using System.Text;
using System.Text.Json;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.AdminUI.ScriptAnalysis;

namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.ScriptAnalysis;

/// <summary>
///     Review D-a I-1 — the diagnostics markers cross the Blazor circuit (JS → .NET, for the Problems list) as ONE
///     hub message. A non-C# paste yields several Roslyn errors per line; uncapped, a few thousand markers exceed
///     the 1 MB hub limit and kill the circuit with every unsaved edit. Both the endpoint response and the circuit
///     report are now bounded; these tests pin the bounds on the C# side of the contract.
/// </summary>
public sealed class MarkerPayloadBoundTests
{
    // ~150 KB of log-ish text: every line is several C# errors.
    private static string NonCSharpPaste()
    {
        var sb = new StringBuilder();
        for (var i = 0; sb.Length < 150 * 1024; i++)
            sb.Append($"2026-10-22 12:00:{i % 60:00} INFO [worker-{i}] value={i}, state=ok; next -> {i + 1} @@ ##\n");
        return sb.ToString();
    }

    [Fact]
    public void A_non_csharp_paste_returns_a_bounded_marker_set_that_still_holds_the_errors()
    {
        var markers = new ScriptAnalysisService().Diagnose(new DiagnoseRequest(NonCSharpPaste())).Markers;

        markers.Count.ShouldBe(ScriptEditorLimits.MaxDiagnosticMarkers);         // positive control: the cap was hit
        markers.ShouldAllBe(m => m.Message.Length <= ScriptEditorLimits.MaxDiagnosticMessageChars);
        markers[0].Severity.ShouldBe(8);                                            // errors first — publish rejects, so must the editor
        markers.Select(m => (m.Severity, m.StartLineNumber, m.StartColumn))
            .ShouldBe(ScriptProblems.Order(markers).Select(m => (m.Severity, m.StartLineNumber, m.StartColumn)));
    }

    [Fact]
    public void A_long_quoted_token_has_its_message_truncated()
    {
        var giant = new string('x', 20_000);
        var markers = new ScriptAnalysisService().Diagnose(new DiagnoseRequest($"return {giant};")).Markers;

        markers.ShouldNotBeEmpty();
        markers.ShouldAllBe(m => m.Message.Length <= ScriptEditorLimits.MaxDiagnosticMessageChars);
        markers.ShouldContain(m => m.Message.EndsWith("…"));
    }

    [Fact]
    public void A_small_script_is_not_truncated()
    {
        // Positive control for the cap: ordinary diagnostics pass through untouched.
        var markers = new ScriptAnalysisService().Diagnose(new DiagnoseRequest("return ctx.Nope();")).Markers;
        markers.ShouldContain(m => m.Severity == 8 && !m.Message.EndsWith("…"));
    }

    [Fact]
    public void The_worst_case_circuit_report_fits_inside_the_sync_budget()
    {
        // The JS sends at most MaxReportedMarkers markers, each message cut to MaxReportedMessageChars. Worst case:
        // control characters (\u0001 → 6 JSON bytes, 7 when escaped again) and the largest line/column numbers.
        var message = new string('\u0001', ScriptEditorLimits.MaxReportedMessageChars);
        var marker = new DiagnosticMarker(8, int.MaxValue, int.MaxValue, int.MaxValue, int.MaxValue, message, "OTSCRIPT_SETVTAG_INERT");
        var report = Enumerable.Repeat(marker, ScriptEditorLimits.MaxReportedMarkers).ToArray();

        var once = JsonSerializer.Serialize(new object[] { report, int.MaxValue });
        var twice = Encoding.UTF8.GetByteCount(JsonSerializer.Serialize(once));

        twice.ShouldBeLessThan(ScriptEditorLimits.MaxEditorSyncBytes);
        ScriptEditorLimits.MaxEditorSyncBytes.ShouldBeLessThan((int)ScriptEditorLimits.HubMaximumReceiveMessageSize);
    }

    [Fact]
    public void A_truncated_report_says_how_many_were_left_out()
    {
        var shown = Enumerable.Range(1, 3).Select(i => new DiagnosticMarker(8, i, 1, i, 2, "m", "CS1002")).ToArray();

        var report = new ScriptProblemReport(shown, 4321);
        report.Omitted.ShouldBe(4318);
        ScriptProblems.Summary(report).ShouldBe("3 errors (showing 3 of 4321)");

        // Positive control: an untruncated report carries no suffix.
        ScriptProblems.Summary(new ScriptProblemReport(shown, 3)).ShouldBe("3 errors");
        ScriptProblemReport.Empty.Omitted.ShouldBe(0);
    }

    [Fact]
    public void A_report_from_js_is_clamped_even_if_the_js_cap_regressed()
    {
        var flood = Enumerable.Range(1, 5000).Select(i => new DiagnosticMarker(4, i, 1, i, 2, new string('m', 2000), "W")).ToArray();

        var report = ScriptProblemReport.FromEditor(flood, total: 5000);

        report.Markers.Count.ShouldBe(ScriptEditorLimits.MaxReportedMarkers);
        report.Total.ShouldBe(5000);
        report.Markers.ShouldAllBe(m => m.Message.Length <= ScriptEditorLimits.MaxReportedMessageChars);
        ScriptProblemReport.FromEditor(null, 0).ShouldBe(ScriptProblemReport.Empty);
    }
}