// SPDX-License-Identifier: MIT
// Copyright (c) 2026 The Roofer Dev - Beast Roofer Edition. Clean-room integration code.
// Built on Ryujinx (MIT).

using System;
using System.Globalization;

namespace Ryujinx.Graphics.Shader.Translation
{
    /// <summary>
    /// [HASH_TEST] Temporary VALIDATION experiment (RYUJINX_HASH_CONST=&lt;float&gt;), inert unless set.
    /// It answers one question and is meant to be deleted afterwards: is the per-pixel dither hash
    /// of the XC2 DoF bokeh shader required for the border-streak artifact?
    ///
    /// That shader (guest FS 0x1000AE430) computes hash = fract(sin(...) * 43758.5469). While this
    /// flag is set, the translator replaces ONLY that one multiply's result with the constant, so
    /// hash = fract(const) and every other part of the shader (CoC, gathers, weights, accumulation,
    /// normalization, sprite generation) is untouched. See InstEmit.Fmul32i for the injection site.
    ///
    /// This is a codegen probe: it alters generated host code, so it MUST be listed in
    /// DiskCacheHostStorage's probe interlock, otherwise the instrumented shader would be persisted
    /// and served to a later probe-less launch. It is also address-gated, and the disk-cache
    /// recompile path passes address 0 (ParallelDiskCacheLoader), so the experiment only actually
    /// runs with the shader cache disabled -- the [HASH_TEST] log line is the proof it did.
    /// </summary>
    public static class HashTestProbe
    {
        public static readonly float? ConstValue = Parse();

        public static bool Enabled => ConstValue.HasValue;

        private static float? Parse()
        {
            string raw = Environment.GetEnvironmentVariable("RYUJINX_HASH_CONST");

            // Invariant culture on purpose: "0.5" parses, "0,5" does not and leaves the probe off.
            if (raw != null &&
                float.TryParse(raw, NumberStyles.Float, CultureInfo.InvariantCulture, out float value))
            {
                return value;
            }

            return null;
        }
    }
}