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

#include <algorithm>
#include <array>
#include <cstddef>
#include <cstring>

#include "common/file_util.h"
#include "common/hex_util.h"
#include "common/logging/log.h"
#include "common/string_util.h"
#include "core/core.h"
#include "core/file_sys/common_funcs.h"
#include "core/file_sys/content_archive.h"
#include "core/file_sys/control_metadata.h"
#include "core/file_sys/ips_layer.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/file_sys/vfs_vector.h"
#include "core/hle/service/filesystem/filesystem.h"
#include "core/loader/loader.h"
#include "core/loader/nso.h"
#include "core/memory/cheat_engine.h"
#include "core/settings.h"

namespace FileSys {
namespace {

constexpr u32 SINGLE_BYTE_MODULUS = 0x100;

constexpr std::array<const char*, 14> EXEFS_FILE_NAMES{
    "main",    "main.npdm", "rtld",    "sdk",     "subsdk0", "subsdk1", "subsdk2",
    "subsdk3", "subsdk4",   "subsdk5", "subsdk6", "subsdk7", "subsdk8", "subsdk9",
};

enum class TitleVersionFormat : u8 {
    ThreeElements, ///< vX.Y.Z
    FourElements,  ///< vX.Y.Z.W
};

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

// Returns a directory with name matching name case-insensitive. Returns nullptr if directory
// doesn't have a directory with name.
VirtualDir FindSubdirectoryCaseless(const VirtualDir dir, std::string_view name) {
#ifdef _WIN32
    return dir->GetSubdirectory(name);
#else
    const auto subdirs = dir->GetSubdirectories();
    for (const auto& subdir : subdirs) {
        std::string dir_name = Common::ToLower(subdir->GetName());
        if (dir_name == name) {
            return subdir;
        }
    }

    return nullptr;
#endif
}

std::optional<std::vector<Core::Memory::CheatEntry>> ReadCheatFileFromFolder(
    u64 title_id, const PatchManager::BuildID& build_id_, const VirtualDir& base_path, bool upper) {
    const auto build_id_raw = Common::HexToString(build_id_, upper);
    const auto build_id = build_id_raw.substr(0, sizeof(u64) * 2);
    const auto file = base_path->GetFile(fmt::format("{}.txt", build_id));

    if (file == nullptr) {
        LOG_INFO(Common_Filesystem, "No cheats file found for title_id={:016X}, build_id={}",
                 title_id, build_id);
        return std::nullopt;
    }

    std::vector<u8> data(file->GetSize());
    if (file->Read(data.data(), data.size()) != data.size()) {
        LOG_INFO(Common_Filesystem, "Failed to read cheats file for title_id={:016X}, build_id={}",
                 title_id, build_id);
        return std::nullopt;
    }

    const Core::Memory::TextCheatParser parser;
    return parser.Parse(std::string_view(reinterpret_cast<const char*>(data.data()), data.size()));
}

void AppendCommaIfNotEmpty(std::string& to, std::string_view with) {
    if (to.empty()) {
        to += with;
    } else {
        to += ", ";
        to += with;
    }
}

bool IsDirValidAndNonEmpty(const VirtualDir& dir) {
    return dir != nullptr && (!dir->GetFiles().empty() || !dir->GetSubdirectories().empty());
}
} // Anonymous namespace

PatchManager::PatchManager(u64 title_id_,
                           const Service::FileSystem::FileSystemController& fs_controller_,
                           const ContentProvider& content_provider_)
    : title_id{title_id_}, fs_controller{fs_controller_}, content_provider{content_provider_} {}

