using System.Collections.Concurrent;
using Microsoft.Extensions.Logging;
using Serilog;
using Serilog.Core;
using Serilog.Events;
using ZB.MOM.WW.ScadaBridge.Commons.Observability;
using ILogger = Microsoft.Extensions.Logging.ILogger;

namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests.Logging;

/// <summary>
/// A Microsoft <see cref="ILogger"/> that writes each call straight to a Serilog logger enriched
/// from <c>LogContext</c> - the shape the host gets from <c>UseSerilog</c> - and keeps the events,
/// so a test can read the <c>ExecutionId</c> a line carried at the moment it was logged.
/// </summary>
internal sealed class LogContextCapture : ILogger, ILogEventSink
{
    private readonly Serilog.ILogger _serilog;

    /// <summary>Creates the capture with its own Serilog pipeline.</summary>
    public LogContextCapture()
        => _serilog = new LoggerConfiguration().MinimumLevel.Verbose()
            .Enrich.FromLogContext().WriteTo.Sink(this).CreateLogger();

    /// <summary>Every event logged so far.</summary>
    public ConcurrentQueue<LogEvent> Events { get; } = new();

    /// <summary>The <c>ExecutionId</c> the first line containing <paramref name="fragment"/> carried (null when none).</summary>
    /// <param name="fragment">Text the rendered message contains.</param>
    /// <returns>The id, or null when the line carried none.</returns>
    public Guid? ExecutionIdOf(string fragment)
    {
        var evt = Events.First(e => e.RenderMessage().Contains(fragment, StringComparison.Ordinal));
        return evt.Properties.TryGetValue(ExecutionLogContext.ExecutionIdProperty, out var value)
            ? Guid.Parse(value.ToString().Trim('"'))
            : null;
    }

    /// <summary>Whether a line containing <paramref name="fragment"/> was logged.</summary>
    /// <param name="fragment">Text the rendered message contains.</param>
    /// <returns>True once such a line exists.</returns>
    public bool Has(string fragment) => Events.Any(e => e.RenderMessage().Contains(fragment, StringComparison.Ordinal));

    /// <inheritdoc />
    public void Emit(LogEvent logEvent) => Events.Enqueue(logEvent);

    /// <inheritdoc />
    public IDisposable? BeginScope<TState>(TState state) where TState : notnull => null;

    /// <inheritdoc />
    public bool IsEnabled(LogLevel logLevel) => true;

    /// <inheritdoc />
    public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception,
        Func<TState, Exception?, string> formatter)
        => _serilog.Write(LogEventLevel.Information, exception, "{Line}", formatter(state, exception));
}