#!/usr/bin/env python3
"""
Header extraction utilities for Gmail API messages.
"""
from typing import Optional
def get_header_value(
headers: list[dict], header_name: str, default: Optional[str] = None
) -> Optional[str]:
"""
Extract a header value from email headers by name.
Args:
headers: List of email header dictionaries with 'name' and 'value' keys
header_name: Name of the header to extract (case-insensitive)
default: Default value if header not found
Returns:
Header value or default
Example:
>>> headers = [{"name": "From", "value": "user@example.com"}]
>>> get_header_value(headers, "from")
'user@example.com'
"""
return next(
(
header.get("value")
for header in headers
if header.get("name", "").lower() == header_name.lower()
),
default,
)
