// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <cstring>
#include <numeric>
#include <type_traits>
#include "common/color.h"
#include "common/common_types.h"
#include "common/logging/log.h"
#include "common/math_util.h"
#include "common/microprofile.h"
#include "common/thread.h"
#include "common/timer.h"
#include "common/vector_math.h"
#include "core/core_timing.h"
#include "core/hle/service/gsp_gpu.h"
#include "core/hle/service/hid/hid.h"
#include "core/hw/gpu.h"
#include "core/hw/hw.h"
#include "core/memory.h"
#include "core/settings.h"
#include "core/tracer/recorder.h"
#include "video_core/command_processor.h"
#include "video_core/debug_utils/debug_utils.h"
#include "video_core/rasterizer_interface.h"
#include "video_core/renderer_base.h"
#include "video_core/utils.h"
#include "video_core/video_core.h"

namespace GPU {

Regs g_regs;

/// 268MHz CPU clocks / 60Hz frames per second
const u64 frame_ticks = 268123480ull / 60;
/// Event id for CoreTiming
static int vblank_event;
/// Total number of frames drawn
static u64 frame_count;
/// Start clock for frame limiter
static u32 time_point;
/// Total delay caused by slow frames
static float time_delay;
constexpr float FIXED_FRAME_TIME = 1000.0f / 60;
// Max lag caused by slow frames. Can be adjusted to compensate for too many slow frames. Higher
// values increases time needed to limit frame rate after spikes
constexpr float MAX_LAG_TIME = 18;

template <typename T>
inline void Read(T& var, const u32 raw_addr) {
    u32 addr = raw_addr - HW::VADDR_GPU;
    u32 index = addr / 4;

    // Reads other than u32 are untested, so I'd rather have them abort than silently fail
    if (index >= Regs::NumIds() || !std::is_same<T, u32>::value) {
        LOG_ERROR(HW_GPU, "unknown Read%lu @ 0x%08X", sizeof(var) * 8, addr);
        return;
    }

    var = g_regs[addr / 4];
}

static Math::Vec4<u8> DecodePixel(Regs::PixelFormat input_format, const u8* src_pixel) {
    switch (input_format) {
    case Regs::PixelFormat::RGBA8:
        return Color::DecodeRGBA8(src_pixel);

    case Regs::PixelFormat::RGB8:
        return Color::DecodeRGB8(src_pixel);

    case Regs::PixelFormat::RGB565:
        return Color::DecodeRGB565(src_pixel);

    case Regs::PixelFormat::RGB5A1:
        return Color::DecodeRGB5A1(src_pixel);

    case Regs::PixelFormat::RGBA4:
        return Color::DecodeRGBA4(src_pixel);

    default:
        LOG_ERROR(HW_GPU, "Unknown source framebuffer format %x", input_format);
        return {0, 0, 0, 0};
    }
}

MICROPROFILE_DEFINE(GPU_DisplayTransfer, "GPU", "DisplayTransfer", MP_RGB(100, 100, 255));
MICROPROFILE_DEFINE(GPU_CmdlistProcessing, "GPU", "Cmdlist Processing", MP_RGB(100, 255, 100));

static void MemoryFill(const Regs::MemoryFillConfig& config) {
    const PAddr start_addr = config.GetStartAddress();
    const PAddr end_addr = config.GetEndAddress();

    // TODO: do hwtest with these cases
    if (!Memory::IsValidPhysicalAddress(start_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid start address 0x%08X", start_addr);
        return;
    }

    if (!Memory::IsValidPhysicalAddress(end_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid end address 0x%08X", end_addr);
        return;
    }

    if (end_addr <= start_addr) {
        LOG_CRITICAL(HW_GPU, "invalid memory range from 0x%08X to 0x%08X", start_addr, end_addr);
        return;
    }

    u8* start = Memory::GetPhysicalPointer(start_addr);
    u8* end = Memory::GetPhysicalPointer(end_addr);

