import re
import datetime
from dataclasses import dataclass
from typing import List


@dataclass
class Ping:
    """
    A ping is a single line in the log file consisting of a UNIX time stamp,
    followed by tags (where each individual string surrounded by spaces is a
    tag), followed by optional comments between square brackets or parentheses.
    The original Perl implementation puts a human readable representation of
    the UNIX time stamp into square brackets. Here are two example pings:

    1601557948 morning_pages                  [2020.10.01 09:12:28 THU]
    1601560369 work_call another_tag          [2020.10.01 09:52:49 THU]
    """
    time: int           # UNIX time stamp
    tags: List[str]     # each separate word is a tag
    comments: List[str]  # each string between [] or () is a comment
    line: str = ""      # the whole line as found in the log file

    r_time = re.compile("^\s*\d{9,11}")
    r_spaces = re.compile("\s+")
    r_comment_parens = re.compile("\(([^\)]*)\)")
    r_comment_square = re.compile("\[([^\]]*)\]")

    def line_to_ping(line: str):
        """
        Parses a string into a Ping object. Raises Exception on failure.

        >>> line_to_ping(" 1601557948 t (c)")
        Ping(time=1601557948, tags=['t'], comments=['c'], line=' 1601557948 t (c)')
        """
        time = int(Ping.r_time.match(line).group())
        tags = Ping.get_tags(line)
        comments = Ping.r_comment_parens.findall(line) + \
            Ping.r_comment_square.findall(line)
        return Ping(time, tags, comments, line)

    def get_tags(line):
        """Extracts the tags from a tag line."""
        line = Ping.r_time.sub("", line)
        line = Ping.r_comment_parens.sub("", line)
        line = Ping.r_comment_square.sub("", line)
        line = Ping.r_spaces.sub(" ", line)
        return line.split()

    def ping_to_line(ping, annotate_time=False, line_length=79) -> str:
        tags = " ".join([t.strip() for t in ping.tags])
        comments = " ".join(["[" + c.strip() + "]" for c in ping.comments])
        line = "{} {} {}".format(ping.time, tags, comments)
        if annotate_time:
            line = Ping.add_time_annotation(ping.time, line, line_length)
        return line

    def add_time_annotation(time: int, line: str, line_length: int) -> str:
        """Appends human readable date/time in square brackets to line."""
        remaining_length = line_length - len(line)
        if remaining_length > 24:
            strf = " [%Y.%m.%d %H:%M:%S %a]"
        elif remaining_length > 18:
            strf = " [%m.%d %H:%M:%S %a]"
        elif remaining_length > 15:
            strf = " [%d %H:%M:%S %a]"
        elif remaining_length > 12:
            strf = " [%H:%M:%S %a]"
        elif remaining_length > 9:
            strf = " [%H:%M %a]"
        elif remaining_length > 5:
            strf = " [%H:%M]"
        else:
            strf = " [%M]"
        time_comment = datetime.datetime.fromtimestamp(time).strftime(strf)
        remaining_length -= len(time_comment)
        line += " " * remaining_length + time_comment
        return line