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# license agreements. See the NOTICE file distributed with
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# ownership. Elasticsearch B.V. licenses this file to you under
# the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# 	http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

import bz2
import json
import logging
import os

from esrally.utils import console

DOCS_COMPRESSOR = bz2.BZ2Compressor
COMP_EXT = ".bz2"


def template_vars(index_name, out_path, doc_count):
    comp_outpath = out_path + COMP_EXT
    return {
        "index_name": index_name,
        "filename": os.path.basename(comp_outpath),
        "path": comp_outpath,
        "doc_count": doc_count,
        "uncompressed_bytes": os.path.getsize(out_path),
        "compressed_bytes": os.path.getsize(comp_outpath),
    }


def get_doc_outpath(outdir, name, suffix=""):
    return os.path.join(outdir, f"{name}-documents{suffix}.json")


def extract(client, output_path, index):
    """
    Scroll an index with a match-all query, dumping document source to ``outdir/documents.json``.

    :param client: Elasticsearch client used to extract data
    :param output_path: Destination directory for corpus dump
    :param index: Name of index to dump
    :return: dict of properties describing the corpus for templates
    """

    logger = logging.getLogger(__name__)

    total_docs = client.count(index=index)["count"]
    if total_docs > 0:
        logger.info("[%d] total docs in index [%s].", total_docs, index)
        docs_path = get_doc_outpath(output_path, index)
        dump_documents(client, index, get_doc_outpath(output_path, index, "-1k"), min(total_docs, 1000), " for test mode")
        dump_documents(client, index, docs_path, total_docs)
        return template_vars(index, docs_path, total_docs)
    else:
        logger.info("Skipping corpus extraction fo index [%s] as it contains no documents.", index)
        return None


def dump_documents(client, index, out_path, total_docs, progress_message_suffix=""):
    # pylint: disable=import-outside-toplevel
    from elasticsearch import helpers

    logger = logging.getLogger(__name__)
    freq = max(1, total_docs // 1000)

    progress = console.progress()
    compressor = DOCS_COMPRESSOR()
    comp_outpath = out_path + COMP_EXT
    with open(out_path, "wb") as outfile:
        with open(comp_outpath, "wb") as comp_outfile:
            logger.info("Dumping corpus for index [%s] to [%s].", index, out_path)
            query = {"query": {"match_all": {}}}
            for n, doc in enumerate(helpers.scan(client, query=query, index=index)):
                if n >= total_docs:
                    break
                data = (json.dumps(doc["_source"], separators=(",", ":")) + "\n").encode("utf-8")

                outfile.write(data)
                comp_outfile.write(compressor.compress(data))

                render_progress(progress, progress_message_suffix, index, n + 1, total_docs, freq)

            comp_outfile.write(compressor.flush())
    progress.finish()


def render_progress(progress, progress_message_suffix, index, cur, total, freq):
    if cur % freq == 0 or total - cur < freq:
        msg = f"Extracting documents for index [{index}]{progress_message_suffix}..."
        percent = (cur * 100) / total
        progress.print(msg, f"{cur}/{total} docs [{percent:.1f}% done]")
