#include <loaders/LoaderIMG.hpp>

#include <cassert>
#include <cctype>
#include <cstring>
#include <algorithm>

#include <rw/debug.hpp>

namespace {

constexpr size_t kAssetRecordSize{2048};

void to_lowercase_inplace(char* name) {
    size_t len = std::strlen(name);

    std::transform(
        name, name+len, name,
        [](char ch) -> char { return std::tolower(ch); }
    );
} // namespace

}

bool LoaderIMG::load(const std::filesystem::path& filepath) {
    assert(m_archive.empty());
    m_archive = filepath;

    auto dirPath = filepath;
    dirPath.replace_extension(".dir");

    std::ifstream file(dirPath.string(), std::ios::binary);
    if (!file.is_open()) {
        RW_ERROR("Failed to open " + dirPath.string());
        return false;
    }

    file.seekg(0, std::ios::end);
    auto fileSize = file.tellg();
    file.seekg(0);

    std::size_t expectedCount = fileSize / sizeof(LoaderIMGFile);
    m_assets.resize(expectedCount);

    file.read(reinterpret_cast<char*>(m_assets.data()), expectedCount * sizeof(LoaderIMGFile));

    if (file.fail() || file.gcount() != fileSize) {\
        m_assets.resize(file.gcount() / sizeof(LoaderIMGFile));
        RW_ERROR("Error reading records in IMG archive");
    }

    for (auto& asset : m_assets) {
        to_lowercase_inplace(asset.name);
    }

    auto imgPath = filepath;
    imgPath.replace_extension(".img");

    m_archive_stream.open(imgPath.string(), std::ios::binary);
    if (!m_archive_stream.is_open()) {
        RW_ERROR("Failed to open " << imgPath.string());
    }

    return true;
}

/// Get the information of a asset in the examining archive
bool LoaderIMG::findAssetInfo(const std::string& assetname,
                              LoaderIMGFile& out) {
    for (const auto& asset : m_assets) {
        if (assetname.compare(asset.name) == 0) {
            out = asset;
            return true;
        }
    }

    return false;
}

std::unique_ptr<char[]> LoaderIMG::loadToMemory(const std::string& assetname) {
    if (!m_archive_stream.is_open()) {
        return nullptr;
    }

    LoaderIMGFile assetInfo;
    bool found = findAssetInfo(assetname, assetInfo);

    if (!found) {
        RW_ERROR("Asset '" << assetname << "' not found!");
        return nullptr;
    }

    std::streamsize asset_size = assetInfo.size * kAssetRecordSize;
    auto raw_data = std::make_unique<char[]>(asset_size);
    m_archive_stream.seekg(assetInfo.offset * kAssetRecordSize);
    m_archive_stream.read(raw_data.get(), asset_size);

    if (m_archive_stream.gcount() != asset_size) {
        RW_ERROR("Error reading asset " << assetInfo.name);
    }

    return raw_data;
}

/// Writes the contents of assetname to filename
bool LoaderIMG::saveAsset(const std::string& assetname,
                          const std::string& filename) {
    auto raw_data = loadToMemory(assetname);
    if (!raw_data) {
        return false;
    }

    LoaderIMGFile asset;
    if (!findAssetInfo(assetname, asset)) {
        return false;
    }

    std::ofstream dump_file(filename, std::ios::binary);
    if (!dump_file.is_open()) {
        return false;
    }

    dump_file.write(raw_data.get(), kAssetRecordSize * asset.size);
    RW_MESSAGE("Saved " << assetname << " to disk with filename " << filename);

    return true;
}