// Luanti
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
// Copyright (C) 2013 Kahrl <kahrl@gmx.net>

#include <fstream>
#include <iterator>
#include "shader.h"
#include "irr_ptr.h"
#include "debug.h"
#include "filesys.h"
#include "util/container.h"
#include "util/thread.h"
#include "settings.h"
#include <ICameraSceneNode.h>
#include <IGPUProgrammingServices.h>
#include <IMaterialRenderer.h>
#include <IMaterialRendererServices.h>
#include <IShaderConstantSetCallBack.h>
#include "client/renderingengine.h"
#include "gettext.h"
#include "log.h"
#include "gamedef.h"
#include "client/tile.h"
#include "config.h"

#include <mt_opengl.h>

/*
	A cache from shader name to shader path
*/
static MutexedMap<std::string, std::string> g_shadername_to_path_cache;

/*
	Gets the path to a shader by first checking if the file
	  name_of_shader/filename
	exists in shader_path and if not, using the data path.

	If not found, returns "".

	Utilizes a thread-safe cache.
*/
std::string getShaderPath(const std::string &name_of_shader,
		const std::string &filename)
{
	std::string combined = name_of_shader + DIR_DELIM + filename;
	std::string fullpath;
	/*
		Check from cache
	*/
	bool incache = g_shadername_to_path_cache.get(combined, &fullpath);
	if(incache)
		return fullpath;

	/*
		Check from shader_path
	*/
	std::string shader_path = g_settings->get("shader_path");
	if (!shader_path.empty()) {
		std::string testpath = shader_path + DIR_DELIM + combined;
		if(fs::PathExists(testpath))
			fullpath = testpath;
	}

	/*
		Check from default data directory
	*/
	if (fullpath.empty()) {
		std::string rel_path = std::string("client") + DIR_DELIM
				+ "shaders" + DIR_DELIM
				+ name_of_shader + DIR_DELIM
				+ filename;
		std::string testpath = porting::path_share + DIR_DELIM + rel_path;
		if(fs::PathExists(testpath))
			fullpath = testpath;
	}

	// Add to cache (also an empty result is cached)
	g_shadername_to_path_cache.set(combined, fullpath);

	// Finally return it
	return fullpath;
}

/*
	SourceShaderCache: A cache used for storing source shaders.
*/

class SourceShaderCache
{
public:
	void insert(const std::string &name_of_shader, const std::string &filename,
		const std::string &program, bool prefer_local)
	{
		std::string combined = name_of_shader + DIR_DELIM + filename;
		// Try to use local shader instead if asked to
		if(prefer_local){
			std::string path = getShaderPath(name_of_shader, filename);
			if(!path.empty()){
				std::string p = readFile(path);
				if (!p.empty()) {
					m_programs[combined] = p;
					return;
				}
			}
		}
		m_programs[combined] = program;
	}

	std::string get(const std::string &name_of_shader,
		const std::string &filename)
	{
		std::string combined = name_of_shader + DIR_DELIM + filename;
		StringMap::iterator n = m_programs.find(combined);
		if (n != m_programs.end())
			return n->second;
		return "";
	}

	// Primarily fetches from cache, secondarily tries to read from filesystem
	std::string getOrLoad(const std::string &name_of_shader,
		const std::string &filename)
	{
		std::string combined = name_of_shader + DIR_DELIM + filename;
		StringMap::iterator n = m_programs.find(combined);
		if (n != m_programs.end())
			return n->second;
		std::string path = getShaderPath(name_of_shader, filename);
		if (path.empty()) {
			infostream << "SourceShaderCache::getOrLoad(): No path found for \""
				<< combined << "\"" << std::endl;
			return "";
		}
		infostream << "SourceShaderCache::getOrLoad(): Loading path \""
			<< path << "\"" << std::endl;
		std::string p = readFile(path);
		if (!p.empty()) {
			m_programs[combined] = p;
			return p;
		}
		return "";
	}
private:
	StringMap m_programs;

	inline std::string readFile(const std::string &path)
	{
		std::string ret;
		if (!fs::ReadFile(path, ret, true))
			ret.clear();
		return ret;
	}
};


