// BeamMP, the BeamNG.drive multiplayer mod.
// Copyright (C) 2024 BeamMP Ltd., BeamMP team and contributors.
//
// BeamMP Ltd. can be contacted by electronic mail via contact@beammp.com.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#include "TResourceManager.h"
#include "Common.h"

#include <algorithm>
#include <filesystem>
#include <fmt/core.h>
#include <ios>
#include <nlohmann/json.hpp>
#include <openssl/evp.h>

namespace fs = std::filesystem;

TResourceManager::TResourceManager() {
    Application::SetSubsystemStatus("ResourceManager", Application::Status::Starting);
    std::string Path = Application::Settings.getAsString(Settings::Key::General_ResourceFolder) + "/Client";
    if (!fs::exists(Path))
        fs::create_directories(Path);
    for (const auto& entry : fs::directory_iterator(Path)) {
        std::string File(entry.path().string());
        if (auto pos = File.find(".zip"); pos != std::string::npos) {
            if (File.length() - pos == 4) {
                std::replace(File.begin(), File.end(), '\\', '/');
                mFileList += File + ';';
                if (auto i = File.find_last_of('/'); i != std::string::npos) {
                    ++i;
                    File = File.substr(i, pos - i);
                }
                mTrimmedList += "/" + fs::path(File).filename().string() + ';';
                mFileSizes += std::to_string(size_t(fs::file_size(entry.path()))) + ';';
                mMaxModSize += size_t(fs::file_size(entry.path()));
                mModsLoaded++;
            }
        }
    }

    if (mModsLoaded) {
        beammp_info("Loaded " + std::to_string(mModsLoaded) + " Mods");
    }

    Application::SetSubsystemStatus("ResourceManager", Application::Status::Good);
}

std::string TResourceManager::NewFileList() const {
    return mMods.dump();
}
void TResourceManager::RefreshFiles() {
    mMods.clear();
    std::unique_lock Lock(mModsMutex);

    std::string Path = Application::Settings.getAsString(Settings::Key::General_ResourceFolder) + "/Client";
    for (const auto& entry : fs::directory_iterator(Path)) {
        std::string File(entry.path().string());

        if (entry.path().extension() != ".zip" || std::filesystem::is_directory(entry.path())) {
            beammp_warnf("'{}' is not a ZIP file and will be ignored", File);
            continue;
        }

        try {
            EVP_MD_CTX* mdctx;
            const EVP_MD* md;
            uint8_t sha256_value[EVP_MAX_MD_SIZE];
            md = EVP_sha256();
            if (md == nullptr) {
                throw std::runtime_error("EVP_sha256() failed");
            }

            mdctx = EVP_MD_CTX_new();
            if (mdctx == nullptr) {
                throw std::runtime_error("EVP_MD_CTX_new() failed");
            }
            if (!EVP_DigestInit_ex2(mdctx, md, NULL)) {
                EVP_MD_CTX_free(mdctx);
                throw std::runtime_error("EVP_DigestInit_ex2() failed");
            }

            std::ifstream stream(File, std::ios::binary);

            const size_t FileSize = std::filesystem::file_size(File);
            size_t Read = 0;
            std::vector<char> Data;
            while (Read < FileSize) {
                Data.resize(size_t(std::min<size_t>(FileSize - Read, 4096)));
                size_t RealDataSize = Data.size();
                stream.read(Data.data(), std::streamsize(Data.size()));
                if (stream.eof() || stream.fail()) {
                    RealDataSize = size_t(stream.gcount());
                }
                Data.resize(RealDataSize);
                if (RealDataSize == 0) {
                    break;
                }
                if (RealDataSize > 0 && !EVP_DigestUpdate(mdctx, Data.data(), Data.size())) {
                    EVP_MD_CTX_free(mdctx);
                    throw std::runtime_error("EVP_DigestUpdate() failed");
                }
                Read += RealDataSize;
            }
            unsigned int sha256_len = 0;
            if (!EVP_DigestFinal_ex(mdctx, sha256_value, &sha256_len)) {
                EVP_MD_CTX_free(mdctx);
                throw std::runtime_error("EVP_DigestFinal_ex() failed");
            }
            EVP_MD_CTX_free(mdctx);

            std::string result;
            for (size_t i = 0; i < sha256_len; i++) {
                result += fmt::format("{:02x}", sha256_value[i]);
            }
            beammp_debugf("sha256('{}'): {}", File, result);
            mMods.push_back(nlohmann::json {
                { "file_name", std::filesystem::path(File).filename() },
                { "file_size", Read },
                { "hash_algorithm", "sha256" },
                { "hash", result },
            });
        } catch (const std::exception& e) {
            beammp_errorf("Sha256 hashing of '{}' failed: {}", File, e.what());
        }
    }
}