from __future__ import annotations

import hashlib
import re
from dataclasses import dataclass
from pathlib import Path

from .rag_index import extract_text_from_path


@dataclass(frozen=True)
class ExtractedText:
    path: Path
    text: str
    status: str
    content_hash: str = ""
    error_message: str = ""
    front_text: str = ""
    section_candidates: list[str] | None = None
    field_candidates: dict[str, str] | None = None


SUPPORTED_EXTENSIONS = {".txt", ".md", ".pdf", ".docx", ".pptx", ".xlsx", ".doc"}


def extract_text(path: str | Path) -> ExtractedText:
    file_path = Path(path)
    if file_path.suffix.lower() not in SUPPORTED_EXTENSIONS:
        return ExtractedText(path=file_path, text="", status="unsupported")
    try:
        text = extract_text_from_path(file_path)
    except Exception as exc:
        return ExtractedText(
            path=file_path,
            text="",
            status="failed",
            error_message=str(exc),
            section_candidates=[],
            field_candidates={},
        )
    content_hash = hashlib.sha256(text.encode("utf-8")).hexdigest() if text else ""
    return ExtractedText(
        path=file_path,
        text=text,
        status="success",
        content_hash=content_hash,
        front_text=_front_text(text),
        section_candidates=_section_candidates(text),
        field_candidates=_field_candidates(text),
    )


def _front_text(text: str, limit: int = 1200) -> str:
    return text[:limit]


def _section_candidates(text: str) -> list[str]:
    candidates = []
    for line in text.splitlines():
        normalized = line.strip()
        if not normalized:
            continue
        if re.match(r"^([一二三四五六七八九十]+[、.．]|[0-9]+(\.[0-9]+)*[、.．\s])", normalized):
            candidates.append(normalized[:120])
        elif any(keyword in normalized for keyword in ["章节目录", "监管信息", "综述资料", "非临床资料", "临床评价资料", "质量管理体系"]):
            candidates.append(normalized[:120])
    return candidates[:80]


def _field_candidates(text: str) -> dict[str, str]:
    fields = {}
    for label in ["产品名称", "型号规格", "预期用途", "管理类别", "分类编码", "注册类型", "临床评价路径"]:
        match = re.search(rf"{label}[:：]\s*([^\n\r]+)", text)
        if match:
            fields[label] = " ".join(match.group(1).strip().split())
    return fields