using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;

namespace NecromancerTome
{
	/// <summary>
	/// Renders every trader in black and white (user request 2026-09-13: "сделать модельки всех
	/// торговцев полупрозрачными и чёрнобелыми", then after two in-game looks: "прозрачность у
	/// торговцев убираем совсем"). Fits the mod - the necromancer deals with the dead, and the
	/// only people still trading are not quite alive.
	///
	/// TRANSPARENCY WAS DROPPED, THEN ASKED BACK FOR AT A SLIVER, THEN RAISED TO 10%. The user
	/// first said "убираем совсем", confirmed the result ("торговец стал непрозрачным и
	/// полностью чёрно-белым, как и требовалось"), then asked for "лёгкую прозрачность,
	/// буквально 1%", and on 2026-09-14 for 10% - "чтобы он выглядел как призрак, а не как
	/// сломанная модель". Dropping it was still the release this effect needed, because it
	/// is what allowed the shader to stay put - see below; the alpha is a separate, optional layer
	/// on top (ApplyTransparency) that cannot break the greyscale if the shaders refuse it.
	///
	/// The two failed attempts are worth keeping written down, because neither could have been
	/// predicted from the decompiler and each was settled by one log line:
	///
	///   1. "Unlit/Transparent Greyscale" (what GameManager uses for greyed-out item icons) has
	///      NO _Color - nowhere to put an alpha. Traders came out opaque, and because that shader
	///      is built for NGUI atlases rather than skinned meshes, the user saw them "в негативе".
	///   2. "Unlit/Transparent Colored" has no _Color either: `has _Color: False` in the log.
	///      NGUI tints through VERTEX colours, not a material property, and a character mesh has
	///      none - so that whole family of shaders was always a dead end here.
	///
	/// WITHOUT THE ALPHA REQUIREMENT THE SHADER DOES NOT HAVE TO BE REPLACED AT ALL, and that is
	/// strictly better than anything above: the material is cloned with its own shader intact and
	/// only its albedo texture is swapped for a desaturated copy. Lighting, normal maps, specular,
	/// skinning - all still the game's own. The trader looks exactly like himself, in black and
	/// white. Nothing can go "negative", because nothing but the pixels changes.
	///
	/// THE ALBEDO IS FOUND, NOT ASSUMED - this is what the earlier runs bought us. The first
	/// attempt reached for _MainTex and produced an untextured silhouette, because traders are
	/// drawn by TWO different shaders and only one of them uses that name. The probe below walks
	/// the shader's declared properties instead, and the log then said exactly what they are:
	///
	///     shader 'Game/Character' texture properties: _Albedo=set, _Normal=set, _RMOE=set,
	///         _texcoord=empty; chosen albedo: HD_Rekt 4096x4096
	///     shader 'Game/Autodesk'  texture properties: _MainTex=set, _BumpMap=set, ...;
	///         chosen albedo: HD_Rekt_Hair 2048x2048
	///
	/// So the body uses _Albedo and the hair uses _MainTex - which is precisely why the name is
	/// discovered rather than hard-coded, and why the probe stays in: Jen is assembled by a
	/// different character system than Rekt (AvatarSDCSController vs AvatarNpcController in
	/// entityclasses.xml) and may well introduce a third shader.
	///
	/// GREYSCALE IS DONE TO THE TEXTURE, via a RenderTexture round trip. The round trip is the
	/// point: game textures are compressed with isReadable=false, so GetPixels on the original
	/// throws - blitting into an ARGB32 RenderTexture and reading THAT back is the standard way to
	/// reach pixels the CPU was never handed. Luma weights 0.299/0.587/0.114 rather than a flat
	/// average, so it reads like a black-and-white photograph instead of a muddy one. Cached per
	/// source texture: these are 4096x4096, and a readback per renderer per sweep would be
	/// indefensible.
	///
	/// THE ALPHA IS TURNED FROM THE CONSOLE, not from this file: `necroghost <percent>`, in
	/// GhostTraderCommand.cs. A rendering balance can only be judged by looking at it, and a
	/// rebuild-restart-walk-to-a-trader cycle per step is not a way to look at anything.
	///
	/// WHY A TICK AND NOT A SPAWN HOOK. Traders are streamed in on approach ("force spawning
	/// pending entity npcTraderRekt" appeared ~4 minutes after the world loaded), and Jen is built
	/// at runtime, so her renderers do not all exist when the entity is added to the world.
	/// Polling with ModEvents.UnityUpdate - the same approach PetFollowPatch.cs already uses here -
	/// avoids guessing at the right moment inside someone else's character pipeline. A trader with
	/// no renderers yet is simply not marked done and is picked up on the next sweep.
	/// </summary>
	public static class GhostTraderPatch
	{
		/// <summary>Seconds between sweeps.</summary>
		public const float SweepInterval = 2f;

