"""Bind German 3rd-person pronouns to the last named person. Local; no new Detect tokens."""
from __future__ import annotations

import re
from dataclasses import dataclass

PLACEHOLDER = re.compile(r"\[\[(PERSON:[^\]]+)\]\]")
PIECE = re.compile(r"\[\[PERSON:[^\]]+\]\]|[A-Za-zÄÖÜäöüß]+")

FEM_CUES = {
    "frau", "partnerin", "tochter", "mutter", "schwester", "freundin",
    "oma", "tante",
}
MASC_CUES = {
    "herr", "mann", "partner", "sohn", "vater", "bruder", "freund",
    "opa", "onkel",
}
FEM_PRON = {"sie", "ihr", "ihre", "ihrem", "ihren", "ihrer", "ihres"}
MASC_PRON = {"er", "ihn", "ihm", "seine", "seinem", "seinen", "seiner", "seines"}
IHR_ADDRESS = {
    "seid", "habt", "wart", "könnt", "müsst", "sollt", "wollt", "dürft",
    "hättet", "wäret", "werdet",
}
PLURAL_VERB = {
    "sind", "waren", "haben", "hatten", "werden", "wurden",
    "können", "müssen", "wollen", "sollen",
}


@dataclass
class BindState:
    last: str | None = None
    last_f: str | None = None
    last_m: str | None = None


def _gender_from_prev(pieces: list[re.Match], index: int) -> str | None:
    seen: list[str] = []
    pos = index - 1
    while pos >= 0 and len(seen) < 3:
        raw = pieces[pos].group(0)
        if PLACEHOLDER.fullmatch(raw):
            break
        seen.append(raw.lower())
        pos -= 1
    window = set(seen)
    if window & FEM_CUES:
        return "f"
    if window & MASC_CUES:
        return "m"
    return None


def _referent(state: BindState, kind: str) -> str | None:
    if kind == "f" and state.last_f:
        return state.last_f
    if kind == "m" and state.last_m:
        return state.last_m
    return state.last


def _is_address_ihr(prev: str, nxt: str) -> bool:
    if nxt in IHR_ADDRESS or prev in IHR_ADDRESS:
        return True
    if prev.endswith("t") and len(prev) >= 4:
        return True
    return False


def bind_pronouns(text: str, state: BindState | None = None) -> tuple[str, BindState]:
    state = state or BindState()
    pieces = list(PIECE.finditer(text or ""))
    replacements: list[tuple[int, int, str]] = []
    for i, match in enumerate(pieces):
        raw = match.group(0)
        person = PLACEHOLDER.fullmatch(raw)
        if person:
            token = person.group(1)
            state.last = token
            gender = _gender_from_prev(pieces, i)
            if gender == "f":
                state.last_f = token
            elif gender == "m":
                state.last_m = token
            continue
        low = raw.lower()
        prev = pieces[i - 1].group(0).lower() if i else ""
        nxt = pieces[i + 1].group(0).lower() if i + 1 < len(pieces) else ""
        if low == "ihr" and _is_address_ihr(prev, nxt):
            continue
        if low == "sie" and nxt in PLURAL_VERB:
            continue
        kind = "f" if low in FEM_PRON else "m" if low in MASC_PRON else ""
        if not kind:
            continue
        ref = _referent(state, kind)
        if not ref:
            continue
        replacements.append((match.start(), match.end(), f"[[{ref}]]"))
    if not replacements:
        return text or "", state
    out = text or ""
    for start, end, repl in reversed(replacements):
        out = out[:start] + repl + out[end:]
    return out, state


def bind_user_lines(text: str) -> str:
    """Only user: lines; state carries across those lines. Instructions stay untouched."""
    state = BindState()
    chunks: list[str] = []
    for line in (text or "").splitlines(keepends=True):
        ended = line.endswith("\n")
        body = line[:-1] if ended else line
        if body.startswith("user:"):
            bound, state = bind_pronouns(body[5:], state)
            chunks.append("user:" + bound + ("\n" if ended else ""))
        else:
            chunks.append(line)
    return "".join(chunks)