage(storage);
        }

        public static Storage Open(string storageFile, StorageMode mode)
        {
            IStorage storage = NativeMethods.StgOpenStorage(storageFile, IntPtr.Zero, (int)mode, IntPtr.Zero, 0);

            return new Storage(storage);
        }

        public void CopyTo(Storage destinationStorage)
        {
            this.storage.CopyTo(0, IntPtr.Zero, IntPtr.Zero, destinationStorage.storage);
        }

        public Storage OpenStorage(string name, bool autoCreate)
        {
            IStorage subStorage;

            try
            {
                this.storage.OpenStorage(name, null, (int)(StorageMode.ReadWrite | StorageMode.ShareExclusive), IntPtr.Zero, 0, out subStorage);
            }
            catch (COMException)
            {
                subStorage = null;
            }

            if (subStorage == null)
            {
                if (autoCreate)
                    return CreateStorage(name);

                return null;
            }

            return new Storage(subStorage);
        }

        public Storage RecurOpenStorage(string name, bool autoCreate)
        {
            string pwcsName;
            if (name == null)
                throw new Biff8ExcelException("名称不得为null");

            int pos = name.IndexOf('\\');
            if (pos > 0)
            {
                pwcsName = name.Substring(0, pos);
                name = name.Substring(pos + 1);
            }
            else
            {
                pwcsName = name;
                name = "";
            }

            Storage subStorage = OpenStorage(pwcsName, autoCreate);
            if (subStorage != null && name.Length > 0)
            {
                return subStorage.RecurOpenStorage(name, autoCreate);
            }

            return subStorage;
        }

        public void Dispose()
        {
            if (!this.disposed)
            {
                Marshal.ReleaseComObject(this.storage);
                this.storage = null;

                this.disposed = true;
            }

            GC.SuppressFinalize(this);
        }

        public Storage CreateStorage(string name)
        {
            IStorage subStorage = null;

            try
            {
                //this.storage.OpenStorage(name, null,
                //                       (int)(StorageMode.ReadWrite | StorageMode.ShareExclusive),
                //                       IntPtr.Zero, 0, out subStorage);
                
                this.storage.CreateStorage(name,
                                           (int)(StorageMode.Create | StorageMode.ReadWrite | StorageMode.ShareExclusive),
                                           0, 0, out subStorage);
                this.storage.Commit(0);

                return new Storage(subStorage);
            }
            catch (COMException)
            {
                if (subStorage != null)
                    Marshal.ReleaseComObject(subStorage);
            }

            return null;
        }

        public COMStream CreateStream(string name)
        {
            IStreamRef subStream = null;

            try
            {
                //this.storage.OpenStream(name, IntPtr.Zero,
                //                      (int)(StorageMode.ReadWrite | StorageMode.ShareExclusive),
                //                      0, out subStream);

                //if (subStream != null)
                //    this.storage.DestroyElement(name);

                //Now create the element
                this.storage.CreateStream(name,
                                        (int)(StorageMode.Create | StorageMode.ReadWrite | StorageMode.ShareExclusive),
                                        0, 0, out subStream);
                this.storage.Commit(0);

                return new COMStream(subStream);
            }
            catch (COMException)
            {
                if (subStream != null)
                    Marshal.ReleaseComObject(subStream);

                return null;
            }
        }

        public COMStream OpenStream(string name)
        {
            IStreamRef subStream;

            try
            {
                this.storage.OpenStream(name, IntPtr.Zero,
                                      (int)(StorageMode.ReadWrite | StorageMode.ShareExclusive),
                                      0, out subStream);

                return new COMStream(subStream);
            }
            catch (COMException)
            {
                return null;
            }
        }

        public void Commit(int grfCommitFlags)
        {
            this.storage.Commit(grfCommitFlags);
        }
    }

}