import os
import cgi
import pylons
import datetime
import ckan.lib.munge as munge
import logging
import ckan.logic as logic


config = pylons.config
log = logging.getLogger(__name__)

_storage_path = None
_max_resource_size = None
_max_image_size = None


def get_storage_path():
    '''Function to cache storage path'''
    global _storage_path

    #None means it has not been set. False means not in config.
    if _storage_path is None:
        storage_path = config.get('ckan.storage_path')
        ofs_impl = config.get('ofs.impl')
        ofs_storage_dir = config.get('ofs.storage_dir')
        if storage_path:
            _storage_path = storage_path
        elif ofs_impl == 'pairtree' and ofs_storage_dir:
            log.warn('''Please use config option ckan.storage_path instead of
                     ofs.storage_dir''')
            _storage_path = ofs_storage_dir
            return _storage_path
        elif ofs_impl:
            log.critical('''We only support local file storage form version 2.2
                         of ckan please specify ckan.storage_path in your
                         config for your uploads''')
            _storage_path = False
        else:
            log.critical('''Please specify a ckan.storage_path in your config
                         for your uploads''')
            _storage_path = False

    return _storage_path


def get_max_image_size():
    global _max_image_size
    if _max_image_size is None:
        _max_image_size = int(config.get('ckan.max_image_size', 2))
    return _max_image_size


def get_max_resource_size():
    global _max_resource_size
    if _max_resource_size is None:
        _max_resource_size = int(config.get('ckan.max_resource_size', 10))
    return _max_resource_size


class Upload(object):
    def __init__(self, object_type, old_filename=None):
        ''' Setup upload by creating  a subdirectory of the storage directory
        of name object_type. old_filename is the name of the file in the url
        field last time'''

        self.storage_path = None
        self.filename = None
        self.filepath = None
        path = get_storage_path()
        if not path:
            return
        self.storage_path = os.path.join(path, 'storage',
                                         'uploads', object_type)
        try:
            os.makedirs(self.storage_path)
        except OSError, e:
            ## errno 17 is file already exists
            if e.errno != 17:
                raise
        self.object_type = object_type
        self.old_filename = old_filename
        if old_filename:
            self.old_filepath = os.path.join(self.storage_path, old_filename)

    def update_data_dict(self, data_dict, url_field, file_field, clear_field):
        ''' Manipulate data from the data_dict.  url_field is the name of the
        field where the upload is going to be. file_field is name of the key
        where the FieldStorage is kept (i.e the field where the file data
        actually is). clear_field is the name of a boolean field which
        requests the upload to be deleted.  This needs to be called before
        it reaches any validators'''

        self.url = data_dict.get(url_field, '')
        self.clear = data_dict.pop(clear_field, None)
        self.file_field = file_field
        self.upload_field_storage = data_dict.pop(file_field, None)

        if not self.storage_path:
            return

        if isinstance(self.upload_field_storage, cgi.FieldStorage):
            self.filename = self.upload_field_storage.filename
            self.filename = str(datetime.datetime.utcnow()) + self.filename
            self.filename = munge.munge_filename(self.filename)
            self.filepath = os.path.join(self.storage_path, self.filename)
            data_dict[url_field] = self.filename
            self.upload_file = self.upload_field_storage.file
            self.tmp_filepath = self.filepath + '~'
        ### keep the file if there has been no change
        elif self.old_filename and not self.old_filename.startswith('http'):
            if not self.clear:
                data_dict[url_field] = self.old_filename
            if self.clear and self.url == self.old_filename:
                data_dict[url_field] = ''

    def upload(self, max_size=2):
        ''' Actually upload the file.
        This should happen just before a commit but after the data has
        been validated and flushed to the db. This is so we do not store
        anything unless the request is actually good.
        max_size is size in MB maximum of the file'''

        if self.filename:
            output_file = open(self.tmp_filepath, 'wb')
            self.upload_file.seek(0)
            current_size = 0
            while True:
                current_size = current_size + 1
                # MB chuncks
                data = self.upload_file.read(2 ** 20)
                if not data:
                    break
                output_file.write(data)
                if current_size > max_size:
                    os.remove(self.tmp_filepath)
                    raise logic.ValidationError(
                        {self.file_field: ['File upload too large']}
                    )
            output_file.close()
            os.rename(self.tmp_filepath, self.filepath)
            self.clear = True

        if (self.clear and self.old_filename
                and not self.old_filename.startswith('http')):
            try:
                os.remove(self.old_filepath)
            except OSError, e:
                pass


class ResourceUpload(object):
    def __init__(self, resource):
        path = get_storage_path()
        if not path:
            self.storage_path = None
            return
        self.storage_path = os.path.join(path, 'resources')
        try:
            os.makedirs(self.storage_path)
        except OSError, e:
            ## errno 17 is file already exists
            if e.errno != 17:
                raise
        self.filename = None

        url = resource.get('url')
        upload_field_storage = resource.pop('upload', None)
        self.clear = resource.pop('clear_upload', None)

        if isinstance(upload_field_storage, cgi.FieldStorage):
            self.filename = upload_field_storage.filename
            self.filename = munge.munge_filename(self.filename)
            resource['url'] = self.filename
            resource['url_type'] = 'upload'
            self.upload_file = upload_field_storage.file
        elif self.clear:
            resource['url_type'] = ''

    def get_directory(self, id):
        directory = os.path.join(self.storage_path,
                                 id[0:3], id[3:6])
        return directory

    def get_path(self, id):
        directory = self.get_directory(id)
        filepath = os.path.join(directory, id[6:])
        return filepath

    def upload(self, id, max_size=10):
        '''Actually upload the file.

        :returns: ``'file uploaded'`` if a new file was successfully uploaded
            (whether it overwrote a previously uploaded file or not),
            ``'file deleted'`` if an existing uploaded file was deleted,
            or ``None`` if nothing changed
        :rtype: ``string`` or ``None``

        '''
        if not self.storage_path:
            return

        # Get directory and filepath on the system
        # where the file for this resource will be stored
        directory = self.get_directory(id)
        filepath = self.get_path(id)

        # If a filename has been provided (a file is being uploaded)
        # we write it to the filepath (and overwrite it if it already
        # exists). This way the uploaded file will always be stored
        # in the same location
        if self.filename:
            try:
                os.makedirs(directory)
            except OSError, e:
                ## errno 17 is file already exists
                if e.errno != 17:
                    raise
            tmp_filepath = filepath + '~'
            output_file = open(tmp_filepath, 'wb+')
            self.upload_file.seek(0)
            current_size = 0
            while True:
                current_size = current_size + 1
                #MB chunks
                data = self.upload_file.read(2 ** 20)
                if not data:
                    break
                output_file.write(data)
                if current_size > max_size:
                    os.remove(tmp_filepath)
                    raise logic.ValidationError(
                        {'upload': ['File upload too large']}
                    )
            output_file.close()
            os.rename(tmp_filepath, filepath)
            return

        # The resource form only sets self.clear (via the input clear_upload)
        # to True when an uploaded file is not replaced by another uploaded
        # file, only if it is replaced by a link to file.
        # If the uploaded file is replaced by a link, we should remove the
        # previously uploaded file to clean up the file system.
        if self.clear:
            try:
                os.remove(filepath)
            except OSError, e:
                pass
