# urllib3/filepost.py
# Copyright 2008-2013 Andrey Petrov and contributors (see CONTRIBUTORS.txt)
#
# This module is part of urllib3 and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

import codecs
import mimetypes

from uuid import uuid4
from io import BytesIO

from .packages import six
from .packages.six import b
from .fields import RequestField

writer = codecs.lookup('utf-8')[3]


def choose_boundary():
    """
    Our embarassingly-simple replacement for mimetools.choose_boundary.
    """
    return uuid4().hex


def iter_field_objects(fields):
    """
    Iterate over fields.

    Supports list of (k, v) tuples and dicts, and lists of
    :class:`~urllib3.fields.RequestField`.

    """
    if isinstance(fields, dict):
        i = six.iteritems(fields)
    else:
        i = iter(fields)

    for field in i:
      if isinstance(field, RequestField):
        yield field
      else:
        yield RequestField.from_tuples(*field)


def iter_fields(fields):
    """
    Iterate over fields.

    .. deprecated ::

      The addition of `~urllib3.fields.RequestField` makes this function
      obsolete. Instead, use :func:`iter_field_objects`, which returns
      `~urllib3.fields.RequestField` objects, instead.

    Supports list of (k, v) tuples and dicts.

    """
    if isinstance(fields, dict):
        return ((k, v) for k, v in six.iteritems(fields))

    return ((k, v) for k, v in fields)


def encode_multipart_formdata(fields, boundary=None):
    """
    Encode a dictionary of ``fields`` using the multipart/form-data MIME format.

    :param fields:
        Dictionary of fields or list of (key, :class:`~urllib3.fields.RequestField`).

    :param boundary:
        If not specified, then a random boundary will be generated using
        :func:`mimetools.choose_boundary`.
    """
    body = BytesIO()
    if boundary is None:
        boundary = choose_boundary()

    for field in iter_field_objects(fields):
        body.write(b('--%s\r\n' % (boundary)))

        writer(body).write(field.render_headers())
        data = field.data

        if isinstance(data, int):
            data = str(data)  # Backwards compatibility

        if isinstance(data, six.text_type):
            writer(body).write(data)
        else:
            body.write(data)

        body.write(b'\r\n')

    body.write(b('--%s--\r\n' % (boundary)))

    content_type = str('multipart/form-data; boundary=%s' % boundary)

    return body.getvalue(), content_type