PatchManager::~PatchManager() = default;

u64 PatchManager::GetTitleID() const {
    return title_id;
}

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

    if (exefs == nullptr)
        return exefs;

    if (Settings::values.dump_exefs) {
        LOG_INFO(Loader, "Dumping ExeFS for title_id={:016X}", title_id);
        const auto dump_dir = fs_controller.GetModificationDumpRoot(title_id);
        if (dump_dir != nullptr) {
            const auto exefs_dir = GetOrCreateDirectoryRelative(dump_dir, "/exefs");
            VfsRawCopyD(exefs, exefs_dir);
        }
    }

    const auto& disabled = Settings::values.disabled_addons[title_id];
    const auto update_disabled =
        std::find(disabled.cbegin(), disabled.cend(), "Update") != disabled.cend();

    // Game Updates
    const auto update_tid = GetUpdateTitleID(title_id);
    const auto update = content_provider.GetEntry(update_tid, ContentRecordType::Program);

    if (!update_disabled && update != nullptr && update->GetExeFS() != nullptr &&
        update->GetStatus() == Loader::ResultStatus::ErrorMissingBKTRBaseRomFS) {
        LOG_INFO(Loader, "    ExeFS: Update ({}) applied successfully",
                 FormatTitleVersion(content_provider.GetEntryVersion(update_tid).value_or(0)));
        exefs = update->GetExeFS();
    }

    // LayeredExeFS
    const auto load_dir = fs_controller.GetModificationLoadRoot(title_id);
    if (load_dir != nullptr && load_dir->GetSize() > 0) {
        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) {
            if (std::find(disabled.begin(), disabled.end(), subdir->GetName()) != disabled.end())
                continue;

            auto exefs_dir = FindSubdirectoryCaseless(subdir, "exefs");
            if (exefs_dir != nullptr)
                layers.push_back(std::move(exefs_dir));
        }
        layers.push_back(exefs);

        auto layered = LayeredVfsDirectory::MakeLayeredDirectory(std::move(layers));
        if (layered != nullptr) {
            LOG_INFO(Loader, "    ExeFS: LayeredExeFS patches applied successfully");
            exefs = std::move(layered);
        }
    }

    return exefs;
}

std::vector<VirtualFile> PatchManager::CollectPatches(const std::vector<VirtualDir>& patch_dirs,
                                                      const std::string& build_id) const {
    const auto& disabled = Settings::values.disabled_addons[title_id];

    std::vector<VirtualFile> out;
    out.reserve(patch_dirs.size());
    for (const auto& subdir : patch_dirs) {
        if (std::find(disabled.cbegin(), disabled.cend(), subdir->GetName()) != disabled.cend())
            continue;

        auto exefs_dir = FindSubdirectoryCaseless(subdir, "exefs");
        if (exefs_dir != nullptr) {
            for (const auto& file : exefs_dir->GetFiles()) {
                if (file->GetExtension() == "ips") {
                    auto name = file->GetName();
                    const auto p1 = name.substr(0, name.find('.'));
                    const auto this_build_id = p1.substr(0, p1.find_last_not_of('0') + 1);

                    if (build_id == this_build_id)
                        out.push_back(file);
                } else if (file->GetExtension() == "pchtxt") {
                    IPSwitchCompiler compiler{file};
                    if (!compiler.IsValid())
                        continue;

                    auto this_build_id = Common::HexToString(compiler.GetBuildID());
                    this_build_id =
                        this_build_id.substr(0, this_build_id.find_last_not_of('0') + 1);

                    if (build_id == this_build_id)
                        out.push_back(file);
                }
            }
        }
    }

    return out;
}

std::vector<u8> PatchManager::PatchNSO(const std::vector<u8>& nso, const std::string& name) const {
    if (nso.size() < sizeof(Loader::NSOHeader)) {
        return nso;
    }