/*
	ShaderCallback: Sets constants that can be used in shaders
*/

class ShaderCallback : public video::IShaderConstantSetCallBack
{
	std::vector<std::unique_ptr<IShaderUniformSetter>> m_setters;
	irr_ptr<IShaderUniformSetterRC> m_extra_setter;

public:
	template <typename Factories>
	ShaderCallback(const std::string &name, const Factories &factories)
	{
		for (auto &&factory : factories) {
			auto *setter = factory->create(name);
			if (setter) {
				// since we use unique_ptr, the object may not be refcounted
				assert(dynamic_cast<IReferenceCounted*>(setter) == nullptr);
				m_setters.emplace_back(setter);
			}
		}
	}

	~ShaderCallback() = default;

	void setExtraSetter(IShaderUniformSetterRC *setter)
	{
		assert(!m_extra_setter);
		m_extra_setter.grab(setter);
	}

	virtual void OnSetConstants(video::IMaterialRendererServices *services, s32 userData) override
	{
		for (auto &&setter : m_setters)
			setter->onSetUniforms(services);
		if (m_extra_setter)
			m_extra_setter->onSetUniforms(services);
	}

	virtual void OnSetMaterial(const video::SMaterial& material) override
	{
		for (auto &&setter : m_setters)
			setter->onSetMaterial(material);
		if (m_extra_setter)
			m_extra_setter->onSetMaterial(material);
	}
};


/*
	MainShaderConstantSetter: Sets some random general constants
*/

class MainShaderConstantSetter : public IShaderConstantSetter
{
public:
	MainShaderConstantSetter() = default;
	~MainShaderConstantSetter() = default;

	void onGenerate(const std::string &name, ShaderConstants &constants) override
	{
		constants["ENABLE_TONE_MAPPING"] = g_settings->getBool("tone_mapping") ? 1 : 0;

		if (g_settings->getBool("enable_dynamic_shadows")) {
			constants["ENABLE_DYNAMIC_SHADOWS"] = 1;
			if (g_settings->getBool("shadow_map_color"))
				constants["COLORED_SHADOWS"] = 1;

			if (g_settings->getBool("shadow_poisson_filter"))
				constants["POISSON_FILTER"] = 1;

			if (g_settings->getBool("enable_water_reflections"))
				constants["ENABLE_WATER_REFLECTIONS"] = 1;

			if (g_settings->getBool("enable_translucent_foliage"))
				constants["ENABLE_TRANSLUCENT_FOLIAGE"] = 1;

			// FIXME: The node specular effect is currently disabled due to mixed in-game
			// results. This shader should not be applied to all nodes equally. See #15898
			if (false)
				constants["ENABLE_NODE_SPECULAR"] = 1;

			s32 shadow_filter = g_settings->getS32("shadow_filters");
			constants["SHADOW_FILTER"] = shadow_filter;

			float shadow_soft_radius = std::max(1.f,
				g_settings->getFloat("shadow_soft_radius"));
			constants["SOFTSHADOWRADIUS"] = shadow_soft_radius;
		}

		if (g_settings->getBool("enable_bloom")) {
			constants["ENABLE_BLOOM"] = 1;
			if (g_settings->getBool("enable_bloom_debug"))
				constants["ENABLE_BLOOM_DEBUG"] = 1;
		}

		if (g_settings->getBool("enable_auto_exposure"))
			constants["ENABLE_AUTO_EXPOSURE"] = 1;

		if (g_settings->get("antialiasing") == "ssaa") {
			constants["ENABLE_SSAA"] = 1;
			u16 ssaa_scale = std::max<u16>(2, g_settings->getU16("fsaa"));
			constants["SSAA_SCALE"] = (float)ssaa_scale;
		}

		if (g_settings->getBool("debanding"))
			constants["ENABLE_DITHERING"] = 1;

		if (g_settings->getBool("enable_volumetric_lighting"))
			constants["VOLUMETRIC_LIGHT"] = 1;
	}
};


/*
	MainShaderUniformSetter: Set basic uniforms required for almost everything
*/

class MainShaderUniformSetter : public IShaderUniformSetter
{
	using SamplerLayer_t = s32;

	CachedVertexShaderSetting<f32, 16> m_world_view_proj{"mWorldViewProj"};
	CachedVertexShaderSetting<f32, 16> m_world{"mWorld"};

	// Modelview matrix
	CachedVertexShaderSetting<float, 16> m_world_view{"mWorldView"};
	// Texture matrix
	CachedVertexShaderSetting<float, 16> m_texture{"mTexture"};

