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package com.oracle.graal.python.builtins.objects.posix;

import static com.oracle.graal.python.nodes.SpecialMethodNames.__ENTER__;
import static com.oracle.graal.python.nodes.SpecialMethodNames.__EXIT__;
import static com.oracle.graal.python.nodes.SpecialMethodNames.__ITER__;
import static com.oracle.graal.python.nodes.SpecialMethodNames.__NEXT__;

import java.util.List;

import com.oracle.graal.python.PythonLanguage;
import com.oracle.graal.python.builtins.Builtin;
import com.oracle.graal.python.builtins.CoreFunctions;
import com.oracle.graal.python.builtins.PythonBuiltinClassType;
import com.oracle.graal.python.builtins.PythonBuiltins;
import com.oracle.graal.python.builtins.objects.PNone;
import com.oracle.graal.python.nodes.function.PythonBuiltinBaseNode;
import com.oracle.graal.python.nodes.function.PythonBuiltinNode;
import com.oracle.graal.python.nodes.function.builtins.PythonUnaryBuiltinNode;
import com.oracle.graal.python.runtime.AsyncHandler.AsyncAction;
import com.oracle.graal.python.runtime.PosixSupportLibrary;
import com.oracle.graal.python.runtime.PosixSupportLibrary.PosixException;
import com.oracle.graal.python.runtime.PythonContext;
import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.TruffleLanguage;
import com.oracle.truffle.api.dsl.GenerateNodeFactory;
import com.oracle.truffle.api.dsl.NodeFactory;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.library.CachedLibrary;
import com.oracle.truffle.api.nodes.RootNode;

@CoreFunctions(extendClasses = PythonBuiltinClassType.PScandirIterator)
public class ScandirIteratorBuiltins extends PythonBuiltins {

    @Override
    protected List<? extends NodeFactory<? extends PythonBuiltinBaseNode>> getNodeFactories() {
        return ScandirIteratorBuiltinsFactory.getFactories();
    }

    @Builtin(name = "close", minNumOfPositionalArgs = 1)
    @GenerateNodeFactory
    abstract static class CloseNode extends PythonUnaryBuiltinNode {
        @Specialization
        PNone close(PScandirIterator self,
                        @CachedLibrary("getPosixSupport()") PosixSupportLibrary posixLib) {
            self.ref.rewindAndClose(posixLib, getPosixSupport());
            return PNone.NONE;
        }
    }

    @Builtin(name = __ITER__, minNumOfPositionalArgs = 1)
    @GenerateNodeFactory
    abstract static class IterNode extends PythonUnaryBuiltinNode {
        @Specialization
        PScandirIterator iter(PScandirIterator self) {
            return self;
        }
    }

    @Builtin(name = __NEXT__, minNumOfPositionalArgs = 1)
    @GenerateNodeFactory
    abstract static class NextNode extends PythonUnaryBuiltinNode {
        @Specialization
        PDirEntry next(VirtualFrame frame, PScandirIterator self,
                        @CachedLibrary("getPosixSupport()") PosixSupportLibrary posixLib) {
            if (self.ref.isReleased()) {
                throw raise(PythonBuiltinClassType.StopIteration);
            }
            try {
                Object dirEntryData = posixLib.readdir(getPosixSupport(), self.ref.getReference());
                if (dirEntryData == null) {
                    self.ref.rewindAndClose(posixLib, getPosixSupport());
                    throw raise(PythonBuiltinClassType.StopIteration);
                }
                return factory().createDirEntry(dirEntryData, self.path);
            } catch (PosixException e) {
                self.ref.rewindAndClose(posixLib, getPosixSupport());
                throw raiseOSErrorFromPosixException(frame, e);
            }
        }
    }

    @Builtin(name = __ENTER__, minNumOfPositionalArgs = 1)
    @GenerateNodeFactory
    abstract static class EnterNode extends PythonUnaryBuiltinNode {
        @Specialization
        PScandirIterator iter(PScandirIterator self) {
            return self;
        }
    }

    @Builtin(name = __EXIT__, minNumOfPositionalArgs = 4)
    @GenerateNodeFactory
    abstract static class ExitNode extends PythonBuiltinNode {
        @Specialization
        @SuppressWarnings("unused")
        PNone exit(PScandirIterator self, Object type, Object value, Object traceback,
                        @CachedLibrary("getPosixSupport()") PosixSupportLibrary posixLib) {
            self.ref.rewindAndClose(posixLib, getPosixSupport());
            return PNone.NONE;
        }
    }

    static class ReleaseCallback implements AsyncAction {

        private final PScandirIterator.DirStreamRef ref;

        ReleaseCallback(PScandirIterator.DirStreamRef ref) {
            this.ref = ref;
        }

        @Override
        public void execute(PythonContext context) {
            if (ref.isReleased()) {
                return;
            }
            PythonLanguage language = context.getLanguage();
            CallTarget callTarget = language.createCachedCallTarget(ReleaserRootNode::new, ReleaserRootNode.class);
            callTarget.call(ref);
        }

        private static class ReleaserRootNode extends RootNode {
            @Child private PosixSupportLibrary posixSupportLibrary = PosixSupportLibrary.getFactory().createDispatched(1);

            ReleaserRootNode(TruffleLanguage<?> language) {
                super(language);
            }

            @Override
            public Object execute(VirtualFrame frame) {
                PScandirIterator.DirStreamRef ref = (PScandirIterator.DirStreamRef) frame.getArguments()[0];
                ref.rewindAndClose(posixSupportLibrary, PythonContext.get(this).getPosixSupport());
                return null;
            }
        }
    }
}