    Loader::NSOHeader header;
    std::memcpy(&header, nso.data(), sizeof(header));

    if (header.magic != Common::MakeMagic('N', 'S', 'O', '0')) {
        return nso;
    }

    const auto build_id_raw = Common::HexToString(header.build_id);
    const auto build_id = build_id_raw.substr(0, build_id_raw.find_last_not_of('0') + 1);

    if (Settings::values.dump_nso) {
        LOG_INFO(Loader, "Dumping NSO for name={}, build_id={}, title_id={:016X}", name, build_id,
                 title_id);
        const auto dump_dir = fs_controller.GetModificationDumpRoot(title_id);
        if (dump_dir != nullptr) {
            const auto nso_dir = GetOrCreateDirectoryRelative(dump_dir, "/nso");
            const auto file = nso_dir->CreateFile(fmt::format("{}-{}.nso", name, build_id));

            file->Resize(nso.size());
            file->WriteBytes(nso);
        }
    }

    LOG_INFO(Loader, "Patching NSO for name={}, build_id={}", name, build_id);

    const auto load_dir = fs_controller.GetModificationLoadRoot(title_id);
    if (load_dir == nullptr) {
        LOG_ERROR(Loader, "Cannot load mods for invalid title_id={:016X}", title_id);
        return nso;
    }

    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(); });
    const auto patches = CollectPatches(patch_dirs, build_id);

    auto out = nso;
    for (const auto& patch_file : patches) {
        if (patch_file->GetExtension() == "ips") {
            LOG_INFO(Loader, "    - Applying IPS patch from mod \"{}\"",
                     patch_file->GetContainingDirectory()->GetParentDirectory()->GetName());
            const auto patched = PatchIPS(std::make_shared<VectorVfsFile>(out), patch_file);
            if (patched != nullptr)
                out = patched->ReadAllBytes();
        } else if (patch_file->GetExtension() == "pchtxt") {
            LOG_INFO(Loader, "    - Applying IPSwitch patch from mod \"{}\"",
                     patch_file->GetContainingDirectory()->GetParentDirectory()->GetName());
            const IPSwitchCompiler compiler{patch_file};
            const auto patched = compiler.Apply(std::make_shared<VectorVfsFile>(out));
            if (patched != nullptr)
                out = patched->ReadAllBytes();
        }
    }

    if (out.size() < sizeof(Loader::NSOHeader)) {
        return nso;
    }

    std::memcpy(out.data(), &header, sizeof(header));
    return out;
}

bool PatchManager::HasNSOPatch(const BuildID& build_id_) const {
    const auto build_id_raw = Common::HexToString(build_id_);
    const auto build_id = build_id_raw.substr(0, build_id_raw.find_last_not_of('0') + 1);

    LOG_INFO(Loader, "Querying NSO patch existence for build_id={}", build_id);

    const auto load_dir = fs_controller.GetModificationLoadRoot(title_id);
    if (load_dir == nullptr) {
        LOG_ERROR(Loader, "Cannot load mods for invalid title_id={:016X}", title_id);
        return false;
    }

    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(); });

    return !CollectPatches(patch_dirs, build_id).empty();
}

std::vector<Core::Memory::CheatEntry> PatchManager::CreateCheatList(
    const BuildID& build_id_) const {
    const auto load_dir = fs_controller.GetModificationLoadRoot(title_id);
    if (load_dir == nullptr) {
        LOG_ERROR(Loader, "Cannot load mods for invalid title_id={:016X}", title_id);
        return {};
    }

    const auto& disabled = Settings::values.disabled_addons[title_id];
    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<Core::Memory::CheatEntry> out;
    for (const auto& subdir : patch_dirs) {
        if (std::find(disabled.cbegin(), disabled.cend(), subdir->GetName()) != disabled.cend()) {
            continue;
        }

        auto cheats_dir = FindSubdirectoryCaseless(subdir, "cheats");
        if (cheats_dir != nullptr) {
            if (const auto res = ReadCheatFileFromFolder(title_id, build_id_, cheats_dir, true)) {
                std::copy(res->begin(), res->end(), std::back_inserter(out));
                continue;
            }

            if (const auto res = ReadCheatFileFromFolder(title_id, build_id_, cheats_dir, false)) {
                std::copy(res->begin(), res->end(), std::back_inserter(out));
            }
        }
    }

