using System;
using System.Collections.Generic;
using System.Linq;
using AppLimit.CloudComputing.SharpBox.Common.IO;
using AppLimit.CloudComputing.SharpBox.Exceptions;
using AppLimit.CloudComputing.SharpBox.StorageProvider.API;
using AppLimit.CloudComputing.SharpBox.StorageProvider.BaseObjects;

namespace AppLimit.CloudComputing.SharpBox.StorageProvider
{
    /// <summary>
    /// The generic storage provider class implements platform independent logic as 
    /// base for all managed storage provider. All platform specific logic has to be implemented 
    /// in the storage provider service interface
    /// </summary>
    public class GenericStorageProvider : ICloudStorageProviderInternal
    {
        /// <summary>
        /// A specific implementation of a storage service interface which contains
        /// all provider specific logic
        /// </summary>
        protected IStorageProviderService Service;

        /// <summary>
        /// A provider specific implementation of a session
        /// </summary>
        protected IStorageProviderSession Session;

        /// <summary>
        /// The constructure need a specific service implementation
        /// </summary>
        /// <param name="service"></param>
        public GenericStorageProvider(IStorageProviderService service)
        {
            Service = service;
        }

        #region ICloudStorageProvider Members        

        /// <summary>
        /// This method opens a session for the implemented storage provider based on an existing
        /// security token.
        /// </summary>
        /// <param name="configuration"></param>
        /// <param name="token"></param>
        /// <returns></returns>
        public ICloudStorageAccessToken Open(ICloudStorageConfiguration configuration, ICloudStorageAccessToken token)
        {
            // Verify the compatibility of the credentials
            if (!Service.VerifyAccessTokenType(token))
                throw new SharpBoxException(SharpBoxErrorCodes.ErrorInvalidCredentialsOrConfiguration);

            // create a new session
            Session = Service.CreateSession(token, configuration);

            // check the session
            if (Session == null)
                throw new SharpBoxException(SharpBoxErrorCodes.ErrorInvalidCredentialsOrConfiguration);

            // return the accesstoken token
            return Session.SessionToken;
        }

        /// <summary>
        /// This method closes the established session to a service provider
        /// </summary>
        public void Close()
        {
            // close the session
            Service.CloseSession(Session);

            // remove reference
            Session = null;
        }

        /// <summary>
        /// This methid returns the root node of the virtual filesystem which 
        /// is abstracted by SharpBox
        /// </summary>
        /// <returns></returns>
        public ICloudDirectoryEntry GetRoot()
        {
            return Service.RequestResource(Session, "/", null) as ICloudDirectoryEntry;
        }

        /// <summary>
        /// This method returns a filesystem object, this can be files or folders
        /// </summary>
        /// <param name="path"></param>
        /// <param name="parent"></param>
        /// <returns></returns>
        public ICloudFileSystemEntry GetFileSystemObject(string path, ICloudDirectoryEntry parent)
        {
            /*
             * This section generates for every higher object the object tree
             */
            var ph = new PathHelper(path);
            var elements = ph.GetPathElements();

            // create the virtual root
            var current = parent ?? GetRoot();

            // build the root

            // check if we request only the root
            if (path.Equals("/"))
                return current;

            if (Service.SupportsDirectRetrieve)
            {
                //Request directly
                return Service.RequestResource(Session, path.TrimStart('/'), current);
            }

            // create the path tree
            for (var i = 0; i <= elements.Length - 1; i++)
            {
                var elem = elements[i];

                if (i == elements.Length - 1)
                {
                    return current.GetChild(elem, false);
                }

                try
                {
                    current = current.GetChild(elem, true) as ICloudDirectoryEntry;
                }
                catch (SharpBoxException e)
                {
                    // if not found, create a virtual one
                    if (e.ErrorCode == SharpBoxErrorCodes.ErrorFileNotFound)
                        current = GenericStorageProviderFactory.CreateDirectoryEntry(Session, elem, current);
                    else
                        throw;
                }
            }

            // looks like an error
            return null;
        }

        /// <summary>
        /// This method creates a folder in a given parent folder.
        /// Override this if your storage support resources having same name in one folder. 
        /// </summary>
        /// <param name="name"></param>
        /// <param name="parent"></param>
        /// <returns></returns>
        public virtual ICloudDirectoryEntry CreateFolder(string name, ICloudDirectoryEntry parent)
        {
            // solve the parent issue
            if (parent == null)
            {
                parent = GetRoot();

                if (parent == null)
                    return null;
            }

            // Don't support resources having same name in one folder by default
            var child = parent.FirstOrDefault(x => x.Name.Equals(name) && x is ICloudDirectoryEntry);
            if (child != null)
                return child as ICloudDirectoryEntry;

            return Service.CreateResource(Session, name, parent) as ICloudDirectoryEntry;
        }

