"""Strip formatting that only makes sense on a screen, before it is spoken.

`VOICE_STYLE` asks Claude not to emit markdown, and mostly he doesn't — but
asking is probabilistic and hearing "asterisk asterisk aloud asterisk asterisk"
once is enough. This is the deterministic half.

Pipecat's `MarkdownTextFilter` does most of it and runs *after* sentence
aggregation, so formatting split across streaming chunks is already reassembled
by the time it sees the text. What it leaves behind, measured:

    'Use ~~strike~~'      -> 'Use ~~strike~~'      still spoken as tildes
    '- first bullet'      -> '- first bullet'      spoken as "dash"
    'the sample_rate is'  -> 'the sample_rate is'  spoken as "underscore"
    'Multiply 3 * 4'      -> 'Multiply 3  4'       the "times" is lost

so this subclass handles those four and tidies the spacing.
"""

import re

from pipecat.utils.text.markdown_text_filter import MarkdownTextFilter

# Run before the markdown filter, which would otherwise eat the asterisk.
_TIMES = re.compile(r"(?<=\d)\s*\*\s*(?=\d)")

_STRIKETHROUGH = re.compile(r"~~(.+?)~~")
# Only at the start of a line, so a hyphenated word is untouched.
_LIST_MARKER = re.compile(r"^[ \t]*[-*•]\s+", re.MULTILINE)
# Identifiers read better as words: "sample_rate" -> "sample rate".
_UNDERSCORE_WORD = re.compile(r"(?<=\w)_(?=\w)")
_EXTRA_SPACE = re.compile(r"[ \t]{2,}")


class SpokenTextFilter(MarkdownTextFilter):
    """Markdown filtering, plus the leftovers that matter when read aloud."""

    def __init__(self, voice_manager=None, **kwargs):
        super().__init__(**kwargs)
        self._voice_manager = voice_manager

    async def filter(self, text: str) -> str:
        if self._voice_manager:
            self._voice_manager.sync_voice()
        text = _TIMES.sub(" times ", text)
        text = await super().filter(text)
        text = _STRIKETHROUGH.sub(r"\1", text)
        text = _LIST_MARKER.sub("", text)
        text = _UNDERSCORE_WORD.sub(" ", text)
        return _EXTRA_SPACE.sub(" ", text)