"""Tests for the persistent parallel pool and running-job guard in cron/scheduler.py.

These verify the fix for the tick-blocking issue where as_completed(timeout=600)
prevented the ticker thread from firing, causing all other jobs to be fast-forwarded.
"""

import concurrent.futures
import threading
import time
from unittest.mock import patch

import pytest


class TestPersistentPool:
    """_get_parallel_pool returns a persistent ThreadPoolExecutor."""

    def test_pool_is_reused(self, monkeypatch):
        """Same pool instance returned when max_workers doesn't change."""
        import cron.scheduler as sched

        # Reset module state.
        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None

        pool1 = sched._get_parallel_pool(4)
        pool2 = sched._get_parallel_pool(4)
        assert pool1 is pool2

        # Cleanup.
        sched._shutdown_parallel_pool()

    def test_pool_is_recreated_on_worker_change(self, monkeypatch):
        """New pool when max_workers changes."""
        import cron.scheduler as sched

        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None

        pool1 = sched._get_parallel_pool(2)
        pool2 = sched._get_parallel_pool(4)
        assert pool1 is not pool2

        sched._shutdown_parallel_pool()

    def test_shutdown_clears_pool(self, monkeypatch):
        """_shutdown_parallel_pool resets state."""
        import cron.scheduler as sched

        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None
        sched._get_parallel_pool(2)

        sched._shutdown_parallel_pool()
        assert sched._parallel_pool is None
        assert sched._parallel_pool_max_workers is None


class TestRunningJobGuard:
    """_running_job_ids prevents double-dispatch of active jobs."""

    def test_running_set_prevents_double_dispatch(self, tmp_path, monkeypatch):
        """A job already in _running_job_ids is skipped on the next tick."""
        import cron.scheduler as sched

        # Reset state.
        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None
        sched._running_job_ids.clear()

        job = {
            "id": "guard-job",
            "name": "guard-test",
            "prompt": "test",
            "schedule": "every 5m",
            "enabled": True,
            "next_run_at": "2020-01-01T00:00:00",
            "deliver": "local",
        }

        # Simulate the job already running.
        sched._running_job_ids.add("guard-job")

        dispatched = []
        monkeypatch.setattr(sched, "get_due_jobs", lambda: [job])
        monkeypatch.setattr(sched, "advance_next_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "run_job", lambda j: dispatched.append(j["id"]) or (True, "out", "resp", None))
        monkeypatch.setattr(sched, "save_job_output", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "mark_job_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "_deliver_result", lambda *_a, **_kw: None)

        n = sched.tick(verbose=False)
        assert n == 0  # skipped, not dispatched
        assert dispatched == []

        sched._running_job_ids.discard("guard-job")
        sched._shutdown_parallel_pool()


class TestSyncMode:
    """tick() blocks by default (sync=True); tick(sync=False) returns immediately."""

    def test_sync_true_blocks_and_returns_correct_count(self, tmp_path, monkeypatch):
        """sync=True waits for jobs and returns actual results."""
        import cron.scheduler as sched

        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None
        sched._running_job_ids.clear()

        jobs = [
            {"id": f"job-{i}", "name": f"Job {i}", "prompt": "test",
             "schedule": "every 5m", "enabled": True,
             "next_run_at": "2020-01-01T00:00:00", "deliver": "local"}
            for i in range(3)
        ]

        monkeypatch.setattr(sched, "get_due_jobs", lambda: jobs)
        monkeypatch.setattr(sched, "advance_next_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "run_job", lambda j: (True, "out", "resp", None))
        monkeypatch.setattr(sched, "save_job_output", lambda *_a, **_kw: "/tmp/out")
        monkeypatch.setattr(sched, "mark_job_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "_deliver_result", lambda *_a, **_kw: None)

        n = sched.tick(verbose=False)
        assert n == 3

        sched._shutdown_parallel_pool()

    def test_sync_false_returns_immediately(self, tmp_path, monkeypatch):
        """sync=False returns before parallel jobs finish (optimistic count)."""
        import cron.scheduler as sched

        sched._parallel_pool = None
        sched._parallel_pool_max_workers = None
        sched._running_job_ids.clear()

        job = {
            "id": "slow-job",
            "name": "slow",
            "prompt": "test",
            "schedule": "every 5m",
            "enabled": True,
            "next_run_at": "2020-01-01T00:00:00",
            "deliver": "local",
        }

        barrier = threading.Barrier(2, timeout=5)

        def slow_run(j):
            barrier.wait()  # blocks until test thread also waits
            return True, "out", "resp", None

        monkeypatch.setattr(sched, "get_due_jobs", lambda: [job])
        monkeypatch.setattr(sched, "advance_next_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "run_job", slow_run)
        monkeypatch.setattr(sched, "save_job_output", lambda *_a, **_kw: "/tmp/out")
        monkeypatch.setattr(sched, "mark_job_run", lambda *_a, **_kw: None)
        monkeypatch.setattr(sched, "_deliver_result", lambda *_a, **_kw: None)

        start = time.monotonic()
        n = sched.tick(verbose=False, sync=False)  # opt-in: non-blocking
        elapsed = time.monotonic() - start

        assert n == 1  # optimistic count
        assert elapsed < 1.0  # returned immediately, didn't wait for slow_run

        # Let the job finish so cleanup works.
        barrier.wait()
        time.sleep(0.1)
        sched._shutdown_parallel_pool()