// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
 
namespace Microsoft.Extensions.Logging.EventLog
{
    /// <summary>
    /// Settings for <see cref="EventLogLogger"/>.
    /// </summary>
    public class EventLogSettings
    {
        private IEventLog? _eventLog;
 
        /// <summary>
        /// Name of the event log. If <c>null</c> or not specified, "Application" is the default.
        /// </summary>
        public string? LogName { get; set; }
 
        /// <summary>
        /// Name of the event log source. If <c>null</c> or not specified, ".NET Runtime" is the default.
        /// </summary>
        public string? SourceName { get; set; }
 
        /// <summary>
        /// Name of the machine having the event log. If <c>null</c> or not specified, local machine is the default.
        /// </summary>
        public string? MachineName { get; set; }
 
        /// <summary>
        /// The function used to filter events based on the log level.
        /// </summary>
        public Func<string, LogLevel, bool>? Filter { get; set; }
 
        internal IEventLog EventLog
        {
            get => _eventLog ??= CreateDefaultEventLog();
 
            // For unit testing purposes only.
            set => _eventLog = value;
        }
 
        private WindowsEventLog CreateDefaultEventLog()
        {
            string logName = string.IsNullOrEmpty(LogName) ? "Application" : LogName;
            string machineName = string.IsNullOrEmpty(MachineName) ? "." : MachineName;
            string sourceName = string.IsNullOrEmpty(SourceName) ? ".NET Runtime" : SourceName;
            int? defaultEventId = null;
 
            if (string.IsNullOrEmpty(SourceName))
            {
                sourceName = ".NET Runtime";
                defaultEventId = 1000;
            }
 
            return new WindowsEventLog(logName, machineName, sourceName) { DefaultEventId = defaultEventId };
        }
    }
}