#ifndef EAX_EFFECT_INCLUDED
#define EAX_EFFECT_INCLUDED


#include <cassert>
#include <memory>

#include "alnumeric.h"
#include "AL/al.h"
#include "core/effects/base.h"
#include "call.h"

struct EaxEffectErrorMessages
{
    static constexpr auto unknown_property_id() noexcept { return "Unknown property id."; }
    static constexpr auto unknown_version() noexcept { return "Unknown version."; }
}; // EaxEffectErrorMessages

/* TODO: Use std::variant (C++17). */
enum class EaxEffectType {
    None, Reverb, Chorus, Autowah, Compressor, Distortion, Echo, Equalizer, Flanger,
    FrequencyShifter, Modulator, PitchShifter, VocalMorpher
};
struct EaxEffectProps {
    EaxEffectType mType;
    union {
        EAXREVERBPROPERTIES mReverb;
        EAXCHORUSPROPERTIES mChorus;
        EAXAUTOWAHPROPERTIES mAutowah;
        EAXAGCCOMPRESSORPROPERTIES mCompressor;
        EAXDISTORTIONPROPERTIES mDistortion;
        EAXECHOPROPERTIES mEcho;
        EAXEQUALIZERPROPERTIES mEqualizer;
        EAXFLANGERPROPERTIES mFlanger;
        EAXFREQUENCYSHIFTERPROPERTIES mFrequencyShifter;
        EAXRINGMODULATORPROPERTIES mModulator;
        EAXPITCHSHIFTERPROPERTIES mPitchShifter;
        EAXVOCALMORPHERPROPERTIES mVocalMorpher;
    };
};

constexpr ALenum EnumFromEaxEffectType(const EaxEffectProps &props)
{
    switch(props.mType)
    {
    case EaxEffectType::None: break;
    case EaxEffectType::Reverb: return AL_EFFECT_EAXREVERB;
    case EaxEffectType::Chorus: return AL_EFFECT_CHORUS;
    case EaxEffectType::Autowah: return AL_EFFECT_AUTOWAH;
    case EaxEffectType::Compressor: return AL_EFFECT_COMPRESSOR;
    case EaxEffectType::Distortion: return AL_EFFECT_DISTORTION;
    case EaxEffectType::Echo: return AL_EFFECT_ECHO;
    case EaxEffectType::Equalizer: return AL_EFFECT_EQUALIZER;
    case EaxEffectType::Flanger: return AL_EFFECT_FLANGER;
    case EaxEffectType::FrequencyShifter: return AL_EFFECT_FREQUENCY_SHIFTER;
    case EaxEffectType::Modulator: return AL_EFFECT_RING_MODULATOR;
    case EaxEffectType::PitchShifter: return AL_EFFECT_PITCH_SHIFTER;
    case EaxEffectType::VocalMorpher: return AL_EFFECT_VOCAL_MORPHER;
    }
    return AL_EFFECT_NULL;
}

struct EaxReverbCommitter {
    struct Exception;

    EaxReverbCommitter(EaxEffectProps &eaxprops, EffectProps &alprops)
        : props_{eaxprops}, al_effect_props_{alprops}
    { }

    EaxEffectProps &props_;
    EffectProps &al_effect_props_;

    [[noreturn]] static void fail(const char* message);
    [[noreturn]] static void fail_unknown_property_id()
    { fail(EaxEffectErrorMessages::unknown_property_id()); }

    template<typename TValidator, typename TProperty>
    static void defer(const EaxCall& call, TProperty& property)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        property = value;
    }

    template<typename TValidator, typename TDeferrer, typename TProperties, typename TProperty>
    static void defer(const EaxCall& call, TProperties& properties, TProperty&)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        TDeferrer{}(properties, value);
    }

    template<typename TValidator, typename TProperty>
    static void defer3(const EaxCall& call, EAXREVERBPROPERTIES& properties, TProperty& property)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        if (value == property)
            return;
        property = value;
        properties.ulEnvironment = EAX_ENVIRONMENT_UNDEFINED;
    }


    bool commit(const EAX_REVERBPROPERTIES &props);
    bool commit(const EAX20LISTENERPROPERTIES &props);
    bool commit(const EAXREVERBPROPERTIES &props);
    bool commit(const EaxEffectProps &props);

    static void SetDefaults(EAX_REVERBPROPERTIES &props);
    static void SetDefaults(EAX20LISTENERPROPERTIES &props);
    static void SetDefaults(EAXREVERBPROPERTIES &props);
    static void SetDefaults(EaxEffectProps &props);

    static void Get(const EaxCall &call, const EAX_REVERBPROPERTIES &props);
    static void Get(const EaxCall &call, const EAX20LISTENERPROPERTIES &props);
    static void Get(const EaxCall &call, const EAXREVERBPROPERTIES &props);
    static void Get(const EaxCall &call, const EaxEffectProps &props);

    static void Set(const EaxCall &call, EAX_REVERBPROPERTIES &props);
    static void Set(const EaxCall &call, EAX20LISTENERPROPERTIES &props);
    static void Set(const EaxCall &call, EAXREVERBPROPERTIES &props);
    static void Set(const EaxCall &call, EaxEffectProps &props);

    static void translate(const EAX_REVERBPROPERTIES& src, EaxEffectProps& dst) noexcept;
    static void translate(const EAX20LISTENERPROPERTIES& src, EaxEffectProps& dst) noexcept;
    static void translate(const EAXREVERBPROPERTIES& src, EaxEffectProps& dst) noexcept;
};

template<typename T>
struct EaxCommitter {
    struct Exception;

