#!/usr/bin/env python3
"""
Convert RFC822 headers into an ABlog post directive.
"""

import sys
import os
import email
import pathlib
import datetime
import logging
import argparse

from dateutil import parser

prog = os.path.basename(sys.argv[0])
doc = __doc__.strip()

logger = logging.getLogger(prog)

TEMPLATE_DEFAULT = pathlib.Path(__file__).parents[1] / "post.rst.in"

arg_parser = argparse.ArgumentParser(
    prog=prog, description=doc)
arg_parser.add_argument(
    "--template-file", type=argparse.FileType("r"),
    help=f"The reStructuredText template for a post directive "
    f"(default: {TEMPLATE_DEFAULT})")
arg_parser.add_argument(
    "properties_file", nargs="?", type=argparse.FileType("r"), default=sys.stdin,
    help="The RFC822 properties file to convert (default: stdin)")
arg_parser.add_argument(
    "rst_path", metavar="rst_file", type=pathlib.Path,
    help="The reStructuredText file to add the post directive to")


def main(
        properties_file=arg_parser.get_default("properties_file"),
        rst_path=arg_parser.get_default("rst_path"),
        template_file=arg_parser.get_default("template_file"),
):
    properties_parsed = email.message_from_file(properties_file)
    properties = dict(properties_parsed)
    properties["now"] = datetime.datetime.now()
    properties["subject"] = (
        properties["subject"].split("\n  ") if properties["subject"].strip() else []
    )
    properties["keywords"] = properties["tags"] = ""
    if properties["subject"]:
        properties["keywords"] = "\n   :keywords: {}".format(
            ", ".join(properties["subject"]),
        )
        properties["tags"] = "\n   :tags: {}".format(
            ", ".join(properties["subject"]),
        )
    for property_name, property_value in list(properties.items()):
        if not (property_name.endswith("_date") or property_name.endswith("Date")):
            continue
        if property_value.lower().strip() == "none":
            property_value = None
        else:
            try:
                property_value = parser.parse(property_value)
            except parser.ParserError:
                property_value = parser.parse(property_value.rsplit(" ", 1)[0])
            properties[property_name] = property_value
    properties["title_underline"] = "#" * len(properties["title"])
    properties["description_underline"] = "*" * len(properties["description"])

    body = ""
    if rst_path.exists():
        with rst_path.open() as rst_file:
            body = rst_file.read()
    properties["body"] = body

    if template_file is None:
        template_file = TEMPLATE_DEFAULT.open()
    template = template_file.read()

    directive = template.format(**properties)
    with rst_path.open(mode="w") as rst_file:
        rst_file.write(directive)


main.__doc__ = __doc__


if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)
    args = arg_parser.parse_args()
    main(**vars(args))