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package com.oracle.truffle.js.nodes.control;

import java.util.Set;

import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.frame.MaterializedFrame;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.instrumentation.Tag;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.nodes.DirectCallNode;
import com.oracle.truffle.api.nodes.NodeCost;
import com.oracle.truffle.api.nodes.NodeInfo;
import com.oracle.truffle.api.object.DynamicObject;
import com.oracle.truffle.api.source.SourceSection;
import com.oracle.truffle.js.nodes.JavaScriptNode;
import com.oracle.truffle.js.nodes.access.JSWriteFrameSlotNode;
import com.oracle.truffle.js.nodes.function.JSFunctionCallNode;
import com.oracle.truffle.js.nodes.promise.AsyncRootNode;
import com.oracle.truffle.js.runtime.JSArguments;
import com.oracle.truffle.js.runtime.JSConfig;
import com.oracle.truffle.js.runtime.JSContext;
import com.oracle.truffle.js.runtime.JSFrameUtil;
import com.oracle.truffle.js.runtime.JavaScriptRootNode;
import com.oracle.truffle.js.runtime.objects.Completion;
import com.oracle.truffle.js.runtime.objects.JSModuleRecord;
import com.oracle.truffle.js.runtime.objects.PromiseCapabilityRecord;
import com.oracle.truffle.js.runtime.objects.Undefined;

public final class TopLevelAwaitModuleBodyNode extends JavaScriptNode {

    @NodeInfo(cost = NodeCost.NONE, language = "JavaScript")
    public static final class TopLevelAwaitModuleRootNode extends JavaScriptRootNode {

        private final JSContext context;
        private final String functionName;

        @Child private JavaScriptNode functionBody;
        @Child private JSFunctionCallNode callResolveNode;
        @Child private JSFunctionCallNode callRejectNode;
        @Child private JSWriteFrameSlotNode writeAsyncResult;
        @Child private TryCatchNode.GetErrorObjectNode getErrorObjectNode;
        @Child private InteropLibrary exceptions;

        TopLevelAwaitModuleRootNode(JSContext context, JavaScriptNode body, JSWriteFrameSlotNode asyncResult, SourceSection functionSourceSection, String functionName) {
            super(context.getLanguage(), functionSourceSection, null);
            this.context = context;
            this.functionBody = body;
            this.callResolveNode = JSFunctionCallNode.createCall();
            this.functionName = functionName;
            this.writeAsyncResult = asyncResult;
        }

        @Override
        public Object execute(VirtualFrame frame) {
            VirtualFrame asyncFrame = JSFrameUtil.castMaterializedFrame(frame.getArguments()[0]);
            PromiseCapabilityRecord promiseCapability = (PromiseCapabilityRecord) frame.getArguments()[1];
            Completion resumptionValue = (Completion) frame.getArguments()[2];
            writeAsyncResult.executeWrite(asyncFrame, resumptionValue);
            try {
                functionBody.execute(asyncFrame);
                Object maybeRecord = JSArguments.getUserArgument(asyncFrame.getArguments(), 0);
                assert maybeRecord instanceof JSModuleRecord;
                JSModuleRecord moduleRecord = (JSModuleRecord) maybeRecord;
                DynamicObject result = context.getEvaluator().getModuleNamespace(moduleRecord);
                promiseCapabilityResolve(callResolveNode, promiseCapability, result);
            } catch (YieldException e) {
                assert e.isAwait();
                // no-op: we called await, so we will resume later.
            } catch (Throwable e) {
                if (shouldCatch(e)) {
                    promiseCapabilityReject(callRejectNode, promiseCapability, getErrorObjectNode.execute(e));
                } else {
                    throw e;
                }
            }
            // The result is undefined for normal completion.
            return Undefined.instance;
        }

        private boolean shouldCatch(Throwable exception) {
            if (getErrorObjectNode == null || callRejectNode == null || exceptions == null) {
                CompilerDirectives.transferToInterpreterAndInvalidate();
                getErrorObjectNode = insert(TryCatchNode.GetErrorObjectNode.create(context));
                callRejectNode = insert(JSFunctionCallNode.createCall());
                exceptions = insert(InteropLibrary.getFactory().createDispatched(JSConfig.InteropLibraryLimit));
            }
            return TryCatchNode.shouldCatch(exception, exceptions);
        }

        @Override
        public boolean isResumption() {
            return true;
        }

