"""
Mail utility helper functions.
"""
import os
import json
import time
from datetime import datetime

def truncate_id(message_id, length=8):
    """
    Truncate a message ID to a reasonable length for display.

    Args:
        message_id (str): The message ID to truncate.
        length (int): The number of characters to keep.

    Returns:
        str: The truncated message ID.
    """
    if not message_id:
        return ""
    if len(message_id) <= length:
        return message_id
    return f"{message_id[:length]}..."

def load_last_sync_timestamp():
    """
    Load the last synchronization timestamp from a file.

    Returns:
        float: The timestamp of the last synchronization, or 0 if not available.
    """
    try:
        with open('sync_timestamp.json', 'r') as f:
            data = json.load(f)
            return data.get('timestamp', 0)
    except (FileNotFoundError, json.JSONDecodeError):
        return 0

def save_sync_timestamp():
    """
    Save the current timestamp as the last synchronization timestamp.

    Returns:
        None
    """
    current_time = time.time()
    with open('sync_timestamp.json', 'w') as f:
        json.dump({'timestamp': current_time}, f)

def format_datetime(dt_str, format_string="%m/%d %I:%M %p"):
    """
    Format a datetime string from ISO format.

    Args:
        dt_str (str): ISO format datetime string.
        format_string (str): Format string for the output.

    Returns:
        str: Formatted datetime string.
    """
    if not dt_str:
        return ""
    try:
        dt = datetime.fromisoformat(dt_str.replace('Z', '+00:00'))
        return dt.strftime(format_string)
    except (ValueError, AttributeError):
        return dt_str

def safe_filename(filename):
    """
    Convert a string to a safe filename.

    Args:
        filename (str): Original filename.

    Returns:
        str: Safe filename with invalid characters replaced.
    """
    invalid_chars = '<>:"/\\|?*'
    for char in invalid_chars:
        filename = filename.replace(char, '_')
    return filename

def ensure_directory_exists(directory):
    """
    Ensure that a directory exists, creating it if necessary.

    Args:
        directory (str): The directory path to check/create.

    Returns:
        None
    """
    if not os.path.exists(directory):
        os.makedirs(directory)

def parse_maildir_name(filename):
    """
    Parse a Maildir filename to extract components.

    Args:
        filename (str): The maildir filename.

    Returns:
        tuple: (message_id, flags) components of the filename.
    """
    # Maildir filename format: unique-id:flags
    if ':' in filename:
        message_id, flags = filename.split(':', 1)
    else:
        message_id = filename
        flags = ''
    return message_id, flags