"""HTTP-layer tests for backend/main.py (FastAPI TestClient + real EPANET DLL).

Run from the repo root:  .venv/Scripts/python -m pytest backend/tests -q
"""
from pathlib import Path

import pytest
from fastapi.testclient import TestClient

from backend import main
from backend.main import app

REPO = Path(__file__).resolve().parents[2]
PUBLIC = REPO / "public"


@pytest.fixture(scope="module")
def client():
    with TestClient(app, raise_server_exceptions=False) as c:
        yield c


def post(client, name: str, data: bytes):
    return client.post("/api/analyze", files={"file": (name, data, "text/plain")})


SIMPLE = b"""[JUNCTIONS]
 J1 10 5
 J2 12 3
[RESERVOIRS]
 R1 50
[PIPES]
 P1 R1 J1 1000 200 100
 P2 J1 J2 1000 150 100
[OPTIONS]
 Units LPS
[END]
"""


def test_health(client):
    r = client.get("/api/health")
    assert r.status_code == 200
    assert r.json() == {"status": "ok"}


def test_net1_runs(client):
    r = post(client, "Net1.inp", (PUBLIC / "Net1.inp").read_bytes())
    assert r.status_code == 200
    body = r.json()
    assert len(body["nodes"]) == 11 and len(body["links"]) == 13
    assert body["units"] == {"flow": "GPM", "pressure": "psi"}
    assert body["reportStep"] > 0
    assert body["engineWarnings"] == []


def test_wrong_extension_rejected(client):
    assert post(client, "a.txt", SIMPLE).status_code == 400


def test_oversized_upload_rejected(client):
    r = post(client, "big.inp", b"x" * (main.MAX_UPLOAD_BYTES + 1))
    assert r.status_code == 413


def test_early_size_check_not_bypassed_by_bad_host(client):
    # request.url is rebuilt from Host; the early 413 must not depend on it.
    big = str(main.MAX_UPLOAD_BYTES + 10 * 1024 * 1024)
    for host in ("localhost", "bad host:abc", "evil.example/../x"):
        r = client.post("/api/analyze", headers={"content-length": big, "host": host}, content=b"")
        assert r.status_code == 413, (host, r.status_code)


def test_invalid_inp_returns_json_with_root_cause(client):
    # Previously: EN_open failure leaked the .rpt handle, cleanup raised
    # PermissionError on Windows, and the client got plain-text 500.
    r = post(client, "bad.inp", b"[JUNCTIONS]\n J1 abc\n[END]\n")
    assert r.status_code == 500
    assert r.headers["content-type"].startswith("application/json")
    detail = r.json()["detail"]
    assert "Error 200" in detail
    assert "Error 202" in detail  # root cause pulled from the report file


def test_warning_codes_collected_even_with_messages_no(client):
    # J1 sits above the reservoir head -> negative pressure (warning 6).
    inp = SIMPLE.replace(b" J1 10 5", b" J1 100 5").replace(
        b"[OPTIONS]", b"[REPORT]\n Messages No\n[OPTIONS]"
    )
    r = post(client, "neg.inp", inp)
    assert r.status_code == 200
    body = r.json()
    assert "WARNING" not in body["reportText"]
    assert any(w["code"] == 6 for w in body["engineWarnings"])


def test_step_amplification_rejected_fast(client):
    inp = SIMPLE.replace(
        b"[OPTIONS]", b"[TIMES]\n Duration 10000:00\n Hydraulic Timestep 0:00:01\n[OPTIONS]"
    )
    r = post(client, "dos.inp", inp)
    assert r.status_code == 413
    assert "Simulation too large" in r.json()["detail"]


def test_columnar_format_carries_identical_values(client):
    import base64
    from array import array

    data = (PUBLIC / "Net1.inp").read_bytes()  # pump + chlorine: every series kind
    obj = client.post("/api/analyze", files={"file": ("Net1.inp", data, "text/plain")}).json()
    col = client.post("/api/analyze?format=columnar", files={"file": ("Net1.inp", data, "text/plain")}).json()
    assert col["format"] == "spipe-columnar-1"
    steps = len(obj["timeSteps"])
    for side, keys in (("nodes", ("demand", "head", "pressure", "quality")), ("links", ("flow", "velocity", "headloss", "quality"))):
        ids = col[side]["ids"]
        assert ids == list(obj[side])
        for key in keys:
            flat = array("d", base64.b64decode(col[side]["series"][key]))
            for i, element_id in enumerate(ids):
                assert list(flat[i * steps:(i + 1) * steps]) == obj[side][element_id]["timeSeries"][key]
    pump = col["links"]["pumps"]["9"]
    assert pump["energySeries"] == obj["links"]["9"]["timeSeries"]["energy"]
    assert pump["totalKwh"] == obj["links"]["9"]["totalKwh"]


def test_overlong_utf8_id_is_engine_error(client):
    # 12 Korean chars = 36 UTF-8 bytes > EPANET MAXID (31 bytes) -> Error 252.
    long_id = "상리배수지유출관로제일번".encode("utf-8")
    inp = SIMPLE.replace(b" J2 12 3", b" " + long_id + b" 12 3").replace(b"J1 J2", b"J1 " + long_id)
    r = post(client, "longid.inp", inp)
    assert r.status_code == 500
    assert "252" in r.json()["detail"]


NET1 = (PUBLIC / "Net1.inp").read_bytes()


def post_job(client, name, inp=SIMPLE, params="{}"):
    return client.post(f"/api/jobs/{name}", files={"file": ("n.inp", inp, "text/plain")}, data={"params": params})


def test_job_summary_runs(client):
    r = post_job(client, "summary", NET1)
    assert r.status_code == 200, r.text
    body = r.json()
    assert body["junctions"] == 9
    assert len(body["times"]) == len(body["minPressure"]) == 25
    assert all(lo <= hi for lo, hi in zip(body["minPressure"], body["maxPressure"]))


def test_job_unknown_and_bad_params(client):
    assert post_job(client, "nope").status_code == 400
    assert post_job(client, "summary", params="[1]").status_code == 400
    assert post_job(client, "summary", params="not json").status_code == 400