using Microsoft.Extensions.Logging;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;

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

/// <summary>
/// Flow Debugger step logs (design 2026-09-09 D6): the decorator installed over the script
/// context's logger while a run is traced. It must forward everything the node would have logged
/// anyway, capture Information and above as <c>runtime</c> rows — including levels the node's own
/// minimum level suppresses, because they are trace data, not node log output — and never capture
/// Debug/Trace chatter.
/// </summary>
public class TraceCapturingLoggerTests
{
    /// <summary>One row the sink's emitter received.</summary>
    private sealed record Row(string Level, string Source, string Message, Exception? Exception, Guid? StepEventId);

    /// <summary>An inner logger that records what it was asked to write, at a configurable minimum level.</summary>
    private sealed class RecordingLogger(LogLevel minimum = LogLevel.Trace) : ILogger
    {
        public List<(LogLevel Level, string Message)> Entries { get; } = [];
        public List<object?> Scopes { get; } = [];

        public IDisposable? BeginScope<TState>(TState state) where TState : notnull
        {
            Scopes.Add(state);
            return null;
        }

        public bool IsEnabled(LogLevel logLevel) => logLevel >= minimum;

        public void Log<TState>(LogLevel level, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter) =>
            Entries.Add((level, formatter(state, exception)));
    }

    private static (TraceCapturingLogger Logger, RecordingLogger Inner, List<Row> Rows) Make(LogLevel innerMinimum = LogLevel.Trace)
    {
        var inner = new RecordingLogger(innerMinimum);
        var rows = new List<Row>();
        var sink = new ScriptLogger(
            new RecordingLogger(),
            (level, source, message, exception, stepEventId) => rows.Add(new Row(level, source, message, exception, stepEventId)),
            maxLines: 200,
            instance: "CvdReactor01",
            script: "OnHeartbeat",
            executionId: Guid.NewGuid());
        return (new TraceCapturingLogger(inner, sink), inner, rows);
    }

    [Fact]
    public void Debug_IsForwarded_ButNotCaptured()
    {
        var (logger, inner, rows) = Make();

        logger.LogDebug("internal chatter");

        Assert.Single(inner.Entries);
        Assert.Empty(rows);
    }

    [Fact]
    public void Warning_IsCapturedAsARuntimeRow_WithItsException()
    {
        var (logger, inner, rows) = Make();
        var boom = new TimeoutException("no reply");

        logger.LogWarning(boom, "tag write timed out after {Ms} ms", 5_000);

        Assert.Single(inner.Entries);
        var row = Assert.Single(rows);
        Assert.Equal("warn", row.Level);
        Assert.Equal("runtime", row.Source);
        Assert.Equal("tag write timed out after 5000 ms", row.Message);
        Assert.Same(boom, row.Exception);
    }

    [Fact]
    public void ErrorAndCritical_AreBothCapturedAsError()
    {
        var (logger, _, rows) = Make();

        logger.LogError("bad");
        logger.LogCritical("worse");

        Assert.Equal(["error", "error"], rows.Select(r => r.Level));
    }

    [Fact]
    public void InformationIsEnabled_EvenWhenTheInnerLoggerSaysNo()
    {
        // A node whose Serilog minimum is Warning must still contribute Information lines to a trace.
        var (logger, inner, rows) = Make(innerMinimum: LogLevel.Warning);

        Assert.False(inner.IsEnabled(LogLevel.Information));
        Assert.True(logger.IsEnabled(LogLevel.Information));

        logger.LogInformation("captured anyway");

        Assert.Empty(inner.Entries);
        var row = Assert.Single(rows);
        Assert.Equal("info", row.Level);
        Assert.Equal("captured anyway", row.Message);
    }

    [Fact]
    public void BelowInformation_TheInnerLoggerDecidesEnablement()
    {
        var (logger, _, _) = Make(innerMinimum: LogLevel.Warning);

        Assert.False(logger.IsEnabled(LogLevel.Debug));
    }

    [Fact]
    public void ADisabledInnerLogger_IsNotWrittenTo_ButTheRowIsStillCaptured()
    {
        var (logger, inner, rows) = Make(innerMinimum: LogLevel.Critical);

        logger.LogWarning("suppressed on the node");

        Assert.Empty(inner.Entries);
        Assert.Single(rows);
    }

    [Fact]
    public void CapturedLines_CarryTheAmbientStepId()
    {
        var (logger, _, rows) = Make();
        var stepId = Guid.NewGuid();

        using (TraceStepScope.Enter(stepId))
        {
            logger.LogInformation("inside the helper");
        }

        Assert.Equal(stepId, Assert.Single(rows).StepEventId);
    }

    [Fact]
    public void Ctor_RejectsAnAlreadyDecoratedLogger()
    {
        // Wrapping twice would forward each script line through two capture stages and emit two
        // runtime rows per line — and would burn the run's line cap at double rate.
        var (already, _, _) = Make();
        var sink = new ScriptLogger(new RecordingLogger(), emit: null, maxLines: 200, "i", "s", null);

        var ex = Assert.Throws<ArgumentException>(() => new TraceCapturingLogger(already, sink));
        Assert.Equal("inner", ex.ParamName);
    }

    [Fact]
    public void Ctor_RequiresBothCollaborators()
    {
        var sink = new ScriptLogger(new RecordingLogger(), emit: null, maxLines: 200, "i", "s", null);

        Assert.Throws<ArgumentNullException>(() => new TraceCapturingLogger(null!, sink));
        Assert.Throws<ArgumentNullException>(() => new TraceCapturingLogger(new RecordingLogger(), null!));
    }

    [Fact]
    public void AThrowingFormatter_IsSwallowed_AndDropsOnlyThatLine()
    {
        // Review M3. Most of what this decorator captures is the runtime's own best-effort
        // "audit write failed" warnings, logged from INSIDE a catch block: a formatter exception
        // escaping here would replace the original failure with a formatting one on a path whose
        // contract is that it never throws. The inner logger is disabled for this level so the
        // decorator's OWN formatter call is the only one under test.
        var (logger, inner, rows) = Make(innerMinimum: LogLevel.Critical);

        logger.Log(LogLevel.Warning, new EventId(0), "state", null,
            (_, _) => throw new InvalidOperationException("formatter broke"));

        Assert.Empty(rows);
        Assert.Empty(inner.Entries);

        // …and the decorator keeps working for the next line.
        logger.LogWarning("still alive");
        Assert.Equal("still alive", Assert.Single(rows).Message);
    }

    [Fact]
    public void BeginScope_DelegatesToTheInnerLogger()
    {
        var (logger, inner, _) = Make();

        logger.BeginScope("state");

        Assert.Equal(["state"], inner.Scopes);
    }
}