"""Utilities for invite code generation and validation."""
import random
from pathlib import Path

# Load BIP39 words from file
_WORDS_FILE = Path(__file__).parent / "words.txt"
with open(_WORDS_FILE) as f:
    BIP39_WORDS = [line.strip() for line in f if line.strip()]

assert len(BIP39_WORDS) == 2048, f"Expected 2048 BIP39 words, got {len(BIP39_WORDS)}"


def generate_invite_identifier() -> str:
    """
    Generate a unique invite identifier.
    
    Format: word1-word2-NN where:
    - word1, word2 are random BIP39 words
    - NN is a two-digit number (00-99)
    
    Returns lowercase identifier.
    """
    word1 = random.choice(BIP39_WORDS)
    word2 = random.choice(BIP39_WORDS)
    number = random.randint(0, 99)
    return f"{word1}-{word2}-{number:02d}"


def normalize_identifier(identifier: str) -> str:
    """
    Normalize an invite identifier for comparison/lookup.
    
    - Converts to lowercase
    - Strips whitespace
    """
    return identifier.strip().lower()


def is_valid_identifier_format(identifier: str) -> bool:
    """
    Check if an identifier has valid format (word-word-NN).
    
    Does NOT check if words are valid BIP39 words.
    """
    parts = identifier.split("-")
    if len(parts) != 3:
        return False
    
    word1, word2, number = parts
    
    # Check words are non-empty
    if not word1 or not word2:
        return False
    
    # Check number is two digits
    if len(number) != 2 or not number.isdigit():
        return False
    
    return True