using System.Collections.Concurrent;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.ScadaBridge.SiteEventLogging;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;

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

/// <summary>
/// A capturing fake <see cref="ISiteEventLogger"/>
/// used by the actor tests to assert that the right operational events are emitted.
/// Thread-safe — the actors fire-and-forget <c>LogEventAsync</c> from background
/// tasks, so multiple captures can land concurrently.
/// </summary>
public sealed class FakeSiteEventLogger : ISiteEventLogger
{
    /// <summary>One captured <see cref="ISiteEventLogger.LogEventAsync"/> invocation.</summary>
    public sealed record Entry(
        string EventType,
        string Severity,
        string? InstanceId,
        string Source,
        string Message,
        string? Details);

    private readonly ConcurrentQueue<Entry> _entries = new();

    /// <summary>All captured events, in arrival order.</summary>
    public IReadOnlyList<Entry> Entries => _entries.ToArray();

    /// <summary>Captured events filtered to a single category.</summary>
    /// <param name="eventType">The event category to filter on.</param>
    /// <returns>The captured events with the given category.</returns>
    public IReadOnlyList<Entry> OfType(string eventType) =>
        _entries.Where(e => e.EventType == eventType).ToArray();

    // Captures the event so tests can assert on it.
    /// <inheritdoc />
    public Task LogEventAsync(
        string eventType,
        string severity,
        string? instanceId,
        string source,
        string message,
        string? details = null)
    {
        _entries.Enqueue(new Entry(eventType, severity, instanceId, source, message, details));
        return Task.CompletedTask;
    }

    // Always zero for this fake.
    /// <inheritdoc />
    public long FailedWriteCount => 0;
}

/// <summary>
/// Minimal <see cref="IServiceProvider"/> that resolves a single
/// <see cref="ISiteEventLogger"/> — enough for the actors' optional
/// <c>_serviceProvider?.GetService&lt;ISiteEventLogger&gt;()</c> resolution
/// without pulling a full DI container into the actor tests.
/// <para>
/// Also serves <see cref="IServiceScopeFactory"/> (returning a scope that just
/// re-exposes this provider) so callers that do
/// <c>serviceProvider.CreateScope()</c> — e.g. <c>ScriptExecutionActor</c> —
/// don't throw before they reach the logging hot path.
/// </para>
/// </summary>
/// <param name="logger">The event logger to resolve for <see cref="ISiteEventLogger"/>.</param>
/// <param name="optionsMonitor">
/// Optional <see cref="IOptionsMonitor{TOptions}"/> for <see cref="SiteRuntimeOptions"/>
/// — resolves for the hot-toggle tests; null (the default) exercises the launcher's
/// constructor-passed-options fallback, matching every earlier caller of this class.
/// </param>
/// <param name="summaryRecorder">
/// Optional <see cref="ScriptRunSummaryRecorder"/> — resolves so a test can assert on
/// the aggregate counters a run produced; null (the default) exercises the launcher's
/// null-safe skip path.
/// </param>
public sealed class SingleServiceProvider(
    ISiteEventLogger logger,
    IOptionsMonitor<SiteRuntimeOptions>? optionsMonitor = null,
    ScriptRunSummaryRecorder? summaryRecorder = null)
    : IServiceProvider, IServiceScopeFactory, IServiceScope
{
    private readonly ISiteEventLogger _logger = logger;
    private readonly IOptionsMonitor<SiteRuntimeOptions>? _optionsMonitor = optionsMonitor;
    private readonly ScriptRunSummaryRecorder? _summaryRecorder = summaryRecorder;

    /// <summary>Resolves the logger, the scope factory and the optional options monitor and summary recorder.</summary>
    /// <param name="serviceType">The service type to resolve.</param>
    /// <returns>The matching service, or null when the type is not served.</returns>
    public object? GetService(Type serviceType)
    {
        if (serviceType == typeof(ISiteEventLogger)) return _logger;
        if (serviceType == typeof(IServiceScopeFactory)) return this;
        if (serviceType == typeof(IOptionsMonitor<SiteRuntimeOptions>)) return _optionsMonitor;
        if (serviceType == typeof(ScriptRunSummaryRecorder)) return _summaryRecorder;
        return null;
    }

    /// <summary>Creates a scope that re-exposes this provider.</summary>
    /// <returns>This instance as the scope.</returns>
    public IServiceScope CreateScope() => this;

    /// <summary>Gets the provider for this scope, which is this instance.</summary>
    public IServiceProvider ServiceProvider => this;

    /// <summary>Does nothing; the scope owns no resources.</summary>
    public void Dispose() { }
}