// 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.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using Microsoft.Extensions.Options;
 
namespace Microsoft.Extensions.Logging.Console
{
    /// <summary>
    /// A provider of <see cref="ConsoleLogger"/> instances.
    /// </summary>
    [UnsupportedOSPlatform("browser")]
    [ProviderAlias("Console")]
    public partial class ConsoleLoggerProvider : ILoggerProvider, ISupportExternalScope
    {
        private readonly IOptionsMonitor<ConsoleLoggerOptions> _options;
        private readonly ConcurrentDictionary<string, ConsoleLogger> _loggers;
        private ConcurrentDictionary<string, ConsoleFormatter> _formatters;
        private readonly ConsoleLoggerProcessor _messageQueue;
 
        private readonly IDisposable? _optionsReloadToken;
        private IExternalScopeProvider _scopeProvider = NullExternalScopeProvider.Instance;
 
        /// <summary>
        /// Creates an instance of <see cref="ConsoleLoggerProvider"/>.
        /// </summary>
        /// <param name="options">The options to create <see cref="ConsoleLogger"/> instances with.</param>
        public ConsoleLoggerProvider(IOptionsMonitor<ConsoleLoggerOptions> options)
            : this(options, Array.Empty<ConsoleFormatter>()) { }
 
        /// <summary>
        /// Creates an instance of <see cref="ConsoleLoggerProvider"/>.
        /// </summary>
        /// <param name="options">The options to create <see cref="ConsoleLogger"/> instances with.</param>
        /// <param name="formatters">Log formatters added for <see cref="ConsoleLogger"/> instances.</param>
        public ConsoleLoggerProvider(IOptionsMonitor<ConsoleLoggerOptions> options, IEnumerable<ConsoleFormatter>? formatters)
        {
            _options = options;
            _loggers = new ConcurrentDictionary<string, ConsoleLogger>();
            SetFormatters(formatters);
            IConsole? console;
            IConsole? errorConsole;
            if (DoesConsoleSupportAnsi())
            {
                console = new AnsiLogConsole();
                errorConsole = new AnsiLogConsole(stdErr: true);
            }
            else
            {
                console = new AnsiParsingLogConsole();
                errorConsole = new AnsiParsingLogConsole(stdErr: true);
            }
            _messageQueue = new ConsoleLoggerProcessor(
                console,
                errorConsole,
                options.CurrentValue.QueueFullMode,
                options.CurrentValue.MaxQueueLength);
 
            ReloadLoggerOptions(options.CurrentValue);
            _optionsReloadToken = _options.OnChange(ReloadLoggerOptions);
        }
 
        [UnsupportedOSPlatformGuard("windows")]
        private static bool DoesConsoleSupportAnsi()
        {
            string? envVar = Environment.GetEnvironmentVariable("DOTNET_SYSTEM_CONSOLE_ALLOW_ANSI_COLOR_REDIRECTION");
            if (envVar is not null && (envVar == "1" || envVar.Equals("true", StringComparison.OrdinalIgnoreCase)))
            {
                // ANSI color support forcibly enabled via environment variable. This logic matches the behaviour
                // found in System.ConsoleUtils.EmitAnsiColorCodes.
                return true;
            }
            if (
#if NETFRAMEWORK
                Environment.OSVersion.Platform != PlatformID.Win32NT
#else
                !RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
#endif
                )
            {
                return true;
            }
 
            // for Windows, check the console mode
            var stdOutHandle = Interop.Kernel32.GetStdHandle(Interop.Kernel32.STD_OUTPUT_HANDLE);
            if (!Interop.Kernel32.GetConsoleMode(stdOutHandle, out int consoleMode))
            {
                return false;
            }
 
            return (consoleMode & Interop.Kernel32.ENABLE_VIRTUAL_TERMINAL_PROCESSING) == Interop.Kernel32.ENABLE_VIRTUAL_TERMINAL_PROCESSING;
        }
 
