try:
    from pydrive.auth import GoogleAuth
    from pydrive.drive import GoogleDrive
    from apiclient import errors
except ImportError:
    pass
import os
from ub import config
import cli
import shutil

from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import *


import web

class Singleton:
    """
    A non-thread-safe helper class to ease implementing singletons.
    This should be used as a decorator -- not a metaclass -- to the
    class that should be a singleton.

    The decorated class can define one `__init__` function that
    takes only the `self` argument. Also, the decorated class cannot be
    inherited from. Other than that, there are no restrictions that apply
    to the decorated class.

    To get the singleton instance, use the `Instance` method. Trying
    to use `__call__` will result in a `TypeError` being raised.

    """

    def __init__(self, decorated):
        self._decorated = decorated

    def Instance(self):
        """
        Returns the singleton instance. Upon its first call, it creates a
        new instance of the decorated class and calls its `__init__` method.
        On all subsequent calls, the already created instance is returned.

        """
        try:
            return self._instance
        except AttributeError:
            self._instance = self._decorated()
            return self._instance

    def __call__(self):
        raise TypeError('Singletons must be accessed through `Instance()`.')

    def __instancecheck__(self, inst):
        return isinstance(inst, self._decorated)


@Singleton
class Gauth:
    def __init__(self):
        self.auth = GoogleAuth(settings_file=os.path.join(config.get_main_dir,'settings.yaml'))


@Singleton
class Gdrive:
    def __init__(self):
        self.drive = getDrive(gauth=Gauth.Instance().auth)


engine = create_engine('sqlite:///{0}'.format(cli.gdpath), echo=False)
Base = declarative_base()

# Open session for database connection
Session = sessionmaker()
Session.configure(bind=engine)
session = scoped_session(Session)


class GdriveId(Base):
    __tablename__ = 'gdrive_ids'

    id = Column(Integer, primary_key=True)
    gdrive_id = Column(Integer, unique=True)
    path = Column(String)
    __table_args__ = (UniqueConstraint('gdrive_id', 'path', name='_gdrive_path_uc'),)

    def __repr__(self):
        return str(self.path)


class PermissionAdded(Base):
    __tablename__ = 'permissions_added'

    id = Column(Integer, primary_key=True)
    gdrive_id = Column(Integer, unique=True)

    def __repr__(self):
        return str(self.gdrive_id)


def migrate():
    if not engine.dialect.has_table(engine.connect(), "permissions_added"):
        PermissionAdded.__table__.create(bind = engine)
    for sql in session.execute("select sql from sqlite_master where type='table'"):
        if 'CREATE TABLE gdrive_ids' in sql[0]:
            currUniqueConstraint = 'UNIQUE (gdrive_id)'
            if currUniqueConstraint in sql[0]:
                sql=sql[0].replace(currUniqueConstraint, 'UNIQUE (gdrive_id, path)')
                sql=sql.replace(GdriveId.__tablename__, GdriveId.__tablename__ + '2')
                session.execute(sql)
                session.execute('INSERT INTO gdrive_ids2 (id, gdrive_id, path) SELECT id, gdrive_id, path FROM gdrive_ids;')
                session.commit()
                session.execute('DROP TABLE %s' % 'gdrive_ids')
                session.execute('ALTER TABLE gdrive_ids2 RENAME to gdrive_ids')
            break

if not os.path.exists(cli.gdpath):
    try:
        Base.metadata.create_all(engine)
    except Exception:
        raise
migrate()


def getDrive(drive=None, gauth=None):
    if not drive:
        if not gauth:
            gauth = GoogleAuth(settings_file=os.path.join(config.get_main_dir,'settings.yaml'))
        # Try to load saved client credentials
        gauth.LoadCredentialsFile(os.path.join(config.get_main_dir,'gdrive_credentials'))
        if gauth.access_token_expired:
            # Refresh them if expired
            try:
                gauth.Refresh()
            except:
                web.app.logger.error("GDrive gdrive_credentials file not present, reauthenticate in config section")
        else:
            # Initialize the saved creds
            gauth.Authorize()
        # Save the current credentials to a file
        return GoogleDrive(gauth)
    if drive.auth.access_token_expired:
        drive.auth.Refresh()
    return drive

def listRootFolders(drive=None):
    drive = getDrive(drive)
    folder = "'root' in parents and mimeType = 'application/vnd.google-apps.folder' and trashed = false"
    fileList = drive.ListFile({'q': folder}).GetList()
    return fileList


def getEbooksFolder(drive=None):
    return getFolderInFolder('root',config.config_google_drive_folder,drive)


def getFolderInFolder(parentId, folderName,drive=None):
    drive = getDrive(drive)
    query=""
    if folderName:
        query = "title = '%s' and " % folderName.replace("'", "\\'")
    folder = query + "'%s' in parents and mimeType = 'application/vnd.google-apps.folder' and trashed = false" % parentId
    fileList = drive.ListFile({'q': folder}).GetList()
    if fileList.__len__() == 0:
        return None
    else:
        return fileList[0]