    EaxCommitter(EaxEffectProps &eaxprops, EffectProps &alprops)
        : props_{eaxprops}, al_effect_props_{alprops}
    { }

    EaxEffectProps &props_;
    EffectProps &al_effect_props_;

    template<typename TValidator, typename TProperty>
    static void defer(const EaxCall& call, TProperty& property)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        property = value;
    }

    template<typename TValidator, typename TDeferrer, typename TProperties, typename TProperty>
    static void defer(const EaxCall& call, TProperties& properties, TProperty&)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        TDeferrer{}(properties, value);
    }

    [[noreturn]] static void fail(const char *message);
    [[noreturn]] static void fail_unknown_property_id()
    { fail(EaxEffectErrorMessages::unknown_property_id()); }

    bool commit(const EaxEffectProps &props);

    static void SetDefaults(EaxEffectProps &props);
    static void Get(const EaxCall &call, const EaxEffectProps &props);
    static void Set(const EaxCall &call, EaxEffectProps &props);
};

struct EaxNullCommitter : public EaxCommitter<EaxNullCommitter> {
    using EaxCommitter<EaxNullCommitter>::EaxCommitter;
};


class EaxEffect {
public:
    EaxEffect() noexcept = default;
    virtual ~EaxEffect() = default;

    ALenum al_effect_type_{AL_EFFECT_NULL};
    EffectProps al_effect_props_{};

    using Props1 = EAX_REVERBPROPERTIES;
    using Props2 = EAX20LISTENERPROPERTIES;
    using Props3 = EAXREVERBPROPERTIES;
    using Props4 = EaxEffectProps;

    struct State1 {
        Props1 i; // Immediate.
        Props1 d; // Deferred.
    };

    struct State2 {
        Props2 i; // Immediate.
        Props2 d; // Deferred.
    };

    struct State3 {
        Props3 i; // Immediate.
        Props3 d; // Deferred.
    };

    struct State4 {
        Props4 i; // Immediate.
        Props4 d; // Deferred.
    };

    int version_{};
    bool changed_{};
    Props4 props_{};
    State1 state1_{};
    State2 state2_{};
    State3 state3_{};
    State4 state4_{};
    State4 state5_{};

    [[deprecated]] virtual void dispatch(const EaxCall& /*call*/) { }

    // Returns "true" if any immediated property was changed.
    /*[[nodiscard]]*/ [[deprecated]] virtual bool commit() { return false; }

    template<typename T, typename ...Args>
    void call_set_defaults(Args&& ...args)
    { return T::SetDefaults(std::forward<Args>(args)...); }

    void call_set_defaults(const ALenum altype, EaxEffectProps &props)
    {
        if(altype == AL_EFFECT_EAXREVERB)
            return call_set_defaults<EaxReverbCommitter>(props);
        return call_set_defaults<EaxNullCommitter>(props);
    }

    template<typename T>
    void init()
    {
        call_set_defaults<EaxReverbCommitter>(state1_.d);
        state1_.i = state1_.d;
        call_set_defaults<EaxReverbCommitter>(state2_.d);
        state2_.i = state2_.d;
        call_set_defaults<EaxReverbCommitter>(state3_.d);
        state3_.i = state3_.d;
        call_set_defaults<T>(state4_.d);
        state4_.i = state4_.d;
        call_set_defaults<T>(state5_.d);
        state5_.i = state5_.d;
    }

    void set_defaults(int eax_version, ALenum altype)
    {
        switch(eax_version)
        {
        case 1: call_set_defaults<EaxReverbCommitter>(state1_.d); break;
        case 2: call_set_defaults<EaxReverbCommitter>(state2_.d); break;
        case 3: call_set_defaults<EaxReverbCommitter>(state3_.d); break;
        case 4: call_set_defaults(altype, state4_.d); break;
        case 5: call_set_defaults(altype, state5_.d); break;
        }
        changed_ = true;
    }


    template<typename T, typename ...Args>
    void do_set(Args&& ...args)
    { return T::Set(std::forward<Args>(args)...); }

    void do_set(const EaxCall &call, EaxEffectProps &props)
    {
        if(props.mType == EaxEffectType::Reverb)
            return do_set<EaxReverbCommitter>(call, props);
        return do_set<EaxNullCommitter>(call, props);
    }

    void set(const EaxCall &call)
    {
        switch(call.get_version())
        {
        case 1: do_set<EaxReverbCommitter>(call, state1_.d); break;
        case 2: do_set<EaxReverbCommitter>(call, state2_.d); break;
        case 3: do_set<EaxReverbCommitter>(call, state3_.d); break;
        case 4: do_set(call, state4_.d); break;
        case 5: do_set(call, state5_.d); break;
        }
        changed_ = true;
    }