	CachedPixelShaderSetting<SamplerLayer_t> m_texture0{"texture0"};
	CachedPixelShaderSetting<SamplerLayer_t> m_texture1{"texture1"};
	CachedPixelShaderSetting<SamplerLayer_t> m_texture2{"texture2"};
	CachedPixelShaderSetting<SamplerLayer_t> m_texture3{"texture3"};

	// common material variables passed to shader
	video::SColor m_material_color;
	CachedPixelShaderSetting<float, 4> m_material_color_setting{"materialColor"};

public:
	~MainShaderUniformSetter() = default;

	virtual void onSetMaterial(const video::SMaterial& material) override
	{
		m_material_color = material.ColorParam;
	}

	virtual void onSetUniforms(video::IMaterialRendererServices *services) override
	{
		video::IVideoDriver *driver = services->getVideoDriver();
		assert(driver);

		// Set world matrix
		core::matrix4 world = driver->getTransform(video::ETS_WORLD);
		m_world.set(world, services);

		// Set clip matrix
		core::matrix4 worldView;
		worldView = driver->getTransform(video::ETS_VIEW);
		worldView *= world;

		core::matrix4 worldViewProj;
		worldViewProj = driver->getTransform(video::ETS_PROJECTION);
		worldViewProj *= worldView;
		m_world_view_proj.set(worldViewProj, services);

		if (driver->getDriverType() == video::EDT_OGLES2 || driver->getDriverType() == video::EDT_OPENGL3) {
			auto &texture = driver->getTransform(video::ETS_TEXTURE_0);
			m_world_view.set(worldView, services);
			m_texture.set(texture, services);
		}

		SamplerLayer_t tex_id;
		tex_id = 0;
		m_texture0.set(&tex_id, services);
		tex_id = 1;
		m_texture1.set(&tex_id, services);
		tex_id = 2;
		m_texture2.set(&tex_id, services);
		tex_id = 3;
		m_texture3.set(&tex_id, services);

		video::SColorf colorf(m_material_color);
		m_material_color_setting.set(colorf, services);
	}
};


class MainShaderUniformSetterFactory : public IShaderUniformSetterFactory
{
public:
	virtual IShaderUniformSetter* create(const std::string &name)
		{ return new MainShaderUniformSetter(); }
};


/*
	ShaderSource
*/

class ShaderSource : public IWritableShaderSource
{
public:
	ShaderSource();
	~ShaderSource() override;

	/*
		- If shader material is found from cache, return the cached id.
		- Otherwise generate the shader material, add to cache and return id.

		The id 0 points to a null shader. Its material is EMT_SOLID.
	*/
	u32 getShaderIdDirect(const std::string &name, const ShaderConstants &input_const,
		video::E_MATERIAL_TYPE base_mat, IShaderUniformSetterRC *setter_cb);

	/*
		If shader specified by the name pointed by the id doesn't
		exist, create it, then return id.

		Can be called from any thread. If called from some other thread
		and not found in cache, the call is queued to the main thread
		for processing.
	*/
	u32 getShader(const std::string &name, const ShaderConstants &input_const,
		video::E_MATERIAL_TYPE base_mat,
		IShaderUniformSetterRC *setter_cb = nullptr) override;

	const ShaderInfo &getShaderInfo(u32 id) override;

	// Processes queued shader requests from other threads.
	// Shall be called from the main thread.
	void processQueue() override;

	// Insert a shader program into the cache without touching the
	// filesystem. Shall be called from the main thread.
	void insertSourceShader(const std::string &name_of_shader,
		const std::string &filename, const std::string &program) override;

	// Rebuild shaders from the current set of source shaders
	// Shall be called from the main thread.
	void rebuildShaders() override;

	void addShaderConstantSetter(std::unique_ptr<IShaderConstantSetter> setter) override
	{
		m_constant_setters.emplace_back(std::move(setter));
	}

	void addShaderUniformSetterFactory(std::unique_ptr<IShaderUniformSetterFactory> setter) override
	{
		m_uniform_factories.emplace_back(std::move(setter));
	}

	bool supportsSampler2DArray() const override
	{
		auto *driver = RenderingEngine::get_video_driver();
		if (driver->getDriverType() == video::EDT_OGLES2) {
			// Funnily OpenGL ES 2.0 may support creating array textures
			// with an extension, but to practically use them you need 3.0.
			return m_have_glsl3;
		}
		return m_fully_programmable;
	}

private:

