from __future__ import annotations

import hashlib
from pathlib import Path

from django.conf import settings

from review_agent.models import RegulatoryInfoPackageArtifact, RegulatoryInfoPackageBatch


def build_batch_work_dir(batch: RegulatoryInfoPackageBatch | None = None, *, batch_no: str = "") -> Path:
    if batch:
        return (
            Path(settings.MEDIA_ROOT)
            / "regulatory_info_package"
            / str(batch.user_id)
            / str(batch.conversation_id)
            / batch.batch_no
        )
    return Path(settings.MEDIA_ROOT) / "regulatory_info_package" / batch_no


def ensure_batch_subdir(batch: RegulatoryInfoPackageBatch, name: str) -> Path:
    root = Path(batch.work_dir) if batch.work_dir else build_batch_work_dir(batch)
    target = root / Path(name).name
    ensure_within_work_dir(batch, target)
    target.mkdir(parents=True, exist_ok=True)
    return target


def ensure_within_work_dir(batch: RegulatoryInfoPackageBatch, path: str | Path) -> Path:
    root = Path(batch.work_dir).resolve()
    target = Path(path).resolve()
    if root != target and root not in target.parents:
        raise ValueError("输出路径必须位于当前材料包批次工作目录内。")
    return target


def compute_file_sha256(path: str | Path) -> str:
    file_path = Path(path)
    digest = hashlib.sha256()
    with file_path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def create_artifact_for_file(
    batch: RegulatoryInfoPackageBatch,
    *,
    path: str | Path,
    artifact_type: str,
    file_format: str,
    name: str = "",
    metadata: dict | None = None,
    created_by_node: str = "",
) -> RegulatoryInfoPackageArtifact:
    file_path = ensure_within_work_dir(batch, path)
    return RegulatoryInfoPackageArtifact.objects.create(
        batch=batch,
        artifact_type=artifact_type,
        file_format=file_format,
        name=name or file_path.stem,
        file_name=file_path.name,
        storage_path=str(file_path),
        file_size=file_path.stat().st_size if file_path.exists() else 0,
        content_hash=compute_file_sha256(file_path) if file_path.exists() else "",
        metadata=metadata or {},
        created_by_node=created_by_node,
    )