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package com.oracle.truffle.nfi;

import com.oracle.truffle.api.dsl.Fallback;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.library.CachedLibrary;
import com.oracle.truffle.api.library.ExportLibrary;
import com.oracle.truffle.api.library.ExportMessage;
import com.oracle.truffle.nfi.api.SignatureLibrary;

final class NFIType {

    final TypeCachedState cachedState;
    final Object backendType;

    final Object runtimeData;

    NFIType(TypeCachedState cachedState, Object backendType) {
        this(cachedState, backendType, null);
    }

    NFIType(TypeCachedState cachedState, Object backendType, Object runtimeData) {
        this.cachedState = cachedState;
        this.backendType = backendType;
        this.runtimeData = runtimeData;
    }

    abstract static class TypeCachedState {

        final int managedArgCount;

        TypeCachedState(int managedArgCount) {
            this.managedArgCount = managedArgCount;
        }
    }

    static final TypeCachedState SIMPLE = new SimpleTypeCachedState();
    static final TypeCachedState CLOSURE = new ClosureTypeCachedState();
    static final TypeCachedState INJECTED = new InjectedTypeCachedState();

    @ExportLibrary(NFITypeLibrary.class)
    static final class SimpleTypeCachedState extends TypeCachedState {

        private SimpleTypeCachedState() {
            super(1);
            // singleton
        }

        @ExportMessage
        Object convertToNative(NFIType type, Object value) {
            assert type.cachedState == this;
            return value;
        }

        @ExportMessage
        Object convertFromNative(NFIType type, Object value) {
            assert type.cachedState == this;
            return value;
        }
    }

    @ExportLibrary(NFITypeLibrary.class)
    static final class ClosureTypeCachedState extends TypeCachedState {

        private ClosureTypeCachedState() {
            super(1);
            // singleton
        }

        @ExportMessage
        static class ConvertToNative {

            @Specialization(limit = "3", guards = "interop.isExecutable(value)")
            static Object convertToNative(ClosureTypeCachedState state, NFIType type, Object value,
                            @SuppressWarnings("unused") @CachedLibrary("value") InteropLibrary interop,
                            @CachedLibrary("type.runtimeData") SignatureLibrary library) {
                assert type.cachedState == state;
                return library.createClosure(type.runtimeData, value);
            }

            @Fallback
            static Object convertToNative(ClosureTypeCachedState state, NFIType type, Object value) {
                // it's not executable, so assume it's already a function pointer
                assert type.cachedState == state;
                return value;
            }
        }

        @ExportMessage
        static class ConvertFromNative {

            @Specialization(limit = "3", guards = "interop.isNull(nullValue)")
            static Object doNull(ClosureTypeCachedState state, NFIType type, Object nullValue,
                            @SuppressWarnings("unused") @CachedLibrary("nullValue") InteropLibrary interop) {
                assert type.cachedState == state;
                return nullValue;
            }

            @Specialization(limit = "3", guards = "!interop.isNull(value)")
            static Object doBind(ClosureTypeCachedState state, NFIType type, Object value,
                            @SuppressWarnings("unused") @CachedLibrary("value") InteropLibrary interop,
                            @CachedLibrary("type.runtimeData") SignatureLibrary library) {
                assert type.cachedState == state;
                return library.bind(type.runtimeData, value);
            }
        }
    }

    @ExportLibrary(NFITypeLibrary.class)
    static final class InjectedTypeCachedState extends TypeCachedState {

        private InjectedTypeCachedState() {
            super(0);
        }

        @ExportMessage
        Object convertFromNative(NFIType type, @SuppressWarnings("unused") Object value) {
            assert type.cachedState == this;
            return null;
        }

        @ExportMessage
        Object convertToNative(NFIType type, Object value) {
            assert type.cachedState == this && value == null;
            return type.runtimeData;
        }
    }
}