	// The id of the thread that is allowed to use irrlicht directly
	std::thread::id m_main_thread;

	// Driver has fully programmable pipeline?
	bool m_fully_programmable = false;
	// Driver supports GLSL (ES) 3.x?
	bool m_have_glsl3 = false;

	// Cache of source shaders
	// This should be only accessed from the main thread
	SourceShaderCache m_sourcecache;

	// A shader id is index in this array.
	// The first position contains a dummy shader.
	std::vector<ShaderInfo> m_shaderinfo_cache;
	// The former container is behind this mutex
	std::mutex m_shaderinfo_cache_mutex;

#if 0
	// Queued shader fetches (to be processed by the main thread)
	RequestQueue<std::string, u32, u8, u8> m_get_shader_queue;
#endif

	// Global constant setter factories
	std::vector<std::unique_ptr<IShaderConstantSetter>> m_constant_setters;

	// Global uniform setter factories
	std::vector<std::unique_ptr<IShaderUniformSetterFactory>> m_uniform_factories;

	// Generate shader for given input parameters.
	void generateShader(ShaderInfo &info);

	/// @brief outputs a constant to an ostream
	inline void putConstant(std::ostream &os, const ShaderConstants::mapped_type &it)
	{
		if (auto *ival = std::get_if<int>(&it); ival)
			os << *ival;
		else
			os << std::get<float>(it);
	}
};

IWritableShaderSource *createShaderSource()
{
	return new ShaderSource();
}

ShaderSource::ShaderSource()
{
	m_main_thread = std::this_thread::get_id();

	// Add a dummy ShaderInfo as the first index, named ""
	m_shaderinfo_cache.emplace_back();

	// Add global stuff
	addShaderConstantSetter(std::make_unique<MainShaderConstantSetter>());
	addShaderUniformSetterFactory(std::make_unique<MainShaderUniformSetterFactory>());

	auto *driver = RenderingEngine::get_video_driver();
	const auto driver_type = driver->getDriverType();
	if (driver_type != video::EDT_NULL) {
		auto *gpu = driver->getGPUProgrammingServices();
		if (!driver->queryFeature(video::EVDF_ARB_GLSL) || !gpu)
			throw ShaderException(gettext("GLSL is not supported by the driver"));

		v2s32 glver = driver->getLimits().GLVersion;
		infostream << "ShaderSource: driver reports GL version " << glver.X << "."
			<< glver.Y << std::endl;
		assert(glver.X >= 2);
		m_fully_programmable = driver_type != video::EDT_OPENGL;
		if (driver_type == video::EDT_OGLES2) {
			m_have_glsl3 = glver.X >= 3;
		} else if (driver_type == video::EDT_OPENGL3) {
			// future TODO
		}
	}
}

ShaderSource::~ShaderSource()
{
	MutexAutoLock lock(m_shaderinfo_cache_mutex);

	// Delete materials
	auto *gpu = RenderingEngine::get_video_driver()->getGPUProgrammingServices();
	u32 n = 0;
	for (ShaderInfo &i : m_shaderinfo_cache) {
		if (!i.name.empty()) {
			gpu->deleteShaderMaterial(i.material);
			n++;
		}
	}
	m_shaderinfo_cache.clear();

	infostream << "~ShaderSource() cleaned up " << n << " materials" << std::endl;
}

u32 ShaderSource::getShader(const std::string &name,
	const ShaderConstants &input_const, video::E_MATERIAL_TYPE base_mat,
	IShaderUniformSetterRC *setter_cb)
{
	/*
		Get shader
	*/

	if (std::this_thread::get_id() == m_main_thread) {
		return getShaderIdDirect(name, input_const, base_mat, setter_cb);
	}

	errorstream << "ShaderSource::getShader(): getting from "
		"other thread not implemented" << std::endl;

#if 0
	// We're gonna ask the result to be put into here

	static ResultQueue<std::string, u32, u8, u8> result_queue;

	// Throw a request in
	m_get_shader_queue.add(name, 0, 0, &result_queue);

