"""The PreToolUse hook's pure helpers. The decision paths are exercised live."""

import importlib.util
from pathlib import Path

import pytest

spec = importlib.util.spec_from_file_location(
    "zerto_guard_hook", Path(__file__).resolve().parent.parent / "hooks" / "zerto_guard_hook.py"
)
hook = importlib.util.module_from_spec(spec)
spec.loader.exec_module(hook)


@pytest.mark.parametrize(
    ("tool_name", "expected"),
    [
        ("mcp__ssh__exec", ("ssh", "exec")),
        ("mcp__winrm__run_ps", ("winrm", "run_ps")),
        # server names may themselves contain underscores; split on the FIRST __
        ("mcp__plugin_my_thing__write_file", ("plugin_my_thing", "write_file")),
        ("mcp__ob1__OB1__search_thoughts", ("ob1", "OB1__search_thoughts")),
        ("Bash", None),
        ("", None),
    ],
)
def test_split_mcp_name(tool_name, expected):
    assert hook.split_mcp_name(tool_name) == expected


def test_resolve_vm_prefers_the_catalog_arg():
    assert hook.resolve_vm({"host": "a", "computer_name": "b"}, "computer_name") == "b"


def test_resolve_vm_falls_back_when_catalog_arg_is_wrong():
    # a slightly wrong catalog entry should degrade to a prompt, not a crash
    assert hook.resolve_vm({"computer_name": "web01"}, "host") == "web01"


def test_resolve_vm_returns_empty_when_no_vm_present():
    assert hook.resolve_vm({"command": "ls"}, "host") == ""


def test_emit_with_no_decision_and_no_context_exits_silently(capsys):
    with pytest.raises(SystemExit) as exc:
        hook.emit(None)
    assert exc.value.code == 0
    assert capsys.readouterr().out == ""


def test_emit_deny_shape(capsys):
    import json

    with pytest.raises(SystemExit) as exc:
        hook.emit("deny", "no checkpoint")
    assert exc.value.code == 0  # exit 2 would discard the JSON and lose the reason
    out = json.loads(capsys.readouterr().out)["hookSpecificOutput"]
    assert out["hookEventName"] == "PreToolUse"
    assert out["permissionDecision"] == "deny"
    assert out["permissionDecisionReason"] == "no checkpoint"


def test_emit_context_without_decision(capsys):
    import json

    with pytest.raises(SystemExit):
        hook.emit(None, context="checkpoint 7180")
    out = json.loads(capsys.readouterr().out)["hookSpecificOutput"]
    assert "permissionDecision" not in out
    assert out["additionalContext"] == "checkpoint 7180"