    // TODO: Consider always accelerating and returning vector of
    //       regions that the accelerated fill did not cover to
    //       reduce/eliminate the fill that the cpu has to do.
    //       This would also mean that the flush below is not needed.
    //       Fill should first flush all surfaces that touch but are
    //       not completely within the fill range.
    //       Then fill all completely covered surfaces, and return the
    //       regions that were between surfaces or within the touching
    //       ones for cpu to manually fill here.
    if (VideoCore::g_renderer->Rasterizer()->AccelerateFill(config))
        return;

    Memory::RasterizerFlushAndInvalidateRegion(config.GetStartAddress(),
                                               config.GetEndAddress() - config.GetStartAddress());

    if (config.fill_24bit) {
        // fill with 24-bit values
        for (u8* ptr = start; ptr < end; ptr += 3) {
            ptr[0] = config.value_24bit_r;
            ptr[1] = config.value_24bit_g;
            ptr[2] = config.value_24bit_b;
        }
    } else if (config.fill_32bit) {
        // fill with 32-bit values
        if (end > start) {
            u32 value = config.value_32bit;
            size_t len = (end - start) / sizeof(u32);
            for (size_t i = 0; i < len; ++i)
                memcpy(&start[i * sizeof(u32)], &value, sizeof(u32));
        }
    } else {
        // fill with 16-bit values
        u16 value_16bit = config.value_16bit.Value();
        for (u8* ptr = start; ptr < end; ptr += sizeof(u16))
            memcpy(ptr, &value_16bit, sizeof(u16));
    }
}

static void DisplayTransfer(const Regs::DisplayTransferConfig& config) {
    const PAddr src_addr = config.GetPhysicalInputAddress();
    const PAddr dst_addr = config.GetPhysicalOutputAddress();

    // TODO: do hwtest with these cases
    if (!Memory::IsValidPhysicalAddress(src_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid input address 0x%08X", src_addr);
        return;
    }

    if (!Memory::IsValidPhysicalAddress(dst_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid output address 0x%08X", dst_addr);
        return;
    }

    if (config.input_width == 0) {
        LOG_CRITICAL(HW_GPU, "zero input width");
        return;
    }

    if (config.input_height == 0) {
        LOG_CRITICAL(HW_GPU, "zero input height");
        return;
    }

    if (config.output_width == 0) {
        LOG_CRITICAL(HW_GPU, "zero output width");
        return;
    }

    if (config.output_height == 0) {
        LOG_CRITICAL(HW_GPU, "zero output height");
        return;
    }

    if (VideoCore::g_renderer->Rasterizer()->AccelerateDisplayTransfer(config))
        return;

    u8* src_pointer = Memory::GetPhysicalPointer(src_addr);
    u8* dst_pointer = Memory::GetPhysicalPointer(dst_addr);

    if (config.scaling > config.ScaleXY) {
        LOG_CRITICAL(HW_GPU, "Unimplemented display transfer scaling mode %u",
                     config.scaling.Value());
        UNIMPLEMENTED();
        return;
    }

    if (config.input_linear && config.scaling != config.NoScale) {
        LOG_CRITICAL(HW_GPU, "Scaling is only implemented on tiled input");
        UNIMPLEMENTED();
        return;
    }

    int horizontal_scale = config.scaling != config.NoScale ? 1 : 0;
    int vertical_scale = config.scaling == config.ScaleXY ? 1 : 0;

    u32 output_width = config.output_width >> horizontal_scale;
    u32 output_height = config.output_height >> vertical_scale;

    u32 input_size =
        config.input_width * config.input_height * GPU::Regs::BytesPerPixel(config.input_format);
    u32 output_size = output_width * output_height * GPU::Regs::BytesPerPixel(config.output_format);

