#include "graphics/shader/recompiler/BindingLayout.h"

#include "graphics/shader/recompiler/ScalarProvenance.h"

#include <algorithm>
#include <array>
#include <set>
#include <utility>

namespace Libs::Graphics::ShaderRecompiler::IR {
namespace {

constexpr uint32_t MaxPushConstantBytes = 128;

constexpr std::array ImageBindingKinds = {
    DescriptorBindingKind::Sampled2D,          DescriptorBindingKind::Sampled2DArray,
    DescriptorBindingKind::Sampled3D,          DescriptorBindingKind::SampledUint2D,
    DescriptorBindingKind::SampledUint2DArray, DescriptorBindingKind::SampledUint3D,
    DescriptorBindingKind::Storage2D,          DescriptorBindingKind::Storage2DArray,
    DescriptorBindingKind::Storage3D,          DescriptorBindingKind::StorageUint2D,
    DescriptorBindingKind::StorageUint2DArray, DescriptorBindingKind::StorageUint3D,
};

bool ImageBinding(const ImageResource& image, DescriptorBindingKind& result) {
	using Dimension = Decoder::ImageDimension;
	using Kind      = DescriptorBindingKind;

	switch (image.kind) {
		case ResourceKind::Image:
			switch (image.dimension) {
				case Dimension::Dim2D: result = Kind::Sampled2D; return true;
				case Dimension::Dim2DArray: result = Kind::Sampled2DArray; return true;
				case Dimension::Dim3D: result = Kind::Sampled3D; return true;
				default: return false;
			}
		case ResourceKind::ImageUint:
			switch (image.dimension) {
				case Dimension::Dim2D: result = Kind::SampledUint2D; return true;
				case Dimension::Dim2DArray: result = Kind::SampledUint2DArray; return true;
				case Dimension::Dim3D: result = Kind::SampledUint3D; return true;
				default: return false;
			}
		case ResourceKind::StorageImage:
			switch (image.dimension) {
				case Dimension::Dim2D: result = Kind::Storage2D; return true;
				case Dimension::Dim2DArray: result = Kind::Storage2DArray; return true;
				case Dimension::Dim3D: result = Kind::Storage3D; return true;
				default: return false;
			}
		case ResourceKind::StorageImageUint:
			switch (image.dimension) {
				case Dimension::Dim2D: result = Kind::StorageUint2D; return true;
				case Dimension::Dim2DArray: result = Kind::StorageUint2DArray; return true;
				case Dimension::Dim3D: result = Kind::StorageUint3D; return true;
				default: return false;
			}
		default: return false;
	}
}

bool CollectValue(const ScalarProvenance& provenance, uint32_t id, std::vector<uint8_t>* visited,
                  std::set<uint32_t>* registers) {
	if (id <= ScalarProvenance::Unknown) {
		return true;
	}
	if (id >= provenance.values.size()) {
		return false;
	}
	if ((*visited)[id] != 0) {
		return true;
	}
	(*visited)[id]    = 1;
	const auto& value = provenance.values[id];
	if (value.op == ScalarValueOp::UserData) {
		registers->insert(value.imm);
		return true;
	}
	if (value.op == ScalarValueOp::Phi) {
		for (const auto arg: value.phi_args) {
			if (!CollectValue(provenance, arg, visited, registers)) {
				return false;
			}
		}
		return true;
	}
	for (uint32_t i = 0; i < ScalarValueArgCount(value.op); i++) {
		if (!CollectValue(provenance, value.args[i], visited, registers)) {
			return false;
		}
	}
	return true;
}

bool CollectSource(const Program& program, uint32_t source, bool allow_unknown,
                   std::vector<uint8_t>* visited, std::set<uint32_t>* registers) {
	if (allow_unknown && source == ScalarProvenance::Unknown) {
		return true;
	}
	if (source < 2u || source - 2u >= program.provenance.descriptors.size()) {
		return false;
	}
	const auto& descriptor = program.provenance.descriptors[source - 2u];
	for (uint32_t i = 0; i < descriptor.dword_count; i++) {
		if (!CollectValue(program.provenance, descriptor.dwords[i], visited, registers)) {
			return false;
		}
	}
	return true;
}

bool CollectUserData(const Program& program, std::vector<uint32_t>& result) {
	std::set<uint32_t>   registers;
	std::vector<uint8_t> visited(program.provenance.values.size());
	for (const auto& buffer: program.info.buffers) {
		if (!CollectSource(program, buffer.source, false, &visited, &registers)) {
			return false;
		}
	}
	for (const auto& image: program.info.images) {
		if (!CollectSource(program, image.source, false, &visited, &registers)) {
			return false;
		}
	}
	for (const auto& sampler: program.info.samplers) {
		if (!CollectSource(program, sampler.source, false, &visited, &registers)) {
			return false;
		}
	}
	for (const auto& address: program.info.addresses) {
		if (!CollectSource(program, address.source, true, &visited, &registers)) {
			return false;
		}
	}
	for (const auto& read: program.srt.reads) {
		if (!CollectValue(program.provenance, read.value, &visited, &registers)) {
			return false;
		}
	}
	for (const auto read: program.srt.dynamic_reads) {
		if (!CollectValue(program.provenance, read, &visited, &registers)) {
			return false;
		}
	}
	for (const auto source: program.srt.dynamic_sources) {
		if (!CollectSource(program, source, true, &visited, &registers)) {
			return false;
		}
	}
	for (const auto& block: program.blocks) {
		for (const auto& inst: block.instructions) {
			if (inst.op == Opcode::SLoadDword && inst.memory.kind == ResourceKind::ScalarBuffer &&
			    !CollectValue(program.provenance, inst.scalar_value, &visited, &registers)) {
				return false;
			}
			for (uint32_t i = 0; i < inst.src_count; i++) {
				if (!CollectValue(program.provenance, inst.scalar_sources[i], &visited,
				                  &registers)) {
					return false;
				}
			}
		}
	}
	result.assign(registers.begin(), registers.end());
	return true;
}

