#include "bootflow_texture_override.h"

#include <Windows.h>

#include <algorithm>
#include <array>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <span>
#include <string_view>

#include "../../../../resources/resource.h"
#include "../../../core/logging/log.h"
#include "../../../core/settings/settings.h"
#include "../../hooking/detour.h"
#include "../../patterns/image_scan.h"

namespace sunrise::client::hooks::bootflow::texture_override {
namespace {

using patterns::scan_main_image_unique;
using patterns::signature;
using patterns::signature_length;

/**
 * Resourcerer's GPU-entry dispatcher, whose switch follows this prologue.
 * Arguments are the resource class, the TagHash, and the decoded entry pointer and byte count.
 */
constexpr std::string_view kGpuEntryDispatcherText =
    "48 89 5C 24 08 48 89 6C 24 10 48 89 74 24 18 57 48 83 EC 20 "
    "49 8B F9 49 8B F0 8B DA 8B E9 E8 ? ? ? ? 84 C0 0F 85 ? ? ? ? "
    "8D 45 FF 83 F8 12";
/** Compiled form of that prologue, scanned for as a unique site in the main image. */
constexpr auto kGpuEntryDispatcher =
    signature<signature_length(kGpuEntryDispatcherText)>(kGpuEntryDispatcherText);

/** Bytes of one Tiger texture descriptor; the dispatcher reads exactly this much. */
constexpr std::size_t kTigerTextureHeaderSize = 0x28;
/** DDS magic plus its 124-byte header, which is where a legacy file's pixels start. */
constexpr std::size_t kDdsLegacyHeaderSize = 4 + 124;
/** A DX10 file adds a 20-byte extension header before its pixels. */
constexpr std::size_t kDdsDx10HeaderSize = kDdsLegacyHeaderSize + 20;
/** "DDS " in file order. */
constexpr std::uint32_t kDdsMagic = 0x20534444U;
/** "DX10" in the FourCC field, which marks the extension header. */
constexpr std::uint32_t kDx10FourCc = 0x30315844U;
/** DDS header size the format fixes at 124 bytes. */
constexpr std::uint32_t kDdsHeaderSizeValue = 124U;
/** DDS pixel-format block size the format fixes at 32 bytes. */
constexpr std::uint32_t kDdsPixelFormatSize = 32U;
/** DDPF_FOURCC: the pixel format is named by the FourCC field. */
constexpr std::uint32_t kDdsPixelFourCc = 0x4U;
/** DDPF_RGB: the pixel format is named by the channel masks. */
constexpr std::uint32_t kDdsPixelRgb = 0x40U;
/** D3D10_RESOURCE_DIMENSION_TEXTURE2D, the only shape this override accepts. */
constexpr std::uint32_t kDdsResourceTexture2d = 3U;
/** D3D10_RESOURCE_MISC_TEXTURECUBE, which this override refuses. */
constexpr std::uint32_t kDdsResourceMiscCube = 0x4U;
/** DXGI_FORMAT_R8G8B8A8_UNORM, the one legacy layout the embedded assets use. */
constexpr std::uint32_t kDxgiR8G8B8A8Unorm = 28U;
/** Bits per pixel of that layout. */
constexpr std::uint32_t kRgba8BitCount = 32U;
/** Channel masks of that layout, in DDS field order. */
constexpr std::uint32_t kRgba8RedMask = 0x000000FFU;
constexpr std::uint32_t kRgba8GreenMask = 0x0000FF00U;
constexpr std::uint32_t kRgba8BlueMask = 0x00FF0000U;
constexpr std::uint32_t kRgba8AlphaMask = 0xFF000000U;
/** Largest width, height or array size a Tiger descriptor field can hold. */
constexpr std::uint32_t kTigerDimensionLimit = 0xFFFFU;
/** A Tiger texture descriptor carries this marker; anything else is not one. */
constexpr std::uint16_t kTigerTextureMarker = 0xCAFEU;
/** Resource class the dispatcher uses for GPU textures. */
constexpr std::uint32_t kGpuTextureClass = 1U;
/** The dispatcher's own bad-argument result, returned when the trampoline is gone. */
constexpr std::uint64_t kDispatchUnavailable = 7U;

