// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Diagnostics;
 
namespace Microsoft.Extensions.Logging.Debug
{
    /// <summary>
    /// A logger that writes messages in the debug output window only when a debugger is attached.
    /// </summary>
    internal sealed partial class DebugLogger : ILogger
    {
        private readonly string _name;
 
        /// <summary>
        /// Initializes a new instance of the <see cref="DebugLogger"/> class.
        /// </summary>
        /// <param name="name">The name of the logger.</param>
        public DebugLogger(string name)
        {
            _name = name;
        }
 
        /// <inheritdoc />
        public IDisposable BeginScope<TState>(TState state) where TState : notnull
        {
            return NullScope.Instance;
        }
 
        /// <inheritdoc />
        public bool IsEnabled(LogLevel logLevel)
        {
            // Everything is enabled unless the debugger is not attached
            return Debugger.IsAttached && logLevel != LogLevel.None;
        }
 
        /// <inheritdoc />
        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
        {
            if (!IsEnabled(logLevel))
            {
                return;
            }
 
            ThrowHelper.ThrowIfNull(formatter);
 
            string message = formatter(state, exception);
 
            if (string.IsNullOrEmpty(message))
            {
                return;
            }
 
            message = $"{logLevel}: {message}";
 
            if (exception != null)
            {
                message += Environment.NewLine + Environment.NewLine + exception;
            }
 
            DebugWriteLine(message, _name);
        }
    }
}