    Memory::RasterizerFlushRegion(config.GetPhysicalInputAddress(), input_size);
    Memory::RasterizerFlushAndInvalidateRegion(config.GetPhysicalOutputAddress(), output_size);

    for (u32 y = 0; y < output_height; ++y) {
        for (u32 x = 0; x < output_width; ++x) {
            Math::Vec4<u8> src_color;

            // Calculate the [x,y] position of the input image
            // based on the current output position and the scale
            u32 input_x = x << horizontal_scale;
            u32 input_y = y << vertical_scale;

            u32 output_y;
            if (config.flip_vertically) {
                // Flip the y value of the output data,
                // we do this after calculating the [x,y] position of the input image
                // to account for the scaling options.
                output_y = output_height - y - 1;
            } else {
                output_y = y;
            }

            u32 dst_bytes_per_pixel = GPU::Regs::BytesPerPixel(config.output_format);
            u32 src_bytes_per_pixel = GPU::Regs::BytesPerPixel(config.input_format);
            u32 src_offset;
            u32 dst_offset;

            if (config.input_linear) {
                if (!config.dont_swizzle) {
                    // Interpret the input as linear and the output as tiled
                    u32 coarse_y = output_y & ~7;
                    u32 stride = output_width * dst_bytes_per_pixel;

                    src_offset = (input_x + input_y * config.input_width) * src_bytes_per_pixel;
                    dst_offset = VideoCore::GetMortonOffset(x, output_y, dst_bytes_per_pixel) +
                                 coarse_y * stride;
                } else {
                    // Both input and output are linear
                    src_offset = (input_x + input_y * config.input_width) * src_bytes_per_pixel;
                    dst_offset = (x + output_y * output_width) * dst_bytes_per_pixel;
                }
            } else {
                if (!config.dont_swizzle) {
                    // Interpret the input as tiled and the output as linear
                    u32 coarse_y = input_y & ~7;
                    u32 stride = config.input_width * src_bytes_per_pixel;

                    src_offset = VideoCore::GetMortonOffset(input_x, input_y, src_bytes_per_pixel) +
                                 coarse_y * stride;
                    dst_offset = (x + output_y * output_width) * dst_bytes_per_pixel;
                } else {
                    // Both input and output are tiled
                    u32 out_coarse_y = output_y & ~7;
                    u32 out_stride = output_width * dst_bytes_per_pixel;

                    u32 in_coarse_y = input_y & ~7;
                    u32 in_stride = config.input_width * src_bytes_per_pixel;

                    src_offset = VideoCore::GetMortonOffset(input_x, input_y, src_bytes_per_pixel) +
                                 in_coarse_y * in_stride;
                    dst_offset = VideoCore::GetMortonOffset(x, output_y, dst_bytes_per_pixel) +
                                 out_coarse_y * out_stride;
                }
            }

            const u8* src_pixel = src_pointer + src_offset;
            src_color = DecodePixel(config.input_format, src_pixel);
            if (config.scaling == config.ScaleX) {
                Math::Vec4<u8> pixel =
                    DecodePixel(config.input_format, src_pixel + src_bytes_per_pixel);
                src_color = ((src_color + pixel) / 2).Cast<u8>();
            } else if (config.scaling == config.ScaleXY) {
                Math::Vec4<u8> pixel1 =
                    DecodePixel(config.input_format, src_pixel + 1 * src_bytes_per_pixel);
                Math::Vec4<u8> pixel2 =
                    DecodePixel(config.input_format, src_pixel + 2 * src_bytes_per_pixel);
                Math::Vec4<u8> pixel3 =
                    DecodePixel(config.input_format, src_pixel + 3 * src_bytes_per_pixel);
                src_color = (((src_color + pixel1) + (pixel2 + pixel3)) / 4).Cast<u8>();
            }

            u8* dst_pixel = dst_pointer + dst_offset;
            switch (config.output_format) {
            case Regs::PixelFormat::RGBA8:
                Color::EncodeRGBA8(src_color, dst_pixel);
                break;

