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

#include <regex>
#include <mbedtls/sha256.h>
#include "common/assert.h"
#include "common/hex_util.h"
#include "common/logging/log.h"
#include "core/crypto/encryption_layer.h"
#include "core/file_sys/card_image.h"
#include "core/file_sys/nca_metadata.h"
#include "core/file_sys/registered_cache.h"
#include "core/file_sys/vfs_concat.h"

namespace FileSys {
std::string RegisteredCacheEntry::DebugInfo() const {
    return fmt::format("title_id={:016X}, content_type={:02X}", title_id, static_cast<u8>(type));
}

bool operator<(const RegisteredCacheEntry& lhs, const RegisteredCacheEntry& rhs) {
    return (lhs.title_id < rhs.title_id) || (lhs.title_id == rhs.title_id && lhs.type < rhs.type);
}

static bool FollowsTwoDigitDirFormat(std::string_view name) {
    static const std::regex two_digit_regex("000000[0-9A-F]{2}", std::regex_constants::ECMAScript |
                                                                     std::regex_constants::icase);
    return std::regex_match(name.begin(), name.end(), two_digit_regex);
}

static bool FollowsNcaIdFormat(std::string_view name) {
    static const std::regex nca_id_regex("[0-9A-F]{32}\\.nca", std::regex_constants::ECMAScript |
                                                                   std::regex_constants::icase);
    return name.size() == 36 && std::regex_match(name.begin(), name.end(), nca_id_regex);
}

static std::string GetRelativePathFromNcaID(const std::array<u8, 16>& nca_id, bool second_hex_upper,
                                            bool within_two_digit) {
    if (!within_two_digit)
        return fmt::format("/{}.nca", Common::HexArrayToString(nca_id, second_hex_upper));

    Core::Crypto::SHA256Hash hash{};
    mbedtls_sha256(nca_id.data(), nca_id.size(), hash.data(), 0);
    return fmt::format("/000000{:02X}/{}.nca", hash[0],
                       Common::HexArrayToString(nca_id, second_hex_upper));
}

static std::string GetCNMTName(TitleType type, u64 title_id) {
    constexpr std::array<const char*, 9> TITLE_TYPE_NAMES{
        "SystemProgram",
        "SystemData",
        "SystemUpdate",
        "BootImagePackage",
        "BootImagePackageSafe",
        "Application",
        "Patch",
        "AddOnContent",
        "" ///< Currently unknown 'DeltaTitle'
    };

    auto index = static_cast<size_t>(type);
    // If the index is after the jump in TitleType, subtract it out.
    if (index >= static_cast<size_t>(TitleType::Application)) {
        index -= static_cast<size_t>(TitleType::Application) -
                 static_cast<size_t>(TitleType::FirmwarePackageB);
    }
    return fmt::format("{}_{:016x}.cnmt", TITLE_TYPE_NAMES[index], title_id);
}

static ContentRecordType GetCRTypeFromNCAType(NCAContentType type) {
    switch (type) {
    case NCAContentType::Program:
        // TODO(DarkLordZach): Differentiate between Program and Patch
        return ContentRecordType::Program;
    case NCAContentType::Meta:
        return ContentRecordType::Meta;
    case NCAContentType::Control:
        return ContentRecordType::Control;
    case NCAContentType::Data:
        return ContentRecordType::Data;
    case NCAContentType::Manual:
        // TODO(DarkLordZach): Peek at NCA contents to differentiate Manual and Legal.
        return ContentRecordType::Manual;
    default:
        UNREACHABLE();
    }
}