    return out;
}

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

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

    const auto& disabled = Settings::values.disabled_addons[title_id];
    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;
    std::vector<VirtualDir> layers_ext;
    layers.reserve(patch_dirs.size() + 1);
    layers_ext.reserve(patch_dirs.size() + 1);
    for (const auto& subdir : patch_dirs) {
        if (std::find(disabled.cbegin(), disabled.cend(), subdir->GetName()) != disabled.cend()) {
            continue;
        }

        auto romfs_dir = FindSubdirectoryCaseless(subdir, "romfs");
        if (romfs_dir != nullptr)
            layers.push_back(std::move(romfs_dir));

        auto ext_dir = FindSubdirectoryCaseless(subdir, "romfs_ext");
        if (ext_dir != nullptr)
            layers_ext.push_back(std::move(ext_dir));
    }

    // When there are no layers to apply, return early as there is no need to rebuild the RomFS
    if (layers.empty() && layers_ext.empty()) {
        return;
    }

    layers.push_back(std::move(extracted));

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

    auto layered_ext = LayeredVfsDirectory::MakeLayeredDirectory(std::move(layers_ext));

    auto packed = CreateRomFS(std::move(layered), std::move(layered_ext));
    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,
                                     VirtualFile update_raw) const {
    const auto log_string = fmt::format("Patching RomFS for title_id={:016X}, type={:02X}",
                                        title_id, static_cast<u8>(type));

    if (type == ContentRecordType::Program || type == ContentRecordType::Data) {
        LOG_INFO(Loader, "{}", log_string);
    } else {
        LOG_DEBUG(Loader, "{}", log_string);
    }

    if (romfs == nullptr) {
        return romfs;
    }

    // Game Updates
    const auto update_tid = GetUpdateTitleID(title_id);
    const auto update = content_provider.GetEntryRaw(update_tid, type);

    const auto& disabled = Settings::values.disabled_addons[title_id];
    const auto update_disabled =
        std::find(disabled.cbegin(), disabled.cend(), "Update") != disabled.cend();

    if (!update_disabled && 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(content_provider.GetEntryVersion(update_tid).value_or(0)));
            romfs = new_nca->GetRomFS();
        }
    } else if (!update_disabled && update_raw != nullptr) {
        const auto new_nca = std::make_shared<NCA>(update_raw, romfs, ivfc_offset);
        if (new_nca->GetStatus() == Loader::ResultStatus::Success &&
            new_nca->GetRomFS() != nullptr) {
            LOG_INFO(Loader, "    RomFS: Update (PACKED) applied successfully");
            romfs = new_nca->GetRomFS();
        }
    }

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

    return romfs;
}

PatchManager::PatchVersionNames PatchManager::GetPatchVersionNames(VirtualFile update_raw) const {
    if (title_id == 0) {
        return {};
    }

    std::map<std::string, std::string, std::less<>> out;
    const auto& disabled = Settings::values.disabled_addons[title_id];

    // Game Updates
    const auto update_tid = GetUpdateTitleID(title_id);
    PatchManager update{update_tid, fs_controller, content_provider};
    const auto metadata = update.GetControlMetadata();
    const auto& nacp = metadata.first;

    const auto update_disabled =
        std::find(disabled.cbegin(), disabled.cend(), "Update") != disabled.cend();
    const auto update_label = update_disabled ? "[D] Update" : "Update";

    if (nacp != nullptr) {
        out.insert_or_assign(update_label, nacp->GetVersionString());
    } else {
        if (content_provider.HasEntry(update_tid, ContentRecordType::Program)) {
            const auto meta_ver = content_provider.GetEntryVersion(update_tid);
            if (meta_ver.value_or(0) == 0) {
                out.insert_or_assign(update_label, "");
            } else {
                out.insert_or_assign(update_label, FormatTitleVersion(*meta_ver));
            }
        } else if (update_raw != nullptr) {
            out.insert_or_assign(update_label, "PACKED");
        }
    }

