"""Contract conformance tests (SPEC.md 0.3.x). Platform-agnostic: framebuffer

dimensions come from the PPM header, read addresses use $0000, and `bank` is

exercised but banking is not required. The one address that must be *writable*

(the mem-write round-trip) is chosen per-platform via `_scratch_ram`, because

low memory is not RAM everywhere — on the eZ80 Agon $0000-$03FFFF is on-chip

flash (MOS ROM) and RAM only begins at $040000. Tests gated on the server's

advertised minor (input injection 0.2; memory write + audio 0.3) skip on older

servers."""

import urllib.error

import urllib.request

import pytest

from emu_control import parse_ppm_header

def _raw(emu, method, path, body=None):

    """Raw request returning (status_code, body) without the client's wrapping,

    so we can assert on 4xx status codes."""

    req = urllib.request.Request(emu.base + path, method=method, data=body)

    try:

        with urllib.request.urlopen(req, timeout=emu.timeout) as r:

            return r.status, r.read()

    except urllib.error.HTTPError as e:

        return e.code, e.read()

def test_status_contract(emu):

    st = emu.status()

    for k in ("contract", "emulator", "platform", "frame", "paused", "running"):

        assert k in st, f"missing /status.{k}"

    assert str(st["contract"]).split(".")[0] == "0", "unexpected contract MAJOR"

    assert isinstance(st["platform"], str) and st["platform"]

    assert isinstance(st["frame"], int)

    assert isinstance(st["paused"], bool)

def test_regs_object(emu):

    r = emu.regs()

    assert isinstance(r, dict) and r, "regs must be a non-empty JSON object"

    assert all(isinstance(v, int) for v in r.values()), "register values must be ints"

def test_mem_exact_length(emu):

    assert len(emu.mem(0x0000, 32)) == 32

    assert len(emu.mem(0x0000, 256)) == 256

    assert len(emu.mem(0x0000, 0)) == 0

def test_mem_bank_param_returns_length(emu):

    # bank is optional (ignored on flat platforms) but must still honour len.

    assert len(emu.mem(0x0000, 8, bank=0)) == 8

def test_screenshot_ppm(emu):

    data = emu.screenshot_ppm()

    w, h, maxval, off = parse_ppm_header(data)

    assert w > 0 and h > 0, f"bad dimensions {w}x{h}"

    assert maxval == 255

    assert len(data) == off + 3 * w * h, "PPM body size mismatches dimensions"

def test_step_is_deterministic(emu):

    emu.pause()

    try:

        a = emu.frame()

        b = emu.step(2); c = emu.frame()

        assert b == c, "/step must return the halted frame counter"

        d = emu.step(2); e = emu.frame()

        assert d == e

        assert c - a > 0, "/step must advance the frame counter"

        assert (c - a) == (e - c), "equal steps must advance by equal amounts"

    finally:

        emu.resume()

def test_pause_resume_toggle(emu):

    emu.pause()

    assert emu.status()["paused"] is True

    emu.resume()

    assert emu.status()["paused"] is False

def test_unknown_path_404(emu):

    code, _ = _raw(emu, "GET", "/no-such-endpoint")

    assert code == 404

def test_step_requires_post(emu):

    code, _ = _raw(emu, "GET", "/step?frames=1")

    assert code == 405

def _contract_minor(emu) -> int:

    return int(str(emu.status()["contract"]).split(".")[1])

# -- contract 0.2: input injection (skipped on 0.1 servers) ------------------

def test_key_injection(emu):

    """/key accepts text= and code= with an optional down=, and rejects a

    request with neither. The key's *effect* is platform/program-specific and

    tested per-port; here we assert only the contract surface."""

    if _contract_minor(emu) < 2:

        pytest.skip("contract < 0.2 (no input injection)")

    emu.key(text="a", down=True)

    emu.key(text="a", down=False)

    emu.key(text="a")                    # tap (press then release)

    emu.key(code=32, down=True)

    emu.key(code=32, down=False)

    code, _ = _raw(emu, "POST", "/key")  # neither text nor code

    assert code == 400

def test_key_requires_post(emu):

    if _contract_minor(emu) < 2:

        pytest.skip("contract < 0.2")

    code, _ = _raw(emu, "GET", "/key?text=a")

    assert code == 405

# -- contract 0.3: memory write + audio (skipped on < 0.3 servers) -----------

def _scratch_ram(emu):

    """A writable RAM address for the platform. Most cores are flat with RAM at

    $0000, but the eZ80 Agon maps $0000-$03FFFF to flash (MOS ROM), so a write

    there is a silent no-op and the read-back returns ROM. RAM starts at

    $040000 there; $050000 is well clear of the MOS load area."""

    plat = (emu.status().get("platform") or "").lower()

    return 0x050000 if "agon" in plat else 0x0400

def test_mem_write_roundtrip(emu):

    """POST /mem pokes bytes; GET /mem reads them back (contract 0.3)."""