/** Fields of a DDS file header, as byte offsets from the magic. */
struct DdsLayout {
    // The DDS file format fixes every offset below.
    static constexpr std::size_t magic = 0x00;
    static constexpr std::size_t headerSize = 0x04;
    static constexpr std::size_t height = 0x0C;
    static constexpr std::size_t width = 0x10;
    static constexpr std::size_t depth = 0x18;
    static constexpr std::size_t pixelFormatSize = 0x4C;
    static constexpr std::size_t pixelFlags = 0x50;
    static constexpr std::size_t fourCc = 0x54;
    static constexpr std::size_t bitCount = 0x58;
    static constexpr std::size_t redMask = 0x5C;
    static constexpr std::size_t greenMask = 0x60;
    static constexpr std::size_t blueMask = 0x64;
    static constexpr std::size_t alphaMask = 0x68;
    static constexpr std::size_t dxgiFormat = 0x80;
    static constexpr std::size_t resourceDimension = 0x84;
    static constexpr std::size_t miscFlag = 0x88;
    static constexpr std::size_t arraySize = 0x8C;
};

/** Fields of a Tiger texture descriptor, as byte offsets from its base. */
struct TigerLayout {
    // The client's descriptor layout fixes every offset below.
    static constexpr std::size_t dataSize = 0x00;
    static constexpr std::size_t format = 0x04;
    static constexpr std::size_t marker = 0x0C;
    static constexpr std::size_t width = 0x0E;
    static constexpr std::size_t height = 0x10;
    static constexpr std::size_t depth = 0x12;
    static constexpr std::size_t arraySize = 0x14;
};

/** Exact stock texture-header/data pairs selected from package 0x010A. */
struct AssetSpec final {
    std::uint32_t headerTag{};
    std::uint32_t dataTag{};
    int resourceId{};
};

/** One row per replaced texture; the dispatcher is intercepted on both of its tags. */
constexpr std::array kAssetSpecs{
    AssetSpec{0x80A145FEU, 0x80A145FFU, IDR_BOOTFLOW_TEXTURE_80A145FF},
    AssetSpec{0x80A14602U, 0x80A14601U, IDR_BOOTFLOW_TEXTURE_80A14601},
    AssetSpec{0x80A14608U, 0x80A14607U, IDR_BOOTFLOW_TEXTURE_80A14607},
    AssetSpec{0x80A1460DU, 0x80A1460EU, IDR_BOOTFLOW_TEXTURE_80A1460E},
    AssetSpec{0x80A1461CU, 0x80A1461DU, IDR_BOOTFLOW_TEXTURE_80A1461D},
    AssetSpec{0x80A14620U, 0x80A1461FU, IDR_BOOTFLOW_TEXTURE_80A1461F},
    AssetSpec{0x80A14622U, 0x80A14621U, IDR_BOOTFLOW_TEXTURE_80A14621},
    AssetSpec{0x80A14623U, 0x80A14624U, IDR_BOOTFLOW_TEXTURE_80A14624},
    AssetSpec{0x80A14626U, 0x80A14625U, IDR_BOOTFLOW_TEXTURE_80A14625},
    AssetSpec{0x80A14627U, 0x80A14628U, IDR_BOOTFLOW_TEXTURE_80A14628},
    AssetSpec{0x80A1462AU, 0x80A14629U, IDR_BOOTFLOW_TEXTURE_80A14629},
    AssetSpec{0x80A1462CU, 0x80A1462BU, IDR_BOOTFLOW_TEXTURE_80A1462B},
    AssetSpec{0x80A1462DU, 0x80A1462EU, IDR_BOOTFLOW_TEXTURE_80A1462E},
    AssetSpec{0x80A14630U, 0x80A1462FU, IDR_BOOTFLOW_TEXTURE_80A1462F},
    AssetSpec{0x80A14632U, 0x80A14631U, IDR_BOOTFLOW_TEXTURE_80A14631},
    AssetSpec{0x80A14634U, 0x80A14633U, IDR_BOOTFLOW_TEXTURE_80A14633},
    AssetSpec{0x80A14635U, 0x80A14636U, IDR_BOOTFLOW_TEXTURE_80A14636},
    AssetSpec{0x80A146D4U, 0x80A146D5U, IDR_BOOTFLOW_TEXTURE_80A146D5},
};

struct DdsView final {
    const std::byte* pixels{};
    std::uint32_t pixelSize{};
    std::uint32_t format{};
    std::uint16_t width{};
    std::uint16_t height{};
    std::uint16_t depth{};
    std::uint16_t arraySize{};
};

