/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-9-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce::midi_ci
{

/**
    A strongly-typed identifier for a 7-bit request ID with a nullable state.

    @tags{Audio}
*/
class RequestID
{
public:
    /** Constructs a RequestID if the provided value is valid, i.e. its most significant bit is
        not set. Otherwise, returns nullopt.
    */
    static std::optional<RequestID> create (uint8_t v)
    {
        if (v < 128)
            return RequestID { v };

        return {};
    }

    /** Constructs a RequestID if the provided value is valid, i.e. its most significant bit is
        not set. Otherwise, returns nullopt.
    */
    static std::optional<RequestID> create (std::byte value)
    {
        return create (static_cast<uint8_t> (value));
    }

    /** Returns the byte corresponding to this ID. */
    std::byte asByte() const
    {
        return std::byte { value };
    }

    /** Returns the int value of this ID. */
    uint8_t asInt() const
    {
        return value;
    }

    /** Equality operator. */
    bool operator== (RequestID other) const
    {
        return value == other.value;
    }

    /** Inequality operator. */
    bool operator!= (RequestID other) const
    {
        return ! operator== (other);
    }

private:
    /*  Constructs a non-null request ID.

        The argument must not have its most significant bit set.
    */
    explicit RequestID (uint8_t index)
        : value (index)
    {
        // IDs must only use the lowest 7 bits
        jassert (value < 128);
    }

    uint8_t value{};
};

/** A strongly-typed 64-bit identifier. */
enum class Token64 : uint64_t {};

/** Compares Token64 instances. */
constexpr bool operator< (Token64 a, Token64 b)
{
    return toUnderlyingType (a) < toUnderlyingType (b);
}

/**
    Accumulates message chunks that have been sent by another device in response
    to a transaction initiated by a local device.

    @tags{Audio}
*/
class InitiatorPropertyExchangeCache
{
public:
    InitiatorPropertyExchangeCache();
    ~InitiatorPropertyExchangeCache();

    InitiatorPropertyExchangeCache (InitiatorPropertyExchangeCache&&) noexcept;
    InitiatorPropertyExchangeCache& operator= (InitiatorPropertyExchangeCache&&) noexcept;

    JUCE_DECLARE_NON_COPYABLE (InitiatorPropertyExchangeCache)

    /** Picks an unused request ID, and prepares the cache for that ID to accumulate message chunks.

        Incoming chunks added with addChunk are generated by another device acting as a responder.
    */
    std::optional<Token64> primeCache (uint8_t maxSimultaneousRequests,
                                       std::function<void (const PropertyExchangeResult&)> onDone);

    /** Terminates/cancels an ongoing transaction.

        Returns true if the termination had an effect (i.e. the transaction was still ongoing), or
        false otherwise (the transaction already ended or never started).
    */
    bool terminate (Token64);

    /** If there's a transaction ongoing with the given request id, returns the token uniquely
        identifying that transaction, otherwise returns nullopt.
    */
    std::optional<Token64> getTokenForRequestId (RequestID) const;

    /** If the token refers to an ongoing transaction, returns the request id of that transaction.
        Otherwise, returns an invalid request id.
    */
    std::optional<RequestID> getRequestIdForToken (Token64) const;

    /** Adds a message chunk for the provided transaction id. */
    void addChunk (RequestID, const Message::DynamicSizePropertyExchange& chunk);

    /** Updates the transaction state based on the contents of the provided notification. */
    void notify (RequestID, Span<const std::byte> header);

    /** Returns all ongoing transactions. */
    std::vector<Token64> getOngoingTransactions() const;

private:
    class Impl;
    std::unique_ptr<Impl> pimpl;
};

//==============================================================================
/**
    Accumulates message chunks that form a request initiated by a remote device.

    @tags{Audio}
*/
class ResponderPropertyExchangeCache
{
public:
    ResponderPropertyExchangeCache();
    ~ResponderPropertyExchangeCache();

    ResponderPropertyExchangeCache (ResponderPropertyExchangeCache&&) noexcept;
    ResponderPropertyExchangeCache& operator= (ResponderPropertyExchangeCache&&) noexcept;

    JUCE_DECLARE_NON_COPYABLE (ResponderPropertyExchangeCache)

    /** Prepares the cache for the given requestID to accumulate message chunks.

        Incoming chunks added with addChunk are generated by another device acting as an initiator.
    */
    void primeCache (uint8_t maxSimultaneousTransactions,
                     std::function<void (const PropertyExchangeResult&)> onDone,
                     RequestID id);

    /** Adds a message chunk for the provided transaction id. */
    void addChunk (RequestID, const Message::DynamicSizePropertyExchange& chunk);

    /** Updates the transaction state based on the contents of the provided notification. */
    void notify (RequestID, Span<const std::byte> header);

    /** Returns the number of transactions that have been started but not finished. */
    int countOngoingTransactions() const;

private:
    class Impl;
    std::unique_ptr<Impl> pimpl;
};

//==============================================================================
/**
    An interface for objects that provide resources for property exchange
    transactions.

    @tags{Audio}
*/
class CacheProvider
{
public:
    virtual ~CacheProvider() = default;

    /** Returns a set containing all of the MUIDs currently known to the provider. */
    virtual std::set<MUID> getDiscoveredMuids() const = 0;

    /** Returns a property exchange cache for accumulating replies to transactions
        we initiated.
    */
    virtual InitiatorPropertyExchangeCache* getCacheForMuidAsInitiator (MUID m) = 0;

    /** Returns a property exchange cache for accumulating requests initiated
        by other devices.
    */
    virtual ResponderPropertyExchangeCache* getCacheForMuidAsResponder (MUID m) = 0;

    /** Returns the maximum sysex size supported by the device with the
        given MUID.
    */
    virtual int getMaxSysexSizeForMuid (MUID m) const = 0;
};

} // namespace juce::midi_ci
