# Copyright 2014 TrilioData Inc.
# All Rights Reserved.


"""Classes to handle image files

Collection of classes to handle image upload/download to/from Image service
(like Glance image storage and retrieval service) from/to ESX/ESXi server.

"""

import http.client
import urllib.request, urllib.parse, urllib.error
import urllib.request, urllib.error, urllib.parse
import urllib.parse

from workloadmgr.openstack.common.gettextutils import _
from workloadmgr.openstack.common import log as logging
from workloadmgr import utils

LOG = logging.getLogger(__name__)

USER_AGENT = "OpenStack-ESX-Adapter"

READ_CHUNKSIZE = 65536


class GlanceFileRead(object):
    """Glance file read handler class."""

    def __init__(self, glance_read_iter):
        self.glance_read_iter = glance_read_iter
        self.iter = self.get_next()

    def read(self, chunk_size):
        """Read an item from the queue.

        The chunk size is ignored for the Client ImageBodyIterator
        uses its own CHUNKSIZE.
        """
        try:
            return next(self.iter)
        except StopIteration:
            return ""

    def get_next(self):
        """Get the next item from the image iterator."""
        for data in self.glance_read_iter:
            yield data

    def close(self):
        """A dummy close just to maintain consistency."""
        pass


class VMwareHTTPFile(object):
    """Base class for HTTP file."""

    def __init__(self, file_handle):
        self.eof = False
        self.file_handle = file_handle

    def set_eof(self, eof):
        """Set the end of file marker."""
        self.eof = eof

    def get_eof(self):
        """Check if the end of file has been reached."""
        return self.eof

    def close(self):
        """Close the file handle."""
        try:
            if hasattr(self, 'file_handle') and self.file_handle:
                self.file_handle.close()
        except Exception as exc:
            LOG.exception(exc)

    def __del__(self):
        """Close the file handle on garbage collection."""
        self.close()

    def _build_vim_cookie_headers(self, vim_cookies):
        """Build ESX host session cookie headers."""
        cookie_header = ""
        for vim_cookie in vim_cookies:
            cookie_header = vim_cookie.name + "=" + vim_cookie.value
            break
        return cookie_header

    def write(self, data):
        """Write data to the file."""
        raise NotImplementedError()

    def read(self, chunk_size):
        """Read a chunk of data."""
        raise NotImplementedError()

    def get_size(self):
        """Get size of the file to be read."""
        raise NotImplementedError()


class VMwareHTTPWriteFile(VMwareHTTPFile):
    """VMware file write handler class."""

    def __init__(self, host, data_center_name, datastore_name, cookies,
                 file_path, file_size, scheme="https"):
        if utils.is_valid_ipv6(host):
            base_url = "%s://[%s]/folder/%s" % (scheme, host, file_path)
        else:
            base_url = "%s://%s/folder/%s" % (scheme, host, file_path)
        param_list = {"dcPath": data_center_name, "dsName": datastore_name}
        base_url = base_url + "?" + urllib.parse.urlencode(param_list)
        _urlparse = urllib.parse.urlparse(base_url)
        scheme, netloc, path, params, query, fragment = _urlparse
        if scheme == "http":
            conn = http.client.HTTPConnection(netloc)
        elif scheme == "https":
            conn = http.client.HTTPSConnection(netloc)
        conn.putrequest("PUT", path + "?" + query)
        conn.putheader("User-Agent", USER_AGENT)
        conn.putheader("Content-Length", file_size)
        conn.putheader("Cookie", self._build_vim_cookie_headers(cookies))
        conn.endheaders()
        self.conn = conn
        VMwareHTTPFile.__init__(self, conn)

    def write(self, data):
        """Write to the file."""
        self.file_handle.send(data)

    def close(self):
        """Get the response and close the connection."""
        try:
            self.conn.getresponse()
        except Exception as excep:
            LOG.info(_("Exception during HTTP connection close in "
                       "VMwareHTTPWrite. Exception is %s") % excep)
            super(VMwareHTTPWriteFile, self).close()
            raise
        super(VMwareHTTPWriteFile, self).close()


class VMwareHTTPReadFile(VMwareHTTPFile):
    """VMware file read handler class."""

    def __init__(self, host, data_center_name, datastore_name, cookies,
                 file_path, scheme="https"):
        base_url = "%s://%s/folder/%s" % (scheme, host,
                                          urllib.request.pathname2url(file_path))
        param_list = {"dcPath": data_center_name, "dsName": datastore_name}
        base_url = base_url + "?" + urllib.parse.urlencode(param_list)
        headers = {'User-Agent': USER_AGENT,
                   'Cookie': self._build_vim_cookie_headers(cookies)}
        request = urllib.request.Request(base_url, None, headers)
        conn = urllib.request.urlopen(request)
        VMwareHTTPFile.__init__(self, conn)

    def __iter__(self):
        """Return an iterator for reading"""
        try:
            if self.file_handle:
                while True:
                    chunk = self.read(READ_CHUNKSIZE)
                    if chunk:
                        yield chunk
                    else:
                        break
        finally:
            self.close()

    def read(self, chunk_size):
        """Read a chunk of data."""
        # We are ignoring the chunk size passed for we want the pipe to hold
        # data items of the chunk-size that Glance Client uses for read
        # while writing.
        return self.file_handle.read(READ_CHUNKSIZE)

    def get_size(self):
        """Get size of the file to be read."""
        return self.file_handle.headers.get("Content-Length", -1)