    if _contract_minor(emu) < 3:

        pytest.skip("contract < 0.3 (no memory write)")

    emu.pause()               # freeze so the machine can't overwrite between write+read

    try:

        addr, payload = _scratch_ram(emu), bytes([0xA5, 0x5A, 0x00, 0xFF])

        assert emu.mem_write(addr, payload) == len(payload)

        assert emu.mem(addr, len(payload)) == payload

    finally:

        emu.resume()

def test_mem_write_requires_post(emu):

    if _contract_minor(emu) < 3:

        pytest.skip("contract < 0.3")

    # GET /mem is the read path (200), never a write — writing needs POST.

    code, _ = _raw(emu, "GET", "/mem?addr=0&len=1")

    assert code == 200

def test_audio_is_valid_wav(emu):

    """GET /audio returns a parseable PCM WAV (contract 0.3)."""

    if _contract_minor(emu) < 3:

        pytest.skip("contract < 0.3 (no audio)")

    import io

    import wave

    emu.pause(); emu.step(4)          # produce a little audio deterministically

    w = wave.open(io.BytesIO(emu.audio()), "rb")

    assert w.getsampwidth() == 2      # signed 16-bit

    assert w.getnchannels() in (1, 2)

    assert w.getframerate() > 0

    emu.resume()

# -- contract 0.4: pointer injection (skipped on < 0.4 servers) --------------

def test_pointer_injection(emu):

    """/pointer accepts absolute (x,y) and relative (dx,dy) with an optional

    buttons= bitmask, and rejects a request with neither. The pointer's *effect*

    is platform-specific and tested per-port; here we assert the contract

    surface only."""

    if _contract_minor(emu) < 4:

        pytest.skip("contract < 0.4 (no pointer injection)")

    emu.pointer(x=10, y=20)                 # absolute move, buttons unchanged

    emu.pointer(x=10, y=20, buttons=1)      # primary button down

    emu.pointer(x=10, y=20, buttons=0)      # buttons released

    emu.pointer(dx=4, dy=-2)                # relative move

    code, _ = _raw(emu, "POST", "/pointer")  # neither x/y nor dx/dy

    assert code == 400

def test_pointer_readback(emu):

    """GET /pointer reports {x, y, buttons} as ints (contract 0.4). Values are

    platform-specific; we assert only shape."""

    if _contract_minor(emu) < 4:

        pytest.skip("contract < 0.4")

    emu.pause()

    try:

        emu.pointer(x=42, y=24, buttons=0)

        emu.step(1)

        p = emu.pointer_get()

        assert {"x", "y", "buttons"} <= p.keys()

        assert all(isinstance(p[k], int) for k in ("x", "y", "buttons"))

    finally:

        emu.resume()

def test_pointer_get_is_get(emu):

    if _contract_minor(emu) < 4:

        pytest.skip("contract < 0.4")

    # GET /pointer is the readback path (200); POST is the inject path.

    code, _ = _raw(emu, "GET", "/pointer")

    assert code == 200

def test_reset(emu):

    """/reset responds and is POST-only. Runs last (it restarts the machine)."""

    if _contract_minor(emu) < 2:

        pytest.skip("contract < 0.2")

    code, _ = _raw(emu, "GET", "/reset")

    assert code == 405

    emu.reset()

# -- contract 0.5: pad injection (skipped on < 0.5 servers) ------------------

def test_pad_injection(emu):

    """/pad presents a virtual controller and sets what is held. The pad's

    *effect* is platform-specific and tested per-port; the contract surface is

    asserted here."""

    if _contract_minor(emu) < 5:

        pytest.skip("contract < 0.5 (no pad injection)")

    emu.pad(buttons=emu.PAD_A)                      # A held, pad plugged in

    emu.pad(buttons=emu.PAD_A | emu.PAD_LEFT)       # two at once

    emu.pad(buttons=0)                              # all released, still there

    emu.pad(index=1, buttons=emu.PAD_B)             # a second pad

    emu.pad(connected=False)                        # unplug pad 0

    emu.pad(connected=False, index=1)

def test_pad_readback(emu):

    """GET /pad reports {index, connected, buttons} (contract 0.5)."""

    if _contract_minor(emu) < 5:

        pytest.skip("contract < 0.5")

    emu.pause()

    try:

        emu.pad(buttons=emu.PAD_A | emu.PAD_RIGHT)

        emu.step(1)

        st = emu.pad_get()

        assert isinstance(st["buttons"], int)

        assert isinstance(st["connected"], bool)

        assert st["index"] == 0

        assert st["connected"] is True, "injected pad reports itself absent"

        # The mask must survive the round trip: this is the check that

        # separates "the server accepted it" from "the backend stored it".

        assert st["buttons"] == emu.PAD_A | emu.PAD_RIGHT, (

            f"held {st['buttons']:#x}, injected "

            f"{emu.PAD_A | emu.PAD_RIGHT:#x}")

    finally:

        emu.pad(buttons=0)

        emu.resume()

def test_pad_is_a_level_not_an_event(emu):

    """A pad HOLDS. Unlike a key tap, an injected press must survive stepping —

    a program that samples input once a frame has to still see it on frame 10.

