"""Libpurple to markdown conversion script.

Conversion script for HTML-based logs from [Pidgin/Libpurple](https://pidgin.im/) chat program.

**This is an one-off script, and is not actively maintained.**

## Motivation

I recently discovered [Obsidian](https://obsidian.md) and liked the prospect of
cross-referencing my notes with my old chat logs. Libpurple uses HTML logs if
you haven't configured it to something else (which I haden't).

I no longer use IRC or Pidgin as my entire friend group have switched to using
Matrix.

## Usage

From the repository root:

```bash
python -m libpurple_to_markdown LOG_DIRECTORY --output OUTPUT_FOLDER
```

It was made specifically for import into Obsidian, so it might not suite your
purposes, but it shouldn't be too difficult to adjust.
"""

import dataclasses
import datetime
import logging
import re
from collections.abc import Iterable, Iterator
from pathlib import Path

import bs4

from ._version import __version__

__all__ = ['__version__']

logger = logging.getLogger(__name__)


@dataclasses.dataclass(frozen=True, order=True)
class Message:
    sent_at: datetime.datetime
    sender: str
    text: str

    def __post_init__(self):
        assert self.sent_at is not None
        assert self.sender is not None
        assert self.text is not None


def datetime_sent(
    chat_start: datetime.datetime,
    message_sent: datetime.time,
) -> datetime.datetime:
    naive = datetime.datetime.combine(
        chat_start.date(),
        message_sent,
        chat_start.tzinfo,
    )
    if chat_start.time() > message_sent:
        naive = naive + datetime.timedelta(days=1)
    return naive


def parse_timestamp(c) -> datetime.time:
    timestamp_obj = c
    if c.font is not None:
        c = c.font
    m = re.match(r'\((\d+):(\d+):(\d+)\)', timestamp_obj.get_text())
    return datetime.time(int(m.group(1)), int(m.group(2)), int(m.group(3)))


def parse_messages_in_chat_file(path: Path) -> list[Message]:
    logger.info('Parsing %s', path)
    chat_start = datetime.datetime.fromisoformat(
        path.stem.removesuffix('CEST').removesuffix('CET'),
    )

    with open(path) as f:
        soup = bs4.BeautifulSoup(f, 'lxml')

    if len(soup.contents) == 0:
        logger.warning('File is empty?')
        return []

    messages = []

    cur_sent_at: datetime.datetime | None = None
    cur_sender: str | None = None
    cur_text: str = ''

    if soup.body.p:
        loglines = soup.body.p.children
    else:
        loglines = soup.body.children

    for c in loglines:
        if c.name in {'font', 'span'} and cur_sent_at is None:
            # Get timestamp
            cur_sent_at = datetime_sent(chat_start, parse_timestamp(c))

            # Get sender
            if c.b:
                assert cur_sender is None
                cur_sender = (
                    c.b.get_text()
                    .strip()
                    .removesuffix(':')
                    .removeprefix('***')
                    .removesuffix('[m]')
                )

        elif c.name in {None, 'span', 'font'}:
            cur_text += c.get_text()

        elif c.name == 'a':
            cur_text += '<' + c['href'] + '>'

        elif c.name == 'br':
            if cur_sender:
                messages.append(Message(cur_sent_at, cur_sender, cur_text.strip()))
            cur_sent_at = None
            cur_sender = None
            cur_text = ''

        elif c.name == 'b':
            # Indicates system message. Ignore
            pass

        elif c.name in {'h1', 'h3'}:
            pass  # Ignore log header

        else:
            assert False, c

    return messages


def parse_messages_in_chat_folder(chat_folder_path: Path) -> list[Message]:
    messages = []
    for file_path in sorted(chat_folder_path.iterdir()):
        messages.extend(parse_messages_in_chat_file(file_path))

    messages.sort()
    return messages


def format_message_as_citation(out: list[str], msg: Message) -> None:
    out.append(f'{msg.sent_at.date()} {msg.sent_at.time()} [[{msg.sender}]]:')
    out.append('\n')
    for line in msg.text.split('\n'):
        line = re.sub(r'(<[\w ]+>)', r'`\1`', line)
        line = re.sub(r'(\$\$\$)', r'`\1`', line)
        out.append(f'> {line}\n')
        del line
    out.append('\n')


def format_message_as_table(out: list[str], msg: Message) -> None:
    out.append(f'| {msg.sent_at} | [[{msg.sender}]] | ')
    for line in msg.text.split('\n'):
        out.append(f'{line}')
        del line
    out.append('|\n')


def format_messages(messages: list[Message], title: str) -> str:
    out = ['# ', title, '\n\n']

    as_table = False

    for msg_idx, msg in enumerate(messages):
        if msg_idx == 0 or messages[msg_idx - 1].sent_at.date() != msg.sent_at.date():
            out.append('---\n')
            out.append(f'## [[{msg.sent_at.date()}]]\n\n')
            if as_table:
                out.append('| sent at | sender | text |\n')
                out.append('| ------- | ------ | ---- |\n')

        if as_table:
            format_message_as_table(out, msg)
        else:
            format_message_as_citation(out, msg)
        del msg

    return ''.join(out)


MSG_ADJACENTCY_DIST = datetime.timedelta(minutes=2)


def is_useless_message(msg: Message) -> bool:
    return msg.sender.endswith('<AUTO-REPLY>') or msg.sender == ''


def filter_useless_messages(messages: Iterable[Message]) -> Iterator[Message]:
    for msg in messages:
        if not is_useless_message(msg):
            yield msg
        else:
            print(msg.text)


def is_adjacent_messages(first: Message, second: Message) -> bool:
    return (
        first.sender == second.sender
        and second.sent_at - first.sent_at <= MSG_ADJACENTCY_DIST
    )


def merge_texts(text1: str, text2: str) -> str:
    punctuated = text1.endswith('.?!,:')
    # return text1 + (' ' if punctuated else '. ') + text2
    return text1 + (' ' if punctuated else '. ') + '\n' + text2


def merge_adjacent_messages(messages: Iterable[Message]) -> list[Message]:
    out = []
    for msg in messages:
        if out and is_adjacent_messages(out[-1], msg):
            out[-1] = dataclasses.replace(
                out[-1],
                text=merge_texts(out[-1].text, msg.text),
            )
        else:
            out.append(msg)
    return out