#include <cmath>
#include <string>

#include "boost/range/algorithm/fill.hpp"

#include "common/assert.h"
#include "common/alignment.h"
#include "common/bit_field.h"
#include "common/common_funcs.h"
#include "common/common_types.h"
#include "common/logging/log.h"

#include "core/memory.h"

#include "debug_utils/debug_utils.h"

#include "pica.h"
#include "pica_state.h"
#include "pica_types.h"
#include "vertex_loader.h"

namespace Pica {

void VertexLoader::Setup(const Pica::Regs &regs) {
    const auto& attribute_config = regs.vertex_attributes;
    base_address = attribute_config.GetPhysicalBaseAddress();
    num_total_attributes = attribute_config.GetNumTotalAttributes();

    boost::fill(vertex_attribute_sources, 0xdeadbeef);

    for (int i = 0; i < 16; i++) {
        vertex_attribute_is_default[i] = attribute_config.IsDefaultAttribute(i);
    }

    // Setup attribute data from loaders
    for (int loader = 0; loader < 12; ++loader) {
        const auto& loader_config = attribute_config.attribute_loaders[loader];

        u32 offset = 0;

        // TODO: What happens if a loader overwrites a previous one's data?
        for (unsigned component = 0; component < loader_config.component_count; ++component) {
            if (component >= 12) {
                LOG_ERROR(HW_GPU, "Overflow in the vertex attribute loader %u trying to load component %u", loader, component);
                continue;
            }

            u32 attribute_index = loader_config.GetComponent(component);
            if (attribute_index < 12) {
                int element_size = attribute_config.GetElementSizeInBytes(attribute_index);
                offset = Common::AlignUp(offset, element_size);
                vertex_attribute_sources[attribute_index] = base_address + loader_config.data_offset + offset;
                vertex_attribute_strides[attribute_index] = static_cast<u32>(loader_config.byte_count);
                vertex_attribute_formats[attribute_index] = attribute_config.GetFormat(attribute_index);
                vertex_attribute_elements[attribute_index] = attribute_config.GetNumElements(attribute_index);
                vertex_attribute_element_size[attribute_index] = element_size;
                offset += attribute_config.GetStride(attribute_index);
            } else if (attribute_index < 16) {
                // Attribute ids 12, 13, 14 and 15 signify 4, 8, 12 and 16-byte paddings, respectively
                offset = Common::AlignUp(offset, 4);
                offset += (attribute_index - 11) * 4;
            } else {
                UNREACHABLE(); // This is truly unreachable due to the number of bits for each component
            }
        }
    }
}

void VertexLoader::LoadVertex(int index, int vertex, Shader::InputVertex &input, MemoryAccesses &memory_accesses) {
    for (int i = 0; i < num_total_attributes; ++i) {
        if (vertex_attribute_elements[i] != 0) {
            // Default attribute values set if array elements have < 4 components. This
            // is *not* carried over from the default attribute settings even if they're
            // enabled for this attribute.
            static const float24 zero = float24::FromFloat32(0.0f);
            static const float24 one = float24::FromFloat32(1.0f);
            input.attr[i] = Math::Vec4<float24>(zero, zero, zero, one);

            // Load per-vertex data from the loader arrays
            for (unsigned int comp = 0; comp < vertex_attribute_elements[i]; ++comp) {
                u32 source_addr = vertex_attribute_sources[i] + vertex_attribute_strides[i] * vertex + comp * vertex_attribute_element_size[i];
                const u8* srcdata = Memory::GetPhysicalPointer(source_addr);

                if (g_debug_context && Pica::g_debug_context->recorder) {
                    memory_accesses.AddAccess(source_addr,
                        (vertex_attribute_formats[i] == Regs::VertexAttributeFormat::FLOAT) ? 4
                        : (vertex_attribute_formats[i] == Regs::VertexAttributeFormat::SHORT) ? 2 : 1);
                }

                const float srcval =
                    (vertex_attribute_formats[i] == Regs::VertexAttributeFormat::BYTE) ? *reinterpret_cast<const s8*>(srcdata) :
                    (vertex_attribute_formats[i] == Regs::VertexAttributeFormat::UBYTE) ? *reinterpret_cast<const u8*>(srcdata) :
                    (vertex_attribute_formats[i] == Regs::VertexAttributeFormat::SHORT) ? *reinterpret_cast<const s16*>(srcdata) :
                    *reinterpret_cast<const float*>(srcdata);

                input.attr[i][comp] = float24::FromFloat32(srcval);
                LOG_TRACE(HW_GPU, "Loaded component %x of attribute %x for vertex %x (index %x) from 0x%08x + 0x%08x + 0x%04x: %f",
                    comp, i, vertex, index,
                    base_address,
                    vertex_attribute_sources[i] - base_address,
                    vertex_attribute_strides[i] * vertex + comp * vertex_attribute_element_size[i],
                    input.attr[i][comp].ToFloat32());
            }
        } else if (vertex_attribute_is_default[i]) {
            // Load the default attribute if we're configured to do so
            input.attr[i] = g_state.vs.default_attributes[i];
            LOG_TRACE(HW_GPU, "Loaded default attribute %x for vertex %x (index %x): (%f, %f, %f, %f)",
                i, vertex, index,
                input.attr[i][0].ToFloat32(), input.attr[i][1].ToFloat32(),
                input.attr[i][2].ToFloat32(), input.attr[i][3].ToFloat32());
        } else {
            // TODO(yuriks): In this case, no data gets loaded and the vertex
            // remains with the last value it had. This isn't currently maintained
            // as global state, however, and so won't work in Citra yet.
        }
    }
}

}  // namespace Pica