#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import os
import sys
import time
import tarfile
import logging
import argparse
import requests
import tempfile


DEFAULT_URL = 'https://clickhouse-datasets.s3.amazonaws.com'

AVAILABLE_DATASETS = {
    'hits': 'hits_v1.tar',
    'visits': 'visits_v1.tar',
}

RETRIES_COUNT = 5

def _get_temp_file_name():
    return os.path.join(tempfile._get_default_tempdir(), next(tempfile._get_candidate_names()))

def build_url(base_url, dataset):
    return os.path.join(base_url, dataset, 'partitions', AVAILABLE_DATASETS[dataset])

def dowload_with_progress(url, path):
    logging.info("Downloading from %s to temp path %s", url, path)
    for i in range(RETRIES_COUNT):
        try:
            with open(path, 'wb') as f:
                response = requests.get(url, stream=True)
                response.raise_for_status()
                total_length = response.headers.get('content-length')
                if total_length is None or int(total_length) == 0:
                    logging.info("No content-length, will download file without progress")
                    f.write(response.content)
                else:
                    dl = 0
                    total_length = int(total_length)
                    logging.info("Content length is %ld bytes", total_length)
                    for data in response.iter_content(chunk_size=4096):
                        dl += len(data)
                        f.write(data)
                        if sys.stdout.isatty():
                            done = int(50 * dl / total_length)
                            percent = int(100 * float(dl) / total_length)
                            sys.stdout.write("\r[{}{}] {}%".format('=' * done, ' ' * (50-done), percent))
                            sys.stdout.flush()
            break
        except Exception as ex:
            sys.stdout.write("\n")
            time.sleep(3)
            logging.info("Exception while downloading %s, retry %s", ex, i + 1)
            if os.path.exists(path):
                os.remove(path)
    else:
        raise Exception("Cannot download dataset from {}, all retries exceeded".format(url))

    sys.stdout.write("\n")
    logging.info("Downloading finished")

def unpack_to_clickhouse_directory(tar_path, clickhouse_path):
    logging.info("Will unpack data from temp path %s to clickhouse db %s", tar_path, clickhouse_path)
    with tarfile.open(tar_path, 'r') as comp_file:
        comp_file.extractall(path=clickhouse_path)
    logging.info("Unpack finished")


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)

    parser = argparse.ArgumentParser(
        description="Simple tool for dowloading datasets for clickhouse from S3")

    parser.add_argument('--dataset-names', required=True, nargs='+', choices=list(AVAILABLE_DATASETS.keys()))
    parser.add_argument('--url-prefix', default=DEFAULT_URL)
    parser.add_argument('--clickhouse-data-path', default='/var/lib/clickhouse/')

    args = parser.parse_args()
    datasets = args.dataset_names
    logging.info("Will fetch following datasets: %s", ', '.join(datasets))
    for dataset in datasets:
        logging.info("Processing %s", dataset)
        temp_archive_path = _get_temp_file_name()
        try:
            download_url_for_dataset = build_url(args.url_prefix, dataset)
            dowload_with_progress(download_url_for_dataset, temp_archive_path)
            unpack_to_clickhouse_directory(temp_archive_path, args.clickhouse_data_path)
        except Exception as ex:
            logging.info("Some exception occured %s", str(ex))
            raise
        finally:
            logging.info("Will remove downloaded file %s from filesystem if it exists", temp_archive_path)
            if os.path.exists(temp_archive_path):
                os.remove(temp_archive_path)
        logging.info("Processing of %s finished", dataset)
    logging.info("Fetch finished, enjoy your tables!")