void AddBinding(BindingLayout* layout, DescriptorBindingKind kind,
                std::vector<uint32_t> resources = {}) {
	layout->descriptors.push_back(
	    {kind, static_cast<uint32_t>(layout->descriptors.size()), std::move(resources)});
}

bool UsesGds(const Program& program) {
	for (const auto& block: program.blocks) {
		for (const auto& inst: block.instructions) {
			if (inst.memory.kind == ResourceKind::Gds) {
				return true;
			}
		}
	}
	return false;
}

} // namespace

bool AllocateBindings(Program* program, const BindingLayoutOptions& options, std::string* error) {
	if (program == nullptr || !program->shader_info_complete || program->binding_layout_complete) {
		if (error != nullptr) {
			*error = program == nullptr               ? "invalid binding-layout program"
			         : !program->shader_info_complete ? "shader info is not ready"
			                                          : "binding layout already allocated";
		}
		return false;
	}
	if (options.push_constant_offset > MaxPushConstantBytes) {
		if (error != nullptr) {
			*error = "push-constant offset exceeds the Vulkan minimum guarantee";
		}
		return false;
	}
	if (options.push_constant_offset % 4u != 0) {
		if (error != nullptr) {
			*error = "push-constant offset is not dword aligned";
		}
		return false;
	}

	BindingLayout next;
	next.descriptor_set       = options.descriptor_set;
	next.push_constant_offset = options.push_constant_offset;
	if (!CollectUserData(*program, next.user_data_registers)) {
		if (error != nullptr) {
			*error = "shader plan contains an invalid scalar provenance reference";
		}
		return false;
	}

	if (!program->info.buffers.empty()) {
		std::vector<uint32_t> resources(program->info.buffers.size());
		for (uint32_t i = 0; i < resources.size(); i++) {
			resources[i] = i;
		}
		AddBinding(&next, DescriptorBindingKind::Buffers, std::move(resources));
	}

	std::array<std::vector<uint32_t>, ImageBindingKinds.size()> image_groups;
	for (uint32_t i = 0; i < program->info.images.size(); i++) {
		DescriptorBindingKind kind;
		if (!ImageBinding(program->info.images[i], kind)) {
			if (error != nullptr) {
				*error = "shader info contains an invalid image binding class";
			}
			return false;
		}
		const auto group = std::find(ImageBindingKinds.begin(), ImageBindingKinds.end(), kind);
		if (group == ImageBindingKinds.end()) {
			if (error != nullptr) {
				*error = "shader info contains an unmapped image binding class";
			}
			return false;
		}
		image_groups[static_cast<size_t>(group - ImageBindingKinds.begin())].push_back(i);
	}
	for (uint32_t i = 0; i < image_groups.size(); i++) {
		if (!image_groups[i].empty()) {
			AddBinding(&next, ImageBindingKinds[i], std::move(image_groups[i]));
		}
	}

	if (!program->info.samplers.empty()) {
		std::vector<uint32_t> resources(program->info.samplers.size());
		for (uint32_t i = 0; i < resources.size(); i++) {
			resources[i] = i;
		}
		AddBinding(&next, DescriptorBindingKind::Samplers, std::move(resources));
	}
	if (UsesGds(*program)) {
		AddBinding(&next, DescriptorBindingKind::Gds);
	}
	if (!program->info.addresses.empty()) {
		std::vector<uint32_t> resources(program->info.addresses.size());
		for (uint32_t i = 0; i < resources.size(); i++) {
			resources[i] = i;
		}
		AddBinding(&next, DescriptorBindingKind::AddressMemory, std::move(resources));
	}
	if (!program->srt.reads.empty()) {
		AddBinding(&next, DescriptorBindingKind::FlattenedSrt);
	}

	const auto available_push_dwords = (MaxPushConstantBytes - options.push_constant_offset) / 4u;
	const auto push_limit            = std::min(options.max_push_dwords, available_push_dwords);
	if (next.user_data_registers.size() <= push_limit) {
		next.push_constant_size = static_cast<uint32_t>(next.user_data_registers.size() * 4u);
	} else {
		AddBinding(&next, DescriptorBindingKind::UserData);
	}

	program->bindings                = std::move(next);
	program->binding_layout_complete = true;
	return true;
}

const DescriptorBinding* FindBinding(const BindingLayout& layout, DescriptorBindingKind kind) {
	for (const auto& binding: layout.descriptors) {
		if (binding.kind == kind) {
			return &binding;
		}
	}
	return nullptr;
}

} // namespace Libs::Graphics::ShaderRecompiler::IR