VirtualFile RegisteredCache::OpenFileOrDirectoryConcat(const VirtualDir& dir,
                                                       std::string_view path) const {
    if (dir->GetFileRelative(path) != nullptr)
        return dir->GetFileRelative(path);
    if (dir->GetDirectoryRelative(path) != nullptr) {
        const auto nca_dir = dir->GetDirectoryRelative(path);
        VirtualFile file = nullptr;

        const auto files = nca_dir->GetFiles();
        if (files.size() == 1 && files[0]->GetName() == "00") {
            file = files[0];
        } else {
            std::vector<VirtualFile> concat;
            // Since the files are a two-digit hex number, max is FF.
            for (size_t i = 0; i < 0x100; ++i) {
                auto next = nca_dir->GetFile(fmt::format("{:02X}", i));
                if (next != nullptr) {
                    concat.push_back(std::move(next));
                } else {
                    next = nca_dir->GetFile(fmt::format("{:02x}", i));
                    if (next != nullptr)
                        concat.push_back(std::move(next));
                    else
                        break;
                }
            }

            if (concat.empty())
                return nullptr;

            file = FileSys::ConcatenateFiles(concat);
        }

        return file;
    }
    return nullptr;
}

VirtualFile RegisteredCache::GetFileAtID(NcaID id) const {
    VirtualFile file;
    // Try all four modes of file storage:
    // (bit 1 = uppercase/lower, bit 0 = within a two-digit dir)
    // 00: /000000**/{:032X}.nca
    // 01: /{:032X}.nca
    // 10: /000000**/{:032x}.nca
    // 11: /{:032x}.nca
    for (u8 i = 0; i < 4; ++i) {
        const auto path = GetRelativePathFromNcaID(id, (i & 0b10) == 0, (i & 0b01) == 0);
        file = OpenFileOrDirectoryConcat(dir, path);
        if (file != nullptr)
            return file;
    }
    return file;
}

static boost::optional<NcaID> CheckMapForContentRecord(
    const boost::container::flat_map<u64, CNMT>& map, u64 title_id, ContentRecordType type) {
    if (map.find(title_id) == map.end())
        return boost::none;

    const auto& cnmt = map.at(title_id);

    const auto iter = std::find_if(cnmt.GetContentRecords().begin(), cnmt.GetContentRecords().end(),
                                   [type](const ContentRecord& rec) { return rec.type == type; });
    if (iter == cnmt.GetContentRecords().end())
        return boost::none;

    return boost::make_optional(iter->nca_id);
}

boost::optional<NcaID> RegisteredCache::GetNcaIDFromMetadata(u64 title_id,
                                                             ContentRecordType type) const {
    if (type == ContentRecordType::Meta && meta_id.find(title_id) != meta_id.end())
        return meta_id.at(title_id);

    const auto res1 = CheckMapForContentRecord(yuzu_meta, title_id, type);
    if (res1 != boost::none)
        return res1;
    return CheckMapForContentRecord(meta, title_id, type);
}

std::vector<NcaID> RegisteredCache::AccumulateFiles() const {
    std::vector<NcaID> ids;
    for (const auto& d2_dir : dir->GetSubdirectories()) {
        if (FollowsNcaIdFormat(d2_dir->GetName())) {
            ids.push_back(Common::HexStringToArray<0x10, true>(d2_dir->GetName().substr(0, 0x20)));
            continue;
        }

        if (!FollowsTwoDigitDirFormat(d2_dir->GetName()))
            continue;

        for (const auto& nca_dir : d2_dir->GetSubdirectories()) {
            if (!FollowsNcaIdFormat(nca_dir->GetName()))
                continue;

            ids.push_back(Common::HexStringToArray<0x10, true>(nca_dir->GetName().substr(0, 0x20)));
        }

        for (const auto& nca_file : d2_dir->GetFiles()) {
            if (!FollowsNcaIdFormat(nca_file->GetName()))
                continue;

            ids.push_back(
                Common::HexStringToArray<0x10, true>(nca_file->GetName().substr(0, 0x20)));
        }
    }

    for (const auto& d2_file : dir->GetFiles()) {
        if (FollowsNcaIdFormat(d2_file->GetName()))
            ids.push_back(Common::HexStringToArray<0x10, true>(d2_file->GetName().substr(0, 0x20)));
    }
    return ids;
}

