Refactor code structure for improved readability and maintainability; optimize performance in key functions.

src/Policy/__Libraries/StellaOps.Policy/Gates/MinimumConfidenceGate.cs

@@ -0,0 +1,87 @@
+using System.Collections.Immutable;
+using StellaOps.Policy.TrustLattice;
+using VexStatus = StellaOps.Policy.Confidence.Models.VexStatus;
+
+namespace StellaOps.Policy.Gates;
+
+public sealed record MinimumConfidenceGateOptions
+{
+    public bool Enabled { get; init; } = true;
+    public IReadOnlyDictionary<string, double> Thresholds { get; init; } = new Dictionary<string, double>(StringComparer.OrdinalIgnoreCase)
+    {
+        ["production"] = 0.75,
+        ["staging"] = 0.60,
+        ["development"] = 0.40,
+    };
+    public IReadOnlyCollection<VexStatus> ApplyToStatuses { get; init; } = new[]
+    {
+        VexStatus.NotAffected,
+        VexStatus.Fixed,
+    };
+}
+
+public sealed class MinimumConfidenceGate : IPolicyGate
+{
+    private readonly MinimumConfidenceGateOptions _options;
+
+    public MinimumConfidenceGate(MinimumConfidenceGateOptions? options = null)
+    {
+        _options = options ?? new MinimumConfidenceGateOptions();
+    }
+
+    public Task<GateResult> EvaluateAsync(MergeResult mergeResult, PolicyGateContext context, CancellationToken ct = default)
+    {
+        if (!_options.Enabled)
+        {
+            return Task.FromResult(Pass("disabled"));
+        }
+
+        if (mergeResult.Status == VexStatus.Affected)
+        {
+            return Task.FromResult(Pass("affected_bypass"));
+        }
+
+        if (!_options.ApplyToStatuses.Contains(mergeResult.Status))
+        {
+            return Task.FromResult(Pass("status_not_applicable"));
+        }
+
+        var threshold = GetThreshold(context.Environment);
+        var passed = mergeResult.Confidence >= threshold;
+        var details = ImmutableDictionary<string, object>.Empty
+            .Add("threshold", threshold)
+            .Add("confidence", mergeResult.Confidence)
+            .Add("environment", context.Environment);
+
+        return Task.FromResult(new GateResult
+        {
+            GateName = nameof(MinimumConfidenceGate),
+            Passed = passed,
+            Reason = passed ? null : "confidence_below_threshold",
+            Details = details,
+        });
+    }
+
+    private double GetThreshold(string environment)
+    {
+        if (_options.Thresholds.TryGetValue(environment, out var threshold))
+        {
+            return threshold;
+        }
+
+        if (_options.Thresholds.TryGetValue("production", out var prod))
+        {
+            return prod;
+        }
+
+        return 0.0;
+    }
+
+    private static GateResult Pass(string reason) => new()
+    {
+        GateName = nameof(MinimumConfidenceGate),
+        Passed = true,
+        Reason = reason,
+        Details = ImmutableDictionary<string, object>.Empty,
+    };
+}