using Microsoft.CodeAnalysis;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.AdminUI.ScriptAnalysis;

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

/// <summary>
///     R04:P2 — the editor used to build a brand-new <c>CSharpCompilation</c> (and re-bind the whole sandbox
///     reference set) on every completion / hover / signature-help / diagnostics request. Each analysis now
///     derives from ONE process-wide base compilation via <c>ReplaceSyntaxTree</c>, so the referenced-assembly
///     binding is done once and shared.
/// </summary>
public sealed class AnalysisCompilationReuseTests
{
    [Fact]
    public void Two_services_share_the_bound_reference_set()
    {
        // Two separate scopes (two HTTP requests) analysing different sources.
        var c1 = new ScriptAnalysisService().CompilationFor("return 1;");
        var c2 = new ScriptAnalysisService().CompilationFor("return 2;");

        // Positive control: the two compilations really carry different user sources.
        c1.SyntaxTrees.Single().ToString().ShouldContain("return 1;");
        c2.SyntaxTrees.Single().ToString().ShouldContain("return 2;");
        c1.ShouldNotBeSameAs(c2);

        // Derived from one bound base: the corlib symbol is the SAME instance, not a re-bound copy.
        c1.GetSpecialType(SpecialType.System_Object)
            .ShouldBeSameAs(c2.GetSpecialType(SpecialType.System_Object));
        c1.GetSpecialType(SpecialType.System_Object)
            .ShouldBeSameAs(ScriptAnalysisService.BaseCompilation.GetSpecialType(SpecialType.System_Object));
    }

    [Fact]
    public void Repeated_analysis_in_one_scope_replaces_the_tree_rather_than_adding_one()
    {
        var svc = new ScriptAnalysisService();
        svc.CompilationFor("return 1;");
        var second = svc.CompilationFor("return 2;");

        second.SyntaxTrees.Count().ShouldBe(1);
        second.SyntaxTrees.Single().ToString().ShouldContain("return 2;");
        second.SyntaxTrees.Single().ToString().ShouldNotContain("return 1;");
    }

    [Fact]
    public void Diagnostics_are_unchanged_by_reuse()
    {
        // A clean script stays clean and an error stays an error across interleaved analyses on one service
        // — a stale tree leaking from the previous call would surface here.
        var svc = new ScriptAnalysisService();
        svc.Diagnose(new DiagnoseRequest("return ctx.Nope();")).Markers.ShouldContain(m => m.Severity == 8);
        svc.Diagnose(new DiagnoseRequest("""return (double)ctx.GetTag("A").Value * 2.0;""")).Markers.ShouldBeEmpty();
        svc.Diagnose(new DiagnoseRequest("var a = 1;\nreturn ctx.Nope();")).Markers
            .ShouldContain(m => m.Severity == 8 && m.StartLineNumber == 2);
    }
}