@task
def build_form_multimedia_zip(domain, xmlns, startdate, enddate, app_id, export_id, zip_name, download_id):

    def find_question_id(form, value):
        for k, v in form.iteritems():
            if isinstance(v, dict):
                ret = find_question_id(v, value)
                if ret:
                    return [k] + ret
            else:
                if v == value:
                    return [k]

        return None

    def filename(form_info, question_id, extension):
        fname = u"%s-%s-%s-%s%s"
        if form_info['cases']:
            fname = u'-'.join(form_info['cases']) + u'-' + fname
        return fname % (form_info['name'],
                        unidecode(question_id),
                        form_info['user'],
                        form_info['id'], extension)

    case_ids = set()

    def extract_form_info(form, properties=None, case_ids=case_ids):
        unknown_number = 0
        meta = form['form'].get('meta', dict())
        # get case ids
        case_blocks = extract_case_blocks(form)
        cases = {c['@case_id'] for c in case_blocks}
        case_ids |= cases

        form_info = {
            'form': form,
            'attachments': list(),
            'name': form['form'].get('@name', 'unknown form'),
            'user': meta.get('username', 'unknown_user'),
            'cases': cases,
            'id': form['_id']
        }
        for k, v in form['_attachments'].iteritems():
            if v['content_type'] == 'text/xml':
                continue
            try:
                question_id = unicode(u'-'.join(find_question_id(form['form'], k)))
            except __HOLE__:
                question_id = unicode(u'unknown' + unicode(unknown_number))
                unknown_number += 1

            if not properties or question_id in properties:
                extension = unicode(os.path.splitext(k)[1])
                form_info['attachments'].append({
                    'size': v['length'],
                    'name': k,
                    'question_id': question_id,
                    'extension': extension,
                    'timestamp': parse(form['received_on']).timetuple(),
                })

        return form_info

    key = [domain, app_id, xmlns]
    form_ids = {f['id'] for f in XFormInstance.get_db().view("attachments/attachments",
                                                             start_key=key + [startdate],
                                                             end_key=key + [enddate, {}],
                                                             reduce=False)}

    properties = set()
    if export_id:
        schema = FormExportSchema.get(export_id)
        for table in schema.tables:
            # - in question id is replaced by . in excel exports
            properties |= {c.display.replace('.', '-') for c in table.columns}

    if not app_id:
        zip_name = 'Unrelated Form'
    forms_info = list()
    for form in iter_docs(XFormInstance.get_db(), form_ids):
        if not zip_name:
            zip_name = unidecode(form['form'].get('@name', 'unknown form'))
        forms_info.append(extract_form_info(form, properties))

    num_forms = len(forms_info)
    DownloadBase.set_progress(build_form_multimedia_zip, 0, num_forms)

    # get case names
    case_id_to_name = {c: c for c in case_ids}
    for case in iter_docs(CommCareCase.get_db(), case_ids):
        if case['name']:
            case_id_to_name[case['_id']] = case['name']

    use_transfer = settings.SHARED_DRIVE_CONF.transfer_enabled
    if use_transfer:
        params = '_'.join(map(str, [xmlns, startdate, enddate, export_id, num_forms]))
        fname = '{}-{}'.format(app_id, hashlib.md5(params).hexdigest())
        fpath = os.path.join(settings.SHARED_DRIVE_CONF.transfer_dir, fname)
    else:
        _, fpath = tempfile.mkstemp()

    if not (os.path.isfile(fpath) and use_transfer):  # Don't rebuild the file if it is already there
        with open(fpath, 'wb') as zfile:
            with zipfile.ZipFile(zfile, 'w') as z:
                for form_number, form_info in enumerate(forms_info):
                    f = XFormInstance.wrap(form_info['form'])
                    form_info['cases'] = {case_id_to_name[case_id] for case_id in form_info['cases']}
                    for a in form_info['attachments']:
                        fname = filename(form_info, a['question_id'], a['extension'])
                        zi = zipfile.ZipInfo(fname, a['timestamp'])
                        z.writestr(zi, f.fetch_attachment(a['name'], stream=True).read(), zipfile.ZIP_STORED)
                    DownloadBase.set_progress(build_form_multimedia_zip, form_number + 1, num_forms)

    common_kwargs = dict(
        mimetype='application/zip',
        content_disposition='attachment; filename="{fname}.zip"'.format(fname=zip_name),
        download_id=download_id,
    )

    if use_transfer:
        expose_file_download(
            fpath,
            use_transfer=use_transfer,
            **common_kwargs
        )
    else:
        expose_cached_download(
            FileWrapper(open(fpath)),
            expiry=(1 * 60 * 60),
            file_extension=file_extention_from_filename(fpath),
            **common_kwargs
        )

    DownloadBase.set_progress(build_form_multimedia_zip, num_forms, num_forms)
dataset/ETHPy150Open dimagi/commcare-hq/corehq/apps/reports/tasks.py/build_form_multimedia_zip