    // General Mods (LayeredFS and IPS)
    const auto mod_dir = fs_controller.GetModificationLoadRoot(title_id);
    if (mod_dir != nullptr && mod_dir->GetSize() > 0) {
        for (const auto& mod : mod_dir->GetSubdirectories()) {
            std::string types;

            const auto exefs_dir = FindSubdirectoryCaseless(mod, "exefs");
            if (IsDirValidAndNonEmpty(exefs_dir)) {
                bool ips = false;
                bool ipswitch = false;
                bool layeredfs = false;

                for (const auto& file : exefs_dir->GetFiles()) {
                    if (file->GetExtension() == "ips") {
                        ips = true;
                    } else if (file->GetExtension() == "pchtxt") {
                        ipswitch = true;
                    } else if (std::find(EXEFS_FILE_NAMES.begin(), EXEFS_FILE_NAMES.end(),
                                         file->GetName()) != EXEFS_FILE_NAMES.end()) {
                        layeredfs = true;
                    }
                }

                if (ips)
                    AppendCommaIfNotEmpty(types, "IPS");
                if (ipswitch)
                    AppendCommaIfNotEmpty(types, "IPSwitch");
                if (layeredfs)
                    AppendCommaIfNotEmpty(types, "LayeredExeFS");
            }
            if (IsDirValidAndNonEmpty(FindSubdirectoryCaseless(mod, "romfs")))
                AppendCommaIfNotEmpty(types, "LayeredFS");
            if (IsDirValidAndNonEmpty(FindSubdirectoryCaseless(mod, "cheats")))
                AppendCommaIfNotEmpty(types, "Cheats");

            if (types.empty())
                continue;

            const auto mod_disabled =
                std::find(disabled.begin(), disabled.end(), mod->GetName()) != disabled.end();
            out.insert_or_assign(mod_disabled ? "[D] " + mod->GetName() : mod->GetName(), types);
        }
    }

    // DLC
    const auto dlc_entries =
        content_provider.ListEntriesFilter(TitleType::AOC, ContentRecordType::Data);
    std::vector<ContentProviderEntry> dlc_match;
    dlc_match.reserve(dlc_entries.size());
    std::copy_if(dlc_entries.begin(), dlc_entries.end(), std::back_inserter(dlc_match),
                 [this](const ContentProviderEntry& entry) {
                     return GetBaseTitleID(entry.title_id) == title_id &&
                            content_provider.GetEntry(entry)->GetStatus() ==
                                Loader::ResultStatus::Success;
                 });
    if (!dlc_match.empty()) {
        // Ensure sorted so DLC IDs show in order.
        std::sort(dlc_match.begin(), dlc_match.end());

        std::string list;
        for (size_t i = 0; i < dlc_match.size() - 1; ++i)
            list += fmt::format("{}, ", dlc_match[i].title_id & 0x7FF);

        list += fmt::format("{}", dlc_match.back().title_id & 0x7FF);

        const auto dlc_disabled =
            std::find(disabled.begin(), disabled.end(), "DLC") != disabled.end();
        out.insert_or_assign(dlc_disabled ? "[D] DLC" : "DLC", std::move(list));
    }

    return out;
}

std::optional<u32> PatchManager::GetGameVersion() const {
    const auto update_tid = GetUpdateTitleID(title_id);
    if (content_provider.HasEntry(update_tid, ContentRecordType::Program)) {
        return content_provider.GetEntryVersion(update_tid);
    }

    return content_provider.GetEntryVersion(title_id);
}

PatchManager::Metadata PatchManager::GetControlMetadata() const {
    const auto base_control_nca = content_provider.GetEntry(title_id, ContentRecordType::Control);
    if (base_control_nca == nullptr) {
        return {};
    }

    return ParseControlNCA(*base_control_nca);
}

PatchManager::Metadata PatchManager::ParseControlNCA(const 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");
    }

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

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

    return {std::move(nacp), icon_file};
}
} // namespace FileSys