        /// <summary>
        /// This method removes a given filesystem object from the cloud storage
        /// </summary>
        /// <param name="fsentry"></param>
        /// <returns></returns>
        public bool DeleteFileSystemEntry(ICloudFileSystemEntry fsentry)
        {
            return Service.DeleteResource(Session, fsentry);
        }

        /// <summary>
        /// This method moves a specifc filesystem object from his current location
        /// into a new folder
        /// </summary>
        /// <param name="fsentry"></param>
        /// <param name="newParent"></param>
        /// <returns></returns>
        public bool MoveFileSystemEntry(ICloudFileSystemEntry fsentry, ICloudDirectoryEntry newParent)
        {
            return Service.MoveResource(Session, fsentry, newParent);
        }

        /// <summary>
        /// This method moves a specifc filesystem object from his current location
        /// into a new folder
        /// </summary>
        /// <param name="fsentry"></param>
        /// <param name="newParent"></param>
        /// <returns></returns>
        public bool CopyFileSystemEntry(ICloudFileSystemEntry fsentry, ICloudDirectoryEntry newParent)
        {
            return Service.CopyResource(Session, fsentry, newParent);
        }

        /// <summary>
        /// This method renames a given filesystem object (file or folder)
        /// </summary>
        /// <param name="fsentry"></param>
        /// <param name="newName"></param>
        /// <returns></returns>
        public bool RenameFileSystemEntry(ICloudFileSystemEntry fsentry, string newName)
        {
            // save the old name
            var renamedId = fsentry.Id;

            // rename the resource
            if (Service.RenameResource(Session, fsentry, newName))
            {
                // get the parent
                var p = fsentry.Parent as BaseDirectoryEntry;

                // remove the old childname
                p.RemoveChildById(renamedId);

                // readd the child
                p.AddChild(fsentry as BaseFileEntry);

                // go ahead
                return true;
            }
            return false;
        }

        /// <summary>
        /// This method creates a file in the cloud storage
        /// </summary>
        /// <param name="parent"></param>
        /// <param name="name"></param>
        /// <returns></returns>
        public virtual ICloudFileSystemEntry CreateFile(ICloudDirectoryEntry parent, string name)
        {
            // build the parent
            if (parent == null)
                parent = GetRoot();

            // build the file entry
            var newEntry = GenericStorageProviderFactory.CreateFileSystemEntry(Session, name, parent);
            return newEntry;
        }

        /// <summary>
        /// This method returns the absolut URL (with all authentication decorators) for a specific file
        /// system object
        /// </summary>
        /// <param name="path"></param>
        /// <param name="parent"></param>
        /// <returns></returns>
        public virtual Uri GetFileSystemObjectUrl(string path, ICloudDirectoryEntry parent)
        {
            var url = Service.GetResourceUrl(Session, parent, path);
            return new Uri(url);
        }

        /// <summary>
        /// This method returns the filesystem path (UNIX style) of a specific object
        /// </summary>
        /// <param name="fsObject"></param>
        /// <returns></returns>
        public virtual string GetFileSystemObjectPath(ICloudFileSystemEntry fsObject)
        {
            if (fsObject is ICloudDirectoryEntry)
                return GenericHelper.GetResourcePath(fsObject);

            return GenericHelper.GetResourcePath(fsObject.Parent) + "/" + fsObject.Id;
        }

        /// <summary>
        /// This method stores the given security token into a tokendictionary
        /// </summary>
        /// <param name="tokendata"></param>
        /// <param name="token"></param>
        public void StoreToken(Dictionary<string, string> tokendata, ICloudStorageAccessToken token)
        {
            Service.StoreToken(Session, tokendata, token);
        }

        /// <summary>
        /// This method loads the given token from the token dictionary
        /// </summary>
        /// <param name="tokendata"></param>
        /// <returns></returns>
        public ICloudStorageAccessToken LoadToken(Dictionary<string, string> tokendata)
        {
            return Service.LoadToken(tokendata);
        }

        /// <summary>
        /// This property returns the current accesstoken
        /// </summary>
        public ICloudStorageAccessToken CurrentAccessToken
        {
            get { return Session == null ? null : Session.SessionToken; }
        }

        #endregion
    }
}