"""S3 uploads with presigned URLs, plus a local-filesystem mock."""
import os
import uuid

from app.core.config import settings

# Must match the StaticFiles mount in main.py (app/../_uploads = backend/app/_uploads)
LOCAL_DIR = os.path.abspath(
    os.path.join(
        os.path.dirname(__file__),
        "..",
        "..",
        "_uploads",
    )
)


async def upload_file(content: bytes, filename: str, content_type: str = "application/octet-stream") -> str:
    key = f"{uuid.uuid4().hex}_{filename}"
    if settings.mock_storage or not (settings.aws_access_key_id and settings.aws_secret_access_key):
        os.makedirs(LOCAL_DIR, exist_ok=True)
        path = os.path.join(LOCAL_DIR, key)
        with open(path, "wb") as f:
            f.write(content)
        # served by FastAPI static mount at /uploads
        return f"/uploads/{key}"
    import boto3
    client = boto3.client(
        "s3", region_name=settings.aws_region,
        aws_access_key_id=settings.aws_access_key_id,
        aws_secret_access_key=settings.aws_secret_access_key,
    )
    client.put_object(Bucket=settings.s3_bucket, Key=key, Body=content, ContentType=content_type)
    return presigned_url(key)


def presigned_url(key: str, expires: int = 3600) -> str:
    import boto3
    client = boto3.client(
        "s3", region_name=settings.aws_region,
        aws_access_key_id=settings.aws_access_key_id,
        aws_secret_access_key=settings.aws_secret_access_key,
    )
    return client.generate_presigned_url(
        "get_object", Params={"Bucket": settings.s3_bucket, "Key": key}, ExpiresIn=expires
    )