from pathlib import Path

import pytest

from agentci.integrations.codegraph import CodeGraph, CodeGraphError


class FakeProcess:
    def __init__(self, returncode: int = 0, stderr: bytes = b"") -> None:
        self.returncode = returncode
        self.stderr = stderr

    async def communicate(self) -> tuple[bytes, bytes]:
        return b"", self.stderr


async def test_initializes_incomplete_index_and_excludes_it_from_git(
    tmp_path: Path, monkeypatch
) -> None:
    workspace = tmp_path / "repo"
    (workspace / ".git" / "info").mkdir(parents=True)
    (workspace / ".codegraph").mkdir()
    calls: list[tuple[object, ...]] = []

    async def create_subprocess_exec(*args, **_kwargs):
        calls.append(args)
        return FakeProcess()

    monkeypatch.setattr(
        "agentci.integrations.codegraph.asyncio.create_subprocess_exec",
        create_subprocess_exec,
    )

    await CodeGraph().prepare(workspace)

    assert calls == [("codegraph", "init", str(workspace))]
    assert (workspace / ".git" / "info" / "exclude").read_text() == ".codegraph/\n"


async def test_syncs_an_existing_index_without_duplicating_exclude(
    tmp_path: Path, monkeypatch
) -> None:
    workspace = tmp_path / "repo"
    (workspace / ".git" / "info").mkdir(parents=True)
    (workspace / ".codegraph").mkdir()
    (workspace / ".codegraph" / "codegraph.db").touch()
    exclude = workspace / ".git" / "info" / "exclude"
    exclude.write_text("# local excludes\n.codegraph/\n")
    calls: list[tuple[object, ...]] = []

    async def create_subprocess_exec(*args, **_kwargs):
        calls.append(args)
        return FakeProcess()

    monkeypatch.setattr(
        "agentci.integrations.codegraph.asyncio.create_subprocess_exec",
        create_subprocess_exec,
    )

    await CodeGraph().prepare(workspace)

    assert calls == [("codegraph", "sync", str(workspace))]
    assert exclude.read_text() == "# local excludes\n.codegraph/\n"


@pytest.mark.parametrize(
    ("initial", "expected"),
    [
        ("*.pyc", "*.pyc\n.codegraph/\n"),
        ("# .codegraph/ is documented here\n", "# .codegraph/ is documented here\n.codegraph/\n"),
        ("  .codegraph/  \n", "  .codegraph/  \n"),
    ],
)
async def test_handles_exclude_file_boundaries(
    tmp_path: Path,
    monkeypatch: pytest.MonkeyPatch,
    initial: str,
    expected: str,
) -> None:
    workspace = tmp_path / "repo"
    exclude = workspace / ".git" / "info" / "exclude"
    exclude.parent.mkdir(parents=True)
    exclude.write_text(initial)

    async def create_subprocess_exec(*_args, **_kwargs):
        return FakeProcess()

    monkeypatch.setattr(
        "agentci.integrations.codegraph.asyncio.create_subprocess_exec",
        create_subprocess_exec,
    )

    await CodeGraph().prepare(workspace)

    assert exclude.read_text() == expected


async def test_reports_missing_executable(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
    workspace = tmp_path / "repo"
    workspace.mkdir()

    async def create_subprocess_exec(*_args, **_kwargs):
        raise FileNotFoundError(2, "No such file or directory", "codegraph")

    monkeypatch.setattr(
        "agentci.integrations.codegraph.asyncio.create_subprocess_exec",
        create_subprocess_exec,
    )

    with pytest.raises(CodeGraphError, match="Could not run CodeGraph:.*codegraph") as raised:
        await CodeGraph().prepare(workspace)

    assert isinstance(raised.value.__cause__, FileNotFoundError)
    assert (workspace / ".git" / "info" / "exclude").read_text() == ".codegraph/\n"


async def test_reports_nonzero_exit_with_bounded_non_utf8_stderr(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
) -> None:
    workspace = tmp_path / "repo"
    workspace.mkdir()
    stderr = b"discarded-prefix" + (b"x" * 1200) + b"\xff useful-tail"

    async def create_subprocess_exec(*_args, **_kwargs):
        return FakeProcess(returncode=7, stderr=stderr)

    monkeypatch.setattr(
        "agentci.integrations.codegraph.asyncio.create_subprocess_exec",
        create_subprocess_exec,
    )

    with pytest.raises(CodeGraphError, match="codegraph init failed") as raised:
        await CodeGraph().prepare(workspace)

    message = str(raised.value)
    assert "discarded-prefix" not in message
    assert "useful-tail" in message
    assert len(message.removeprefix("codegraph init failed: ")) == 1000