/* Copyright (c) 2015 Stanislaw Halik
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 */

#pragma once

#include "plugin-api.hpp"

#include <memory>
#include <algorithm>
#include <cstring>

#include <QDebug>
#include <QString>
#include <QLibrary>
#include <QList>
#include <QDir>
#include <QList>
#include <QIcon>

#if defined(__APPLE__)
#   define OPENTRACK_SOLIB_EXT "dylib"
#elif defined(_WIN32)
#   define OPENTRACK_SOLIB_EXT "dll"
#else
#   define OPENTRACK_SOLIB_EXT "so"
#endif

#ifdef _MSC_VER
#   define OPENTRACK_SOLIB_PREFIX ""
#else
#   define OPENTRACK_SOLIB_PREFIX "lib"
#endif

extern "C" typedef void* (*OPENTRACK_CTOR_FUNPTR)(void);
extern "C" typedef Metadata* (*OPENTRACK_METADATA_FUNPTR)(void);

struct dylib final
{
    enum Type : unsigned { Filter = 0xdeadbabeu, Tracker = 0xcafebeefu, Protocol = 0xdeadf00du, Invalid = 0xcafebabeu };

    dylib(const QString& filename_, Type t) :
        type(Invalid),
        full_filename(filename_),
        module_name(trim_filename(filename_)),
        Dialog(nullptr),
        Constructor(nullptr),
        Meta(nullptr)
    {
        // otherwise dlopen opens the calling executable
        if (filename_.size() == 0 || module_name.size() == 0)
            return;

        handle.setFileName(filename_);
        handle.setLoadHints(QLibrary::DeepBindHint | QLibrary::ResolveAllSymbolsHint);

        if (check(!handle.load()))
            return;

        if (check((Dialog = (OPENTRACK_CTOR_FUNPTR) handle.resolve("GetDialog"), !Dialog)))
            return;

        if (check((Constructor = (OPENTRACK_CTOR_FUNPTR) handle.resolve("GetConstructor"), !Constructor)))
            return;

        if (check((Meta = (OPENTRACK_METADATA_FUNPTR) handle.resolve("GetMetadata"), !Meta)))
            return;

        auto m = std::unique_ptr<Metadata>(Meta());

        icon = m->icon();
        name = m->name();

        type = t;
    }
    ~dylib()
    {
        // QLibrary refcounts the .dll's so don't forcefully unload
    }

    static QList<std::shared_ptr<dylib>> enum_libraries(const QString& library_path)
    {
        QDir module_directory(library_path);
        QList<std::shared_ptr<dylib>> ret;

        static const struct filter_ {
            Type type;
            QString glob;
        } filters[] = {
            { Filter, QStringLiteral(OPENTRACK_SOLIB_PREFIX "opentrack-filter-*." OPENTRACK_SOLIB_EXT), },
            { Tracker, QStringLiteral(OPENTRACK_SOLIB_PREFIX "opentrack-tracker-*." OPENTRACK_SOLIB_EXT), },
            { Protocol, QStringLiteral(OPENTRACK_SOLIB_PREFIX "opentrack-proto-*." OPENTRACK_SOLIB_EXT), },
        };

        for (const filter_& filter : filters)
        {
            for (const QString& filename : module_directory.entryList({ filter.glob }, QDir::Files, QDir::Name))
            {
                std::shared_ptr<dylib> lib = std::make_shared<dylib>(QStringLiteral("%1/%2").arg(library_path).arg(filename), filter.type);

                if (lib->type == Invalid)
                    continue;

                if (std::any_of(ret.cbegin(),
                                ret.cend(),
                                [&lib](const std::shared_ptr<dylib>& a) {
                                    return a->type == lib->type && a->name == lib->name;
                                }))
                {
                    qDebug() << "duplicate lib" << filename << "ident" << lib->name;
                    continue;
                }

                ret.push_back(lib);
            }
        }

        return ret;
    }

    Type type;
    QString full_filename;
    QString module_name;

    QIcon icon;
    QString name;

    OPENTRACK_CTOR_FUNPTR Dialog;
    OPENTRACK_CTOR_FUNPTR Constructor;
    OPENTRACK_METADATA_FUNPTR Meta;
private:
    QLibrary handle;

    static QString trim_filename(const QString& in_)
    {
        QStringRef in(&in_);

        const int idx = in.lastIndexOf("/");

        if (idx != -1)
        {
            in = in.mid(idx + 1);

            if (in.startsWith(OPENTRACK_SOLIB_PREFIX) &&
                in.endsWith("." OPENTRACK_SOLIB_EXT))
            {
                static constexpr unsigned pfx_len = sizeof(OPENTRACK_SOLIB_PREFIX) - 1;
                static constexpr unsigned rst_len = sizeof("." OPENTRACK_SOLIB_EXT) - 1;

                in = in.mid(pfx_len);
                in = in.left(in.size() - rst_len);

                static const char* names[] =
                {
                    "opentrack-tracker-",
                    "opentrack-proto-",
                    "opentrack-filter-",
                };

                for (auto name : names)
                {
                    if (in.startsWith(name))
                        return in.mid(std::strlen(name)).toString();
                }
            }
        }
        return QStringLiteral("");
    }

    bool check(bool fail)
    {
        if (fail)
        {
            qDebug() << "library" << module_name << "failed:" << handle.errorString();

            if (handle.isLoaded())
                (void) handle.unload();

            Constructor = nullptr;
            Dialog = nullptr;
            Meta = nullptr;

            type = Invalid;
        }

        return fail;
    }
};

struct Modules final
{
    using dylib_ptr = std::shared_ptr<dylib>;
    using dylib_list = QList<dylib_ptr>;

    Modules(const QString& library_path) :
        module_list(dylib::enum_libraries(library_path)),
        filter_modules(filter(dylib::Filter)),
        tracker_modules(filter(dylib::Tracker)),
        protocol_modules(filter(dylib::Protocol))
    {}
    dylib_list& filters() { return filter_modules; }
    dylib_list& trackers() { return tracker_modules; }
    dylib_list& protocols() { return protocol_modules; }
private:
    dylib_list module_list;
    dylib_list filter_modules;
    dylib_list tracker_modules;
    dylib_list protocol_modules;

    static dylib_list& sorted(dylib_list& xs)
    {
        std::sort(xs.begin(), xs.end(), [&](const dylib_ptr& a, const dylib_ptr& b) { return a->name.toLower() < b->name.toLower(); });
        return xs;
    }

    dylib_list filter(dylib::Type t)
    {
        QList<std::shared_ptr<dylib>> ret;
        for (auto x : module_list)
            if (x->type == t)
                ret.push_back(x);

        return sorted(ret);
    }
};

template<typename t>
static inline std::shared_ptr<t> make_dylib_instance(const std::shared_ptr<dylib>& lib)
{
    std::shared_ptr<t> ret;
    if (lib != nullptr && lib->Constructor)
        ret = std::shared_ptr<t>(reinterpret_cast<t*>(reinterpret_cast<OPENTRACK_CTOR_FUNPTR>(lib->Constructor)()));
    return ret;
}