import argparse
import os
import json
import subprocess
import signal
import time

from ros2cli.node.strategy import NodeStrategy
from ros2topic.api import get_topic_names_and_types

OUTPUT_FILE = "topics.json"
TOPICS_FILTER = ["/parameter_events", "/rosout"]

def get_script_args(cfg):
    args = cfg["command"].split()
    args.append(cfg["package"])
    args.append(cfg["executable"])
    return args

def get_topics(filename, path):
    jsonpath = os.path.join(path, filename)

    with NodeStrategy({}) as node:
        topic_names_and_types = get_topic_names_and_types(node=node, include_hidden_topics=False)

    topic_info = []
    for (topic_name, topic_types) in topic_names_and_types:
        if not topic_name in TOPICS_FILTER:
            topic_info.append({"name": topic_name, "type": topic_types[0]})

    print(f"---> number of topics: {len(topic_info)}")

    j_data = {"topics": topic_info}
    with open(jsonpath, "w") as fh:
        json.dump(j_data, fh, indent=2)

    for topic in topic_info:
        print(topic["name"])

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("--package", required=True, help="Json-string/file with package parameters")
    parser.add_argument("--path", default="", help="Output path")
    parser.add_argument("--json", default=OUTPUT_FILE, help="Output file name in json-format")
    parser.add_argument('--delay', default=5, type=int, help="Delay in seconds")
    args = parser.parse_args()

    if args.package[-5:] == ".json":
        if not os.path.isfile(args.package):
            print(f"Error: no such file '{args.package}'")
            exit(-1)
        with open(args.package, "r") as f:
            j_data = f.read()
    else:
        j_data = args.package
    try:
        cfg = json.loads(j_data)
    except json.JSONDecodeError as e:
        print(f"JSon error: {e}")
        exit(-2)

    cmd = get_script_args(cfg)
    process = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

    time.sleep(args.delay)
    get_topics(args.json, args.path)

    process.send_signal(signal.SIGINT)