"""Turn a server reply into something worth *hearing*.

The server's persona writes for a chat window: markdown emphasis, bullet
lists, emoji, bare URLs. A TTS voice reads those literally ("asterisk
asterisk OS colon", "https colon slash slash..."), so everything spoken goes
through for_speech() first. Pure string logic, no Qt/audio imports — cheap to
unit test (see tests/test_speech_text.py).

for_display() is the lighter sibling used for the speech bubble: it drops the
markdown *syntax* but keeps emoji and punctuation, since those render fine.
"""

from __future__ import annotations

import re

# Pictographs, symbols, flags, dingbats, arrows, box drawing, variation
# selectors, ZWJ — anything a voice would either skip or read as a name
# ("black right-pointing triangle").
_EMOJI = re.compile(
    "["
    "\U0001F000-\U0001FAFF"  # emoji / pictographs / symbols blocks
    "\U00002190-\U000021FF"  # arrows
    "\U00002300-\U000023FF"  # misc technical (⌘ ⏱ …)
    "\U000025A0-\U000027BF"  # geometric shapes, misc symbols, dingbats
    "\U00002B00-\U00002BFF"  # extra arrows / shapes
    "\U0000FE00-\U0000FE0F"  # variation selectors
    "\U0001F1E6-\U0001F1FF"  # regional indicators (flags)
    "\U0000200D"             # zero-width joiner
    "]+",
    flags=re.UNICODE,
)

# Characters that are markup or decoration rather than speech. Kept out of
# the spoken text entirely; ordinary punctuation (. , ! ? ; : ' " ( ) -) is
# preserved because it shapes prosody.
_UNSPEAKABLE = re.compile(r"[*_#`~^|<>\\{}\[\]/=+@©®™•·–—]+")

_FENCED_CODE = re.compile(r"```.*?```", re.DOTALL)
_INLINE_CODE = re.compile(r"`([^`]*)`")
_MD_IMAGE = re.compile(r"!\[([^\]]*)\]\([^)]*\)")
_MD_LINK = re.compile(r"\[([^\]]+)\]\([^)]*\)")
_URL = re.compile(r"\b(?:https?://|www\.)\S+")
_HEADING = re.compile(r"^\s{0,3}#{1,6}\s*", re.MULTILINE)
_BLOCKQUOTE = re.compile(r"^\s{0,3}>\s?", re.MULTILINE)
_RULE = re.compile(r"^\s*([-*_=])(?:\s*\1){2,}\s*$", re.MULTILINE)
_BULLET = re.compile(r"^\s*(?:[-*+•·]|\d+[.)])\s+", re.MULTILINE)
_EMPHASIS = re.compile(r"(\*{1,3}|_{1,3})(\S(?:.*?\S)?)\1", re.DOTALL)
_TABLE_PIPE = re.compile(r"[ \t]*\|[ \t]*")

# Symbols worth saying out loud rather than dropping — a bare "&" read as
# nothing turns "R&D" into "RD". Split in two because the non-ASCII ones sit
# inside the arrow/symbol blocks _EMOJI strips, so they have to be worded
# before that pass; the ASCII ones must wait until *after* markdown parsing
# (an "=" turned into " equals " would stop a "====" rule matching _RULE).
_PRE_SPOKEN_SYMBOLS = {
    "→": " to ",
    "×": " by ",
    "°": " degrees ",
    "≈": " about ",
}
_SPOKEN_SYMBOLS = {
    "&": " and ",
    "%": " percent ",
    "@": " at ",
    "+": " plus ",
    "=": " equals ",
}

_MULTI_SPACE = re.compile(r"[ \t]+")
_MULTI_PUNCT = re.compile(r"(?:\s*\.){2,}")


def _strip_markdown(text: str, *, keep_emoji: bool) -> str:
    text = _FENCED_CODE.sub(" (code) ", text)
    text = _INLINE_CODE.sub(r"\1", text)
    text = _MD_IMAGE.sub(r"\1", text)
    text = _MD_LINK.sub(r"\1", text)
    text = _RULE.sub("", text)
    text = _HEADING.sub("", text)
    text = _BLOCKQUOTE.sub("", text)
    text = _EMPHASIS.sub(r"\2", text)
    if not keep_emoji:
        text = _EMOJI.sub(" ", text)
    return text


def _bullets_to_sentences(text: str) -> str:
    """A read-aloud list needs pauses where the eye would see line breaks,
    otherwise "OS Linux Uptime 1 day CPU load moderate" runs together."""
    lines = [_BULLET.sub("", line).strip() for line in text.splitlines()]
    lines = [line for line in lines if line]
    if len(lines) < 2:
        return lines[0] if lines else ""
    # A bullet like "OS: Linux" ends mid-thought — give the voice a full stop
    # so consecutive items don't slur into one run-on sentence.
    return " ".join(line if line[-1] in ".!?:,;" else line + "." for line in lines)


def for_speech(text: str) -> str:
    """Plain prose for the TTS engine: no markdown, no emoji, no bare URLs,
    no stray symbols that would be read out character by character."""
    text = (text or "").strip()
    if not text:
        return ""
    for symbol, spoken in _PRE_SPOKEN_SYMBOLS.items():
        text = text.replace(symbol, spoken)
    text = _strip_markdown(text, keep_emoji=False)
    text = _URL.sub(" link ", text)
    text = _TABLE_PIPE.sub(", ", text)
    text = _bullets_to_sentences(text)
    for symbol, spoken in _SPOKEN_SYMBOLS.items():
        text = text.replace(symbol, spoken)
    text = _UNSPEAKABLE.sub(" ", text)
    text = _MULTI_PUNCT.sub(".", text)
    text = _MULTI_SPACE.sub(" ", text)
    text = re.sub(r"\s+([.,!?;:])", r"\1", text)
    return text.strip()


def is_question(text: str) -> bool:
    """True if the reply *ends* by asking the user something — the cue for
    the pet to keep listening instead of making you say the wake word again.

    Deliberately only looks at the end. A reply that asks something in
    passing ("What time is it? It's 7:15.") isn't waiting on an answer,
    whereas one that finishes on a question mark is. The test runs on the
    spoken form, so a '?' that only exists inside a stripped code block or a
    URL doesn't count, and trailing decoration (emoji, quotes, brackets) is
    peeled off first so "Ready to go? 🚀" still reads as a question."""
    spoken = for_speech(text)
    while spoken and not (spoken[-1].isalnum() or spoken[-1] == "?"):
        spoken = spoken[:-1]
    return spoken.endswith("?")


def for_display(text: str) -> str:
    """What the speech bubble shows: markdown syntax removed (the bubble
    can't render it) but emoji and layout-ish punctuation left alone."""
    text = (text or "").strip()
    if not text:
        return ""
    text = _strip_markdown(text, keep_emoji=True)
    lines = [_BULLET.sub("• ", line).strip() for line in text.splitlines()]
    text = " ".join(line for line in lines if line)
    return _MULTI_SPACE.sub(" ", text).strip()