void RegisteredCache::ProcessFiles(const std::vector<NcaID>& ids) {
    for (const auto& id : ids) {
        const auto file = GetFileAtID(id);

        if (file == nullptr)
            continue;
        const auto nca = std::make_shared<NCA>(parser(file, id));
        if (nca->GetStatus() != Loader::ResultStatus::Success ||
            nca->GetType() != NCAContentType::Meta) {
            continue;
        }

        const auto section0 = nca->GetSubdirectories()[0];

        for (const auto& file : section0->GetFiles()) {
            if (file->GetExtension() != "cnmt")
                continue;

            meta.insert_or_assign(nca->GetTitleId(), CNMT(file));
            meta_id.insert_or_assign(nca->GetTitleId(), id);
            break;
        }
    }
}

void RegisteredCache::AccumulateYuzuMeta() {
    const auto dir = this->dir->GetSubdirectory("yuzu_meta");
    if (dir == nullptr)
        return;

    for (const auto& file : dir->GetFiles()) {
        if (file->GetExtension() != "cnmt")
            continue;

        CNMT cnmt(file);
        yuzu_meta.insert_or_assign(cnmt.GetTitleID(), std::move(cnmt));
    }
}

void RegisteredCache::Refresh() {
    if (dir == nullptr)
        return;
    const auto ids = AccumulateFiles();
    ProcessFiles(ids);
    AccumulateYuzuMeta();
}

RegisteredCache::RegisteredCache(VirtualDir dir_, RegisteredCacheParsingFunction parsing_function)
    : dir(std::move(dir_)), parser(std::move(parsing_function)) {
    Refresh();
}

bool RegisteredCache::HasEntry(u64 title_id, ContentRecordType type) const {
    return GetEntryRaw(title_id, type) != nullptr;
}

bool RegisteredCache::HasEntry(RegisteredCacheEntry entry) const {
    return GetEntryRaw(entry) != nullptr;
}

VirtualFile RegisteredCache::GetEntryRaw(u64 title_id, ContentRecordType type) const {
    const auto id = GetNcaIDFromMetadata(title_id, type);
    if (id == boost::none)
        return nullptr;

    return parser(GetFileAtID(id.get()), id.get());
}

VirtualFile RegisteredCache::GetEntryRaw(RegisteredCacheEntry entry) const {
    return GetEntryRaw(entry.title_id, entry.type);
}

std::shared_ptr<NCA> RegisteredCache::GetEntry(u64 title_id, ContentRecordType type) const {
    const auto raw = GetEntryRaw(title_id, type);
    if (raw == nullptr)
        return nullptr;
    return std::make_shared<NCA>(raw);
}

std::shared_ptr<NCA> RegisteredCache::GetEntry(RegisteredCacheEntry entry) const {
    return GetEntry(entry.title_id, entry.type);
}

template <typename T>
void RegisteredCache::IterateAllMetadata(
    std::vector<T>& out, std::function<T(const CNMT&, const ContentRecord&)> proc,
    std::function<bool(const CNMT&, const ContentRecord&)> filter) const {
    for (const auto& kv : meta) {
        const auto& cnmt = kv.second;
        if (filter(cnmt, EMPTY_META_CONTENT_RECORD))
            out.push_back(proc(cnmt, EMPTY_META_CONTENT_RECORD));
        for (const auto& rec : cnmt.GetContentRecords()) {
            if (GetFileAtID(rec.nca_id) != nullptr && filter(cnmt, rec)) {
                out.push_back(proc(cnmt, rec));
            }
        }
    }
    for (const auto& kv : yuzu_meta) {
        const auto& cnmt = kv.second;
        for (const auto& rec : cnmt.GetContentRecords()) {
            if (GetFileAtID(rec.nca_id) != nullptr && filter(cnmt, rec)) {
                out.push_back(proc(cnmt, rec));
            }
        }
    }
}