		/// <summary>What a fresh game boots with. 1 = solid; 0.3 is what the hunt actually landed
		/// on - the user set 70% transparency in game on 2026-09-14 once the body was blending
		/// instead of dithering, and kept it. THE VALUE FOUND IN GAME BELONGS HERE: the console
		/// command turns GhostAlpha for the session only and deliberately persists nothing, so a
		/// number worth keeping has to be written into this line.
		///
		/// The road here was 1% -> 10% -> 70%, and the last jump was not a change of taste: at 10%
		/// the body was still being dithered, and a dither is only bearable while it is faint. Once
		/// it became real blending, far more of it turned out to look right.</summary>
		public const float DefaultGhostAlpha = 0.3f;

		/// <summary>The opacity actually in use. THIS IS THE ONE NUMBER TO TURN when hunting the
		/// balance between "ghost" and "broken model" - everything else in this file is about
		/// making the number mean what it says - and `necroghost &lt;percent&gt;` turns it live
		/// (GhostTraderCommand.cs), because every step of that hunt otherwise costs a rebuild, a
		/// restart and the four-minute walk to a trader.
		///
		/// Which way to turn it is decided by WHICH failure you are looking at, and the two look
		/// nothing alike:
		///   - reads as a solid person, no ghost at all -> lower it (0.85, 0.8).
		///   - the world shows through him but he still reads as one body -> this is the target.
		///   - you can see his teeth through his cheek, eyes through eyelids, an arm through the
		///     chest -> that is the "broken model", and it is NOT this number's fault. It means
		///     depth writing came off somewhere; see _ZWrite in ApplyTransparency. Dropping the
		///     alpha further only makes it worse.
		/// THE OLD "nothing below ~0.7" NOTE WAS WRONG, and it is worth saying why rather than
		/// quietly deleting: it was written while the body was still dithering, where a low value
		/// means a coarse pattern and the silhouette falls apart early. With the body blending,
		/// 0.3 reads as a ghost and holds together - the limit belonged to the technique, not to
		/// the eye. Depth writing is what keeps him one body, and it does not care how low the
		/// number goes.</summary>
		public static float GhostAlpha = DefaultGhostAlpha;

		/// <summary>One opacity lever this patch installed on a trader, remembered so the alpha
		/// can be turned again WITHOUT rebuilding anything. Keeping the base value is the whole
		/// point: the live value is always base * GhostAlpha, never "multiply what is there now by
		/// the new number" - that would compound (0.9 then 0.8 would land on 0.72) and the second
		/// turn of the dial would lie about where it put you.
		///
		/// IsColour says which of the two kinds this is - the alpha channel of a colour, or a
		/// plain float - because a trader needs BOTH and they are not interchangeable: the body
		/// only has the float (_Fade) and the hair only has the colour (_Color). One material can
		/// therefore contribute one entry, and one trader contributes several of both kinds.</summary>
		public struct GhostMaterial
		{
			public Material Material;
			public string Property;
			public bool IsColour;
			public float BaseValue;
		}

		/// <summary>A renderer this patch has taken over, with the materials it had before. The
		/// originals are the reason a mode can be switched at all: after the first pass
		/// renderer.sharedMaterials hands back OUR clones, so rebuilding from what is currently
		/// on the renderer would re-shade an already re-shaded material and there would be no way
		/// back to the body's real one. Rebuilding always starts here instead.</summary>
		public struct GhostRenderer
		{
			public Renderer Renderer;
			public Material[] Originals;
		}

		/// <summary>Every renderer taken over, in the order it was found. Pruned of destroyed
		/// renderers as they are walked; dropped wholesale when the world unloads.</summary>
		public static readonly List<GhostRenderer> Converted = new List<GhostRenderer>();

		/// <summary>Every material installed on a live trader that has somewhere to put an alpha.
		/// Retint walks this instead of redoing the work: re-running the sweep would re-clone the
		/// materials and, far worse, hand the 4096x4096 desaturation another readback per trader.
		/// Entries go stale when the game destroys the material with its trader - Retint prunes
		/// those, and WorldShuttingDown drops the lot.</summary>
		public static readonly List<GhostMaterial> TintedMaterials = new List<GhostMaterial>();

		/// <summary>Colour properties that might carry an alpha, best first. Confirmed in game:
		/// the hair/beard shader "Game/Autodesk" has _Color; the BODY shader "Game/Character" has
		/// no colour property at all - see FadeNameHints.</summary>
		public static readonly string[] TintNameHints = { "_Color", "_BaseColor", "_TintColor", "_Tint" };