struct Asset final {
    AssetSpec spec{};
    DdsView dds{};
    std::array<std::byte, kTigerTextureHeaderSize> header{};
    bool headerReady{};
    bool reported{};
};

using GpuEntryDispatcher = std::uint64_t(__fastcall*)(std::uint32_t resourceClass,
                                                      std::uint32_t tag,
                                                      const void* decoded,
                                                      std::uint64_t decodedSize) noexcept;

hooking::detour::Handle g_handle{};
SRWLOCK g_assetLock{SRWLOCK_INIT};
std::array<Asset, kAssetSpecs.size()> g_assets{};

template <typename Value>
[[nodiscard]] bool
load_value(const std::byte* bytes, std::size_t size, std::size_t offset, Value& output) noexcept {
    if (bytes == nullptr || offset > size || sizeof(Value) > size - offset) {
        return false;
    }
    std::memcpy(&output, bytes + offset, sizeof output);
    return true;
}

template <typename Value>
void store_value(std::span<std::byte> bytes, std::size_t offset, Value value) noexcept {
    if (offset <= bytes.size() && sizeof(Value) <= bytes.size() - offset) {
        std::memcpy(bytes.data() + offset, &value, sizeof value);
    }
}

/**
 * Names the DXGI format of a legacy DDS pixel block.
 * Only R8G8B8A8_UNORM is accepted; any other authored layout is refused rather than converted.
 * @param bytes DDS file bytes.
 * @param size Bytes available.
 * @param output Receives the DXGI format value.
 * @return False when the file is not the accepted layout.
 */
[[nodiscard]] bool
legacy_format(const std::byte* bytes, std::size_t size, std::uint32_t& output) noexcept {
    std::uint32_t flags = 0;
    std::uint32_t bits = 0;
    std::uint32_t red = 0;
    std::uint32_t green = 0;
    std::uint32_t blue = 0;
    std::uint32_t alpha = 0;
    if (!load_value(bytes, size, DdsLayout::pixelFlags, flags)
        || !load_value(bytes, size, DdsLayout::bitCount, bits)
        || !load_value(bytes, size, DdsLayout::redMask, red)
        || !load_value(bytes, size, DdsLayout::greenMask, green)
        || !load_value(bytes, size, DdsLayout::blueMask, blue)
        || !load_value(bytes, size, DdsLayout::alphaMask, alpha)) {
        return false;
    }
    if ((flags & kDdsPixelRgb) == 0 || bits != kRgba8BitCount || red != kRgba8RedMask
        || green != kRgba8GreenMask || blue != kRgba8BlueMask || alpha != kRgba8AlphaMask) {
        return false;
    }
    output = kDxgiR8G8B8A8Unorm;
    return true;
}