            case Regs::PixelFormat::RGB8:
                Color::EncodeRGB8(src_color, dst_pixel);
                break;

            case Regs::PixelFormat::RGB565:
                Color::EncodeRGB565(src_color, dst_pixel);
                break;

            case Regs::PixelFormat::RGB5A1:
                Color::EncodeRGB5A1(src_color, dst_pixel);
                break;

            case Regs::PixelFormat::RGBA4:
                Color::EncodeRGBA4(src_color, dst_pixel);
                break;

            default:
                LOG_ERROR(HW_GPU, "Unknown destination framebuffer format %x",
                          config.output_format.Value());
                break;
            }
        }
    }
}

static void TextureCopy(const Regs::DisplayTransferConfig& config) {
    const PAddr src_addr = config.GetPhysicalInputAddress();
    const PAddr dst_addr = config.GetPhysicalOutputAddress();

    // TODO: do hwtest with these cases
    if (!Memory::IsValidPhysicalAddress(src_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid input address 0x%08X", src_addr);
        return;
    }

    if (!Memory::IsValidPhysicalAddress(dst_addr)) {
        LOG_CRITICAL(HW_GPU, "invalid output address 0x%08X", dst_addr);
        return;
    }

    if (config.texture_copy.input_width == 0) {
        LOG_CRITICAL(HW_GPU, "zero input width");
        return;
    }

    if (config.texture_copy.output_width == 0) {
        LOG_CRITICAL(HW_GPU, "zero output width");
        return;
    }

    if (config.texture_copy.size == 0) {
        LOG_CRITICAL(HW_GPU, "zero size");
        return;
    }

    if (VideoCore::g_renderer->Rasterizer()->AccelerateTextureCopy(config))
        return;

    u8* src_pointer = Memory::GetPhysicalPointer(src_addr);
    u8* dst_pointer = Memory::GetPhysicalPointer(dst_addr);

    u32 input_width = config.texture_copy.input_width * 16;
    u32 input_gap = config.texture_copy.input_gap * 16;
    u32 output_width = config.texture_copy.output_width * 16;
    u32 output_gap = config.texture_copy.output_gap * 16;

    size_t contiguous_input_size =
        config.texture_copy.size / input_width * (input_width + input_gap);
    Memory::RasterizerFlushRegion(config.GetPhysicalInputAddress(),
                                  static_cast<u32>(contiguous_input_size));

    size_t contiguous_output_size =
        config.texture_copy.size / output_width * (output_width + output_gap);
    Memory::RasterizerFlushAndInvalidateRegion(config.GetPhysicalOutputAddress(),
                                               static_cast<u32>(contiguous_output_size));

    u32 remaining_size = config.texture_copy.size;
    u32 remaining_input = input_width;
    u32 remaining_output = output_width;
    while (remaining_size > 0) {
        u32 copy_size = std::min({remaining_input, remaining_output, remaining_size});

        std::memcpy(dst_pointer, src_pointer, copy_size);
        src_pointer += copy_size;
        dst_pointer += copy_size;

        remaining_input -= copy_size;
        remaining_output -= copy_size;
        remaining_size -= copy_size;

        if (remaining_input == 0) {
            remaining_input = input_width;
            src_pointer += input_gap;
        }
        if (remaining_output == 0) {
            remaining_output = output_width;
            dst_pointer += output_gap;
        }
    }
}

template <typename T>
inline void Write(u32 addr, const T data) {
    addr -= HW::VADDR_GPU;
    u32 index = addr / 4;