		/// <summary>How the BODY is made see-through. The two are not two settings of one thing,
		/// they are two different renderers' worth of behaviour, and only a look in game can pick
		/// between them - which is why both stay reachable from the console.
		///
		/// Dither is the game's own _Fade, and on 2026-09-14 the user reported what it actually
		/// looks like: "тело гаснет, но идёт мелкой сеточкой". That is screen-door transparency -
		/// the shader is not blending anything, it is THROWING PIXELS AWAY in a fixed pattern.
		/// It is what an opaque-queue character shader can do without a transparent pass, and no
		/// value of GhostAlpha turns a dropped pixel into a translucent one.
		///
		/// Blend re-shades the body onto the shader the HAIR is already drawn with, which does
		/// have a transparent pass. The existence proof is on the same model in the same frame:
		/// the beard has been fading smoothly this whole time while the body was dithering.</summary>
		public enum BodyOpacityMode
		{
			Dither,
			Blend
		}

		/// <summary>Blend by default: dither has been looked at and rejected. `necroghost blend`
		/// and `necroghost dither` switch it live - see GhostTraderCommand.cs.</summary>
		public static BodyOpacityMode BodyMode = BodyOpacityMode.Blend;

		/// <summary>The hair's shader, kept once it is found on a real trader. Taken off the model
		/// rather than through Shader.Find so it is the exact shader already proven to work in
		/// this scene - name lookups can miss a stripped or renamed shader and hand back null,
		/// and the mod has been down that road twice already with the Unlit family.</summary>
		public static Shader BlendShader;

		/// <summary>Normal-map properties, best first. "Game/Character" calls it _Normal, the hair
		/// shader wants _BumpMap - the same disagreement the albedo has.</summary>
		public static readonly string[] NormalNameHints = { "_BumpMap", "_Normal", "_NormalMap", "_NormalTex" };

		/// <summary>Float properties that fade the whole material out, best first. This is the
		/// body's only lever and the game's own: EntityModel.SetFade writes exactly "_Fade", and
		/// guards it with `material.HasProperty("_Fade") && shader.name.Contains("Game/Character")`
		/// - the same shader our traders' bodies are drawn with. EntityAlive.Update drives it from
		/// renderFade, and SetVisible(renderFade > 0.01f) right next to it settles the direction
		/// beyond doubt: 1 = solid, 0 = gone, exactly like an alpha.</summary>
		public static readonly string[] FadeNameHints = { "_Fade" };

		/// <summary>Entity ids already converted. Cleared when the world unloads.</summary>
		public static readonly HashSet<int> Ghosted = new HashSet<int>();

		/// <summary>Source shader names already described in the log, so the probe says each
		/// distinct thing once rather than once per trader per part.</summary>
		public static readonly HashSet<string> ProbedShaders = new HashSet<string>();

		/// <summary>Desaturated copies, keyed by the texture they came from.</summary>
		public static readonly Dictionary<Texture, Texture2D> GreyTextures = new Dictionary<Texture, Texture2D>();

		/// <summary>Property names that look like an albedo, best first. Confirmed in game:
		/// "Game/Character" uses _Albedo, "Game/Autodesk" uses _MainTex. Anything else falls
		/// through to "the first texture property that has something in it".</summary>
		public static readonly string[] AlbedoNameHints =
		{
			"_MainTex", "_Albedo", "_BaseMap", "_BaseColorMap", "_AlbedoMap", "_DiffuseMap",
			"_Diffuse", "_ColorMap", "_MainTexture", "_Texture"
		};

		public static float timer;

		/// <summary>Called from ModEntry.InitMod.</summary>
		public static void Init()
		{
			ModEvents.UnityUpdate.RegisterHandler(OnUnityUpdate);
			ModEvents.WorldShuttingDown.RegisterHandler(OnWorldShuttingDown);
		}

		public static void OnWorldShuttingDown(ref ModEvents.SWorldShuttingDownData _data)
		{
			Ghosted.Clear();
			GreyTextures.Clear();
			TintedMaterials.Clear();
			Converted.Clear();
			BlendShader = null;
			timer = 0f;
		}

		public static void OnUnityUpdate(ref ModEvents.SUnityUpdateData _data)
		{
			timer += Time.deltaTime;
			if (timer < SweepInterval)
			{
				return;
			}
			timer = 0f;

			World world = GameManager.Instance != null ? GameManager.Instance.World : null;
			if (world == null || world.EntityAlives == null)
			{
				return;
			}

			for (int i = 0; i < world.EntityAlives.Count; i++)
			{
				EntityAlive entity = world.EntityAlives[i];
				if (!(entity is EntityTrader trader) || trader.IsDead())
				{
					continue;
				}
				if (Ghosted.Contains(trader.entityId))
				{
					continue;
				}
				if (ApplyGreyscale(trader))
				{
					Ghosted.Add(trader.entityId);
				}
			}
		}

