#!/usr/bin/env python3
"""Planets and aggregators reader."""

import argparse
import pathlib
import sys
import webbrowser

import xdg.BaseDirectory  # pylint: disable=import-error
import yaml

EXAMPLE_CONFIG = """---
general:
  # For the list of available browsers, consult
  # https://docs.python.org/3/library/webbrowser.html?highlight=webbrowser#webbrowser.register
  browser: w3m
sites:
  shore: https://www.shore.co.il/blog/
"""


def build_arg_parser():
    """Build and return the argument parser."""
    parser = argparse.ArgumentParser(description=__doc__)

    parser.add_argument(
        "-C",
        "--config",
        type=pathlib.Path,
        help="Use a different configuration file.",
    )
    parser.add_argument(
        "-l", "--list", action="store_true", help="List available sites."
    )
    parser.add_argument("-b", "--browser", help="Use a specific browser.")
    parser.add_argument("site", nargs="?", help="Name of the site to open.")
    return parser


def get_config(path=None):
    """Returns a configuration dictionary.

    If a path is passed, that file path is used. Otherwise, use the default
    path. If path is None and the default doesn't exist, an example file is
    created."""
    if path:
        path = path.expanduser()
        if not path.exists() and not path.is_file():
            arg_parser.error("Configuration file does not exist.")

    else:
        base_dir = pathlib.Path(xdg.BaseDirectory.save_config_path("planet"))
        path = base_dir / "config.yaml"
    if not path.exists():
        with open(path, "w", encoding="utf-8") as configfile:
            configfile.write(EXAMPLE_CONFIG)
            arg_parser.error(
                f"Missing config file, generated an example one at {path}."
            )
    try:
        with open(path, "r", encoding="utf-8") as configfile:
            config = yaml.safe_load(configfile)
    except Exception as exception:  # pylint: disable=broad-except
        arg_parser.error(str(exception))
    if "sites" not in config or not isinstance(config["sites"], dict):
        arg_parser.error(
            "Config file missing 'sites' key or 'sites' is not a dictionary."
        )
    return config


def list_sites(config):
    """Prints a list of sites from the config."""
    for site in config["sites"].keys():
        print(site)


def open_site(config, site, browser_name=None):
    """Opens a site from the config in a webbrowser."""
    if browser_name == "":
        browser_name = None
    elif browser_name is not None:
        pass
    elif "general" in config and "browser" in config["general"]:
        browser_name = config["general"]["browser"]
    else:
        browser_name = None
    browser = webbrowser.get(using=browser_name)
    if site not in config["sites"]:
        arg_parser.error(f"Unknown site {site}.")
    browser.open(config["sites"][site])


if __name__ == "__main__":
    arg_parser = build_arg_parser()
    args = arg_parser.parse_args()
    if not args.list and not args.site:
        arg_parser.error(
            "You must specify either site name or -l to list the available sites."  # noqa: E501
        )
    conf = get_config(args.config)
    if args.list:
        list_sites(conf)
    else:
        open_site(conf, args.site, args.browser)
    sys.exit()