#include "thunderstore.h"

#include "Engine/Core/Json/json.h"
#include "Engine/Vfs/mod_list.h"

#include <Windows.h>

#include <miniz.h>

#include <algorithm>
#include <array>
#include <cstdlib>
#include <stdexcept>

namespace dingosdk::thunderstore {
namespace {

[[noreturn]] void fail(const std::string& message) { throw std::runtime_error(message); }

std::wstring widen(std::string_view value) {
    if (value.empty()) return {};
    const auto length = MultiByteToWideChar(CP_UTF8, 0, value.data(), static_cast<int>(value.size()), nullptr, 0);
    std::wstring output(static_cast<std::size_t>(std::max(length, 0)), L'\0');
    MultiByteToWideChar(CP_UTF8, 0, value.data(), static_cast<int>(value.size()), output.data(), length);
    return output;
}

// Thunderstore's own rule for names and namespaces.
bool plain_name(std::string_view value) {
    return !value.empty() && std::all_of(value.begin(), value.end(), [](char ch) {
        return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || (ch >= '0' && ch <= '9') || ch == '_';
    });
}

std::string text(const Json& row, std::string_view key) {
    return row.contains(key) && row.at(key).is_string() ? row.at(key).string() : std::string();
}

std::uint64_t count(const Json& row, std::string_view key) {
    if (!row.contains(key) || !row.at(key).is_number()) return 0;
    const auto value = row.at(key).get<double>();
    return value > 0 ? static_cast<std::uint64_t>(value) : 0;
}

bool flag(const Json& row, std::string_view key) {
    return row.contains(key) && row.at(key).is_boolean() && row.at(key).get<bool>();
}

std::vector<std::string> strings(const Json& row, std::string_view key) {
    std::vector<std::string> result;
    if (!row.contains(key) || !row.at(key).is_array()) return result;
    for (const auto& item : row.at(key))
        if (item.is_string()) result.push_back(item.string());
    return result;
}

bool https(std::string_view url) { return url.starts_with("https://"); }

std::optional<Version> parse_version(const Json& row) {
    if (!row.is_object() || (row.contains("is_active") && !flag(row, "is_active"))) return std::nullopt;
    Version version;
    version.number = text(row, "version_number");
    version.full_name = text(row, "full_name");
    version.description = text(row, "description");
    version.icon = text(row, "icon");
    version.download_url = text(row, "download_url");
    version.website_url = text(row, "website_url");
    version.date_created = text(row, "date_created");
    version.downloads = count(row, "downloads");
    version.file_size = count(row, "file_size");
    if (version.number.empty() || !https(version.download_url)) return std::nullopt;
    if (!https(version.icon)) version.icon.clear();
    return version;
}

std::optional<Package> parse_package(const Json& row) {
    if (!row.is_object()) return std::nullopt;
    Package package;
    package.name = text(row, "name");
    package.owner = text(row, "owner");
    package.full_name = text(row, "full_name");
    package.package_url = text(row, "package_url");
    package.date_created = text(row, "date_created");
    package.date_updated = text(row, "date_updated");
    package.categories = strings(row, "categories");
    package.rating = static_cast<int>(std::min<std::uint64_t>(count(row, "rating_score"), 1u << 30));
    package.pinned = flag(row, "is_pinned");
    package.deprecated = flag(row, "is_deprecated");
    package.nsfw = flag(row, "has_nsfw_content");
    if (!plain_name(package.name) || !plain_name(package.owner) ||
        package.full_name != package.owner + "-" + package.name) return std::nullopt;
    if (!https(package.package_url)) package.package_url.clear();
    if (row.contains("versions") && row.at("versions").is_array())
        for (const auto& item : row.at("versions"))
            if (auto version = parse_version(item)) {
                package.downloads += version->downloads;
                package.versions.push_back(std::move(*version));
            }
    if (package.versions.empty()) return std::nullopt;
    std::stable_sort(package.versions.begin(), package.versions.end(),
        [](const Version& a, const Version& b) { return compare_versions(a.number, b.number) > 0; });
    return package;
}

constexpr JsonLimits listing_limits{256ull * 1024 * 1024, 16, 64ull * 1024 * 1024};

std::uint32_t little32(const unsigned char* bytes) {
    return bytes[0] | (bytes[1] << 8) | (bytes[2] << 16) | (static_cast<std::uint32_t>(bytes[3]) << 24);
}

