import json
from pathlib import Path

import numpy as np

from services.sam3_engine import SAM3Engine


class _Completed:
    def __init__(self, returncode=0, stdout="", stderr=""):
        self.returncode = returncode
        self.stdout = stdout
        self.stderr = stderr


def _external_settings(monkeypatch, python_path: Path):
    python_path.write_text("#!/usr/bin/env python\n", encoding="utf-8")
    python_path.chmod(0o755)
    monkeypatch.setattr("services.sam3_engine.SAM3_PACKAGE_AVAILABLE", False)
    monkeypatch.setattr("services.sam3_engine.TORCH_AVAILABLE", False)
    monkeypatch.setattr("services.sam3_engine.settings.sam3_external_enabled", True)
    monkeypatch.setattr("services.sam3_engine.settings.sam3_external_python", str(python_path))
    monkeypatch.setattr("services.sam3_engine.settings.sam3_timeout_seconds", 10)
    monkeypatch.setattr("services.sam3_engine.settings.sam3_status_cache_seconds", 30)
    monkeypatch.setattr("services.sam3_engine.settings.sam3_confidence_threshold", 0.4)


def test_sam3_status_reports_external_runtime_ready(tmp_path, monkeypatch):
    _external_settings(monkeypatch, tmp_path / "python")

    def fake_run(args, **_kwargs):
        assert "--status" in args
        return _Completed(stdout=json.dumps({
            "available": True,
            "package_available": True,
            "python_ok": True,
            "torch_ok": True,
            "cuda_available": True,
            "device": "cuda",
            "message": "ready",
        }))

    monkeypatch.setattr("services.sam3_engine.subprocess.run", fake_run)

    status = SAM3Engine().status()

    assert status["available"] is True
    assert status["external_available"] is True
    assert status["package_available"] is True
    assert status["python_ok"] is True
    assert status["message"] == "SAM 3 external runtime is ready; model will load in the helper process on inference."


def test_sam3_predict_semantic_uses_external_worker(tmp_path, monkeypatch):
    _external_settings(monkeypatch, tmp_path / "python")
    calls = []

    def fake_run(args, **_kwargs):
        calls.append(args)
        if "--status" in args:
            return _Completed(stdout=json.dumps({
                "available": True,
                "package_available": True,
                "python_ok": True,
                "torch_ok": True,
                "cuda_available": True,
                "device": "cuda",
                "message": "ready",
            }))
        request_path = Path(args[-1])
        request = json.loads(request_path.read_text(encoding="utf-8"))
        assert request["text"] == "vessel"
        assert request["confidence_threshold"] == 0.4
        assert Path(request["image_path"]).exists()
        return _Completed(stdout=json.dumps({
            "polygons": [[[0.1, 0.1], [0.9, 0.1], [0.9, 0.9]]],
            "scores": [0.91],
        }))

    monkeypatch.setattr("services.sam3_engine.subprocess.run", fake_run)

    polygons, scores = SAM3Engine().predict_semantic(np.zeros((8, 8, 3), dtype=np.uint8), " vessel ")

    assert polygons == [[[0.1, 0.1], [0.9, 0.1], [0.9, 0.9]]]
    assert scores == [0.91]
    assert any("--request" in args for args in calls)


def test_sam3_predict_semantic_reports_external_errors(tmp_path, monkeypatch):
    _external_settings(monkeypatch, tmp_path / "python")

    def fake_run(args, **_kwargs):
        if "--status" in args:
            return _Completed(stdout=json.dumps({
                "available": True,
                "package_available": True,
                "python_ok": True,
                "torch_ok": True,
                "cuda_available": True,
                "device": "cuda",
                "message": "ready",
            }))
        return _Completed(returncode=1, stderr=json.dumps({"error": "HF access denied"}))

    monkeypatch.setattr("services.sam3_engine.subprocess.run", fake_run)

    try:
        SAM3Engine().predict_semantic(np.zeros((8, 8, 3), dtype=np.uint8), "vessel")
    except RuntimeError as exc:
        assert "HF access denied" in str(exc)
    else:
        raise AssertionError("Expected SAM 3 external inference failure.")