import uuid
import magic
from fastapi import HTTPException, UploadFile
from app.config import settings
from app.enums import DocumentType

def generate_document_id() -> str:
    """Generate UUID for document"""
    return str(uuid.uuid4())

def s3_path_prefix(org_id: str, document_id: str) -> str:
    """Generate S3 path prefix for document operations"""
    return f"documents/{org_id}/{document_id}/"

def detect_content_type(file: UploadFile) -> str:
    """Detect content type using python-magic"""
    file.file.seek(0)
    content = file.file.read(2048)
    file.file.seek(0)

    mime = magic.Magic(mime=True)
    return mime.from_buffer(content)

def detect_document_type(filename: str, content_type: str) -> DocumentType:
    """Detect document type from filename and content type"""
    # Try content type first
    doc_type = DocumentType.from_mime_type(content_type)
    if doc_type:
        return doc_type

    # Fall back to extension
    return DocumentType.from_extension(filename)

def get_file_size_limit(document_type: DocumentType) -> int:
    """Get max file size for document type"""
    limits = {
        DocumentType.PDF: settings.max_file_size_pdf,
        DocumentType.DOCX: settings.max_file_size_docx,
        DocumentType.XLSX: settings.max_file_size_xlsx,
        DocumentType.JPG: settings.max_file_size_jpg,
        DocumentType.JPEG: settings.max_file_size_jpeg,
        DocumentType.PNG: settings.max_file_size_png,
        DocumentType.GIF: settings.max_file_size_gif,
    }
    return limits.get(document_type, settings.max_file_size_default)

def validate_file_size(file_size: int, document_type: DocumentType) -> None:
    """Validate file size against limits"""
    max_size = get_file_size_limit(document_type)
    if file_size > max_size:
        raise HTTPException(
            status_code=413,
            detail=f"File size {file_size} exceeds maximum {max_size} for {document_type.value}"
        )

def document_s3_key(org_id: str, document_id: str, filename: str) -> str:
    """Generate S3 key for document"""
    return f"{s3_path_prefix(org_id, document_id)}{filename}"

def sanitize_filename(filename: str) -> str:
    """URL encode filename for S3"""
    from urllib.parse import quote
    return quote(filename, safe="")