# Search for id of root folder in gdrive database, if not found request from gdrive and store in internal database
def getEbooksFolderId(drive=None):
    storedPathName = session.query(GdriveId).filter(GdriveId.path == '/').first()
    if storedPathName:
        return storedPathName.gdrive_id
    else:
        gDriveId = GdriveId()
        try:
            gDriveId.gdrive_id = getEbooksFolder(drive)['id']
        except:
            pass
            # ToDo Path not exisiting
        gDriveId.path = '/'
        session.merge(gDriveId)
        session.commit()
        return


def getFile(pathId, fileName, drive=None):
    drive = getDrive(Gdrive.Instance().drive)
    metaDataFile = "'%s' in parents and trashed = false and title = '%s'" % (pathId, fileName.replace("'", "\\'"))

    fileList = drive.ListFile({'q': metaDataFile}).GetList()
    if fileList.__len__() == 0:
        return None
    else:
        return fileList[0]


def getFolderId(path, drive=None):
    drive = getDrive(drive)
    currentFolderId = getEbooksFolderId(drive)
    sqlCheckPath = path if path[-1] == '/' else path + '/'
    storedPathName = session.query(GdriveId).filter(GdriveId.path == sqlCheckPath).first()

    if not storedPathName:
        dbChange = False
        s = path.split('/')
        for i, x in enumerate(s):
            if len(x) > 0:
                currentPath = "/".join(s[:i+1])
                if currentPath[-1] != '/':
                    currentPath = currentPath + '/'
                storedPathName = session.query(GdriveId).filter(GdriveId.path == currentPath).first()
                if storedPathName:
                    currentFolderId = storedPathName.gdrive_id
                else:
                    currentFolder = getFolderInFolder(currentFolderId, x, drive)
                    if currentFolder:
                        gDriveId = GdriveId()
                        gDriveId.gdrive_id = currentFolder['id']
                        gDriveId.path = currentPath
                        session.merge(gDriveId)
                        dbChange = True
                        currentFolderId = currentFolder['id']
                    else:
                        currentFolderId= None
                        break
        if dbChange:
            session.commit()
    else:
        currentFolderId = storedPathName.gdrive_id
    return currentFolderId


def getFileFromEbooksFolder(path, fileName):
    drive = getDrive(Gdrive.Instance().drive)
    if path:
        # sqlCheckPath=path if path[-1] =='/' else path + '/'
        folderId = getFolderId(path, drive)
    else:
        folderId = getEbooksFolderId(drive)
    if folderId:
        return getFile(folderId, fileName, drive)
    else:
        return None


def copyDriveFileRemote(drive, origin_file_id, copy_title):
    drive = getDrive(drive)
    copied_file = {'title': copy_title}
    try:
        file_data = drive.auth.service.files().copy(
        fileId = origin_file_id, body=copied_file).execute()
        return drive.CreateFile({'id': file_data['id']})
    except errors.HttpError as error:
        print ('An error occurred: %s' % error)
    return None


def downloadFile(path, filename, output):
    # drive = getDrive(drive)
    f = getFileFromEbooksFolder(path, filename)
    f.GetContentFile(output)


def backupCalibreDbAndOptionalDownload(drive, f=None):
    drive = getDrive(drive)
    metaDataFile = "'%s' in parents and title = 'metadata.db' and trashed = false" % getEbooksFolderId()
    fileList = drive.ListFile({'q': metaDataFile}).GetList()
    databaseFile = fileList[0]
    if f:
        databaseFile.GetContentFile(f)


def copyToDrive(drive, uploadFile, createRoot, replaceFiles,
        ignoreFiles=None,
        parent=None, prevDir=''):
    ignoreFiles = ignoreFiles or []
    drive = getDrive(drive)
    isInitial = not bool(parent)
    if not parent:
        parent = getEbooksFolder(drive)
    if os.path.isdir(os.path.join(prevDir,uploadFile)):
        existingFolder = drive.ListFile({'q': "title = '%s' and '%s' in parents and trashed = false" % (os.path.basename(uploadFile), parent['id'])}).GetList()
        if len(existingFolder) == 0 and (not isInitial or createRoot):
            parent = drive.CreateFile({'title': os.path.basename(uploadFile), 'parents': [{"kind": "drive#fileLink", 'id': parent['id']}],
                "mimeType": "application/vnd.google-apps.folder"})
            parent.Upload()
        else:
            if (not isInitial or createRoot) and len(existingFolder) > 0:
                parent = existingFolder[0]
        for f in os.listdir(os.path.join(prevDir, uploadFile)):
            if f not in ignoreFiles:
                copyToDrive(drive, f, True, replaceFiles, ignoreFiles, parent, os.path.join(prevDir, uploadFile))
    else:
        if os.path.basename(uploadFile) not in ignoreFiles:
            existingFiles = drive.ListFile({'q': "title = '%s' and '%s' in parents and trashed = false" % (os.path.basename(uploadFile), parent['id'])}).GetList()
            if len(existingFiles) > 0:
                driveFile = existingFiles[0]
            else:
                driveFile = drive.CreateFile({'title': os.path.basename(uploadFile), 'parents': [{"kind":"drive#fileLink", 'id': parent['id']}], })
            driveFile.SetContentFile(os.path.join(prevDir, uploadFile))
            driveFile.Upload()