/**
 * Parses one embedded 2D DDS without allocating or copying its pixel payload.
 * @param bytes DDS file bytes, which outlive the view.
 * @param size Bytes available.
 * @param output Receives a view over the file's pixels; cleared on failure.
 * @return False when the file is not an accepted 2D texture.
 */
[[nodiscard]] bool parse_dds(const std::byte* bytes, std::size_t size, DdsView& output) noexcept {
    output = {};
    std::uint32_t magic = 0;
    std::uint32_t headerSize = 0;
    std::uint32_t pixelHeaderSize = 0;
    std::uint32_t pixelFlags = 0;
    std::uint32_t formatFourCc = 0;
    if (size < kDdsLegacyHeaderSize || !load_value(bytes, size, DdsLayout::magic, magic)
        || !load_value(bytes, size, DdsLayout::headerSize, headerSize)
        || !load_value(bytes, size, DdsLayout::pixelFormatSize, pixelHeaderSize)
        || !load_value(bytes, size, DdsLayout::pixelFlags, pixelFlags)
        || !load_value(bytes, size, DdsLayout::fourCc, formatFourCc) || magic != kDdsMagic
        || headerSize != kDdsHeaderSizeValue || pixelHeaderSize != kDdsPixelFormatSize) {
        return false;
    }
    const bool dx10 = (pixelFlags & kDdsPixelFourCc) != 0 && formatFourCc == kDx10FourCc;
    const std::size_t pixelOffset = dx10 ? kDdsDx10HeaderSize : kDdsLegacyHeaderSize;
    std::uint32_t width = 0;
    std::uint32_t height = 0;
    std::uint32_t arraySize = 1;
    std::uint32_t resourceDimension = kDdsResourceTexture2d;
    std::uint32_t miscFlag = 0;
    std::uint32_t format = 0;
    if (size <= pixelOffset || !load_value(bytes, size, DdsLayout::width, width)
        || !load_value(bytes, size, DdsLayout::height, height)) {
        return false;
    }
    if (dx10) {
        if (!load_value(bytes, size, DdsLayout::dxgiFormat, format)
            || !load_value(bytes, size, DdsLayout::resourceDimension, resourceDimension)
            || !load_value(bytes, size, DdsLayout::miscFlag, miscFlag)
            || !load_value(bytes, size, DdsLayout::arraySize, arraySize)) {
            return false;
        }
    } else if (!legacy_format(bytes, size, format)) {
        return false;
    }
    const std::size_t pixelSize = size - pixelOffset;
    if (width == 0 || height == 0 || width > kTigerDimensionLimit || height > kTigerDimensionLimit
        || pixelSize == 0 || format == 0 || resourceDimension != kDdsResourceTexture2d
        || (miscFlag & kDdsResourceMiscCube) != 0 || arraySize == 0
        || arraySize > kTigerDimensionLimit) {
        return false;
    }
    output = DdsView{bytes + pixelOffset,
                     static_cast<std::uint32_t>(pixelSize),
                     format,
                     static_cast<std::uint16_t>(width),
                     static_cast<std::uint16_t>(height),
                     1,
                     static_cast<std::uint16_t>(arraySize)};
    return true;
}

/** Loads and validates every embedded DDS before the detour can expose any of them. */
[[nodiscard]] bool load_assets(HMODULE module) noexcept {
    if (module == nullptr) {
        return false;
    }
    for (std::size_t index = 0; index < kAssetSpecs.size(); ++index) {
        const AssetSpec& spec = kAssetSpecs[index];
        const HRSRC resource = FindResourceW(module, MAKEINTRESOURCEW(spec.resourceId), RT_RCDATA);
        if (resource == nullptr) {
            return false;
        }
        const HGLOBAL loaded = LoadResource(module, resource);
        const DWORD size = SizeofResource(module, resource);
        const auto* bytes = static_cast<const std::byte*>(LockResource(loaded));
        Asset asset{};
        asset.spec = spec;
        if (loaded == nullptr || bytes == nullptr || size == 0
            || !parse_dds(bytes, static_cast<std::size_t>(size), asset.dds)) {
            return false;
        }
        g_assets[index] = asset;
    }
    return true;
}

/** @return The asset owning this exact header or data TagHash. */
[[nodiscard]] Asset* find_asset(std::uint32_t tag, bool& header) noexcept {
    for (Asset& asset : g_assets) {
        if (asset.spec.headerTag == tag) {
            header = true;
            return &asset;
        }
        if (asset.spec.dataTag == tag) {
            header = false;
            return &asset;
        }
    }
    return nullptr;
}

/** Builds one replacement Tiger descriptor from its stock descriptor and embedded DDS. */
[[nodiscard]] const void*
prepare_header(Asset& asset, const void* stock, std::uint64_t stockSize, bool& report) noexcept {
    report = false;
    if (stock == nullptr || stockSize < kTigerTextureHeaderSize) {
        return stock;
    }
    AcquireSRWLockExclusive(&g_assetLock);
    if (!asset.headerReady) {
        std::memcpy(asset.header.data(), stock, asset.header.size());
        std::uint16_t marker = 0;
        std::memcpy(&marker, asset.header.data() + TigerLayout::marker, sizeof marker);
        if (marker == kTigerTextureMarker) {
            const std::span header(asset.header);
            store_value(header, TigerLayout::dataSize, asset.dds.pixelSize);
            store_value(header, TigerLayout::format, asset.dds.format);
            store_value(header, TigerLayout::width, asset.dds.width);
            store_value(header, TigerLayout::height, asset.dds.height);
            store_value(header, TigerLayout::depth, asset.dds.depth);
            store_value(header, TigerLayout::arraySize, asset.dds.arraySize);
            asset.headerReady = true;
        }
    }
    if (asset.headerReady && !asset.reported) {
        asset.reported = true;
        report = true;
    }
    const void* result = asset.headerReady ? asset.header.data() : stock;
    ReleaseSRWLockExclusive(&g_assetLock);
    return result;
}

