import multiprocessing
import os
from pathlib import Path

import pytest

from tht.jobs.locking import JobAlreadyRunningError, WorkspaceJobLock


def _hold_lock(root: str, ready, release):
    with WorkspaceJobLock(Path(root), "demo", "evidence"):
        ready.set()
        release.wait(10)


def _crash_with_lock(root: str, ready):
    lock = WorkspaceJobLock(Path(root), "demo", "evidence")
    lock.acquire()
    ready.set()
    raise SystemExit(7)


def test_same_workspace_and_job_are_exclusive_across_processes(tmp_path):
    context = multiprocessing.get_context("spawn")
    ready = context.Event()
    release = context.Event()
    process = context.Process(target=_hold_lock, args=(str(tmp_path), ready, release))
    process.start()
    assert ready.wait(10)
    try:
        with pytest.raises(JobAlreadyRunningError):
            WorkspaceJobLock(tmp_path, "demo", "evidence").acquire()
    finally:
        release.set()
        process.join(10)
    assert process.exitcode == 0


def test_evidence_and_dwh_jobs_have_distinct_locks(tmp_path):
    with (
        WorkspaceJobLock(tmp_path, "demo", "evidence"),
        WorkspaceJobLock(tmp_path, "demo", "dwh"),
    ):
        pass


def test_lock_keys_cannot_escape_lock_directory(tmp_path):
    with pytest.raises(ValueError, match="filesystem-safe"):
        WorkspaceJobLock(tmp_path, "demo", "../evidence")


def test_preexisting_lock_symlink_is_rejected(tmp_path):
    lock = WorkspaceJobLock(tmp_path, "demo", "evidence")
    lock.path.parent.mkdir(parents=True)
    target = tmp_path / "target"
    target.write_text("do not modify")
    lock.path.symlink_to(target)
    with pytest.raises(OSError):
        lock.acquire()
    assert target.read_text() == "do not modify"


def test_preexisting_locks_directory_symlink_is_rejected(tmp_path):
    jobs = tmp_path / ".tht-jobs"
    jobs.mkdir()
    outside = tmp_path / "outside"
    outside.mkdir()
    (jobs / ".locks").symlink_to(outside, target_is_directory=True)
    with pytest.raises(OSError):
        WorkspaceJobLock(tmp_path, "demo", "evidence").acquire()
    assert list(outside.iterdir()) == []


def test_lock_file_is_owner_only_regular_single_link(tmp_path):
    with WorkspaceJobLock(tmp_path, "demo", "evidence") as lock:
        stat = os.stat(lock.path, follow_symlinks=False)
        assert stat.st_uid == os.getuid()
        assert stat.st_nlink == 1
        assert stat.st_mode & 0o777 == 0o600


def test_lock_is_recoverable_after_process_crash_without_stale_deletion(tmp_path):
    context = multiprocessing.get_context("spawn")
    ready = context.Event()
    process = context.Process(target=_crash_with_lock, args=(str(tmp_path), ready))
    process.start()
    assert ready.wait(10)
    process.join(10)
    assert process.exitcode == 7

    lock_path = WorkspaceJobLock(tmp_path, "demo", "evidence").path
    assert lock_path.exists()
    with WorkspaceJobLock(tmp_path, "demo", "evidence"):
        assert lock_path.exists()