    // Writes other than u32 are untested, so I'd rather have them abort than silently fail
    if (index >= Regs::NumIds() || !std::is_same<T, u32>::value) {
        LOG_ERROR(HW_GPU, "unknown Write%lu 0x%08X @ 0x%08X", sizeof(data) * 8, (u32)data, addr);
        return;
    }

    g_regs[index] = static_cast<u32>(data);

    switch (index) {

    // Memory fills are triggered once the fill value is written.
    case GPU_REG_INDEX_WORKAROUND(memory_fill_config[0].trigger, 0x00004 + 0x3):
    case GPU_REG_INDEX_WORKAROUND(memory_fill_config[1].trigger, 0x00008 + 0x3): {
        const bool is_second_filler = (index != GPU_REG_INDEX(memory_fill_config[0].trigger));
        auto& config = g_regs.memory_fill_config[is_second_filler];

        if (config.trigger) {
            MemoryFill(config);
            LOG_TRACE(HW_GPU, "MemoryFill from 0x%08x to 0x%08x", config.GetStartAddress(),
                      config.GetEndAddress());

            // It seems that it won't signal interrupt if "address_start" is zero.
            // TODO: hwtest this
            if (config.GetStartAddress() != 0) {
                if (!is_second_filler) {
                    GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PSC0);
                } else {
                    GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PSC1);
                }
            }

            // Reset "trigger" flag and set the "finish" flag
            // NOTE: This was confirmed to happen on hardware even if "address_start" is zero.
            config.trigger.Assign(0);
            config.finished.Assign(1);
        }
        break;
    }

    case GPU_REG_INDEX(display_transfer_config.trigger): {
        MICROPROFILE_SCOPE(GPU_DisplayTransfer);

        const auto& config = g_regs.display_transfer_config;
        if (config.trigger & 1) {

            if (Pica::g_debug_context)
                Pica::g_debug_context->OnEvent(Pica::DebugContext::Event::IncomingDisplayTransfer,
                                               nullptr);

            if (config.is_texture_copy) {
                TextureCopy(config);
                LOG_TRACE(HW_GPU, "TextureCopy: 0x%X bytes from 0x%08X(%u+%u)-> "
                                  "0x%08X(%u+%u), flags 0x%08X",
                          config.texture_copy.size, config.GetPhysicalInputAddress(),
                          config.texture_copy.input_width * 16, config.texture_copy.input_gap * 16,
                          config.GetPhysicalOutputAddress(), config.texture_copy.output_width * 16,
                          config.texture_copy.output_gap * 16, config.flags);
            } else {
                DisplayTransfer(config);
                LOG_TRACE(HW_GPU, "DisplayTransfer: 0x%08x(%ux%u)-> "
                                  "0x%08x(%ux%u), dst format %x, flags 0x%08X",
                          config.GetPhysicalInputAddress(), config.input_width.Value(),
                          config.input_height.Value(), config.GetPhysicalOutputAddress(),
                          config.output_width.Value(), config.output_height.Value(),
                          config.output_format.Value(), config.flags);
            }

            g_regs.display_transfer_config.trigger = 0;
            GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PPF);
        }
        break;
    }

    // Seems like writing to this register triggers processing
    case GPU_REG_INDEX(command_processor_config.trigger): {
        const auto& config = g_regs.command_processor_config;
        if (config.trigger & 1) {
            MICROPROFILE_SCOPE(GPU_CmdlistProcessing);

            u32* buffer = (u32*)Memory::GetPhysicalPointer(config.GetPhysicalAddress());

            if (Pica::g_debug_context && Pica::g_debug_context->recorder) {
                Pica::g_debug_context->recorder->MemoryAccessed(
                    (u8*)buffer, config.size * sizeof(u32), config.GetPhysicalAddress());
            }

            Pica::CommandProcessor::ProcessCommandList(buffer, config.size);

            g_regs.command_processor_config.trigger = 0;
        }
        break;
    }

    default:
        break;
    }

    // Notify tracer about the register write
    // This is happening *after* handling the write to make sure we properly catch all memory reads.
    if (Pica::g_debug_context && Pica::g_debug_context->recorder) {
        // addr + GPU VBase - IO VBase + IO PBase
        Pica::g_debug_context->recorder->RegisterWritten<T>(
            addr + 0x1EF00000 - 0x1EC00000 + 0x10100000, data);
    }
}

