from __future__ import annotations

import hashlib
import json
from datetime import UTC, datetime
from pathlib import Path

import httpx
import pytest

from gcmd_classifier.config import DatasetDocumentSettings
from gcmd_classifier.datasets.cmr import resolve_cmr_collection, validate_cmr_url
from gcmd_classifier.datasets.documents import retrieve_selected_readme, validate_pdf_bytes
from gcmd_classifier.datasets.errors import (
    READMEDocumentError,
    READMERetrievalError,
    READMESelectionError,
)
from gcmd_classifier.datasets.models import BlindCollectionView, CMRRetrievedSource, DatasetIdentity
from gcmd_classifier.datasets.readme_discovery import (
    discover_readme_candidates,
    select_readme_candidate,
)
from tests.datasets.fixture_manifest import load_fixture_manifest

URL = "https://docs.example.test/readme.pdf"
NOW = datetime(2026, 8, 13, 13, 0, tzinfo=UTC)
PDF = b"%PDF-1.7\n1 0 obj\n<<>>\nendobj\nstartxref\n9\n%%EOF\n"
PUBLIC4 = "93.184.216.34"
PUBLIC6 = "2606:2800:220:1:248:1893:25c8:1946"


def _selection(url: str = URL):
    view = BlindCollectionView(
        identity=DatasetIdentity(
            concept_id="C1-P",
            native_id="TARGET_001",
            short_name="TARGET",
            version="001",
            cmr_revision_id=4,
        ),
        derived_native_id="TARGET_001",
        related_urls=({"Subtype": "READ-ME", "URL": url, "Description": "README"},),
        blind_view_sha256="a" * 64,
    )
    discovery = discover_readme_candidates(view, cmr_source_sha256="b" * 64)
    return select_readme_candidate(discovery, [(0, url)], utc_now=lambda: NOW)


def _client(handler) -> httpx.Client:
    return httpx.Client(transport=httpx.MockTransport(handler), follow_redirects=False)


def _ok(
    request: httpx.Request,
    *,
    body: bytes = PDF,
    content_type: str = "application/pdf",
    headers=None,
):
    return httpx.Response(
        200,
        headers={"content-type": content_type, **(headers or {})},
        content=body,
        request=request,
    )


def _retrieve(
    tmp_path: Path, handler=_ok, *, resolver=lambda host: [PUBLIC4], settings=None, selection=None
):
    with _client(handler) as client:
        return retrieve_selected_readme(
            selection or _selection(),
            client=client,
            resolver=resolver,
            artifact_directory=tmp_path,
            settings=settings,
            utc_now=lambda: NOW,
        )


@pytest.mark.parametrize("addresses", ([PUBLIC4], [PUBLIC6], [PUBLIC4, PUBLIC6]))
def test_public_ipv4_ipv6_and_mixed_public_addresses_are_allowed(
    tmp_path: Path, addresses: list[str]
) -> None:
    result = _retrieve(tmp_path, resolver=lambda host: addresses)
    assert result.content == PDF
    assert result.record.artifact.sha256 == hashlib.sha256(PDF).hexdigest()
    storage_reference = result.record.artifact.storage_reference
    assert storage_reference is not None
    assert (tmp_path / storage_reference).read_bytes() == PDF
    assert not Path(storage_reference).is_absolute()


@pytest.mark.parametrize(
    "address",
    (
        "10.0.0.1",
        "127.0.0.1",
        "169.254.1.1",
        "192.0.2.1",
        "0.0.0.0",
        "224.0.0.1",
        "169.254.169.254",
        "::1",
        "fe80::1",
        "2001:db8::1",
        "::",
    ),
)
def test_non_public_destinations_are_rejected_without_http(tmp_path: Path, address: str) -> None:
    calls = 0

    def handler(request):
        nonlocal calls
        calls += 1
        return _ok(request)

    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, handler, resolver=lambda host: [address])
    assert captured.value.code == "README_NON_PUBLIC_ADDRESS"
    assert calls == 0


def test_mixed_public_nonpublic_and_dns_rebinding_are_rejected(tmp_path: Path) -> None:
    with pytest.raises(READMERetrievalError):
        _retrieve(tmp_path, resolver=lambda host: [PUBLIC4, "10.0.0.1"])
    answers = iter(([PUBLIC4], ["127.0.0.1"]))
    with pytest.raises(READMERetrievalError):
        _retrieve(tmp_path, resolver=lambda host: next(answers))


def test_valid_redirect_revalidates_destination_and_preserves_history(tmp_path: Path) -> None:
    target = "https://cdn.example.test/file"
    requests = []

    def handler(request):
        requests.append(str(request.url))
        return (
            httpx.Response(302, headers={"location": target}, request=request)
            if len(requests) == 1
            else _ok(request)
        )

    result = _retrieve(tmp_path, handler)
    assert requests == [URL, target]
    assert result.record.final_url == target
    assert result.record.redirects[0].target_url == target