	/* infostream<<"Waiting for shader from main thread, name=\""
			<<name<<"\""<<std::endl;*/

	while(true) {
		GetResult<std::string, u32, u8, u8>
			result = result_queue.pop_frontNoEx();

		if (result.key == name) {
			return result.item;
		}

		errorstream << "Got shader with invalid name: " << result.key << std::endl;
	}

	infostream << "getShader(): Failed" << std::endl;
#endif

	return 0;
}

/*
	This method generates all the shaders
*/
u32 ShaderSource::getShaderIdDirect(const std::string &name,
	const ShaderConstants &input_const, video::E_MATERIAL_TYPE base_mat,
	IShaderUniformSetterRC *setter_cb)
{
	// Empty name means shader 0
	if (name.empty()) {
		infostream<<"getShaderIdDirect(): name is empty"<<std::endl;
		return 0;
	}

	// Check if already have such instance
	for (u32 i = 0; i < m_shaderinfo_cache.size(); i++) {
		auto &info = m_shaderinfo_cache[i];
		if (info.name == name && info.base_material == base_mat &&
			info.input_constants == input_const && info.setter_cb == setter_cb)
			return i;
	}

	// Calling only allowed from main thread
	sanity_check(std::this_thread::get_id() == m_main_thread);

	ShaderInfo info;
	info.name = name;
	info.input_constants = input_const;
	info.base_material = base_mat;
	info.setter_cb.grab(setter_cb);

	generateShader(info);

	/*
		Add shader to caches
	*/

	MutexAutoLock lock(m_shaderinfo_cache_mutex);

	u32 id = m_shaderinfo_cache.size();
	m_shaderinfo_cache.push_back(std::move(info));
	return id;
}


const ShaderInfo &ShaderSource::getShaderInfo(u32 id)
{
	MutexAutoLock lock(m_shaderinfo_cache_mutex);

	if (id >= m_shaderinfo_cache.size()) {
		static ShaderInfo empty;
		return empty;
	}
	return m_shaderinfo_cache[id];
}

void ShaderSource::processQueue()
{


}

void ShaderSource::insertSourceShader(const std::string &name_of_shader,
		const std::string &filename, const std::string &program)
{
	/*infostream<<"ShaderSource::insertSourceShader(): "
			"name_of_shader=\""<<name_of_shader<<"\", "
			"filename=\""<<filename<<"\""<<std::endl;*/

	sanity_check(std::this_thread::get_id() == m_main_thread);

	m_sourcecache.insert(name_of_shader, filename, program, true);
}

void ShaderSource::rebuildShaders()
{
	MutexAutoLock lock(m_shaderinfo_cache_mutex);

	// Delete materials
	auto *gpu = RenderingEngine::get_video_driver()->getGPUProgrammingServices();
	assert(gpu);
	for (ShaderInfo &i : m_shaderinfo_cache) {
		if (!i.name.empty()) {
			gpu->deleteShaderMaterial(i.material);
			i.material = video::EMT_INVALID;
		}
	}

	infostream << "ShaderSource: recreating " << m_shaderinfo_cache.size()
			<< " shaders" << std::endl;

	// Recreate shaders
	for (ShaderInfo &i : m_shaderinfo_cache) {
		if (!i.name.empty()) {
			generateShader(i);
		}
	}
}


void ShaderSource::generateShader(ShaderInfo &shaderinfo)
{
	const auto &name = shaderinfo.name;
	const auto &input_const = shaderinfo.input_constants;

	// fixed pipeline materials don't make sense here
	assert(shaderinfo.base_material != video::EMT_TRANSPARENT_VERTEX_ALPHA &&
		shaderinfo.base_material != video::EMT_ONETEXTURE_BLEND);

	auto *driver = RenderingEngine::get_video_driver();
	// The null driver doesn't support shaders (duh), but we can pretend it does.
	if (driver->getDriverType() == video::EDT_NULL) {
		shaderinfo.material = shaderinfo.base_material;
		return;
	}

	auto *gpu = driver->getGPUProgrammingServices();
	assert(gpu);