    This is the difference that makes /pad worth having rather than reusing

    /key, so it is asserted rather than assumed."""

    if _contract_minor(emu) < 5:

        pytest.skip("contract < 0.5")

    emu.pause()

    try:

        emu.pad(buttons=emu.PAD_B)

        emu.step(10)

        assert emu.pad_get()["buttons"] == emu.PAD_B, (

            "the held mask did not survive 10 frames — /pad is behaving "

            "like a momentary key tap")

    finally:

        emu.pad(buttons=0)

        emu.resume()

def test_pad_unplug_is_observable(emu):

    """connected=0 must actually unplug. A program that offers two-player only

    when a second controller is present needs both answers to be reachable, so

    a backend that always reports 'connected' is not conformant."""

    if _contract_minor(emu) < 5:

        pytest.skip("contract < 0.5")

    emu.pause()

    try:

        emu.pad(connected=False)

        if emu.pad_get()["connected"]:

            pytest.skip(

                "a physical controller is present at index 0, so `connected` "

                "cannot go false — the SPEC says it reports anything present, "

                "real or virtual. Re-run with the controller unplugged.")

        emu.pad(buttons=0)                     # plugging in is what we assert

        assert emu.pad_get()["connected"] is True, (

            "injecting did not make the pad present")

        emu.pad(connected=False)

        assert emu.pad_get()["connected"] is False, (

            "the pad still reports connected after connected=0")

    finally:

        emu.pad(connected=False)

        emu.resume()

# -- contract 0.6: performance metrics (skipped on < 0.6 servers) ------------

def test_capabilities_list_the_groups(emu):

    """/status.capabilities names each group the server serves. Always the

    four 0.1 groups; at 0.6 also perf, and the groups below it the ladder

    implies."""

    if _contract_minor(emu) < 6:

        pytest.skip("contract < 0.6 (no capabilities)")

    caps = emu.capabilities()

    for c in ("mem", "regs", "screenshot", "step", "key", "mem-write", "audio", "pointer", "pad", "perf"):

        assert c in caps, (c, caps)

def _perf_on(emu):

    emu.perf_config(enabled=True)

def test_perf_shape(emu):

    """GET /perf's sections and their arithmetic: work = total - idle, main =

    work - irq, the windows asked for, raw frames oldest first. The numbers

    themselves are the platform's and the program's; only their relations are

    the contract's."""

    if _contract_minor(emu) < 6:

        pytest.skip("contract < 0.6")

    _perf_on(emu)

    emu.pause()

    try:

        emu.step(10)

        p = emu.perf(windows=[1, "session"], frames=5)

    finally:

        emu.resume()

    assert p["enabled"] is True

    b = p["budget"]

    for k in ("targetFps", "vsyncHz", "cyclesPerFrame", "scanlinesPerFrame", "cyclesPerScanline",

              "budgetCycles", "framesPerBudget", "historyFrames", "totalFrames", "idleMode"):

        assert k in b, k

    assert b["cyclesPerFrame"] > 0 and b["budgetCycles"] > 0

    c = p["current"]

    assert c["workCycles"] == c["totalCycles"] - c["idleCycles"], c

    assert c["mainCycles"] == c["workCycles"] - c["irqCycles"], c

    assert isinstance(c["overBudget"], bool)

    assert [w["name"] for w in p["windows"]] == ["1s", "session"], p["windows"]

    for w in p["windows"]:

        for series in ("work", "budgetWork", "total", "irq", "hostUs"):

            s = w[series]

            assert s["min"] <= s["p50"] <= s["p95"] <= s["p99"] <= s["max"], (series, s)

    assert isinstance(p["zones"], list) and isinstance(p["platform"], dict)

    frames = [f["frame"] for f in p["frames"]]

    assert 1 <= len(frames) <= 5 and frames == sorted(frames), frames

    assert frames[-1] == c["frame"], (frames, c["frame"])

def test_perf_since_misses_no_frame(emu):

    """since=<f> returns every completed frame after f, so a harness that

    polls with the last frame it saw gets each frame exactly once."""

    if _contract_minor(emu) < 6:

        pytest.skip("contract < 0.6")

    _perf_on(emu)

    emu.pause()

    try:

        emu.step(2)

        last = emu.perf(zones=False)["current"]["frame"]

        emu.step(5)

        got = [f["frame"] for f in emu.perf(zones=False, since=last)["frames"]]

    finally:

        emu.resume()

    assert got == list(range(last + 1, last + 6)), (last, got)

def test_perf_zones_name_a_marker_region(emu):

    """POST /perf's zones replace the list, and a {name, marker} entry names

    the guest's marker region; the zone is reported under that name whether

    or not the program has entered it yet."""

    if _contract_minor(emu) < 6:

        pytest.skip("contract < 0.6")

    try:

        emu.perf_config(enabled=True, zones=[{"name": "conformance", "marker": 63}])

        names = [z["name"] for z in emu.perf()["zones"]]

        assert "conformance" in names, names

    finally:

        emu.perf_config(zones=[])

def test_perf_rejects_a_bad_body(emu):

    if _contract_minor(emu) < 6:

        pytest.skip("contract < 0.6")

    code, _ = _raw(emu, "POST", "/perf", b"not json")

    assert code == 400