from datetime import datetime, timedelta

from mail_intake.models.message import MailIntakeMessage
from mail_intake.models.thread import MailIntakeThread


def test_message_is_immutable():
    msg = MailIntakeMessage(
        message_id="m1",
        thread_id="t1",
        timestamp=datetime.utcnow(),
        from_email="alice@example.com",
        from_name="Alice",
        subject="Hello",
        body_text="Body",
        snippet="Snippet",
        raw_headers={"from": "Alice <alice@example.com>"},
    )

    try:
        msg.subject = "Changed"
        assert False, "Message should be immutable"
    except Exception:
        assert True


def test_thread_add_message_updates_participants_and_timestamp():
    t0 = datetime.utcnow()
    t1 = t0 + timedelta(minutes=5)

    msg1 = MailIntakeMessage(
        message_id="m1",
        thread_id="t1",
        timestamp=t0,
        from_email="alice@example.com",
        from_name="Alice",
        subject="Hello",
        body_text="Body",
        snippet="Snippet",
        raw_headers={},
    )

    msg2 = MailIntakeMessage(
        message_id="m2",
        thread_id="t1",
        timestamp=t1,
        from_email="bob@example.com",
        from_name="Bob",
        subject="Re: Hello",
        body_text="Reply",
        snippet="Reply",
        raw_headers={},
    )

    thread = MailIntakeThread(
        thread_id="t1",
        normalized_subject="Hello",
    )

    thread.add_message(msg1)
    assert thread.last_activity_at == t0
    assert "alice@example.com" in thread.participants

    thread.add_message(msg2)
    assert thread.last_activity_at == t1
    assert "bob@example.com" in thread.participants
    assert len(thread.messages) == 2


def test_thread_handles_messages_without_sender():
    msg = MailIntakeMessage(
        message_id="m1",
        thread_id="t1",
        timestamp=datetime.utcnow(),
        from_email="",
        from_name=None,
        subject="System Message",
        body_text="Body",
        snippet="Snippet",
        raw_headers={},
    )

    thread = MailIntakeThread(
        thread_id="t1",
        normalized_subject="System Message",
    )

    thread.add_message(msg)

    assert len(thread.participants) == 0
    assert thread.last_activity_at is not None