refactor: Introduce utility functions for exception handling and database operations; update auth and playlist services to use new exception methods

app/utils/validation.py

@@ -0,0 +1,140 @@
+"""Common validation utility functions."""
+
+import re
+from pathlib import Path
+from typing import Any, Optional
+
+# Password validation constants
+MIN_PASSWORD_LENGTH = 8
+
+
+def validate_email(email: str) -> bool:
+    """Validate email address format.
+
+    Args:
+        email: Email address to validate
+
+    Returns:
+        True if email format is valid, False otherwise
+    """
+    pattern = r"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$"
+    return bool(re.match(pattern, email))
+
+
+def validate_password_strength(password: str) -> tuple[bool, str | None]:
+    """Validate password meets security requirements.
+
+    Args:
+        password: Password to validate
+
+    Returns:
+        Tuple of (is_valid, error_message)
+    """
+    if len(password) < MIN_PASSWORD_LENGTH:
+        msg = f"Password must be at least {MIN_PASSWORD_LENGTH} characters long"
+        return False, msg
+
+    if not re.search(r"[A-Z]", password):
+        return False, "Password must contain at least one uppercase letter"
+
+    if not re.search(r"[a-z]", password):
+        return False, "Password must contain at least one lowercase letter"
+
+    if not re.search(r"\d", password):
+        return False, "Password must contain at least one number"
+
+    return True, None
+
+
+def validate_filename(
+    filename: str, allowed_extensions: list[str] | None = None
+) -> bool:
+    """Validate filename format and extension.
+
+    Args:
+        filename: Filename to validate
+        allowed_extensions: List of allowed file extensions (with dots)
+
+    Returns:
+        True if filename is valid, False otherwise
+    """
+    if not filename or filename.startswith(".") or "/" in filename or "\\" in filename:
+        return False
+
+    if allowed_extensions:
+        file_path = Path(filename)
+        return file_path.suffix.lower() in [ext.lower() for ext in allowed_extensions]
+
+    return True
+
+
+def validate_audio_filename(filename: str) -> bool:
+    """Validate audio filename has allowed extension.
+
+    Args:
+        filename: Audio filename to validate
+
+    Returns:
+        True if filename has valid audio extension, False otherwise
+    """
+    audio_extensions = [".mp3", ".wav", ".flac", ".ogg", ".m4a", ".aac", ".wma"]
+    return validate_filename(filename, audio_extensions)
+
+
+def sanitize_filename(filename: str) -> str:
+    """Sanitize filename by removing/replacing invalid characters.
+
+    Args:
+        filename: Filename to sanitize
+
+    Returns:
+        Sanitized filename safe for filesystem
+    """
+    # Remove or replace problematic characters
+    sanitized = re.sub(r'[<>:"/\\|?*]', "_", filename)
+
+    # Remove leading/trailing whitespace and dots
+    sanitized = sanitized.strip(" .")
+
+    # Ensure not empty
+    if not sanitized:
+        sanitized = "untitled"
+
+    return sanitized
+
+
+def validate_url(url: str) -> bool:
+    """Validate URL format.
+
+    Args:
+        url: URL to validate
+
+    Returns:
+        True if URL format is valid, False otherwise
+    """
+    pattern = r"^https?://[^\s/$.?#].[^\s]*$"
+    return bool(re.match(pattern, url))
+
+
+def validate_positive_integer(value: Any, field_name: str = "value") -> int:
+    """Validate and convert value to positive integer.
+
+    Args:
+        value: Value to validate and convert
+        field_name: Name of field for error messages
+
+    Returns:
+        Validated positive integer
+
+    Raises:
+        ValueError: If value is not a positive integer
+    """
+    try:
+        int_value = int(value)
+        if int_value <= 0:
+            msg = f"{field_name} must be a positive integer"
+            raise ValueError(msg)
+        return int_value
+    except (TypeError, ValueError) as e:
+        msg = f"{field_name} must be a positive integer"
+        raise ValueError(msg) from e