// Magic number for the Rust proxy to call using the same mechanism as every other method,
// to free the callback once it's dropped by Rust.
internal const val IDX_CALLBACK_FREE = 0
// Callback return codes
internal const val UNIFFI_CALLBACK_SUCCESS = 0
internal const val UNIFFI_CALLBACK_ERROR = 1
internal const val UNIFFI_CALLBACK_UNEXPECTED_ERROR = 2

public abstract class FfiConverterCallbackInterface<CallbackInterface: Any>: FfiConverter<CallbackInterface, Long> {
    internal val handleMap = UniffiHandleMap<CallbackInterface>()

    internal fun drop(handle: Long) {
        handleMap.remove(handle)
    }

    override fun lift(value: Long): CallbackInterface {
        return handleMap.get(value)
    }

    override fun read(buf: ByteBuffer) = lift(buf.getLong())

    override fun lower(value: CallbackInterface) = handleMap.insert(value)

    override fun allocationSize(value: CallbackInterface) = 8UL

    override fun write(value: CallbackInterface, buf: ByteBuffer) {
        buf.putLong(lower(value))
    }
}