		/// <summary>False when there is nothing to work on yet (model not built), so the caller
		/// leaves this trader unmarked and tries again on the next sweep.</summary>
		public static bool ApplyGreyscale(EntityTrader _trader)
		{
			Renderer[] renderers = _trader.GetComponentsInChildren<Renderer>(true);
			if (renderers == null || renderers.Length == 0)
			{
				return false;
			}

			// Before anything is touched, because the body's replacement shader is found on the
			// trader's OWN hair and the hair is not guaranteed to come first in this array.
			FindBlendShader(renderers);

			int converted = 0;
			int leversBefore = TintedMaterials.Count;
			foreach (Renderer renderer in renderers)
			{
				if (renderer == null || renderer is ParticleSystemRenderer)
				{
					continue;
				}

				Material[] sources = renderer.sharedMaterials;
				if (sources == null || sources.Length == 0)
				{
					continue;
				}

				Converted.Add(new GhostRenderer { Renderer = renderer, Originals = sources });
				if (Convert(renderer, sources))
				{
					converted++;
				}
			}

			// The lever count is the half that answers "will the console command reach him":
			// desaturation and opacity come from different properties, and the body had the first
			// without the second until 2026-09-14. Fewer levers than converted renderers means
			// some part of this trader can only ever be black-and-white, never transparent.
			Debug.Log("[NecromancerTome] GhostTraderPatch: " + _trader.EntityClass.entityClassName +
			          " (entity " + _trader.entityId + ") - " + converted + " of " + renderers.Length +
			          " renderer(s) desaturated, " + (TintedMaterials.Count - leversBefore) + " opacity lever(s) installed");
			return true;
		}

		/// <summary>Builds and installs this renderer's ghost materials from the ORIGINALS it was
		/// handed. True when anything was actually changed - a renderer nothing could be done to
		/// keeps the materials it has rather than being handed a half-built array.</summary>
		public static bool Convert(Renderer _renderer, Material[] _sources)
		{
			Material[] ghosts = new Material[_sources.Length];
			bool anyChanged = false;
			for (int i = 0; i < _sources.Length; i++)
			{
				ghosts[i] = MakeGreyMaterial(_sources[i], ref anyChanged);
			}
			if (anyChanged)
			{
				_renderer.materials = ghosts;
			}
			return anyChanged;
		}

		/// <summary>Rebuilds every trader already converted, from their original materials, under
		/// whatever BodyMode is set now. This is the expensive path and exists only for the mode
		/// switch; changing the alpha alone goes through Retint, which touches no materials at
		/// all. Even here the 4096x4096 desaturation is not redone - GreyTextures is keyed by the
		/// source texture, and the source is the same original every time.</summary>
		public static int Reapply()
		{
			TintedMaterials.Clear();
			int rebuilt = 0;
			for (int i = Converted.Count - 1; i >= 0; i--)
			{
				GhostRenderer entry = Converted[i];
				if (entry.Renderer == null)
				{
					Converted.RemoveAt(i);
					continue;
				}
				if (Convert(entry.Renderer, entry.Originals))
				{
					rebuilt++;
				}
			}
			return rebuilt;
		}

		/// <summary>Remembers the first shader on this model that can actually blend - it needs
		/// both a colour to put an alpha in and a blend mode to honour it. On a trader that is the
		/// hair's shader. Falls back to looking the name up only if the model somehow has no such
		/// material, and says so either way, because a null here silently disables the whole Blend
		/// mode and leaves the body dithering with no explanation.</summary>
		public static Shader FindBlendShader(Renderer[] _renderers)
		{
			if (BlendShader != null)
			{
				return BlendShader;
			}

			foreach (Renderer renderer in _renderers)
			{
				if (renderer == null || renderer is ParticleSystemRenderer)
				{
					continue;
				}
				Material[] materials = renderer.sharedMaterials;
				if (materials == null)
				{
					continue;
				}
				foreach (Material material in materials)
				{
					if (material == null || material.shader == null || !CanBlendInPlace(material))
					{
						continue;
					}
					BlendShader = material.shader;
					Debug.Log("[NecromancerTome] GhostTraderPatch: blend shader taken off the model: '" +
					          BlendShader.name + "'");
					return BlendShader;
				}
			}

			BlendShader = Shader.Find("Game/Autodesk");
			Debug.Log("[NecromancerTome] GhostTraderPatch: no blend-capable material on this model; " +
			          "the shader was looked up by name instead and came back " +
			          (BlendShader != null ? BlendShader.name : "NULL - the body stays dithered"));
			return BlendShader;
		}

		/// <summary>Whether this material can be made see-through where it stands: somewhere to
		/// put an alpha, and a blend mode to make the alpha mean something. The body fails both
		/// halves and the hair passes both - which is the whole difference between them, and the
		/// reason this is a capability test rather than a check on the shader's name.</summary>
		public static bool CanBlendInPlace(Material _material)
		{
			if (!_material.HasProperty("_SrcBlend") || !_material.HasProperty("_DstBlend"))
			{
				return false;
			}
			foreach (string hint in TintNameHints)
			{
				if (_material.HasProperty(hint))
				{
					return true;
				}
			}
			return false;
		}

