import argparse
import bisect
import json
import re
import sys
import unicodedata
from dataclasses import asdict, dataclass
from pathlib import Path
from typing import Callable, List, Optional, Sequence, Tuple

_HERE = Path(__file__).resolve().parent
if str(_HERE) not in sys.path:          # чтобы `core/` нашёлся из любого cwd
    sys.path.insert(0, str(_HERE))

WINDOW_WORDPIECES = 384
DEFAULT_RULES = _HERE / "gitleaks.toml"
_BOUNDARY_RE = re.compile(r"(?:\n+|[.!?]\s+)")


@dataclass(frozen=True)
class Span:
    start: int
    end: int
    label: str
    source: str            # ner | regex | both
    score: Optional[float]  # None у спанов детерминированного слоя
    text: str


def plan_windows(
    text: str, count: Callable[[str], int], maximum: int = WINDOW_WORDPIECES
) -> List[Tuple[int, int]]:
    """Режет текст на куски не длиннее `maximum` wordpiece, по границам
    предложений и абзацев там, где это возможно. Возвращает пары (начало, конец)
    в символах."""
    if not text:
        return []
    if count(text) <= maximum:
        return [(0, len(text))]

    boundaries = sorted({0, *(m.end() for m in _BOUNDARY_RE.finditer(text)), len(text)})

    def fitting_end(left: int) -> int:
        low, step = left, maximum * 4
        high = min(len(text), left + step)
        while high < len(text) and count(text[left:high]) <= maximum:
            low, step = high, step * 2
            high = min(len(text), left + step)
        if high == len(text) and count(text[left:high]) <= maximum:
            return high
        while low + 1 < high:
            middle = (low + high) // 2
            if count(text[left:middle]) <= maximum:
                low = middle
            else:
                high = middle
        return low

    windows: List[Tuple[int, int]] = []
    start = 0
    while start < len(text):
        candidate = fitting_end(start)
        if candidate <= start:
            raise RuntimeError(f"ни один непустой префикс не влезает в {maximum} wordpiece на {start}")
        boundary = boundaries[bisect.bisect_right(boundaries, candidate) - 1]
        end = boundary if boundary > start else candidate
        if count(text[start:end]) > maximum:
            end = candidate
        windows.append((start, end))
        if end >= len(text):
            break
        start = end
    return windows


def extract_entities(bio: Sequence[str]) -> List[Tuple[int, int, str]]:
    """BIO-теги → (начало, конец, метка) в индексах токенов. I- без своего B-
    открывает сущность: модель не обязана быть согласованной, а терять
    предсказание из-за этого нельзя."""
    ents: List[Tuple[int, int, str]] = []
    cur_label: Optional[str] = None
    cur_start = 0
    for i, tag in enumerate(list(bio) + ["O"]):
        if tag.startswith("B-"):
            if cur_label is not None:
                ents.append((cur_start, i, cur_label))
            cur_label, cur_start = tag[2:], i
        elif tag.startswith("I-"):
            label = tag[2:]
            if cur_label == label:
                continue
            if cur_label is not None:
                ents.append((cur_start, i, cur_label))
            cur_label, cur_start = label, i
        else:
            if cur_label is not None:
                ents.append((cur_start, i, cur_label))
            cur_label = None
    return ents


def _lower_score(left: Optional[float], right: Optional[float]) -> Optional[float]:
    present = [s for s in (left, right) if s is not None]
    return min(present) if present else None


def merge(spans: List[Span], text: str) -> List[Span]:
    """Склеивает пересекающиеся и примыкающие однометочные спаны. Метку задаёт
    первый спан — самый левый, затем самый длинный, затем NER вперёд regex."""
    if not spans:
        return []
    ordered = sorted(
        spans,
        key=lambda s: (s.start, -(s.end - s.start), 0 if s.source == "ner" else 1),
    )
    out: List[Span] = [ordered[0]]
    for sp in ordered[1:]:
        prev = out[-1]
        if sp.start < prev.end or (sp.start == prev.end and sp.label == prev.label):
            end = max(prev.end, sp.end)
            out[-1] = Span(
                prev.start, end, prev.label,
                prev.source if sp.source == prev.source else "both",
                prev.score if sp.start < prev.end else _lower_score(prev.score, sp.score),
                text[prev.start:end],
            )
        else:
            out.append(sp)
    return out


class Detector:
    def __init__(
        self,
        model_id: str = "fef2/ner_rus_bert-secret_detection",
        device: str = "cpu",
        fp16: Optional[bool] = None,
        window_wordpieces: int = WINDOW_WORDPIECES,
        batch_size: int = 32,
        rules: Optional[str | Path] = DEFAULT_RULES,
    ) -> None:
        import torch
        from transformers import AutoModelForTokenClassification, AutoTokenizer

        self.torch = torch
        self.device = device
        self.window = window_wordpieces
        self.max_length = window_wordpieces + 2  # [CLS] … [SEP]
        self.batch_size = max(1, batch_size)