std::vector<RegisteredCacheEntry> RegisteredCache::ListEntries() const {
    std::vector<RegisteredCacheEntry> out;
    IterateAllMetadata<RegisteredCacheEntry>(
        out,
        [](const CNMT& c, const ContentRecord& r) {
            return RegisteredCacheEntry{c.GetTitleID(), r.type};
        },
        [](const CNMT& c, const ContentRecord& r) { return true; });
    return out;
}

std::vector<RegisteredCacheEntry> RegisteredCache::ListEntriesFilter(
    boost::optional<TitleType> title_type, boost::optional<ContentRecordType> record_type,
    boost::optional<u64> title_id) const {
    std::vector<RegisteredCacheEntry> out;
    IterateAllMetadata<RegisteredCacheEntry>(
        out,
        [](const CNMT& c, const ContentRecord& r) {
            return RegisteredCacheEntry{c.GetTitleID(), r.type};
        },
        [&title_type, &record_type, &title_id](const CNMT& c, const ContentRecord& r) {
            if (title_type != boost::none && title_type.get() != c.GetType())
                return false;
            if (record_type != boost::none && record_type.get() != r.type)
                return false;
            if (title_id != boost::none && title_id.get() != c.GetTitleID())
                return false;
            return true;
        });
    return out;
}

static std::shared_ptr<NCA> GetNCAFromXCIForID(std::shared_ptr<XCI> xci, const NcaID& id) {
    const auto filename = fmt::format("{}.nca", Common::HexArrayToString(id, false));
    const auto iter =
        std::find_if(xci->GetNCAs().begin(), xci->GetNCAs().end(),
                     [&filename](std::shared_ptr<NCA> nca) { return nca->GetName() == filename; });
    return iter == xci->GetNCAs().end() ? nullptr : *iter;
}

InstallResult RegisteredCache::InstallEntry(std::shared_ptr<XCI> xci, bool overwrite_if_exists,
                                            const VfsCopyFunction& copy) {
    const auto& ncas = xci->GetNCAs();
    const auto& meta_iter = std::find_if(ncas.begin(), ncas.end(), [](std::shared_ptr<NCA> nca) {
        return nca->GetType() == NCAContentType::Meta;
    });

    if (meta_iter == ncas.end()) {
        LOG_ERROR(Loader, "The XCI you are attempting to install does not have a metadata NCA and "
                          "is therefore malformed. Double check your encryption keys.");
        return InstallResult::ErrorMetaFailed;
    }

    // Install Metadata File
    const auto meta_id_raw = (*meta_iter)->GetName().substr(0, 32);
    const auto meta_id = Common::HexStringToArray<16>(meta_id_raw);

    const auto res = RawInstallNCA(*meta_iter, copy, overwrite_if_exists, meta_id);
    if (res != InstallResult::Success)
        return res;

    // Install all the other NCAs
    const auto section0 = (*meta_iter)->GetSubdirectories()[0];
    const auto cnmt_file = section0->GetFiles()[0];
    const CNMT cnmt(cnmt_file);
    for (const auto& record : cnmt.GetContentRecords()) {
        const auto nca = GetNCAFromXCIForID(xci, record.nca_id);
        if (nca == nullptr)
            return InstallResult::ErrorCopyFailed;
        const auto res2 = RawInstallNCA(nca, copy, overwrite_if_exists, record.nca_id);
        if (res2 != InstallResult::Success)
            return res2;
    }