@pytest.mark.parametrize(
    "target",
    (
        "ftp://example.test/a.pdf",
        "https://example.test:444/a.pdf",
        "https://u:p@example.test/a.pdf",
        "https://example.test/a.pdf#x",
        "https://example.test/a.pdf?token=x",
        "https://example.test/login",
    ),
)
def test_unsafe_and_authentication_redirects_are_rejected(tmp_path: Path, target: str) -> None:
    def handler(request):
        return httpx.Response(302, headers={"location": target}, request=request)

    with pytest.raises(READMERetrievalError):
        _retrieve(tmp_path, handler)


def test_redirect_loop_and_limit(tmp_path: Path) -> None:
    second = "https://docs.example.test/second.pdf"

    def loop(request):
        target = second if str(request.url) == URL else URL
        return httpx.Response(302, headers={"location": target}, request=request)

    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, loop)
    assert captured.value.code == "README_REDIRECT_LOOP"
    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, loop, settings=DatasetDocumentSettings(max_redirects=0))
    assert captured.value.code == "README_REDIRECT_LIMIT"


@pytest.mark.parametrize("status", (401, 403))
def test_authentication_status_is_not_public(tmp_path: Path, status: int) -> None:
    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, lambda request: httpx.Response(status, request=request))
    assert captured.value.code == "README_NOT_PUBLIC"


def test_login_html_is_not_public(tmp_path: Path) -> None:
    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(
            tmp_path,
            lambda request: _ok(
                request,
                body=b"<html><form><input type='password'></form></html>",
                content_type="text/html",
            ),
        )
    assert captured.value.code == "README_NOT_PUBLIC"


@pytest.mark.parametrize(
    "exc", (httpx.ReadTimeout("x"), httpx.ConnectError("x"), httpx.ConnectError("tls"))
)
def test_transport_failures_are_typed_and_preserve_no_false_success(
    tmp_path: Path, exc: Exception
) -> None:
    def handler(request):
        raise exc

    with pytest.raises(READMERetrievalError):
        _retrieve(tmp_path, handler)


def test_size_content_length_truncation_and_operation_limits(tmp_path: Path) -> None:
    settings = DatasetDocumentSettings(max_download_bytes=10)
    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, settings=settings)
    assert captured.value.code == "README_TOO_LARGE"

    def truncated(request):
        return _ok(request, headers={"content-length": str(len(PDF) + 1)})

    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path, truncated)
    assert captured.value.code == "README_TRUNCATED"


@pytest.mark.parametrize(
    ("body", "media"),
    (
        (b"<html>not pdf</html>", "text/html"),
        (b"{}", "application/json"),
        (b"plain", "text/plain"),
        (b"", "application/pdf"),
        (b"%PDF-1.7 malformed", "application/pdf"),
        (b"PNG", "application/pdf"),
    ),
)
def test_unsupported_and_misleading_content_is_rejected(body: bytes, media: str) -> None:
    with pytest.raises(READMEDocumentError):
        validate_pdf_bytes(body, media)


@pytest.mark.parametrize("media", ("application/pdf", "application/octet-stream", None))
def test_pdf_byte_validation_is_extension_independent_and_stable(media: str | None) -> None:
    assert validate_pdf_bytes(PDF, media)[0] == "application/pdf"


def test_raw_url_local_path_and_tampered_selection_cannot_enter_retriever(tmp_path: Path) -> None:
    with _client(_ok) as client, pytest.raises(READMESelectionError):
        retrieve_selected_readme(
            URL, client=client, resolver=lambda host: [PUBLIC4], artifact_directory=tmp_path
        )
    selected = _selection()
    changed = selected.model_copy(update={"selected_url": "tests/fixtures/datasets/pdf/file.pdf"})
    with _client(_ok) as client, pytest.raises(READMESelectionError):
        retrieve_selected_readme(
            changed, client=client, resolver=lambda host: [PUBLIC4], artifact_directory=tmp_path
        )


def test_failure_preserves_partial_artifact_and_performs_no_cleanup(tmp_path: Path) -> None:
    with pytest.raises(READMEDocumentError):
        _retrieve(
            tmp_path,
            lambda request: _ok(request, body=b"not a pdf", content_type="application/pdf"),
        )
    partials = list(tmp_path.rglob("document.partial"))
    assert len(partials) == 1 and partials[0].read_bytes() == b"not a pdf"


