// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <array>
#include <cstddef>

#include "common/logging/log.h"
#include "core/file_sys/content_archive.h"
#include "core/file_sys/control_metadata.h"
#include "core/file_sys/patch_manager.h"
#include "core/file_sys/registered_cache.h"
#include "core/file_sys/romfs.h"
#include "core/file_sys/vfs_layered.h"
#include "core/hle/service/filesystem/filesystem.h"
#include "core/loader/loader.h"

namespace FileSys {

constexpr u64 SINGLE_BYTE_MODULUS = 0x100;

std::string FormatTitleVersion(u32 version, TitleVersionFormat format) {
    std::array<u8, sizeof(u32)> bytes{};
    bytes[0] = version % SINGLE_BYTE_MODULUS;
    for (std::size_t i = 1; i < bytes.size(); ++i) {
        version /= SINGLE_BYTE_MODULUS;
        bytes[i] = version % SINGLE_BYTE_MODULUS;
    }

    if (format == TitleVersionFormat::FourElements)
        return fmt::format("v{}.{}.{}.{}", bytes[3], bytes[2], bytes[1], bytes[0]);
    return fmt::format("v{}.{}.{}", bytes[3], bytes[2], bytes[1]);
}

constexpr std::array<const char*, 2> PATCH_TYPE_NAMES{
    "Update",
    "LayeredFS",
};

std::string FormatPatchTypeName(PatchType type) {
    return PATCH_TYPE_NAMES.at(static_cast<std::size_t>(type));
}

PatchManager::PatchManager(u64 title_id) : title_id(title_id) {}

PatchManager::~PatchManager() = default;

VirtualDir PatchManager::PatchExeFS(VirtualDir exefs) const {
    LOG_INFO(Loader, "Patching ExeFS for title_id={:016X}", title_id);

    if (exefs == nullptr)
        return exefs;

    const auto installed = Service::FileSystem::GetUnionContents();

    // Game Updates
    const auto update_tid = GetUpdateTitleID(title_id);
    const auto update = installed->GetEntry(update_tid, ContentRecordType::Program);
    if (update != nullptr) {
        if (update->GetStatus() == Loader::ResultStatus::ErrorMissingBKTRBaseRomFS &&
            update->GetExeFS() != nullptr) {
            LOG_INFO(Loader, "    ExeFS: Update ({}) applied successfully",
                     FormatTitleVersion(installed->GetEntryVersion(update_tid).get_value_or(0)));
            exefs = update->GetExeFS();
        }
    }

    return exefs;
}

static void ApplyLayeredFS(VirtualFile& romfs, u64 title_id, ContentRecordType type) {
    const auto load_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
    if (type != ContentRecordType::Program || load_dir == nullptr || load_dir->GetSize() <= 0) {
        return;
    }

    auto extracted = ExtractRomFS(romfs);
    if (extracted == nullptr) {
        return;
    }

    auto patch_dirs = load_dir->GetSubdirectories();
    std::sort(patch_dirs.begin(), patch_dirs.end(),
              [](const VirtualDir& l, const VirtualDir& r) { return l->GetName() < r->GetName(); });

    std::vector<VirtualDir> layers;
    layers.reserve(patch_dirs.size() + 1);
    for (const auto& subdir : patch_dirs) {
        auto romfs_dir = subdir->GetSubdirectory("romfs");
        if (romfs_dir != nullptr)
            layers.push_back(std::move(romfs_dir));
    }
    layers.push_back(std::move(extracted));

    auto layered = LayeredVfsDirectory::MakeLayeredDirectory(std::move(layers));
    if (layered == nullptr) {
        return;
    }

    auto packed = CreateRomFS(std::move(layered));
    if (packed == nullptr) {
        return;
    }

    LOG_INFO(Loader, "    RomFS: LayeredFS patches applied successfully");
    romfs = std::move(packed);
}

VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
                                     ContentRecordType type) const {
    LOG_INFO(Loader, "Patching RomFS for title_id={:016X}, type={:02X}", title_id,
             static_cast<u8>(type));

    if (romfs == nullptr)
        return romfs;

    const auto installed = Service::FileSystem::GetUnionContents();

    // Game Updates
    const auto update_tid = GetUpdateTitleID(title_id);
    const auto update = installed->GetEntryRaw(update_tid, type);
    if (update != nullptr) {
        const auto new_nca = std::make_shared<NCA>(update, romfs, ivfc_offset);
        if (new_nca->GetStatus() == Loader::ResultStatus::Success &&
            new_nca->GetRomFS() != nullptr) {
            LOG_INFO(Loader, "    RomFS: Update ({}) applied successfully",
                     FormatTitleVersion(installed->GetEntryVersion(update_tid).get_value_or(0)));
            romfs = new_nca->GetRomFS();
        }
    }

    // LayeredFS
    ApplyLayeredFS(romfs, title_id, type);

    return romfs;
}

std::map<PatchType, std::string> PatchManager::GetPatchVersionNames() const {
    std::map<PatchType, std::string> out;
    const auto installed = Service::FileSystem::GetUnionContents();

    const auto update_tid = GetUpdateTitleID(title_id);
    PatchManager update{update_tid};
    auto [nacp, discard_icon_file] = update.GetControlMetadata();

    if (nacp != nullptr) {
        out[PatchType::Update] = nacp->GetVersionString();
    } else {
        if (installed->HasEntry(update_tid, ContentRecordType::Program)) {
            const auto meta_ver = installed->GetEntryVersion(update_tid);
            if (meta_ver == boost::none || meta_ver.get() == 0) {
                out[PatchType::Update] = "";
            } else {
                out[PatchType::Update] =
                    FormatTitleVersion(meta_ver.get(), TitleVersionFormat::ThreeElements);
            }
        }
    }

    const auto lfs_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
    if (lfs_dir != nullptr && lfs_dir->GetSize() > 0)
        out.insert_or_assign(PatchType::LayeredFS, "");

    return out;
}

std::pair<std::shared_ptr<NACP>, VirtualFile> PatchManager::GetControlMetadata() const {
    const auto& installed{Service::FileSystem::GetUnionContents()};

    const auto base_control_nca = installed->GetEntry(title_id, ContentRecordType::Control);
    if (base_control_nca == nullptr)
        return {};

    return ParseControlNCA(base_control_nca);
}

std::pair<std::shared_ptr<NACP>, VirtualFile> PatchManager::ParseControlNCA(
    const std::shared_ptr<NCA>& nca) const {
    const auto base_romfs = nca->GetRomFS();
    if (base_romfs == nullptr)
        return {};

    const auto romfs = PatchRomFS(base_romfs, nca->GetBaseIVFCOffset(), ContentRecordType::Control);
    if (romfs == nullptr)
        return {};

    const auto extracted = ExtractRomFS(romfs);
    if (extracted == nullptr)
        return {};

    auto nacp_file = extracted->GetFile("control.nacp");
    if (nacp_file == nullptr)
        nacp_file = extracted->GetFile("Control.nacp");

    const auto nacp = nacp_file == nullptr ? nullptr : std::make_shared<NACP>(nacp_file);

    VirtualFile icon_file;
    for (const auto& language : FileSys::LANGUAGE_NAMES) {
        icon_file = extracted->GetFile("icon_" + std::string(language) + ".dat");
        if (icon_file != nullptr)
            break;
    }

    return {nacp, icon_file};
}
} // namespace FileSys