        @Override
        public String getName() {
            if (functionName != null && !"".equals(functionName)) {
                return functionName;
            }
            return ":top-level-await-module";
        }

        private static void promiseCapabilityResolve(JSFunctionCallNode promiseCallNode, PromiseCapabilityRecord promiseCapability, Object result) {
            promiseCallNode.executeCall(JSArguments.createOneArg(Undefined.instance, promiseCapability.getResolve(), result));
        }

        private static void promiseCapabilityReject(JSFunctionCallNode promiseCallNode, PromiseCapabilityRecord promiseCapability, Object result) {
            promiseCallNode.executeCall(JSArguments.createOneArg(Undefined.instance, promiseCapability.getReject(), result));
        }
    }

    private final JSContext context;

    @CompilationFinal private volatile CallTarget resumptionTarget;

    @Child private JavaScriptNode moduleBodyNode;
    @Child private JSWriteFrameSlotNode writeAsyncResult;
    @Child private volatile DirectCallNode asyncCallNode;
    @Child private JSWriteFrameSlotNode writeAsyncContextNode;

    private TopLevelAwaitModuleBodyNode(JSContext context, JavaScriptNode body, JSWriteFrameSlotNode asyncResult, JSWriteFrameSlotNode writeAsyncContextNode) {
        this.context = context;
        this.moduleBodyNode = body;
        this.writeAsyncContextNode = writeAsyncContextNode;
        this.writeAsyncResult = asyncResult;
    }

    public static JavaScriptNode create(JSContext context, JavaScriptNode body, JSWriteFrameSlotNode asyncContext, JSWriteFrameSlotNode writeAsyncContextNode) {
        return new TopLevelAwaitModuleBodyNode(context, body, asyncContext, writeAsyncContextNode);
    }

    @Override
    public Object execute(VirtualFrame frame) {
        JSModuleRecord moduleRecord = (JSModuleRecord) JSArguments.getUserArgument(frame.getArguments(), 0);
        MaterializedFrame moduleFrame = moduleRecord.getEnvironment() != null ? moduleRecord.getEnvironment() : frame.materialize();
        PromiseCapabilityRecord promiseCapability = (PromiseCapabilityRecord) JSArguments.getUserArgument(frame.getArguments(), 1);
        if (promiseCapability == null) {
            // no capability provided: we are initializing the module.
            try {
                return moduleBodyNode.execute(moduleFrame);
            } catch (YieldException e) {
                assert e.isYield();
                moduleRecord.setEnvironment(moduleFrame);
                return Undefined.instance;
            }
        } else {
            // capability was provided: we are executing the module as an async function.
            ensureAsyncCallTargetInitialized();
            writeAsyncContextNode.executeWrite(moduleFrame, AsyncRootNode.createAsyncContext(resumptionTarget, promiseCapability, moduleFrame));
            Completion unusedInitialResult = null;
            asyncCallNode.call(moduleFrame, promiseCapability, unusedInitialResult);
            return promiseCapability.getPromise();
        }
    }

    private boolean asyncCallTargetInitializationRequired() {
        return resumptionTarget == null || asyncCallNode == null;
    }

    private void ensureAsyncCallTargetInitialized() {
        if (asyncCallTargetInitializationRequired()) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            initializeAsyncCallTarget();
        }
    }

    private void initializeAsyncCallTarget() {
        CompilerAsserts.neverPartOfCompilation();
        atomic(() -> {
            if (asyncCallTargetInitializationRequired()) {
                TopLevelAwaitModuleRootNode asyncRootNode = new TopLevelAwaitModuleRootNode(context, moduleBodyNode, writeAsyncResult, getRootNode().getSourceSection(), "");
                this.resumptionTarget = Truffle.getRuntime().createCallTarget(asyncRootNode);
                this.asyncCallNode = insert(DirectCallNode.create(resumptionTarget));
                // these children have been transferred to the async root node and are now disowned
                this.moduleBodyNode = null;
                this.writeAsyncResult = null;
            }
        });
    }

    @Override
    protected JavaScriptNode copyUninitialized(Set<Class<? extends Tag>> materializedTags) {
        return create(context, cloneUninitialized(moduleBodyNode, materializedTags), cloneUninitialized(writeAsyncResult, materializedTags),
                        cloneUninitialized(writeAsyncContextNode, materializedTags));
    }

}