        self.tokenizer = AutoTokenizer.from_pretrained(model_id, use_fast=True)
        if not self.tokenizer.is_fast:
            raise SystemExit("нужен fast-токенизатор: без offset_mapping смещения не восстановить")

        model = AutoModelForTokenClassification.from_pretrained(model_id).eval()
        if fp16 is None:
            fp16 = device.startswith("cuda")
        if fp16:
            model = model.half()
        self.model = model.to(device)
        self.id2label = {int(k): v for k, v in model.config.id2label.items()}

        self.rules: list = []
        if rules is not None:
            from core.scrubber import load_gitleaks_rules

            self.rules, skipped = load_gitleaks_rules(Path(rules))
            if not self.rules:
                raise SystemExit(f"правила не загрузились: {rules}")
            self.rules_skipped = skipped

    def _count(self, text: str) -> int:
        return len(self.tokenizer(text, add_special_tokens=False)["input_ids"])

    def spans(self, text: str) -> List[Span]:
        """Спаны по NFC-нормализованному тексту. Нормализуйте вход тем же NFC,
        прежде чем резать его по этим индексам."""
        text = unicodedata.normalize("NFC", text)
        found: List[Span] = []
        windows = plan_windows(text, self._count, self.window)
        for i in range(0, len(windows), self.batch_size):
            found.extend(self._forward(text, windows[i:i + self.batch_size]))
        found.extend(self.regex_spans(text))
        return merge(found, text)

    def regex_spans(self, text: str) -> List[Span]:
        """Детерминированный слой: kv-детектор, CLI-детектор и правила gitleaks
        по непрозрачным значениям. Без модели, без GPU."""
        if not self.rules:
            return []
        from core.scrubber import credential_sites

        return [Span(s.start, s.end, s.label, "regex", None, text[s.start:s.end])
                for s in credential_sites(text, self.rules)]

    def _forward(self, text: str, windows: Sequence[Tuple[int, int]]) -> List[Span]:
        torch = self.torch
        enc = self.tokenizer(
            [text[a:b] for a, b in windows],
            return_offsets_mapping=True,
            return_special_tokens_mask=True,
            truncation=True,
            max_length=self.max_length,
            padding=True,
            return_tensors="pt",
        )
        with torch.inference_mode():
            logits = self.model(
                input_ids=enc["input_ids"].to(self.device),
                attention_mask=enc["attention_mask"].to(self.device),
            ).logits
        preds = logits.argmax(-1).cpu()
        confidence = logits.float().softmax(-1).max(-1).values.cpu()
        offsets = enc["offset_mapping"].tolist()
        special = enc["special_tokens_mask"].tolist()

        out: List[Span] = []
        for bi, (base, _) in enumerate(windows):
            real = [i for i, m in enumerate(special[bi]) if m == 0]
            bio = [self.id2label[int(preds[bi, i])] for i in real]
            for begin, end, label in extract_entities(bio):
                start = base + offsets[bi][real[begin]][0]
                stop = base + offsets[bi][real[end - 1]][1]
                if stop > start:
                    score = min(float(confidence[bi, real[i]]) for i in range(begin, end))
                    out.append(Span(start, stop, label, "ner", round(score, 4), text[start:stop]))
        return out

    def mask(self, text: str, template: str = "[REDACTED:{label}]") -> str:
        text = unicodedata.normalize("NFC", text)
        parts, cursor = [], 0
        for sp in self.spans(text):
            parts.append(text[cursor:sp.start])
            parts.append(template.format(label=sp.label))
            cursor = sp.end
        parts.append(text[cursor:])
        return "".join(parts)


def main() -> int:
    ap = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    src = ap.add_mutually_exclusive_group()
    src.add_argument("--text", help="текст прямо в аргументе")
    src.add_argument("--file", help="файл с текстом (иначе — stdin)")
    ap.add_argument("--model", default="fef2/ner_rus_bert-secret_detection",
                    help="id на Hub или локальный каталог")
    ap.add_argument("--device", default="cpu", help="cpu | cuda | cuda:0 | mps")
    ap.add_argument("--rules", default=str(DEFAULT_RULES), help="путь к gitleaks.toml")
    ap.add_argument("--no-rules", action="store_true", help="только NER, без детерминированного слоя")
    ap.add_argument("--json", action="store_true", help="спаны в JSON")
    ap.add_argument("--spans", action="store_true", help="спаны построчно")
    args = ap.parse_args()

    if args.text is not None:
        text = args.text
    elif args.file:
        text = open(args.file, encoding="utf-8").read()
    else:
        text = sys.stdin.read()

    det = Detector(args.model, device=args.device, rules=None if args.no_rules else args.rules)
    if args.json:
        print(json.dumps([asdict(s) for s in det.spans(text)], ensure_ascii=False, indent=2))
    elif args.spans:
        for s in det.spans(text):
            score = "  ----" if s.score is None else f"{s.score:.4f}"
            print(f"{s.start:>7} {s.end:>7}  {s.label:<16} {s.source:<5} {score}  {s.text!r}")
    else:
        print(det.mask(text))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())