		/// <summary>
		/// The body, re-shaded onto the hair's shader so it can blend the way the hair does, with
		/// the black-and-white albedo it would have had anyway.
		///
		/// ONLY WHAT IS UNDERSTOOD IS CARRIED OVER - albedo and normal map. The body's third map,
		/// _RMOE, is a packed roughness/metallic/occlusion/emission texture, and the destination
		/// shader's _MetallicGlossMap expects metallic in R and smoothness in A: the channels do
		/// not line up, and wiring them by hope is exactly how a character comes out looking like
		/// wet plastic or a negative. It is left empty and the two floats are set by hand instead
		/// - no metal, barely any gloss, which is what a dead man in black and white should be.
		///
		/// This is a real trade and worth stating plainly: the body loses the character shader's
		/// own lighting response and gets standard lighting instead. In exchange it can actually
		/// be translucent rather than dithered. If it reads wrong in game, `necroghost dither` is
		/// one line away and nothing has to be rebuilt.
		/// </summary>
		public static Material MakeBlendMaterial(Material _source, Texture2D _albedo)
		{
			Material blend = new Material(BlendShader);
			blend.SetTexture("_MainTex", _albedo);

			Texture normal = FindTexture(_source, NormalNameHints);
			if (normal != null && blend.HasProperty("_BumpMap"))
			{
				blend.SetTexture("_BumpMap", normal);
			}
			MakeMatte(blend);
			// Standard's own "Fade" setting. The shader branches on keywords rather than on this
			// float, and ApplyTransparency sets those - but a material inspected later with its
			// mode still reading "Opaque" is a trap for whoever looks next.
			if (blend.HasProperty("_Mode"))
			{
				blend.SetFloat("_Mode", 2f);
			}

			ApplyTransparency(blend);
			return blend;
		}

		/// <summary>
		/// Takes the shine off (user request 2026-09-14, once the body was blending properly:
		/// "слишком оно бликует, я бы вообще сделал матовым"). Applied to EVERY ghost material, not just the
		/// re-shaded body: the hair is drawn by the same shader and was keeping its own shine, and
		/// a matte body under a glossy beard would have read worse than either.
		///
		/// THREE THINGS, BECAUSE THEY FAIL DIFFERENTLY:
		///
		///   - _Glossiness (smoothness) to 0. This one is plain shader maths and always works -
		///     the surface becomes maximally rough, and a rough surface has no tight highlight.
		///     It is the load-bearing half of this method.
		///   - _SpecularHighlights / _GlossyReflections to 0 WITH their keywords. These are the
		///     Standard shader's [ToggleOff] pair: the float is only what the inspector shows, the
		///     shader branches on _SPECULARHIGHLIGHTS_OFF / _GLOSSYREFLECTIONS_OFF, so setting the
		///     float alone does nothing at all. They kill the direct highlight and the reflection
		///     probe contribution outright.
		///   - The gloss MAPS, cleared if anything is in them. A map wins over the float: leave
		///     one in place and _Glossiness is ignored, which is the silent way for all of this to
		///     appear to do nothing. They are empty on these traders today - this is for the next
		///     model that is not.
		///
		/// HONEST LIMIT: those two keywords are `shader_feature`, which Unity strips at build time
		/// if no material in the game ships with them set. If they were stripped, EnableKeyword is
		/// a no-op and only the roughness half lands. That is why the roughness half is not
		/// treated as a fallback but as the main lever - and why this is not attempted at all on
		/// the body's own "Game/Character" shader, which has none of these properties: its shine
		/// lives inside the packed _RMOE texture and would have to be repainted, not switched off.
		/// </summary>
		public static void MakeMatte(Material _material)
		{
			if (_material.HasProperty("_Glossiness"))
			{
				_material.SetFloat("_Glossiness", 0f);
			}
			if (_material.HasProperty("_GlossMapScale"))
			{
				_material.SetFloat("_GlossMapScale", 0f);
			}
			if (_material.HasProperty("_Metallic"))
			{
				_material.SetFloat("_Metallic", 0f);
			}
			if (_material.HasProperty("_SpecularHighlights"))
			{
				_material.SetFloat("_SpecularHighlights", 0f);
				_material.EnableKeyword("_SPECULARHIGHLIGHTS_OFF");
			}
			if (_material.HasProperty("_GlossyReflections"))
			{
				_material.SetFloat("_GlossyReflections", 0f);
				_material.EnableKeyword("_GLOSSYREFLECTIONS_OFF");
			}
			ClearTexture(_material, "_SpecGlossMap");
			ClearTexture(_material, "_MetallicGlossMap");
		}

