import json
import os
import time
import logging
from target_simulator.utils.config_manager import ConfigManager


def test_skip_write_when_empty_preserves_existing(tmp_path, caplog):
    caplog.set_level(logging.INFO)
    settings_path = str(tmp_path / "settings.json")
    scenarios_path = str(tmp_path / "scenarios.json")

    # Create an existing scenarios file
    with open(scenarios_path, "w", encoding="utf-8") as f:
        json.dump({"existing": 1}, f)

    cm = ConfigManager(filename=settings_path, scenarios_filename=scenarios_path)
    # Force in-memory scenarios empty and call save
    cm._scenarios = {}
    cm._save_scenarios()

    # File should remain unchanged
    with open(scenarios_path, "r", encoding="utf-8") as f:
        data = json.load(f)
    assert data == {"existing": 1}

    # Ensure we logged skipping behavior
    assert any("Skipping saving scenarios" in r.message for r in caplog.records)


def test_atomic_write_and_backup_created(tmp_path):
    settings_path = str(tmp_path / "settings.json")
    scenarios_path = str(tmp_path / "scenarios.json")

    # Start with an existing scenarios file
    with open(scenarios_path, "w", encoding="utf-8") as f:
        json.dump({"old": True}, f)

    cm = ConfigManager(filename=settings_path, scenarios_filename=scenarios_path)

    # Now update scenarios and save - should create a backup and then write
    cm._scenarios = {"new": 123}
    cm._save_scenarios()

    # scenarios.json should now contain the new content
    with open(scenarios_path, "r", encoding="utf-8") as f:
        data = json.load(f)
    assert data == {"new": 123}

    # A backup should exist with the previous content
    bak1 = scenarios_path + ".bak1"
    assert os.path.exists(bak1)
    with open(bak1, "r", encoding="utf-8") as f:
        bak = json.load(f)
    assert bak == {"old": True}


def test_rotation_keeps_last_n_backups(tmp_path):
    settings_path = str(tmp_path / "settings.json")
    scenarios_path = str(tmp_path / "scenarios.json")
    cm = ConfigManager(filename=settings_path, scenarios_filename=scenarios_path)

    # create multiple writes to generate backups
    # create initial file
    with open(scenarios_path, "w", encoding="utf-8") as f:
        json.dump({"v": 0}, f)

    cm._scenarios = {"v": 1}
    cm._save_scenarios()
    time.sleep(0.01)
    cm._scenarios = {"v": 2}
    cm._save_scenarios()
    time.sleep(0.01)
    cm._scenarios = {"v": 3}
    cm._save_scenarios()
    time.sleep(0.01)
    cm._scenarios = {"v": 4}
    cm._save_scenarios()
    time.sleep(0.01)
    cm._scenarios = {"v": 5}
    cm._save_scenarios()

    # bak1 should exist and contain v=4 (previous before last write)
    bak1 = scenarios_path + ".bak1"
    assert os.path.exists(bak1)
    with open(bak1, "r", encoding="utf-8") as f:
        bak = json.load(f)
    assert isinstance(bak, dict)

    # bak5 may exist depending on rotates; ensure we don't have more than 5 backups
    backups = [scenarios_path + f".bak{i}" for i in range(1, 7)]
    existing = [p for p in backups if os.path.exists(p)]
    assert len(existing) <= 5