#!/usr/bin/env python3
"""Independent golden models for L03; no RTL implementation is imported."""

import sys


def task01() -> None:
    counter = 0
    previous = 0
    pulses = 0
    consecutive = 0
    for _ in range(16):
        enable = int(counter == 3)
        counter = 0 if enable else counter + 1
        pulses += enable
        consecutive += int(enable and previous)
        previous = enable
    assert (pulses, consecutive, counter) == (4, 0, 0)
    print("PASS task01 pulses=4 consecutive=0 final_count=0")


def task02() -> None:
    sequence = []
    counter = 0
    for _ in range(16):
        counter = (counter + 1) & 0xF
        sequence.append((counter >> 2) & 1)
    edges = [index + 1 for index in range(16) if sequence[index] != (sequence[index - 1] if index else 0)]
    assert edges == [4, 8, 12, 16]
    print("PASS task02 led_edges=4,8,12,16 period=8")


def task03() -> None:
    pattern = [0x1, 0x2, 0x4, 0x8, 0x8, 0x4, 0x2, 0x1]
    observed = [pattern[index & 7] for index in range(10)]
    assert observed == [1, 2, 4, 8, 8, 4, 2, 1, 1, 2]
    print("PASS task03 pattern=1,2,4,8,8,4,2,1 wrap=1,2")


TASKS = {
    "task01_clock_enable": task01,
    "task02_counter_blinker": task02,
    "task03_pattern_rom": task03,
}


if len(sys.argv) != 2 or sys.argv[1] not in TASKS:
    raise SystemExit(f"usage: {sys.argv[0]} {'|'.join(TASKS)}")
TASKS[sys.argv[1]]()