        [MemberNotNull(nameof(_formatters))]
        private void SetFormatters(IEnumerable<ConsoleFormatter>? formatters = null)
        {
            var cd = new ConcurrentDictionary<string, ConsoleFormatter>(StringComparer.OrdinalIgnoreCase);
 
            bool added = false;
            if (formatters != null)
            {
                foreach (ConsoleFormatter formatter in formatters)
                {
                    cd.TryAdd(formatter.Name, formatter);
                    added = true;
                }
            }
 
            if (!added)
            {
                cd.TryAdd(ConsoleFormatterNames.Simple, new SimpleConsoleFormatter(new FormatterOptionsMonitor<SimpleConsoleFormatterOptions>(new SimpleConsoleFormatterOptions())));
                cd.TryAdd(ConsoleFormatterNames.Systemd, new SystemdConsoleFormatter(new FormatterOptionsMonitor<ConsoleFormatterOptions>(new ConsoleFormatterOptions())));
                cd.TryAdd(ConsoleFormatterNames.Json, new JsonConsoleFormatter(new FormatterOptionsMonitor<JsonConsoleFormatterOptions>(new JsonConsoleFormatterOptions())));
            }
 
            _formatters = cd;
        }
 
        // warning:  ReloadLoggerOptions can be called before the ctor completed,... before registering all of the state used in this method need to be initialized
        private void ReloadLoggerOptions(ConsoleLoggerOptions options)
        {
            if (options.FormatterName == null || !_formatters.TryGetValue(options.FormatterName, out ConsoleFormatter? logFormatter))
            {
#pragma warning disable CS0618
                logFormatter = options.Format switch
                {
                    ConsoleLoggerFormat.Systemd => _formatters[ConsoleFormatterNames.Systemd],
                    _ => _formatters[ConsoleFormatterNames.Simple],
                };
                if (options.FormatterName == null)
                {
                    UpdateFormatterOptions(logFormatter, options);
                }
#pragma warning restore CS0618
            }
 
            _messageQueue.FullMode = options.QueueFullMode;
            _messageQueue.MaxQueueLength = options.MaxQueueLength;
 
            foreach (KeyValuePair<string, ConsoleLogger> logger in _loggers)
            {
                logger.Value.Options = options;
                logger.Value.Formatter = logFormatter;
            }
        }
 
        /// <inheritdoc />
        public ILogger CreateLogger(string name)
        {
            if (_options.CurrentValue.FormatterName == null || !_formatters.TryGetValue(_options.CurrentValue.FormatterName, out ConsoleFormatter? logFormatter))
            {
#pragma warning disable CS0618
                logFormatter = _options.CurrentValue.Format switch
                {
                    ConsoleLoggerFormat.Systemd => _formatters[ConsoleFormatterNames.Systemd],
                    _ => _formatters[ConsoleFormatterNames.Simple],
                };
#pragma warning restore CS0618
 
                if (_options.CurrentValue.FormatterName == null)
                {
                    UpdateFormatterOptions(logFormatter, _options.CurrentValue);
                }
            }
 
            return _loggers.TryGetValue(name, out ConsoleLogger? logger) ?
                logger :
                _loggers.GetOrAdd(name, new ConsoleLogger(name, _messageQueue, logFormatter, _scopeProvider, _options.CurrentValue));
        }
 
#pragma warning disable CS0618
        private static void UpdateFormatterOptions(ConsoleFormatter formatter, ConsoleLoggerOptions deprecatedFromOptions)
        {
            // kept for deprecated apis:
            if (formatter is SimpleConsoleFormatter defaultFormatter)
            {
                defaultFormatter.FormatterOptions = new SimpleConsoleFormatterOptions()
                {
                    ColorBehavior = deprecatedFromOptions.DisableColors ? LoggerColorBehavior.Disabled : LoggerColorBehavior.Default,
                    IncludeScopes = deprecatedFromOptions.IncludeScopes,
                    TimestampFormat = deprecatedFromOptions.TimestampFormat,
                    UseUtcTimestamp = deprecatedFromOptions.UseUtcTimestamp,
                };
            }
            else
            if (formatter is SystemdConsoleFormatter systemdFormatter)
            {
                systemdFormatter.FormatterOptions = new ConsoleFormatterOptions()
                {
                    IncludeScopes = deprecatedFromOptions.IncludeScopes,
                    TimestampFormat = deprecatedFromOptions.TimestampFormat,
                    UseUtcTimestamp = deprecatedFromOptions.UseUtcTimestamp,
                };
            }
        }
#pragma warning restore CS0618
 
        /// <inheritdoc />
        public void Dispose()
        {
            _optionsReloadToken?.Dispose();
            _messageQueue.Dispose();
        }
 
        /// <inheritdoc />
        public void SetScopeProvider(IExternalScopeProvider scopeProvider)
        {
            _scopeProvider = scopeProvider;
 
            foreach (System.Collections.Generic.KeyValuePair<string, ConsoleLogger> logger in _loggers)
            {
                logger.Value.ScopeProvider = _scopeProvider;
            }
        }
    }
}