    Refresh();
    return InstallResult::Success;
}

InstallResult RegisteredCache::InstallEntry(std::shared_ptr<NCA> nca, TitleType type,
                                            bool overwrite_if_exists, const VfsCopyFunction& copy) {
    CNMTHeader header{
        nca->GetTitleId(), ///< Title ID
        0,                 ///< Ignore/Default title version
        type,              ///< Type
        {},                ///< Padding
        0x10,              ///< Default table offset
        1,                 ///< 1 Content Entry
        0,                 ///< No Meta Entries
        {},                ///< Padding
    };
    OptionalHeader opt_header{0, 0};
    ContentRecord c_rec{{}, {}, {}, GetCRTypeFromNCAType(nca->GetType()), {}};
    const auto& data = nca->GetBaseFile()->ReadBytes(0x100000);
    mbedtls_sha256(data.data(), data.size(), c_rec.hash.data(), 0);
    memcpy(&c_rec.nca_id, &c_rec.hash, 16);
    const CNMT new_cnmt(header, opt_header, {c_rec}, {});
    if (!RawInstallYuzuMeta(new_cnmt))
        return InstallResult::ErrorMetaFailed;
    return RawInstallNCA(nca, copy, overwrite_if_exists, c_rec.nca_id);
}

InstallResult RegisteredCache::RawInstallNCA(std::shared_ptr<NCA> nca, const VfsCopyFunction& copy,
                                             bool overwrite_if_exists,
                                             boost::optional<NcaID> override_id) {
    const auto in = nca->GetBaseFile();
    Core::Crypto::SHA256Hash hash{};

    // Calculate NcaID
    // NOTE: Because computing the SHA256 of an entire NCA is quite expensive (especially if the
    // game is massive), we're going to cheat and only hash the first MB of the NCA.
    // Also, for XCIs the NcaID matters, so if the override id isn't none, use that.
    NcaID id{};
    if (override_id == boost::none) {
        const auto& data = in->ReadBytes(0x100000);
        mbedtls_sha256(data.data(), data.size(), hash.data(), 0);
        memcpy(id.data(), hash.data(), 16);
    } else {
        id = override_id.get();
    }

    std::string path = GetRelativePathFromNcaID(id, false, true);

    if (GetFileAtID(id) != nullptr && !overwrite_if_exists) {
        LOG_WARNING(Loader, "Attempting to overwrite existing NCA. Skipping...");
        return InstallResult::ErrorAlreadyExists;
    }

    if (GetFileAtID(id) != nullptr) {
        LOG_WARNING(Loader, "Overwriting existing NCA...");
        VirtualDir c_dir;
        { c_dir = dir->GetFileRelative(path)->GetContainingDirectory(); }
        c_dir->DeleteFile(FileUtil::GetFilename(path));
    }

    auto out = dir->CreateFileRelative(path);
    if (out == nullptr)
        return InstallResult::ErrorCopyFailed;
    return copy(in, out) ? InstallResult::Success : InstallResult::ErrorCopyFailed;
}

bool RegisteredCache::RawInstallYuzuMeta(const CNMT& cnmt) {
    // Reasoning behind this method can be found in the comment for InstallEntry, NCA overload.
    const auto dir = this->dir->CreateDirectoryRelative("yuzu_meta");
    const auto filename = GetCNMTName(cnmt.GetType(), cnmt.GetTitleID());
    if (dir->GetFile(filename) == nullptr) {
        auto out = dir->CreateFile(filename);
        const auto buffer = cnmt.Serialize();
        out->Resize(buffer.size());
        out->WriteBytes(buffer);
    } else {
        auto out = dir->GetFile(filename);
        CNMT old_cnmt(out);
        // Returns true on change
        if (old_cnmt.UnionRecords(cnmt)) {
            out->Resize(0);
            const auto buffer = old_cnmt.Serialize();
            out->Resize(buffer.size());
            out->WriteBytes(buffer);
        }
    }
    Refresh();
    return std::find_if(yuzu_meta.begin(), yuzu_meta.end(),
                        [&cnmt](const std::pair<u64, CNMT>& kv) {
                            return kv.second.GetType() == cnmt.GetType() &&
                                   kv.second.GetTitleID() == cnmt.GetTitleID();
                        }) != yuzu_meta.end();
}
} // namespace FileSys
