import pytest
from dataset.problem_20.buggy import analyze_user_activity

def test_analyze_user_activity():
    logs = [
        {'user_id': 'u1', 'timestamp': '2023-10-01 10:00:00', 'action': 'login', 'duration_seconds': 120},
        {'user_id': 'u1', 'timestamp': '2023-10-02 11:00:00', 'action': 'view', 'duration_seconds': 300},
        {'user_id': 'u2', 'timestamp': '2023-09-20 09:00:00', 'action': 'login', 'duration_seconds': 60},
        {'user_id': 'u2', 'timestamp': '2023-10-05 14:00:00', 'action': 'view', 'duration_seconds': 150},
        {'user_id': 'u3', 'timestamp': '2023-10-06 16:00:00', 'action': 'view', 'duration_seconds': 200}
    ]
    
    current_date = '2023-10-07'
    
    result = analyze_user_activity(logs, current_date)
    
    # Active users last 7 days: 2023-10-01 to 2023-10-07
    # u1 (Oct 1, Oct 2), u2 (Oct 5), u3 (Oct 6)
    # Expected: 3
    assert result['active_users_last_7_days'] == 3
    
    # Most common action
    # login: 2, view: 3 -> 'view'
    assert result['most_common_action'] == 'view'
    
    # Average session duration
    # Total = 120 + 300 + 60 + 150 + 200 = 830
    # Count = 5 -> 830 / 5 = 166.0
    assert result['average_session_duration'] == 166.0
    
    # Engagement scores (duration / days active)
    # u1: duration = 420, days = 2 -> 210.0
    # u2: duration = 210, days = 2 -> 105.0
    # u3: duration = 200, days = 1 -> 200.0
    scores = result['user_engagement_scores']
    assert scores['u1'] == 210.0
    assert scores['u2'] == 105.0
    assert scores['u3'] == 200.0
    
def test_empty_logs():
    result = analyze_user_activity([], '2023-10-07')
    assert result['active_users_last_7_days'] == 0
    assert result['most_common_action'] is None
    assert result['average_session_duration'] == 0.0
    assert result['user_engagement_scores'] == {}