#!/usr/bin/env python3
"""Generate and verify first 20 Fibonacci numbers - stdlib only."""

def fibonacci(n: int) -> list[int]:
    """Generate first n Fibonacci numbers."""
    if n <= 0:
        return []
    if n == 1:
        return [0]
    seq = [0, 1]
    for _ in range(n - 2):
        seq.append(seq[-1] + seq[-2])
    return seq

def verify_fibonacci(seq: list[int]) -> bool:
    """Verify sequence is valid Fibonacci."""
    if len(seq) < 2:
        return True
    if seq[0] != 0 or seq[1] != 1:
        return False
    for i in range(2, len(seq)):
        if seq[i] != seq[i-1] + seq[i-2]:
            return False
    return True

def main():
    numbers = fibonacci(20)
    output_file = "/root/.hermes/wizard-outputs/spark/fibonacci_output.txt"
    
    with open(output_file, "w") as f:
        f.write("First 20 Fibonacci numbers:\n")
        for i, n in enumerate(numbers, 1):
            f.write(f"{i}: {n}\n")
    
    is_valid = verify_fibonacci(numbers)
    expected_sum = sum(numbers)
    
    verification_file = "/root/.hermes/wizard-outputs/spark/verification.txt"
    with open(verification_file, "w") as f:
        f.write(f"Sequence valid: {is_valid}\n")
        f.write(f"Sum of first 20: {expected_sum}\n")
        f.write(f"Last number: {numbers[-1]}\n")
    
    print(f"Generated {len(numbers)} Fibonacci numbers")
    print(f"Sum: {expected_sum}")
    print(f"Valid: {is_valid}")

if __name__ == "__main__":
    main()