from __future__ import annotations

from .shared import *

def _resolve_tenant_id(user: User, fallback_tenant_id: int) -> int:
    try:
        return int(getattr(user, "tenant_id") or fallback_tenant_id or 1)
    except Exception:
        return int(fallback_tenant_id or 1)

def _safe_decode_bytes(raw: bytes) -> str:
    for encoding in ("utf-8", "utf-8-sig", "gb18030", "latin-1"):
        try:
            return raw.decode(encoding)
        except Exception:
            continue
    return raw.decode("utf-8", errors="ignore")

def _extract_text_from_upload(filename: str, raw: bytes) -> tuple[str, str]:
    name = str(filename or "uploaded.txt")
    suffix = name.rsplit(".", 1)[-1].lower() if "." in name else "txt"

    if suffix in {"txt", "md", "markdown", "csv", "json", "py", "ts", "tsx", "js", "jsx"}:
        return ("md" if suffix in {"md", "markdown"} else "txt", _safe_decode_bytes(raw))

    if suffix == "pdf":
        try:
            from pypdf import PdfReader  # type: ignore
        except Exception as exc:
            raise HTTPException(status_code=400, detail=f"PDF 解析依赖缺失: {exc}") from exc
        reader = PdfReader(io.BytesIO(raw))
        parts: list[str] = []
        for idx, page in enumerate(reader.pages, start=1):
            page_text = (page.extract_text() or "").strip()
            if not page_text:
                continue
            # 写入页码标记，向量分块时会保留 page_number 元数据，便于引用来源页码。
            parts.append(f"[[PAGE:{idx}]]\n{page_text}")
        text = "\n\n".join(parts)
        return ("pdf", text)

    if suffix in {"docx", "doc"}:
        try:
            from docx import Document  # type: ignore
        except Exception as exc:
            raise HTTPException(status_code=400, detail=f"Word 解析依赖缺失: {exc}") from exc
        doc = Document(io.BytesIO(raw))
        text = "\n".join([p.text for p in doc.paragraphs if p.text])
        return ("word", text)

    raise HTTPException(status_code=400, detail=f"不支持的文件类型: .{suffix}")