def uploadFileToEbooksFolder(destFile, f):
    drive = getDrive(Gdrive.Instance().drive)
    parent = getEbooksFolder(drive)
    splitDir = destFile.split('/')
    for i, x in enumerate(splitDir):
        if i == len(splitDir)-1:
            existingFiles = drive.ListFile({'q': "title = '%s' and '%s' in parents and trashed = false" % (x, parent['id'])}).GetList()
            if len(existingFiles) > 0:
                driveFile = existingFiles[0]
            else:
                driveFile = drive.CreateFile({'title': x, 'parents': [{"kind": "drive#fileLink", 'id': parent['id']}],})
            driveFile.SetContentFile(f)
            driveFile.Upload()
        else:
            existingFolder = drive.ListFile({'q': "title = '%s' and '%s' in parents and trashed = false" % (x, parent['id'])}).GetList()
            if len(existingFolder) == 0:
                parent = drive.CreateFile({'title': x, 'parents': [{"kind": "drive#fileLink", 'id': parent['id']}],
                    "mimeType": "application/vnd.google-apps.folder"})
                parent.Upload()
            else:
                parent = existingFolder[0]


def watchChange(drive, channel_id, channel_type, channel_address,
              channel_token=None, expiration=None):
    drive = getDrive(drive)
    # Watch for all changes to a user's Drive.
    # Args:
    # service: Drive API service instance.
    # channel_id: Unique string that identifies this channel.
    # channel_type: Type of delivery mechanism used for this channel.
    # channel_address: Address where notifications are delivered.
    # channel_token: An arbitrary string delivered to the target address with
    #               each notification delivered over this channel. Optional.
    # channel_address: Address where notifications are delivered. Optional.
    # Returns:
    # The created channel if successful
    # Raises:
    # apiclient.errors.HttpError: if http request to create channel fails.
    body = {
        'id': channel_id,
        'type': channel_type,
        'address': channel_address
    }
    if channel_token:
        body['token'] = channel_token
    if expiration:
        body['expiration'] = expiration
    return drive.auth.service.changes().watch(body=body).execute()


def watchFile(drive, file_id, channel_id, channel_type, channel_address,
              channel_token=None, expiration=None):
    """Watch for any changes to a specific file.
    Args:
    service: Drive API service instance.
    file_id: ID of the file to watch.
    channel_id: Unique string that identifies this channel.
    channel_type: Type of delivery mechanism used for this channel.
    channel_address: Address where notifications are delivered.
    channel_token: An arbitrary string delivered to the target address with
                   each notification delivered over this channel. Optional.
    channel_address: Address where notifications are delivered. Optional.
    Returns:
    The created channel if successful
    Raises:
    apiclient.errors.HttpError: if http request to create channel fails.
    """
    drive = getDrive(drive)

    body = {
        'id': channel_id,
        'type': channel_type,
        'address': channel_address
    }
    if channel_token:
        body['token'] = channel_token
    if expiration:
        body['expiration'] = expiration
    return drive.auth.service.files().watch(fileId=file_id, body=body).execute()


def stopChannel(drive, channel_id, resource_id):
    """Stop watching to a specific channel.
    Args:
    service: Drive API service instance.
    channel_id: ID of the channel to stop.
    resource_id: Resource ID of the channel to stop.
    Raises:
    apiclient.errors.HttpError: if http request to create channel fails.
    """
    drive = getDrive(drive)
    # service=drive.auth.service
    body = {
        'id': channel_id,
        'resourceId': resource_id
    }
    return drive.auth.service.channels().stop(body=body).execute()


def getChangeById (drive, change_id):
    drive = getDrive(drive)
    # Print a single Change resource information.
    #
    # Args:
    # service: Drive API service instance.
    # change_id: ID of the Change resource to retrieve.
    try:
        change = drive.auth.service.changes().get(changeId=change_id).execute()
        return change
    except (errors.HttpError) as error:
        app.logger.info(error.message)
        return None

# Deletes the local hashes database to force search for new folder names
def deleteDatabaseOnChange():
    session.query(GdriveId).delete()
    session.commit()

def updateGdriveCalibreFromLocal():
    backupCalibreDbAndOptionalDownload(Gdrive.Instance().drive)
    copyToDrive(Gdrive.Instance().drive, config.config_calibre_dir, False, True)
    for x in os.listdir(config.config_calibre_dir):
        if os.path.isdir(os.path.join(config.config_calibre_dir, x)):
            shutil.rmtree(os.path.join(config.config_calibre_dir, x))

# update gdrive.db on edit of books title
def updateDatabaseOnEdit(ID,newPath):
    storedPathName = session.query(GdriveId).filter(GdriveId.gdrive_id == ID).first()
    if storedPathName:
        storedPathName.path = newPath
        session.commit()