		/// <summary>Empties a texture slot if this material has one and it is not already empty.
		/// </summary>
		public static void ClearTexture(Material _material, string _property)
		{
			if (_material.HasProperty(_property) && _material.GetTexture(_property) != null)
			{
				_material.SetTexture(_property, null);
			}
		}

		/// <summary>First texture among these property names that this material actually has
		/// something in.</summary>
		public static Texture FindTexture(Material _source, string[] _hints)
		{
			foreach (string hint in _hints)
			{
				if (_source.HasProperty(hint))
				{
					Texture texture = _source.GetTexture(hint);
					if (texture != null)
					{
						return texture;
					}
				}
			}
			return null;
		}

		/// <summary>
		/// This material's ghost version. Two shapes, and which one it takes is decided by what
		/// the material can do rather than by what it is called:
		///
		///   - CAN be made see-through where it stands (the hair) -> a clone with the SAME shader
		///     and only its albedo swapped for a black-and-white copy. Lighting, normal maps,
		///     specular, skinning - all still the game's own.
		///   - CANNOT (the body: no colour, no blend mode) -> under BodyMode.Blend it is re-shaded
		///     onto the shader the hair uses, which can. Under BodyMode.Dither it takes the clone
		///     path anyway and gets the _Fade lever, which works but throws pixels away.
		///
		/// The albedo is desaturated first either way, because both shapes need it and the result
		/// is cached per source texture - the re-shaded body is not paying for a second readback.
		/// </summary>
		public static Material MakeGreyMaterial(Material _source, ref bool _changed)
		{
			if (_source == null)
			{
				return null;
			}

			ProbeShaderOnce(_source);

			string albedoProperty = FindAlbedoProperty(_source);
			Texture2D desaturated = albedoProperty != null
				? Desaturate(_source.GetTexture(albedoProperty))
				: null;

			// Re-shading without an albedo to hand over would produce an untextured silhouette -
			// the exact failure this patch already shipped once, on 2026-09-13. If the texture
			// could not be read, the body keeps its own shader and stays dithered instead, and
			// the lever count in the log is what says so.
			if (BodyMode == BodyOpacityMode.Blend && BlendShader != null && desaturated != null &&
			    !CanBlendInPlace(_source))
			{
				_changed = true;
				return MakeBlendMaterial(_source, desaturated);
			}

			Material grey = new Material(_source);
			MakeMatte(grey);
			if (ApplyTransparency(grey))
			{
				_changed = true;
			}
			if (desaturated == null)
			{
				// Nothing to desaturate on this material; hand back the clone unchanged rather
				// than dropping the renderer's material entirely.
				return grey;
			}

			grey.SetTexture(albedoProperty, desaturated);
			_changed = true;
			return grey;
		}

		/// <summary>
		/// Dials this material's opacity down to GhostAlpha. THREE levers, each conditional,
		/// because a trader is drawn by two different shaders that have almost nothing in common -
		/// and the first version of this method only had the levers the hair happens to own, which
		/// is why the user reported on 2026-09-14 that the console command "управляет только
		/// прозрачностью бороды". The probe had already printed the reason, one line each:
		///
		///     shader 'Game/Character' - albedo: _Albedo -> HD_Rekt 4096x4096;
		///         tint property: <none>; blend-mode properties present: False
		///     shader 'Game/Autodesk'  - albedo: _MainTex -> HD_Rekt_Hair 2048x2048;
		///         tint property: _Color (alpha 1); blend-mode properties present: True
		///
		/// The BODY has no colour property and no blend mode at all. Two of the three levers below
		/// simply do not exist on it, and no value of GhostAlpha was ever going to reach it.
		///
		///   - A COLOUR with an alpha channel (_Color and friends). The hair's lever; the body
		///     does not have one.
		///   - THE FADE FLOAT (_Fade). The body's lever, and the game's own: EntityModel.SetFade
		///     writes this exact property and guards it with a check for the "Game/Character"
		///     shader by name, so this is not a property we found and hoped about - it is the one
		///     the engine itself fades these very models with. Nothing else in the body's property
		///     list can carry an opacity: the rest is _Albedo/_Normal/_RMOE, an alpha-CUTOUT
		///     cluster (_AlphaCut, _AlphaCutoff, _SoftAlphaCutoff, _AlphaSoftness - a dissolve,
		///     which punches holes rather than making glass), _EmissiveColor, and flags.
		///   - THE BLEND MODE (_SrcBlend/_DstBlend). An opaque shader ignores any alpha it is
		///     handed, so without this the COLOUR lever does nothing visible - the same wall the
		///     mod's first transparency attempt hit back on 2026-08-28 with the summoned pets.
		///     The recipe is the game's own: MeshDescription.SetupMaterialWithBlendMode writes
		///     exactly these properties plus _ZWrite and the _ALPHABLEND_ON keyword. The _Fade
		///     lever needs none of it - the shader does its own fading internally, which is
		///     exactly why it exists.
		///
		/// _ZWrite IS LEFT ALONE ON PURPOSE, AND AT 10% THAT IS THE WHOLE BALANCE. The usual
		/// transparency recipe switches depth writing off, which is right for glass and wrong for
		/// a person: without it every surface of the model blends over every other one, and the
		/// trader becomes teeth through cheeks, eyeballs through eyelids, the far arm through the
		/// chest - exactly the "сломанная модель" the user does not want. With it on, the depth
		/// test keeps only the nearest surface and that one surface blends with the WORLD behind
		/// him. So he goes see-through without coming apart: a ghost, not a mess.
		///
		/// At 99% this cost nothing because there was nothing to see through; at 90% it is the
		/// reason the effect is usable at all. Note that it is not set here either way - these
		/// shaders write depth by default, and leaving the property untouched is what keeps it.
		///
		/// Whatever is missing is reported by the probe rather than silently skipped - if neither
		/// lever exists on these shaders, the traders stay solid black-and-white and the log says
		/// why.
		/// </summary>
		public static bool ApplyTransparency(Material _material)
		{
			bool touched = false;