def test_all_frozen_cases_require_discovery_selection_and_exact_mocked_bytes(
    tmp_path: Path,
) -> None:
    manifest, cases = load_fixture_manifest(Path("tests/fixtures/datasets/cases.json"))
    before = {
        path: path.read_bytes() for case in cases for path in (case.cmr_path, case.readme_path)
    }
    assert len(manifest.cases) == 4
    for case in cases:
        meta = case.metadata
        cmr_bytes = case.cmr_path.read_bytes()
        pdf_bytes = case.readme_path.read_bytes()
        validated = validate_cmr_url(meta.cmr_url)
        source = CMRRetrievedSource(
            submitted_url=meta.cmr_url,
            final_url=meta.cmr_url,
            retrieved_at="2026-08-13T00:00:00Z",
            status_code=200,
            response_bytes=cmr_bytes,
            source_text=cmr_bytes.decode(),
            sha256=hashlib.sha256(cmr_bytes).hexdigest(),
            parsed_json=json.loads(cmr_bytes),
        )
        resolved = resolve_cmr_collection(validated, source)
        discovery = discover_readme_candidates(resolved.blind_view, cmr_source_sha256=source.sha256)
        matching = [c for c in discovery.candidates if c.url == meta.selected_readme_url]
        assert len(matching) == 1
        selected = select_readme_candidate(
            discovery, [(matching[0].source_index, matching[0].url)], utc_now=lambda: NOW
        )

        def exact_transport(request, expected=meta.selected_readme_url, content=pdf_bytes):
            assert str(request.url) == expected
            return _ok(request, body=content)

        result = _retrieve(tmp_path / meta.case_id, exact_transport, selection=selected)
        assert result.content == pdf_bytes
        assert result.record.artifact.sha256 == meta.readme_sha256
        assert result.record.identity.concept_id == meta.expected_concept_id
        assert result.record.identity.native_id == meta.native_id
        assert result.record.identity.short_name == meta.short_name
        assert result.record.identity.version == meta.version
        assert "ScienceKeywords" not in discovery.model_dump_json()
    assert {path: path.read_bytes() for path in before} == before


def test_operation_metadata_encoding_client_state_and_run_collision_controls(
    tmp_path: Path,
) -> None:
    values = iter((0.0, 61.0))
    with _client(_ok) as client, pytest.raises(READMERetrievalError) as captured:
        retrieve_selected_readme(
            _selection(),
            client=client,
            resolver=lambda host: [PUBLIC4],
            artifact_directory=tmp_path / "time",
            monotonic=lambda: next(values),
        )
    assert captured.value.code == "README_OPERATION_TIMEOUT"

    metadata_settings = DatasetDocumentSettings(max_response_metadata_bytes=4)
    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path / "metadata", settings=metadata_settings)
    assert captured.value.code == "README_RESPONSE_METADATA_TOO_LARGE"

    def encoded(request):
        return httpx.Response(
            200,
            headers={"content-type": "application/pdf", "content-encoding": "gzip"},
            stream=httpx.ByteStream(PDF),
            request=request,
        )

    with pytest.raises(READMERetrievalError) as captured:
        _retrieve(tmp_path / "encoding", encoded)
    assert captured.value.code == "README_CONTENT_ENCODING"

    with (
        httpx.Client(
            transport=httpx.MockTransport(_ok), headers={"Authorization": "Bearer secret"}
        ) as client,
        pytest.raises(READMERetrievalError) as captured,
    ):
        retrieve_selected_readme(
            _selection(),
            client=client,
            resolver=lambda host: [PUBLIC4],
            artifact_directory=tmp_path / "auth",
        )
    assert captured.value.code == "README_CLIENT_STATE"

    collision_root = tmp_path / "collision"
    (collision_root / "fixed").mkdir(parents=True)
    with _client(_ok) as client, pytest.raises(READMERetrievalError) as captured:
        retrieve_selected_readme(
            _selection(),
            client=client,
            resolver=lambda host: [PUBLIC4],
            artifact_directory=collision_root,
            run_id_factory=lambda: "fixed",
        )
    assert captured.value.code == "README_ARTIFACT_EXISTS"


@pytest.mark.parametrize(
    "url",
    (
        "file:///tmp/readme.pdf",
        "https://-bad.example/readme.pdf",
        "https://bad_host.example/readme.pdf",
        "https://example.test:444/readme.pdf",
        "https://user:pass@example.test/readme.pdf",
        "https://example.test/readme.pdf#fragment",
    ),
)
def test_selected_url_policy_rejects_unsafe_destinations(tmp_path: Path, url: str) -> None:
    selected = _selection(url)
    with _client(_ok) as client, pytest.raises(READMERetrievalError):
        retrieve_selected_readme(
            selected,
            client=client,
            resolver=lambda host: [PUBLIC4],
            artifact_directory=tmp_path,
        )


def test_empty_invalid_dns_results_are_typed(tmp_path: Path) -> None:
    for answers, code in (([], "README_DNS_EMPTY"), (["not-an-ip"], "README_DNS_ADDRESS_INVALID")):
        with pytest.raises(READMERetrievalError) as captured:
            _retrieve(tmp_path / code, resolver=lambda host, values=answers: values)
        assert captured.value.code == code