src/application/dtos/audio_upload_dto.py

"""Audio Upload Data Transfer Object"""

from dataclasses import dataclass
from typing import Optional
import mimetypes
import os


@dataclass
class AudioUploadDto:
    """DTO for file upload data
    
    Handles audio file upload information including filename,
    content, and content type validation.
    """
    filename: str
    content: bytes
    content_type: str
    size: Optional[int] = None
    
    def __post_init__(self):
        """Validate the DTO after initialization"""
        self._validate()
        if self.size is None:
            self.size = len(self.content)
    
    def _validate(self):
        """Validate audio upload data"""
        if not self.filename:
            raise ValueError("Filename cannot be empty")
        
        if not self.content:
            raise ValueError("Audio content cannot be empty")
        
        if not self.content_type:
            raise ValueError("Content type cannot be empty")
        
        # Validate file extension
        _, ext = os.path.splitext(self.filename.lower())
        supported_extensions = ['.wav', '.mp3', '.m4a', '.flac', '.ogg']
        if ext not in supported_extensions:
            raise ValueError(f"Unsupported file extension: {ext}. Supported: {supported_extensions}")
        
        # Validate content type
        expected_content_type = mimetypes.guess_type(self.filename)[0]
        if expected_content_type and not self.content_type.startswith('audio/'):
            raise ValueError(f"Invalid content type: {self.content_type}. Expected audio/* type")
        
        # Validate file size (max 100MB)
        max_size = 100 * 1024 * 1024  # 100MB
        if len(self.content) > max_size:
            raise ValueError(f"File too large: {len(self.content)} bytes. Maximum: {max_size} bytes")
        
        # Validate minimum file size (at least 1KB)
        min_size = 1024  # 1KB
        if len(self.content) < min_size:
            raise ValueError(f"File too small: {len(self.content)} bytes. Minimum: {min_size} bytes")
    
    @property
    def file_extension(self) -> str:
        """Get the file extension"""
        return os.path.splitext(self.filename.lower())[1]
    
    @property
    def base_filename(self) -> str:
        """Get filename without extension"""
        return os.path.splitext(self.filename)[0]
    
    def to_dict(self) -> dict:
        """Convert to dictionary representation"""
        return {
            'filename': self.filename,
            'content_type': self.content_type,
            'size': self.size,
            'file_extension': self.file_extension
        }