# sanitize.py — Unified agent name sanitization contract for herdr 0.8.0 (E3 & E4)

import re

def sanitize_herdr_agent_name(name: str) -> str:
    """
    Sanitizes an agent name according to herdr 0.8.0 rules:
    1. Convert to lowercase.
    2. Replace invalid characters ([^a-z0-9_-]) with '-'.
    3. Ensure starts with a lowercase letter [a-z], prefixing with 'x-' if needed.
    4. Truncate to maximum 32 characters (16 + '-' + 15).
    """
    if not name:
        return "agent"
    
    # 1. Lowercase
    s = str(name).lower()
    
    # 2. Replace illegal characters with '-'
    s = re.sub(r'[^a-z0-9_-]', '-', s)
    
    # 3. Ensure starts with a letter [a-z]
    if not s or not s[0].isalpha():
        s = "x-" + s
    
    # 4. Truncate to 32 chars if needed
    if len(s) > 32:
        s = s[:16] + '-' + s[-15:]
    
    return s