} // namespace

std::string community() {
    std::array<char, 128> value{};
    std::size_t length{};
    if (getenv_s(&length, value.data(), value.size(), "RESKATE_THUNDERSTORE_COMMUNITY") == 0 && length > 1) {
        const std::string name(value.data());
        const bool slug = std::all_of(name.begin(), name.end(), [](char ch) {
            return (ch >= 'a' && ch <= 'z') || (ch >= '0' && ch <= '9') || ch == '-';
        });
        if (slug) return name;
    }
    return default_community;
}

std::wstring listing_index_url(std::string_view community) {
    return widen(std::string(site) + "/c/" + std::string(community) + "/api/v1/package-listing-index/");
}

std::wstring listing_url(std::string_view community) {
    return widen(std::string(site) + "/c/" + std::string(community) + "/api/v1/package/");
}

std::wstring community_page(std::string_view community) {
    return widen(std::string(site) + "/c/" + std::string(community) + "/");
}

std::string Package::title() const {
    auto result = name;
    std::replace(result.begin(), result.end(), '_', ' ');
    return result;
}

bool Package::in_category(std::string_view category) const {
    return std::find(categories.begin(), categories.end(), category) != categories.end();
}

std::vector<Package> parse_listing(std::string_view json) {
    const auto root = Json::parse(json, listing_limits);
    if (!root.is_array()) fail("The Thunderstore listing is not a JSON array.");
    std::vector<Package> packages;
    for (const auto& row : root)
        if (auto package = parse_package(row)) packages.push_back(std::move(*package));
    return packages;
}

std::vector<std::wstring> parse_index(std::string_view json) {
    const auto root = Json::parse(json, JsonLimits{1024 * 1024, 4, 65536});
    if (!root.is_array()) fail("The Thunderstore listing index is not a JSON array.");
    std::vector<std::wstring> urls;
    for (const auto& item : root) {
        if (!item.is_string() || !https(item.string())) fail("The Thunderstore listing index names a non-HTTPS chunk.");
        urls.push_back(widen(item.string()));
    }
    return urls;
}

std::string gunzip(std::string_view data, std::size_t limit) {
    const auto* bytes = reinterpret_cast<const unsigned char*>(data.data());
    if (data.size() < 2 || bytes[0] != 0x1f || bytes[1] != 0x8b) {
        if (data.size() > limit) fail("The Thunderstore listing is too large.");
        return std::string(data);
    }
    if (data.size() < 18 || bytes[2] != 8) fail("The Thunderstore listing is not a gzip stream miniz can read.");
    const unsigned flags = bytes[3];
    std::size_t offset = 10;
    const auto need = [&](std::size_t more) { if (offset + more > data.size() - 8) fail("The Thunderstore listing is truncated."); };
    if (flags & 0x04) { // FEXTRA
        need(2);
        const std::size_t extra = bytes[offset] | (bytes[offset + 1] << 8);
        offset += 2;
        need(extra);
        offset += extra;
    }
    for (const unsigned field : {0x08u, 0x10u}) { // FNAME, FCOMMENT: zero-terminated
        if (!(flags & field)) continue;
        while (true) { need(1); if (bytes[offset++] == 0) break; }
    }
    if (flags & 0x02) { need(2); offset += 2; } // FHCRC
    const auto crc = little32(bytes + data.size() - 8);
    const std::size_t size = little32(bytes + data.size() - 4);
    if (size > limit) fail("The Thunderstore listing is too large.");
    std::string output(size, '\0');
    const auto written = tinfl_decompress_mem_to_mem(output.data(), output.size(), bytes + offset,
        data.size() - 8 - offset, 0);
    if (written == TINFL_DECOMPRESS_MEM_TO_MEM_FAILED || written != size ||
        mz_crc32(MZ_CRC32_INIT, reinterpret_cast<const unsigned char*>(output.data()), output.size()) != crc)
        fail("The Thunderstore listing is damaged (gzip check failed).");
    return output;
}

int compare_versions(std::string_view a, std::string_view b) {
    while (!a.empty() || !b.empty()) {
        const auto take = [](std::string_view& value) {
            const auto dot = value.find('.');
            const auto part = value.substr(0, dot);
            value = dot == std::string_view::npos ? std::string_view() : value.substr(dot + 1);
            return part;
        };
        const auto left = take(a), right = take(b);
        const bool numeric = left.find_first_not_of("0123456789") == std::string_view::npos &&
                             right.find_first_not_of("0123456789") == std::string_view::npos;
        if (numeric) {
            // Leading zeros aside, the longer number is the larger one.
            auto l = left.substr(std::min(left.find_first_not_of('0'), left.size()));
            auto r = right.substr(std::min(right.find_first_not_of('0'), right.size()));
            if (l.size() != r.size()) return l.size() < r.size() ? -1 : 1;
            if (const auto order = l.compare(r)) return order < 0 ? -1 : 1;
        } else if (const auto order = left.compare(right)) {
            return order < 0 ? -1 : 1;
        }
    }
    return 0;
}

std::string folder_for(std::string_view full_name) {
    return std::string(full_name.substr(0, std::min(full_name.size(), mods::maximum_mod_name)));
}

bool update_available(const Package& package, const Installed& installed) {
    const auto found = installed.find(folder_for(package.full_name));
    return found != installed.end() && !found->second.empty() && compare_versions(package.latest().number, found->second) > 0;
}

} // namespace dingosdk::thunderstore