			foreach (string hint in TintNameHints)
			{
				if (!_material.HasProperty(hint))
				{
					continue;
				}
				Color tint = _material.GetColor(hint);
				float baseAlpha = tint.a;
				tint.a = baseAlpha * GhostAlpha;
				_material.SetColor(hint, tint);
				TintedMaterials.Add(new GhostMaterial
				{
					Material = _material,
					Property = hint,
					IsColour = true,
					BaseValue = baseAlpha
				});
				touched = true;
				break;
			}

			foreach (string hint in FadeNameHints)
			{
				if (!_material.HasProperty(hint))
				{
					continue;
				}
				// A base of 0 would mean the material is already fully faded out, which no
				// standing trader is - it means the property is sitting at a default nobody set.
				// Multiplying by it would make him vanish outright and no value of GhostAlpha
				// could bring him back, so it is read as "solid" instead.
				float baseFade = _material.GetFloat(hint);
				if (baseFade <= 0f)
				{
					baseFade = 1f;
				}
				_material.SetFloat(hint, baseFade * GhostAlpha);
				TintedMaterials.Add(new GhostMaterial
				{
					Material = _material,
					Property = hint,
					IsColour = false,
					BaseValue = baseFade
				});
				touched = true;
				break;
			}

			if (_material.HasProperty("_SrcBlend") && _material.HasProperty("_DstBlend"))
			{
				_material.SetFloat("_SrcBlend", (float)BlendMode.SrcAlpha);
				_material.SetFloat("_DstBlend", (float)BlendMode.OneMinusSrcAlpha);
				_material.EnableKeyword("_ALPHABLEND_ON");
				_material.renderQueue = (int)RenderQueue.Transparent;
				touched = true;
			}

			return touched;
		}

		/// <summary>Pushes the current GhostAlpha onto every trader already standing in the world,
		/// and returns how many materials took it. Traders that spawn later need nothing from this
		/// - ApplyTransparency reads the same field on the way past.
		///
		/// Unity's fake null is the reason for the rebuild-in-place rather than a simple loop: a
		/// destroyed Material compares equal to null but is still a live list entry, and touching
		/// it throws. Walking backwards and dropping those as we go keeps the list from growing
		/// across a session of traders streaming in and out.</summary>
		public static int Retint()
		{
			int applied = 0;
			for (int i = TintedMaterials.Count - 1; i >= 0; i--)
			{
				GhostMaterial entry = TintedMaterials[i];
				if (entry.Material == null)
				{
					TintedMaterials.RemoveAt(i);
					continue;
				}
				if (entry.IsColour)
				{
					Color tint = entry.Material.GetColor(entry.Property);
					tint.a = entry.BaseValue * GhostAlpha;
					entry.Material.SetColor(entry.Property, tint);
				}
				else
				{
					entry.Material.SetFloat(entry.Property, entry.BaseValue * GhostAlpha);
				}
				applied++;
			}
			return applied;
		}

		/// <summary>Name of the texture property holding this material's albedo, or null. Walks
		/// the shader's declared properties rather than assuming a name - the body and the hair of
		/// the same trader disagree about it.</summary>
		public static string FindAlbedoProperty(Material _source)
		{
			Shader shader = _source.shader;
			if (shader == null)
			{
				return null;
			}

			foreach (string hint in AlbedoNameHints)
			{
				if (_source.HasProperty(hint) && _source.GetTexture(hint) != null)
				{
					return hint;
				}
			}

			int count = shader.GetPropertyCount();
			for (int i = 0; i < count; i++)
			{
				if (shader.GetPropertyType(i) != ShaderPropertyType.Texture)
				{
					continue;
				}
				string name = shader.GetPropertyName(i);
				if (_source.GetTexture(name) != null)
				{
					return name;
				}
			}
			return null;
		}

