using ZB.MOM.WW.ScadaBridge.ScriptAnalysis;

namespace ZB.MOM.WW.ScadaBridge.ScriptAnalysis.Tests;

/// <summary>
/// Review 2026-10-21 04/P3: <see cref="ScriptTrustValidator.FindViolations(string, IEnumerable{Microsoft.CodeAnalysis.MetadataReference})"/>
/// is memoised by code hash for the default (policy) reference set, so the bundle
/// importer's preview and apply passes — which call it with no change at their call
/// sites — do not redo a full-framework semantic analysis per script. A cache hit
/// returns the very same verdict instance, which is what these tests observe.
/// </summary>
public class ScriptTrustValidatorCacheTests
{
    /// <summary>Verifies that the same violating code analysed twice is served from the cache.</summary>
    [Fact]
    public void FindViolations_SameCodeTwice_SecondCallIsCacheHit()
    {
        var code = $"var x = System.IO.File.Exists(\"{Guid.NewGuid()}\");";
        var first = ScriptTrustValidator.FindViolations(code);
        var second = ScriptTrustValidator.FindViolations(code);

        Assert.NotEmpty(second);
        Assert.Same(first, second);   // pre-fix: a fresh list per call
    }

    /// <summary>Verifies that a clean verdict is cached too.</summary>
    [Fact]
    public void FindViolations_CleanCodeTwice_SecondCallIsCacheHit()
    {
        var code = $"var x = \"{Guid.NewGuid()}\".Length;";
        var first = ScriptTrustValidator.FindViolations(code);
        var second = ScriptTrustValidator.FindViolations(code);

        Assert.Empty(second);
        Assert.Same(first, second);
    }

    /// <summary>
    /// Verifies that a call with extra references is never served from (or stored in)
    /// the cache — extra references can change symbol resolution, so the verdict is a
    /// pure function of the code only for the default reference set.
    /// </summary>
    [Fact]
    public void FindViolations_WithExtraReferences_BypassesCache()
    {
        var code = $"var x = System.IO.File.Exists(\"{Guid.NewGuid()}\");";
        var extra = new[] { Microsoft.CodeAnalysis.MetadataReference.CreateFromFile(typeof(ScriptCompileSurface).Assembly.Location) };
        var a = ScriptTrustValidator.FindViolations(code, extra);
        var b = ScriptTrustValidator.FindViolations(code, extra);
        var cached = ScriptTrustValidator.FindViolations(code);

        Assert.NotSame(a, b);
        Assert.NotSame(a, cached);
        Assert.NotSame(b, cached);
    }

    /// <summary>Verifies that the shared verdict cannot be mutated by a caller to poison the cache.</summary>
    [Fact]
    public void FindViolations_ReturnedList_IsReadOnly()
    {
        var code = $"var x = System.IO.File.Exists(\"{Guid.NewGuid()}\");";
        var verdict = ScriptTrustValidator.FindViolations(code);
        Assert.False(verdict is List<string>);
        Assert.True(verdict is System.Collections.Generic.ICollection<string> { IsReadOnly: true });
    }
}