#!/usr/bin/python3

import argparse
import sys
import yaml
from pathlib import Path


def parse_arguments():
    description = "Synapse config parser"

    config_parser = argparse.ArgumentParser(description=description)
    config_parser.add_argument(
        "-c",
        "--config-path",
        action="append",
        type=Path,
        metavar="CONFIG_FILE",
        help="Specify config file. Can be given multiple times and"
        " may specify directories containing *.yaml files.",
    )

    config_parser.add_argument(
        "--keys-directory",
        metavar="DIRECTORY",
        type=Path,
        help="Where files such as certs and signing keys are stored when"
        " their location is not given explicitly in the config."
        " Defaults to the directory containing the last config file",
    )
    config_parser.add_argument(
        "config_key",
        metavar="KEY",
        type=str,
        help="Configuration setting to query",
    )
    return config_parser.parse_args()


def find_config_files(search_paths):
    config_files = []
    if search_paths:
        for config_path in search_paths:
            if config_path.is_dir():
                # We accept specifying directories as config paths, we search
                # inside that directory for all files matching *.yaml, and then
                # we apply them in *sorted* order.
                config_files.extend(sorted(config_path.glob('*.yaml')))
            else:
                config_files.append(config_path)
    return config_files


def read_config_files(config_files):
    specified_config = {}
    for config_file in config_files:
        with config_file.open() as file_stream:
            yaml_config = yaml.safe_load(file_stream)

        if not isinstance(yaml_config, dict):
            err = "File %r is empty or doesn't parse into a key-value map. IGNORING."
            print(err % (config_file,), file=sys.stderr)
            continue

        specified_config.update(yaml_config)
    return specified_config


config_args = parse_arguments()
config_files = find_config_files(search_paths=config_args.config_path)
if not config_files:
    print("Must supply a config file.", file=sys.stderr)
    sys.exit(1)

if config_args.keys_directory:
    config_dir_path = config_args.keys_directory
else:
    config_dir_path = config_files[-1].parent
config_dir_path = config_dir_path.resolve()
data_dir_path = Path.cwd()
config_dict = read_config_files(config_files)

print(config_dict[config_args.config_key])