	// Create shaders header
	std::ostringstream shaders_header;
	shaders_header
		<< std::noboolalpha
		<< std::showpoint // for GLSL ES
		;
	std::string vertex_header, fragment_header, geometry_header;
	if (m_fully_programmable) {
		const bool use_glsl3 = m_have_glsl3;
		if (driver->getDriverType() == video::EDT_OPENGL3) {
			assert(!use_glsl3);
			shaders_header << "#version 150\n"
				<< "#define CENTROID_ centroid\n";
		} else if (driver->getDriverType() == video::EDT_OGLES2) {
			if (use_glsl3) {
				shaders_header << "#version 300 es\n"
					<< "#define CENTROID_ centroid\n";
			} else {
				shaders_header << "#version 100\n"
					<< "#define CENTROID_\n";
			}
			// Precision is only meaningful on GLES
			shaders_header << "precision mediump float;\n"
				"precision mediump sampler2D;\n";
		} else {
			assert(false);
		}
		if (use_glsl3) {
			shaders_header << "#define ATTRIBUTE_(n) layout(location = n) in\n"
				"#define texture2D texture\n";
		} else {
			shaders_header << "#define ATTRIBUTE_(n) attribute\n";
		}

		// cf. EVertexAttributes.h for the predefined ones
		vertex_header = R"(
			uniform highp mat4 mWorldView;
			uniform highp mat4 mWorldViewProj;
			uniform mediump mat4 mTexture;

			ATTRIBUTE_(0) highp vec4 inVertexPosition;
			ATTRIBUTE_(1) mediump vec3 inVertexNormal;
			ATTRIBUTE_(2) lowp vec4 inVertexColor;
			ATTRIBUTE_(3) mediump float inVertexAux;
			ATTRIBUTE_(4) mediump vec2 inTexCoord0;
			ATTRIBUTE_(5) mediump vec2 inTexCoord1;
			ATTRIBUTE_(6) mediump vec4 inVertexTangent;
			ATTRIBUTE_(7) mediump vec4 inVertexBinormal;
		)";
		if (use_glsl3) {
			vertex_header += "#define VARYING_ out\n";
		} else {
			vertex_header += "#define VARYING_ varying\n";
		}
		// Our vertex color has components reversed compared to what OpenGL
		// normally expects, so we need to take that into account.
		vertex_header += "#define inVertexColor (inVertexColor.bgra)\n";

		fragment_header = "";
		if (use_glsl3) {
			fragment_header += "#define VARYING_ in\n"
				"#define gl_FragColor outFragColor\n"
				"layout(location = 0) out vec4 outFragColor;\n";
		} else {
			fragment_header += "#define VARYING_ varying\n";
		}
	} else {
		/* legacy OpenGL driver */
		shaders_header << R"(
			#version 120
			#define lowp
			#define mediump
			#define highp
		)";
		vertex_header = R"(
			#define mWorldView gl_ModelViewMatrix
			#define mWorldViewProj gl_ModelViewProjectionMatrix
			#define mTexture (gl_TextureMatrix[0])

			#define inVertexPosition gl_Vertex
			#define inVertexColor gl_Color
			#define inTexCoord0 gl_MultiTexCoord0
			#define inVertexNormal gl_Normal
			#define inVertexTangent gl_MultiTexCoord1
			#define inVertexBinormal gl_MultiTexCoord2

			#define VARYING_ varying
			#define CENTROID_ centroid
		)";
		fragment_header = R"(
			#define VARYING_ varying
			#define CENTROID_ centroid
		)";
	}

	// legacy semantic texture name
	fragment_header += "#define baseTexture texture0\n";

	/// Unique name of this shader, for debug/logging
	std::string log_name = name;
	for (auto &it : input_const) {
		if (log_name.size() > 60) { // it shouldn't be too long
			log_name.append("...");
			break;
		}
		std::ostringstream oss;
		putConstant(oss, it.second);
		log_name.append(" ").append(it.first).append("=").append(oss.str());
	}

	ShaderConstants constants = input_const;

	bool use_discard = m_fully_programmable;
	if (!use_discard) {
		// workaround for a certain OpenGL implementation lacking GL_ALPHA_TEST
		const char *renderer = reinterpret_cast<const char*>(GL.GetString(GL.RENDERER));
		if (strstr(renderer, "GC7000"))
			use_discard = true;
	}
	if (use_discard) {
		if (shaderinfo.base_material == video::EMT_TRANSPARENT_ALPHA_CHANNEL)
			constants["USE_DISCARD"] = 1;
		else if (shaderinfo.base_material == video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF)
			constants["USE_DISCARD_REF"] = 1;
	}

