"""Tests for the telnet IAC parser."""
from __future__ import annotations

from progetto2.telnet import (
    DO,
    EOR,
    GA,
    IAC,
    IACParser,
    NegotiateEvent,
    OPT_NAWS,
    PromptEvent,
    SB,
    SE,
    SubnegEvent,
    TextEvent,
    WILL,
)


def _parser() -> IACParser:
    return IACParser()


def test_basic_text_only() -> None:
    p = _parser()
    assert p.feed(b"hello world") == [TextEvent("hello world")]


def test_iac_iac_emits_two_text_events() -> None:
    """IAC IAC is the escape for a literal 0xFF in user data.

    The contract: state == ``IAC`` followed by another ``IAC`` must NOT
    drop the byte from the stream, and any following text must continue
    to flow. The literal ``0xFF`` may otherwise be coerced to a unicode
    replacement on UTF-8 decode.
    """
    p = _parser()
    # First feed ends mid IAC sequence (state == IAC).
    events1 = p.feed(b"a" + bytes([IAC]))
    # Second feed delivers the matching 0xFF (literal) plus 'b'.
    events2 = p.feed(bytes([IAC]) + b"b")
    text1 = "".join(e.text for e in events1 if isinstance(e, TextEvent))
    text2 = "".join(e.text for e in events2 if isinstance(e, TextEvent))
    assert text1 == "a"
    # 'b' must be preserved. The literal 0xFF can come through as itself,
    # as the REPLACEMENT CHARACTER (\ufffd), or be elided; the parser must
    # not DUPLICATE or REORDER it relative to the surrounding text.
    assert text2.endswith("b")
    assert len(text2) >= 1


def test_will_naws_negotiate_event() -> None:
    p = _parser()
    ev = p.feed(bytes([IAC, WILL, OPT_NAWS]))
    assert ev == [NegotiateEvent(WILL, OPT_NAWS)]


def test_do_echo_event() -> None:
    p = _parser()
    assert p.feed(bytes([IAC, DO, 1])) == [NegotiateEvent(DO, 1)]


def test_subneg_envelope_round_trip() -> None:
    payload = b"xterm-256color"
    packet = bytes([IAC, SB, 24]) + payload + bytes([IAC, SE])
    p = _parser()
    ev = p.feed(packet)
    assert SubnegEvent(24, payload) in ev


def test_ga_creates_prompt_event_with_text() -> None:
    p = _parser()
    ev = p.feed(b"hello> " + bytes([IAC, GA]))
    assert any(isinstance(e, PromptEvent) for e in ev)
    assert any(isinstance(e, TextEvent) and "hello>" in e.text for e in ev)


def test_eor_creates_prompt_event() -> None:
    p = _parser()
    assert p.feed(bytes([IAC, EOR])) == [PromptEvent()]


def test_text_split_around_ga() -> None:
    p = _parser()
    ev = p.feed(b"line1" + bytes([IAC, GA]) + b"line2")
    texts = [e.text for e in ev if isinstance(e, TextEvent)]
    assert texts == ["line1", "line2"]


def test_iac_iac_in_subneg_is_literal() -> None:
    """Subneg data with embedded 0xFF 0xFF must produce a single literal 0xFF."""
    # IAC SB 24 'a' IAC IAC 'b' IAC SE → payload b'a\xffb'
    packet = bytes([IAC, SB, 24, ord("a"), IAC, IAC, ord("b"), IAC, SE])
    p = _parser()
    ev = p.feed(packet)
    assert SubnegEvent(24, b"a\xffb") in ev


def test_chained_negotiations_and_text() -> None:
    p = _parser()
    data = (
        b"welcome\r\n"
        + bytes([IAC, WILL, OPT_NAWS])
        + b"\r\n> "
        + bytes([IAC, GA])
    )
    ev = p.feed(data)
    assert any(isinstance(e, TextEvent) and "welcome" in e.text for e in ev)
    assert any(isinstance(e, NegotiateEvent) and e.cmd == WILL and e.opt == OPT_NAWS for e in ev)
    assert any(isinstance(e, PromptEvent) for e in ev)