		/// <summary>Black-and-white copy of a texture. See the class comment for why this goes
		/// through a RenderTexture instead of reading the source directly.</summary>
		public static Texture2D Desaturate(Texture _source)
		{
			if (_source == null)
			{
				return null;
			}
			if (GreyTextures.TryGetValue(_source, out Texture2D cached))
			{
				return cached;
			}

			Texture2D grey = null;
			RenderTexture rt = null;
			RenderTexture previous = RenderTexture.active;
			try
			{
				rt = RenderTexture.GetTemporary(_source.width, _source.height, 0,
					RenderTextureFormat.ARGB32, RenderTextureReadWrite.sRGB);
				Graphics.Blit(_source, rt);
				RenderTexture.active = rt;

				grey = new Texture2D(_source.width, _source.height, TextureFormat.RGBA32, false);
				grey.ReadPixels(new Rect(0f, 0f, _source.width, _source.height), 0, 0);

				Color32[] pixels = grey.GetPixels32();
				for (int i = 0; i < pixels.Length; i++)
				{
					Color32 p = pixels[i];
					byte luma = (byte)((p.r * 299 + p.g * 587 + p.b * 114) / 1000);
					p.r = luma;
					p.g = luma;
					p.b = luma;
					pixels[i] = p;
				}
				grey.SetPixels32(pixels);
				grey.Apply(false, false);
			}
			catch (System.Exception e)
			{
				Debug.LogError("[NecromancerTome] GhostTraderPatch: could not desaturate '" + _source.name + "': " + e.Message);
				grey = null;
			}
			finally
			{
				RenderTexture.active = previous;
				if (rt != null)
				{
					RenderTexture.ReleaseTemporary(rt);
				}
			}

			// Cached even on failure (as null) so an unreadable texture is not retried per trader.
			GreyTextures[_source] = grey;
			return grey;
		}

		/// <summary>Says, once per distinct source shader, which texture properties it has and
		/// which carry anything. This is what told us the body uses _Albedo and the hair _MainTex;
		/// it stays in because the next trader built by a different character system will announce
		/// itself the same way.</summary>
		public static void ProbeShaderOnce(Material _source)
		{
			Shader shader = _source.shader;
			string shaderName = shader != null ? shader.name : "<null shader>";
			if (!ProbedShaders.Add(shaderName) || shader == null)
			{
				return;
			}

			// EVERY property, not just the textures. The texture-only version answered the
			// "where is the albedo" question; this one has to answer "is there anything here that
			// can make it transparent at all", and that lives among the floats and colours.
			System.Text.StringBuilder sb = new System.Text.StringBuilder();
			int count = shader.GetPropertyCount();
			for (int i = 0; i < count; i++)
			{
				string name = shader.GetPropertyName(i);
				ShaderPropertyType type = shader.GetPropertyType(i);
				sb.Append(sb.Length > 0 ? ", " : "").Append(name).Append(':').Append(type);
				if (type == ShaderPropertyType.Texture)
				{
					sb.Append(_source.GetTexture(name) != null ? "=set" : "=empty");
				}
			}

			string chosen = FindAlbedoProperty(_source);
			Texture chosenTexture = chosen != null ? _source.GetTexture(chosen) : null;
			string tint = "<none>";
			foreach (string hint in TintNameHints)
			{
				if (_source.HasProperty(hint))
				{
					tint = hint + " (alpha " + _source.GetColor(hint).a.ToString("0.###") + ")";
					break;
				}
			}
			string fade = "<none>";
			foreach (string hint in FadeNameHints)
			{
				if (_source.HasProperty(hint))
				{
					fade = hint + " (" + _source.GetFloat(hint).ToString("0.###") + ")";
					break;
				}
			}
			bool canBlend = _source.HasProperty("_SrcBlend") && _source.HasProperty("_DstBlend");

			Debug.Log("[NecromancerTome] GhostTraderPatch: shader '" + shaderName + "' properties: " +
			          (sb.Length > 0 ? sb.ToString() : "<none>"));
			Debug.Log("[NecromancerTome] GhostTraderPatch: shader '" + shaderName + "' - albedo: " + (chosen ?? "<none>") +
			          " -> " + (chosenTexture != null ? chosenTexture.name + " " + chosenTexture.width + "x" + chosenTexture.height : "<none>") +
			          "; tint property: " + tint + "; fade property: " + fade +
			          "; blend-mode properties present: " + canBlend);
		}
	}
}