	/* Let the constant setters do their job and emit constants */
	for (auto &setter : m_constant_setters) {
		setter->onGenerate(name, constants);
	}

	for (auto &it : constants) {
		// spaces could cause duplicates
		assert(trim(it.first) == it.first);
		shaders_header << "#define " << it.first << ' ';
		putConstant(shaders_header, it.second);
		shaders_header << '\n';
	}

	std::string common_header = shaders_header.str();
	const char *final_header = "#line 0\n"; // reset the line counter for meaningful diagnostics

	std::string vertex_shader = m_sourcecache.getOrLoad(name, "opengl_vertex.glsl");
	std::string fragment_shader = m_sourcecache.getOrLoad(name, "opengl_fragment.glsl");
	std::string geometry_shader = m_sourcecache.getOrLoad(name, "opengl_geometry.glsl");

	if (vertex_shader.empty() || fragment_shader.empty()) {
		throw ShaderException(fmtgettext("Failed to find \"%s\" shader files.", name.c_str()));
	}

	vertex_shader = common_header + vertex_header + final_header + vertex_shader;
	fragment_shader = common_header + fragment_header + final_header + fragment_shader;
	const char *geometry_shader_ptr = nullptr; // optional
	if (!geometry_shader.empty()) {
		geometry_shader = common_header + geometry_header + final_header + geometry_shader;
		geometry_shader_ptr = geometry_shader.c_str();
	}

	auto cb = make_irr<ShaderCallback>(name, m_uniform_factories);
	cb->setExtraSetter(shaderinfo.setter_cb.get());

	infostream << "Compiling high level shaders for " << log_name << std::endl;
	s32 shadermat = gpu->addHighLevelShaderMaterial(
		vertex_shader.c_str(), fragment_shader.c_str(), geometry_shader_ptr,
		log_name.c_str(), scene::EPT_TRIANGLES, scene::EPT_TRIANGLES, 0,
		cb.get(), shaderinfo.base_material);
	if (shadermat == -1) {
		errorstream << "generateShader(): failed to generate shaders for "
			<< log_name << ", addHighLevelShaderMaterial failed." << std::endl;
		dumpShaderProgram(warningstream, "vertex", vertex_shader);
		dumpShaderProgram(warningstream, "fragment", fragment_shader);
		if (geometry_shader_ptr)
			dumpShaderProgram(warningstream, "geometry", geometry_shader);
		throw ShaderException(
			fmtgettext("Failed to compile the \"%s\" shader.", log_name.c_str()) +
			strgettext("\nCheck debug.txt for details."));
	}

	// Apply the newly created material type
	shaderinfo.material = (video::E_MATERIAL_TYPE) shadermat;
}

/*
	Other functions and helpers
*/

u32 IShaderSource::getShader(const std::string &name,
	MaterialType material_type, NodeDrawType drawtype, bool array_texture)
{
	ShaderConstants input_const;
	input_const["MATERIAL_TYPE"] = (int)material_type;
	(void) drawtype; // unused
	if (array_texture)
		input_const["USE_ARRAY_TEXTURE"] = 1;

	video::E_MATERIAL_TYPE base_mat = video::EMT_SOLID;
	switch (material_type) {
		case TILE_MATERIAL_ALPHA:
		case TILE_MATERIAL_PLAIN_ALPHA:
		case TILE_MATERIAL_LIQUID_TRANSPARENT:
		case TILE_MATERIAL_WAVING_LIQUID_TRANSPARENT:
			base_mat = video::EMT_TRANSPARENT_ALPHA_CHANNEL;
			break;
		case TILE_MATERIAL_BASIC:
		case TILE_MATERIAL_PLAIN:
		case TILE_MATERIAL_WAVING_LEAVES:
		case TILE_MATERIAL_WAVING_PLANTS:
		case TILE_MATERIAL_WAVING_LIQUID_BASIC:
			base_mat = video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
			break;
		default:
			break;
	}

	return getShader(name, input_const, base_mat);
}

void dumpShaderProgram(std::ostream &os,
		const std::string &program_type, std::string_view program)
{
	os << program_type << " shader program:\n"
		"----------------------------------" << '\n';
	size_t pos = 0, prev = 0;
	int nline = 1;
	while ((pos = program.find('\n', prev)) != std::string::npos) {
		auto line = program.substr(prev, pos - prev);
		// Be smart about line number reset
		if (trim(line) == "#line 0")
			nline = 0;
		os << (nline++) << ": " << line << '\n';
		prev = pos + 1;
	}
	os << nline << ": " << program.substr(prev) << '\n' <<
		"End of " << program_type << " shader program.\n \n" << std::flush;
}