    template<typename T, typename ...Args>
    void do_get(Args&& ...args)
    { return T::Get(std::forward<Args>(args)...); }

    void do_get(const EaxCall &call, const EaxEffectProps &props)
    {
        if(props.mType == EaxEffectType::Reverb)
            return do_get<EaxReverbCommitter>(call, props);
        return do_get<EaxNullCommitter>(call, props);
    }

    void get(const EaxCall &call)
    {
        switch(call.get_version())
        {
        case 1: do_get<EaxReverbCommitter>(call, state1_.d); break;
        case 2: do_get<EaxReverbCommitter>(call, state2_.d); break;
        case 3: do_get<EaxReverbCommitter>(call, state3_.d); break;
        case 4: do_get(call, state4_.d); break;
        case 5: do_get(call, state5_.d); break;
        }
    }


    template<typename T, typename ...Args>
    bool call_commit(Args&& ...args)
    { return T{props_, al_effect_props_}.commit(std::forward<Args>(args)...); }

    bool call_commit(const EaxEffectProps &props)
    {
        if(props.mType == EaxEffectType::Reverb)
            return call_commit<EaxReverbCommitter>(props);
        return call_commit<EaxNullCommitter>(props);
    }

    bool do_commit(int eax_version)
    {
        changed_ |= version_ != eax_version;
        if(!changed_) return false;

        bool ret{version_ != eax_version};
        version_ = eax_version;
        changed_ = false;

        switch(eax_version)
        {
        case 1:
            state1_.i = state1_.d;
            ret |= call_commit<EaxReverbCommitter>(state1_.d);
            break;
        case 2:
            state2_.i = state2_.d;
            ret |= call_commit<EaxReverbCommitter>(state2_.d);
            break;
        case 3:
            state3_.i = state3_.d;
            ret |= call_commit<EaxReverbCommitter>(state3_.d);
            break;
        case 4:
            state4_.i = state4_.d;
            ret |= call_commit(state4_.d);
            break;
        case 5:
            state5_.i = state5_.d;
            ret |= call_commit(state5_.d);
            break;
        }
        al_effect_type_ = EnumFromEaxEffectType(props_);
        return ret;
    }
}; // EaxEffect

// Base class for EAX4+ effects.
template<typename TException>
class EaxEffect4 : public EaxEffect
{
public:
    EaxEffect4(ALenum, int) { }

    void initialize()
    {
        set_defaults();
        set_efx_defaults();
    }

    void dispatch(const EaxCall& call) override
    { call.is_get() ? get(call) : set(call); }

    bool commit() final
    {
        switch (version_)
        {
            case 4: return commit_state(state4_);
            case 5: return commit_state(state5_);
            default: fail_unknown_version();
        }
    }

protected:
    using Exception = TException;

    template<typename TValidator, typename TProperty>
    static void defer(const EaxCall& call, TProperty& property)
    {
        const auto& value = call.get_value<Exception, const TProperty>();
        TValidator{}(value);
        property = value;
    }

    virtual void set_defaults(Props4& props) = 0;
    virtual void set_efx_defaults() = 0;

    virtual void get(const EaxCall& call, const Props4& props) = 0;
    virtual void set(const EaxCall& call, Props4& props) = 0;

    virtual bool commit_props(const Props4& props) = 0;

    [[noreturn]] static void fail(const char* message)
    {
        throw Exception{message};
    }

    [[noreturn]] static void fail_unknown_property_id()
    {
        fail(EaxEffectErrorMessages::unknown_property_id());
    }

    [[noreturn]] static void fail_unknown_version()
    {
        fail(EaxEffectErrorMessages::unknown_version());
    }

private:
    void set_defaults()
    {
        set_defaults(props_);
        state4_.i = props_;
        state4_.d = props_;
        state5_.i = props_;
        state5_.d = props_;
    }

    void get(const EaxCall& call)
    {
        switch (call.get_version())
        {
            case 4: get(call, state4_.i); break;
            case 5: get(call, state5_.i); break;
            default: fail_unknown_version();
        }
    }

    void set(const EaxCall& call)
    {
        const auto version = call.get_version();
        switch (version)
        {
            case 4: set(call, state4_.d); break;
            case 5: set(call, state5_.d); break;
            default: fail_unknown_version();
        }
        version_ = version;
    }

    bool commit_state(State4& state)
    {
        const auto props = props_;
        state.i = state.d;
        props_ = state.d;
        return commit_props(props);
    }
}; // EaxEffect4

using EaxEffectUPtr = std::unique_ptr<EaxEffect>;

// Creates EAX4+ effect.
template<typename TEffect>
EaxEffectUPtr eax_create_eax4_effect(int eax_version)
{
    auto effect = std::make_unique<TEffect>(eax_version);
    effect->initialize();
    return effect;
}

#endif // !EAX_EFFECT_INCLUDED