#include <iostream>
#include <stdexcept>
#include <optional>
#include <filesystem>
#include <senseApis/senseApiManager.h>
#include <senseApis/senseApiLib.h>
#include <opts.h>
#include <user/senseApiDesc.h>

namespace fs = std::filesystem;

namespace hk {
namespace sense_api {

struct DlCloser {
    void operator()(void* handle) const {
        if (handle) {
            dlclose(handle);
        }
    }
};

static std::optional<std::string> findLibraryPath(
    const std::string& libraryPath)
{
    std::vector<std::string> searchPaths = {
        fs::current_path().string(),
        fs::path("/proc/self/exe").parent_path().string()
    };

    if (!OptionParser::getOptions().senseApiLibPath.empty())
    {
        searchPaths.insert(
            searchPaths.begin(), OptionParser::getOptions().senseApiLibPath);
    }

    for (const auto& path : searchPaths)
    {
        fs::path fullPath = fs::path(path) / libraryPath;
        if (fs::exists(fullPath))
        {
            return fullPath.string();
        }
    }

    std::cerr << std::string(__func__) + ": library '"
              + libraryPath + "' isn't in search bespoke search paths: ";
    for (const auto& path : searchPaths)
    {
        std::cerr << path << " ";
    }
    std::cerr << std::endl;
    std::cerr << "Trying to load " + libraryPath + " from system default search "
        "paths\n";

    return std::nullopt;
}

SenseApiLib& SenseApiManager::loadSenseApiLib(const std::string& libraryPath)
{
    const CSenseApiDesc *libApiDesc;
    std::optional<std::string> fullPath = findLibraryPath(libraryPath);
    std::string resolvedPath = fullPath.value_or(libraryPath);

    // Clear any existing error
    dlerror();
    auto dlopen_handle = std::unique_ptr<void, DlCloser>(
        dlopen(resolvedPath.c_str(), RTLD_LAZY));
    if (!dlopen_handle && fullPath.has_value())
    {
        // Fallback to using the supplied libraryPath
        dlerror();
        dlopen_handle.reset(dlopen(libraryPath.c_str(), RTLD_LAZY));
    }

    if (!dlopen_handle)
    {
        const char *dlerr = dlerror();

        std::string error = (dlerr
            ? dlerr
            : "Unknown error while opening shlib");
        throw std::runtime_error(
            std::string(__func__) + ": Cannot load library '"
            + libraryPath + "': "
            + error);
    }

    // Initialize getSenseApiDescriptor
    auto func = reinterpret_cast<getSenseApiDescFn *>(
        dlsym(dlopen_handle.get(), HK_GET_SENSE_API_DESC_FN_NAME_STR));
    if (!func)
    {
        throw std::runtime_error(
            std::string(__func__) + ": dlsym('"
            HK_GET_SENSE_API_DESC_FN_NAME_STR "') failed for library '"
            + libraryPath + "'");
    }

    libApiDesc = func();
    if (!libApiDesc)
    {
        throw std::runtime_error(
            std::string(__func__) + ": getSenseApiDesc() returned NULL for "
            "library '" + libraryPath + "'");
    }

    auto lib = std::make_unique<SenseApiLib>(
        libraryPath, dlopen_handle.release(), func);
    lib->setSenseApiDesc(libApiDesc);
    senseApiLibs.push_back(std::move(lib));
    return *senseApiLibs.back();
}

std::optional<std::reference_wrapper<SenseApiLib>>
SenseApiManager::getSenseApiLib(const std::string& libraryPath)
{
    auto it = std::find_if(senseApiLibs.begin(), senseApiLibs.end(),
        [&libPath = libraryPath](const std::unique_ptr<SenseApiLib>& lib) {
            return lib->libraryPath == libPath;
        }
    );

    if (it != senseApiLibs.end()) { return **it; }
    return std::nullopt;
}

void SenseApiManager::unloadSenseApiLib(const std::string& libraryPath)
{
    auto it = std::find_if(senseApiLibs.begin(), senseApiLibs.end(),
        [&lpath = libraryPath](const std::unique_ptr<SenseApiLib>& lib) {
            return lib->libraryPath == lpath;
        }
    );

    if (it != senseApiLibs.end())
    {
        senseApiLibs.erase(it);
        return;
    }

    std::cerr << std::string(__func__) + ": Library not found: "
        << libraryPath << '\n';
}

void SenseApiManager::loadAllSenseApiLibsFromOptions()
{
    const auto& options = OptionParser::getOptions();
    for (const auto& libPath : options.senseApiLibs) {
        loadSenseApiLib(libPath);
    }
}

std::string SenseApiManager::stringifyLibs() const
{
    std::string result;
    for (const auto& lib : senseApiLibs) {
        result += lib->stringify() + "\n";
    }
    return result;
}

} // namespace sense_api
} // namespace hk