#!/usr/bin/env python3
import argparse
import json
from typing import Any, Dict, List

import zulip

usage = """\nGets the complete history of a particular stream or a particular topic in Zulip
and store them in JSON format.

    get-history --stream <stream_name> [--topic <topic_name> --filename <file_to_store_messages>]

Example: get-history --stream announce --topic important"""

parser = zulip.add_default_arguments(argparse.ArgumentParser(usage=usage))
parser.add_argument("--stream", required=True, help="The stream name to get the history")
parser.add_argument("--topic", help="The topic name to get the history")
parser.add_argument(
    "--filename",
    default="history.json",
    help="The file name to store the fetched  \
                    history.\n Default 'history.json'",
)
options = parser.parse_args()

client = zulip.init_from_options(options)

narrow = [{"operator": "stream", "operand": options.stream}]
if options.topic:
    narrow.append({"operator": "topic", "operand": options.topic})

request = {
    # Initially we have the anchor as 0, so that it starts fetching
    # from the oldest message in the narrow
    "anchor": 0,
    "num_before": 0,
    "num_after": 1000,
    "narrow": narrow,
    "client_gravatar": False,
    "apply_markdown": False,
}

all_messages = []  # type: List[Dict[str, Any]]
found_newest = False

while not found_newest:
    result = client.get_messages(request)
    try:
        found_newest = result["found_newest"]
        if result["messages"]:
            # Setting the anchor to the next immediate message after the last fetched message.
            request["anchor"] = result["messages"][-1]["id"] + 1

            all_messages.extend(result["messages"])
    except KeyError:
        # Might occur when the request is not returned with a success status
        print("Error occured: Payload was:")
        print(result)
        quit()

with open(options.filename, "w+") as f:
    print("Writing %d messages..." % len(all_messages))
    f.write(json.dumps(all_messages))