// Explicitly instantiate template functions because we aren't defining this in the header:

template void Read<u64>(u64& var, const u32 addr);
template void Read<u32>(u32& var, const u32 addr);
template void Read<u16>(u16& var, const u32 addr);
template void Read<u8>(u8& var, const u32 addr);

template void Write<u64>(u32 addr, const u64 data);
template void Write<u32>(u32 addr, const u32 data);
template void Write<u16>(u32 addr, const u16 data);
template void Write<u8>(u32 addr, const u8 data);

static void FrameLimiter() {
    time_delay += FIXED_FRAME_TIME;
    time_delay = MathUtil::Clamp(time_delay, -MAX_LAG_TIME, MAX_LAG_TIME);
    s32 desired_time = static_cast<s32>(time_delay);
    s32 elapsed_time = static_cast<s32>(Common::Timer::GetTimeMs() - time_point);

    if (elapsed_time < desired_time) {
        Common::SleepCurrentThread(desired_time - elapsed_time);
    }

    u32 frame_time = Common::Timer::GetTimeMs() - time_point;

    time_delay -= frame_time;
}

/// Update hardware
static void VBlankCallback(u64 userdata, int cycles_late) {
    frame_count++;
    VideoCore::g_renderer->SwapBuffers();

    // Signal to GSP that GPU interrupt has occurred
    // TODO(yuriks): hwtest to determine if PDC0 is for the Top screen and PDC1 for the Sub
    // screen, or if both use the same interrupts and these two instead determine the
    // beginning and end of the VBlank period. If needed, split the interrupt firing into
    // two different intervals.
    GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PDC0);
    GSP_GPU::SignalInterrupt(GSP_GPU::InterruptId::PDC1);

    // Check for user input updates
    Service::HID::Update();

    if (!Settings::values.use_vsync && Settings::values.toggle_framelimit) {
        FrameLimiter();
    }

    time_point = Common::Timer::GetTimeMs();

    // Reschedule recurrent event
    CoreTiming::ScheduleEvent(frame_ticks - cycles_late, vblank_event);
}

/// Initialize hardware
void Init() {
    memset(&g_regs, 0, sizeof(g_regs));

    auto& framebuffer_top = g_regs.framebuffer_config[0];
    auto& framebuffer_sub = g_regs.framebuffer_config[1];

    // Setup default framebuffer addresses (located in VRAM)
    // .. or at least these are the ones used by system applets.
    // There's probably a smarter way to come up with addresses
    // like this which does not require hardcoding.
    framebuffer_top.address_left1 = 0x181E6000;
    framebuffer_top.address_left2 = 0x1822C800;
    framebuffer_top.address_right1 = 0x18273000;
    framebuffer_top.address_right2 = 0x182B9800;
    framebuffer_sub.address_left1 = 0x1848F000;
    framebuffer_sub.address_left2 = 0x184C7800;

    framebuffer_top.width.Assign(240);
    framebuffer_top.height.Assign(400);
    framebuffer_top.stride = 3 * 240;
    framebuffer_top.color_format.Assign(Regs::PixelFormat::RGB8);
    framebuffer_top.active_fb = 0;

    framebuffer_sub.width.Assign(240);
    framebuffer_sub.height.Assign(320);
    framebuffer_sub.stride = 3 * 240;
    framebuffer_sub.color_format.Assign(Regs::PixelFormat::RGB8);
    framebuffer_sub.active_fb = 0;

    frame_count = 0;
    time_point = Common::Timer::GetTimeMs();

    vblank_event = CoreTiming::RegisterEvent("GPU::VBlankCallback", VBlankCallback);
    CoreTiming::ScheduleEvent(frame_ticks, vblank_event);

    LOG_DEBUG(HW_GPU, "initialized OK");
}

/// Shutdown hardware
void Shutdown() {
    LOG_DEBUG(HW_GPU, "shutdown OK");
}

} // namespace