/** Reports one asset the first time its descriptor is handed to the dispatcher. */
void report_override(const Asset& asset) noexcept {
    std::array<char, core::log::kLineCapacity> line{};
    const int written = std::snprintf(line.data(),
                                      line.size(),
                                      "ev=bootflow_texture stage=entry tag=0x%08X size=%u "
                                      "width=%u height=%u result=override",
                                      static_cast<unsigned>(asset.spec.dataTag),
                                      static_cast<unsigned>(asset.dds.pixelSize),
                                      static_cast<unsigned>(asset.dds.width),
                                      static_cast<unsigned>(asset.dds.height));
    if (written > 0) {
        core::log::write(
            core::log::Channel::client,
            core::log::Level::info,
            {line.data(), (std::min)(static_cast<std::size_t>(written), line.size() - 1)});
    }
}

/** Replaces only selected decoded GPU texture entries, then preserves the native dispatcher. */
std::uint64_t __fastcall dispatch(std::uint32_t resourceClass,
                                  std::uint32_t tag,
                                  const void* decoded,
                                  std::uint64_t decodedSize) noexcept {
    const auto original = reinterpret_cast<GpuEntryDispatcher>(g_handle.original);
    if (original == nullptr) {
        return kDispatchUnavailable;
    }
    bool header = false;
    Asset* const asset = resourceClass == kGpuTextureClass ? find_asset(tag, header) : nullptr;
    if (asset == nullptr) {
        return original(resourceClass, tag, decoded, decodedSize);
    }
    if (!header) {
        return original(resourceClass, tag, asset->dds.pixels, asset->dds.pixelSize);
    }
    bool report = false;
    const void* const replacement = prepare_header(*asset, decoded, decodedSize, report);
    if (report) {
        report_override(*asset);
    }
    return original(resourceClass,
                    tag,
                    replacement,
                    replacement == decoded ? decodedSize : kTigerTextureHeaderSize);
}

void clear_assets() noexcept {
    AcquireSRWLockExclusive(&g_assetLock);
    g_assets = {};
    ReleaseSRWLockExclusive(&g_assetLock);
}

} // namespace

/** Loads embedded DDS files and attaches the decoded GPU-entry dispatcher. */
bool install(void* module) noexcept {
    if (g_handle.attached) {
        return true;
    }
    if (!core::settings::get().client.customBootflowTextures) {
        core::log::write(core::log::Channel::client,
                         core::log::Level::info,
                         "ev=bootflow_texture stage=setting enabled=0 result=skip");
        return true;
    }
    if (!load_assets(static_cast<HMODULE>(module))) {
        clear_assets();
        core::log::write(core::log::Channel::client,
                         core::log::Level::error,
                         "ev=bootflow_texture stage=resources result=fail");
        return false;
    }
    std::byte* const target =
        scan_main_image_unique(kGpuEntryDispatcher, "bootflow_gpu_entry_dispatcher");
    const hooking::detour::Spec spec{target, reinterpret_cast<void*>(&dispatch)};
    if (target == nullptr || !hooking::detour::install(spec, g_handle)) {
        clear_assets();
        core::log::write(core::log::Channel::client,
                         core::log::Level::error,
                         "ev=bootflow_texture stage=attach result=fail");
        return false;
    }
    std::array<char, core::log::kLineCapacity> line{};
    const int written = std::snprintf(line.data(),
                                      line.size(),
                                      "ev=bootflow_texture stage=attach count=%zu result=ok",
                                      kAssetSpecs.size());
    if (written > 0) {
        core::log::write(
            core::log::Channel::client,
            core::log::Level::info,
            {line.data(), (std::min)(static_cast<std::size_t>(written), line.size() - 1)});
    }
    return true;
}

/** Detaches before releasing the resource views and generated Tiger descriptors. */
bool uninstall() noexcept {
    if (g_handle.attached && !hooking::detour::uninstall(g_handle)) {
        return false;
    }
    clear_assets();
    return true;
}

/** @return True while the decoded GPU-entry dispatcher is attached. */
bool is_installed() noexcept {
    return g_handle.attached;
}

} // namespace sunrise::client::hooks::bootflow::texture_override