"""Simulated card reads, so the output can be checked without hardware."""

from __future__ import annotations

import random
import time

from .card import (
    DEFAULT_HEARTBEAT_INTERVAL,
    EVENT_INVALID,
    EVENT_INSERTED,
    EVENT_REMOVED,
    CardData,
    CardEvent,
    format_event,
)

# Card ids with the checksum the real protocol would produce
# (XOR of the type byte and the four id bytes), so the output looks genuine.
DEMO_CARDS = (
    CardData(value=0x00C4A0B5, checksum=0xDE, type=0x0F, is_valid=True),
    CardData(value=0x1A2B3C4D, checksum=0x4F, type=0x0F, is_valid=True),
    CardData(value=0xDEADBEEF, checksum=0x00, type=0x0F, is_valid=False),
)


def _emit(event: CardEvent, as_json: bool) -> None:
    print(event.to_json() if as_json else format_event(event), flush=True)


def run_demo(
    count: int = 3,
    heartbeat: float = DEFAULT_HEARTBEAT_INTERVAL,
    as_json: bool = False,
    seed: int = 1234,
) -> int:
    """Print *count* simulated card read cycles. Returns a process exit code."""
    rng = random.Random(seed)
    print("Demo mode - no hardware is used, values are simulated.\n", flush=True)

    for _ in range(max(1, count)):
        card = rng.choice(DEMO_CARDS)
        event_name = EVENT_INSERTED if card.is_valid else EVENT_INVALID
        _emit(CardEvent.from_card(event_name, card, "demo"), as_json)

        time.sleep(max(0.1, heartbeat))
        if card.is_valid:
            _emit(CardEvent.from_card(EVENT_REMOVED, card, "demo"), as_json)
        time.sleep(0.3)

    print("\nDemo finished.", flush=True)
    return 0