using System.Collections.Concurrent;
using Serilog;
using Serilog.Core;
using Serilog.Events;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Core.Scripting;
using ZB.MOM.WW.OtOpcUa.Core.Scripting.OutOfProcess;

namespace ZB.MOM.WW.OtOpcUa.ScriptWorker.Tests;

/// <summary>Collects Serilog events in memory.</summary>
internal sealed class CapturingSink : ILogEventSink
{
    public ConcurrentQueue<LogEvent> Events { get; } = new();

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

    public ILogger CreateLogger() => new LoggerConfiguration().MinimumLevel.Verbose().WriteTo.Sink(this).CreateLogger();

    public IEnumerable<string> Rendered => Events.Select(e => e.RenderMessage());
}

internal static class Scripts
{
    public static readonly IReadOnlyDictionary<string, DataValueSnapshot> NoInputs =
        new Dictionary<string, DataValueSnapshot>(StringComparer.Ordinal);

    public static IReadOnlyDictionary<string, DataValueSnapshot> Input(string path, object? value, uint status = 0)
        => new Dictionary<string, DataValueSnapshot>(StringComparer.Ordinal)
        {
            [path] = new DataValueSnapshot(value, status, DateTime.UtcNow, DateTime.UtcNow),
        };

    public static ScriptInvocation Vt(string key, string source, TimeSpan? timeout = null,
        IReadOnlyDictionary<string, DataValueSnapshot>? inputs = null, ILogger? logger = null)
        => new(key, ScriptContextKind.VirtualTag, source, inputs ?? NoInputs, timeout ?? TimeSpan.FromSeconds(5), logger);

    /// <summary>
    ///     Name of the environment variable that points the suite at a different worker entry than the one built beside
    ///     the tests — e.g. the apphost of a self-contained <c>script-worker/</c> from a <c>-r win-x64</c> Host publish.
    /// </summary>
    public const string WorkerUnderTestVariable = "OTOPCUA_SCRIPTWORKER_TEST_PATH";

    /// <summary>The worker entry named by <see cref="WorkerUnderTestVariable"/>, or null for the built one.</summary>
    public static string? WorkerUnderTest
        => Environment.GetEnvironmentVariable(WorkerUnderTestVariable) is { Length: > 0 } path ? path : null;

    /// <summary>Options for a single-shard runner with short budgets, so the containment tests run in seconds.</summary>
    public static ScriptingOptions Options(int shards = 1, TimeSpan? hardGrace = null, int quarantineAfterKills = 2,
        int probation = 20, TimeSpan? unavailableGrace = null, string? workerPath = null, long heapLimit = 256L * 1024 * 1024,
        string? peCacheDir = null, TimeSpan? isolationIdle = null, TimeSpan? circuitOpenAfter = null)
        => new()
        {
            Runner = ScriptRunnerMode.OutOfProcess,
            QuarantineAfterConsecutiveTimeouts = 100,
            Worker = new ScriptWorkerOptions
            {
                Shards = shards,
                HardGrace = hardGrace ?? TimeSpan.FromMilliseconds(500),
                QuarantineAfterKills = quarantineAfterKills,
                IsolationProbationRuns = probation,
                UnavailableGrace = unavailableGrace ?? TimeSpan.FromSeconds(30),
                ExecutablePath = workerPath ?? WorkerUnderTest,
                HeapLimitBytes = heapLimit,
                PeCacheDir = peCacheDir,
                IsolationIdleTimeout = isolationIdle ?? ScriptWorkerOptions.DefaultIsolationIdleTimeout,
                CircuitOpenAfter = circuitOpenAfter ?? ScriptWorkerOptions.DefaultCircuitOpenAfter,
            },
        };

    /// <summary>A fresh, empty temp directory, deleted by <see cref="IDisposable.Dispose"/>.</summary>
    public sealed class TempDir : IDisposable
    {
        public TempDir()
        {
            Path = System.IO.Path.Combine(System.IO.Path.GetTempPath(), "otopcua-sw-test-" + Guid.NewGuid().ToString("N")[..12]);
            Directory.CreateDirectory(Path);
        }

        public string Path { get; }

        public void Dispose()
        {
            try { Directory.Delete(Path, recursive: true); } catch { /* best effort */ }
        }
    }

    public static OutOfProcessScriptRunner Runner(ScriptingOptions options, ILogger? log = null,
        TimeSpan? maintenanceInterval = null, string? markerDirectory = null)
        => new(options, log ?? new LoggerConfiguration().CreateLogger(), null,
            heartbeatInterval: TimeSpan.FromSeconds(1), loadTimeout: TimeSpan.FromSeconds(60),
            maintenanceInterval: maintenanceInterval, markerDirectory: markerDirectory);

    public static async Task<T> Eventually<T>(Func<T?> probe, TimeSpan timeout, string what) where T : class
    {
        var deadline = DateTime.UtcNow + timeout;
        while (DateTime.UtcNow < deadline)
        {
            if (probe() is { } value) return value;
            await Task.Delay(20);
        }
        throw new TimeoutException($"timed out waiting for {what}");
    }

    public static async Task Eventually(Func<bool> probe, TimeSpan timeout, string what)
    {
        var deadline = DateTime.UtcNow + timeout;
        while (DateTime.UtcNow < deadline)
        {
            if (probe()) return;
            await Task.Delay(20);
        }
        throw new TimeoutException($"timed out waiting for {what}");
    }
}