using Microsoft.Extensions.Logging;
using System.Text;

namespace System.Logging
{
    /// <summary>
    /// 客户端日志
    /// <para>https://github.com/dotnet/extensions/blob/v3.1.5/src/Logging/Logging.Console/src/ConsoleLogger.cs</para>
    /// </summary>
    public abstract class ClientLogger : ILogger
    {
        static readonly string _messagePadding;
        static readonly string _newLineWithMessagePadding;

        static ClientLogger()
        {
            _messagePadding = new string(' ', 6);
            _newLineWithMessagePadding = Environment.NewLine + _messagePadding;
        }

        protected readonly string name;

        public ClientLogger(string name) => this.name = name;

        public virtual IDisposable BeginScope<TState>(TState state)
        {
            return NullScope.Instance;
        }

        public virtual bool IsEnabled(LogLevel logLevel) => logLevel != LogLevel.None;

        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
        {
            if (!IsEnabled(logLevel))
            {
                return;
            }

            if (formatter == null)
            {
                throw new ArgumentNullException(nameof(formatter));
            }

            var message = formatter(state, exception);

            if (!string.IsNullOrEmpty(message) || exception != null)
            {
                WriteMessage(logLevel, name, eventId.Id, message, exception);
            }
        }

        public virtual void WriteMessage(LogLevel logLevel, string logName, int eventId, string? message, Exception? exception)
        {
            var logBuilder = new StringBuilder();

            CreateDefaultLogMessage(logBuilder, logName, eventId, message, exception);

            var logMessage = logBuilder.ToString();
            WriteMessage(logLevel, logMessage);
        }

        void CreateDefaultLogMessage(StringBuilder logBuilder, string logName, int eventId, string? message, Exception? exception)
        {
            // Example:
            // INFO: ConsoleApp.Program[10]
            //       Request received

            // category and event id
            logBuilder.Append(logName);
            logBuilder.Append("[");
            logBuilder.Append(eventId);
            logBuilder.AppendLine("]");

            if (!string.IsNullOrEmpty(message))
            {
                // message
                logBuilder.Append(_messagePadding);

                var len = logBuilder.Length;
                logBuilder.AppendLine(message);
                logBuilder.Replace(Environment.NewLine, _newLineWithMessagePadding, len, message.Length);
            }

            // Example:
            // System.InvalidOperationException
            //    at Namespace.Class.Function() in File:line X
            if (exception != null)
            {
                // exception message
                logBuilder.AppendLine(exception.ToString());
            }
        }

        public abstract void WriteMessage(LogLevel logLevel, string message);
    }
}