/*
 * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.parser.rfc7950.stmt;

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.Beta;
import com.google.common.collect.ImmutableList;
import java.util.Collection;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.model.api.meta.DeclaredStatement;
import org.opendaylight.yangtools.yang.model.api.meta.StatementSource;

/**
 * An abstract base class for {@link DeclaredStatement} implementations. This is a direct competition to
 * {@link org.opendaylight.yangtools.yang.parser.spi.meta.AbstractDeclaredStatement}, providing lower-footprint
 * implementations.
 */
@Beta
// FIXME: 7.0.0: we should be able to promote this to model.spi.meta package.
public abstract class AbstractDeclaredStatement<A> extends AbstractModelStatement<A> implements DeclaredStatement<A> {
    protected AbstractDeclaredStatement() {
    }

    @Override
    public StatementSource getStatementSource() {
        return StatementSource.DECLARATION;
    }

    @Override
    public Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
        // Default to reduce load on subclasses and keep the number of implementations down
        return ImmutableList.of();
    }

    /**
     * Utility method for recovering singleton lists squashed by {@link #maskList(ImmutableList)}.
     *
     * @param masked list to unmask
     * @return Unmasked list
     * @throws NullPointerException if masked is null
     * @throws ClassCastException if masked object does not match DeclaredStatement
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    protected static final @NonNull ImmutableList<? extends DeclaredStatement<?>> unmaskList(
            final @NonNull Object masked) {
        return (ImmutableList) unmaskList(masked, DeclaredStatement.class);
    }

    public abstract static class WithRawArgument<A> extends AbstractDeclaredStatement<A> {
        private final String rawArgument;

        protected WithRawArgument(final String rawArgument) {
            this.rawArgument = rawArgument;
        }

        @Override
        public final String rawArgument() {
            return rawArgument;
        }
    }

    public abstract static class WithQNameArgument extends AbstractDeclaredStatement<QName> {
        public abstract static class WithSubstatements extends WithQNameArgument {
            private final @NonNull Object substatements;

            protected WithSubstatements(final QName argument,
                    final ImmutableList<? extends DeclaredStatement<?>> substatements) {
                super(argument);
                this.substatements = maskList(substatements);
            }

            @Override
            public final Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
                return unmaskList(substatements);
            }
        }

        private final @NonNull QName argument;

        protected WithQNameArgument(final QName argument) {
            this.argument = requireNonNull(argument);
        }

        @Override
        public final @NonNull QName argument() {
            return argument;
        }

        @Override
        public final String rawArgument() {
            return argument.getLocalName();
        }
    }

    public abstract static class WithRawStringArgument extends WithRawArgument<String> {
        public abstract static class WithSubstatements extends WithRawStringArgument {
            private final @NonNull Object substatements;

            protected WithSubstatements(final String rawArgument,
                    final ImmutableList<? extends DeclaredStatement<?>> substatements) {
                super(rawArgument);
                this.substatements = maskList(substatements);
            }

            @Override
            public final Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
                return unmaskList(substatements);
            }
        }

        protected WithRawStringArgument(final String rawArgument) {
            super(rawArgument);
        }

        @Override
        public final String argument() {
            return rawArgument();
        }
    }

    public abstract static class WithArgument<A> extends WithRawArgument<A> {
        public abstract static class WithSubstatements<A> extends WithArgument<A> {
            private final @NonNull Object substatements;

            protected WithSubstatements(final String rawArgument, final A argument,
                    final ImmutableList<? extends DeclaredStatement<?>> substatements) {
                super(rawArgument, argument);
                this.substatements = maskList(substatements);
            }

            @Override
            public final Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
                return unmaskList(substatements);
            }
        }

        private final A argument;

        protected WithArgument(final String rawArgument, final A argument) {
            super(rawArgument);
            this.argument = argument;
        }

        @Override
        public final A argument() {
            return argument;
        }
    }

    public abstract static class ArgumentToString<A> extends AbstractDeclaredStatement<A> {
        public abstract static class WithSubstatements<A> extends ArgumentToString<A> {
            private final @NonNull Object substatements;

            protected WithSubstatements(final A argument,
                    final ImmutableList<? extends DeclaredStatement<?>> substatements) {
                super(argument);
                this.substatements = maskList(substatements);
            }

            @Override
            public final Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
                return unmaskList(substatements);
            }
        }

        private final @NonNull A argument;

        protected ArgumentToString(final A argument) {
            this.argument = requireNonNull(argument);
        }

        @Override
        public final @NonNull A argument() {
            return argument;
        }

        @Override
        public final String rawArgument() {
            return argument.toString();
        }
    }

    public abstract static class WithoutArgument extends AbstractDeclaredStatement<Void> {
        public abstract static class WithSubstatements extends WithoutArgument {
            private final @NonNull Object substatements;

            protected WithSubstatements(final ImmutableList<? extends DeclaredStatement<?>> substatements) {
                this.substatements = maskList(substatements);
            }

            @Override
            public final Collection<? extends DeclaredStatement<?>> declaredSubstatements() {
                return unmaskList(substatements);
            }
        }

        @Override
        public final Void argument() {
            return null;
        }

        @Override
        public final String rawArgument() {
            return null;
        }
    }
}