import mimetypes
from uuid import uuid4


def encode_multipart_formdata(fields, files):
    """
    fields is a sequence of (name, value) elements for regular form fields.
    files is a sequence of (name, filename, value) elements for data to be
    uploaded as files.
    Return (content_type, body) ready for httplib.HTTP instance
    """
    boundary = uuid4().hex
    CRLF = '\r\n'
    L = []
    for (key, value) in fields:
        L.append('--' + boundary)
        L.append('Content-Disposition: form-data; name="%s"' % key)
        L.append('')
        L.append(value)
    for (key, filename, value) in files:
        L.append('--' + boundary)
        L.append(
            'Content-Disposition: form-data; name="%s"; filename="%s"' % (
                key, filename
            )
        )
        L.append('Content-Type: %s' % get_content_type(filename))
        L.append('')
        L.append(value)
    L.append('--' + boundary + '--')
    L.append('')
    body = CRLF.join(L)
    content_type = 'multipart/form-data; boundary=%s' % boundary
    return content_type, body


def get_content_type(filename):
    return mimetypes.guess_type(filename)[0] or 'application/octet-stream'