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package com.oracle.graal.python.nodes.call.special;

import static com.oracle.graal.python.builtins.PythonBuiltinClassType.TypeError;

import com.oracle.graal.python.builtins.PythonBuiltinClassType;
import com.oracle.graal.python.builtins.objects.PNone;
import com.oracle.graal.python.builtins.objects.PNotImplemented;
import com.oracle.graal.python.builtins.objects.function.BuiltinMethodDescriptor;
import com.oracle.graal.python.builtins.objects.function.PBuiltinFunction;
import com.oracle.graal.python.builtins.objects.method.PBuiltinMethod;
import com.oracle.graal.python.builtins.objects.type.PythonBuiltinClass;
import com.oracle.graal.python.builtins.objects.type.SpecialMethodSlot;
import com.oracle.graal.python.builtins.objects.type.TypeNodes;
import com.oracle.graal.python.builtins.objects.type.TypeNodes.GetNameNode;
import com.oracle.graal.python.nodes.ErrorMessages;
import com.oracle.graal.python.nodes.PGuards;
import com.oracle.graal.python.nodes.PRaiseNode;
import com.oracle.graal.python.nodes.call.special.LookupAndCallReversibleBinaryNodeGen.AreSameCallablesNodeGen;
import com.oracle.graal.python.nodes.classes.IsSubtypeNode;
import com.oracle.graal.python.nodes.object.GetClassNode;
import com.oracle.graal.python.runtime.PythonOptions;
import com.oracle.graal.python.runtime.exception.PException;
import com.oracle.graal.python.util.Supplier;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Fallback;
import com.oracle.truffle.api.dsl.ImportStatic;
import com.oracle.truffle.api.dsl.ReportPolymorphism;
import com.oracle.truffle.api.dsl.ReportPolymorphism.Megamorphic;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.profiles.BranchProfile;
import com.oracle.truffle.api.profiles.ConditionProfile;

// cpython://Objects/abstract.c#binary_op1
// Order operations are tried until either a valid result or error: w.op(v,w)[*], v.op(v,w), w.op(v,w)
//
//       [*] only when v->ob_type != w->ob_type && w->ob_type is a subclass of v->ob_type
@ImportStatic(PythonOptions.class)
@ReportPolymorphism
abstract class LookupAndCallReversibleBinaryNode extends LookupAndCallBinaryNode {

    protected final SpecialMethodSlot slot;
    protected final SpecialMethodSlot rslot;
    private final boolean alwaysCheckReverse;

    @Child private PRaiseNode raiseNode;
    @Child private GetNameNode getNameNode;
    @Child private CallBinaryMethodNode reverseDispatchNode;

    LookupAndCallReversibleBinaryNode(SpecialMethodSlot slot, SpecialMethodSlot rslot, Supplier<NotImplementedHandler> handlerFactory, boolean alwaysCheckReverse, boolean ignoreDescriptorException) {
        super(handlerFactory, ignoreDescriptorException);
        assert slot != null;
        assert rslot != null;
        this.slot = slot;
        this.rslot = rslot;
        this.alwaysCheckReverse = alwaysCheckReverse;
    }

    private PRaiseNode ensureRaiseNode() {
        if (raiseNode == null) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            raiseNode = insert(PRaiseNode.create());
        }
        return raiseNode;
    }

    private GetNameNode ensureGetNameNode() {
        if (getNameNode == null) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            getNameNode = insert(GetNameNode.create());
        }
        return getNameNode;
    }

    private CallBinaryMethodNode ensureReverseDispatch() {
        // this also serves as a branch profile
        if (reverseDispatchNode == null) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            reverseDispatchNode = insert(CallBinaryMethodNode.create());
        }
        return reverseDispatchNode;
    }

    @Specialization(guards = {"left.getClass() == cachedLeftClass", "right.getClass() == cachedRightClass"}, limit = "5")
    Object callObjectGenericR(VirtualFrame frame, Object left, Object right,
                    @SuppressWarnings("unused") @Cached("left.getClass()") Class<?> cachedLeftClass,
                    @SuppressWarnings("unused") @Cached("right.getClass()") Class<?> cachedRightClass,
                    @Cached("create(slot)") LookupSpecialMethodSlotNode getattr,
                    @Cached("create(rslot)") LookupSpecialMethodSlotNode getattrR,
                    @Cached GetClassNode getLeftClassNode,
                    @Cached GetClassNode getRightClassNode,
                    @Cached TypeNodes.IsSameTypeNode isSameTypeNode,
                    @Cached IsSubtypeNode isSubtype,
                    @Cached ConditionProfile hasLeftCallable,
                    @Cached ConditionProfile hasRightCallable,
                    @Cached ConditionProfile notImplementedProfile,
                    @Cached BranchProfile noLeftBuiltinClassType,
                    @Cached BranchProfile noRightBuiltinClassType,
                    @Cached BranchProfile gotResultBranch,
                    @Cached("createAreSameCallables()") AreSameCallables areSameCallables,
                    @Cached GetEnclosingType getEnclosingType) {
        return doCallObjectR(frame, left, right, getattr, getattrR, getLeftClassNode, getRightClassNode, isSameTypeNode, isSubtype, hasLeftCallable, hasRightCallable, notImplementedProfile,
                        noLeftBuiltinClassType, noRightBuiltinClassType, gotResultBranch, areSameCallables, getEnclosingType);
    }

    @Specialization(replaces = "callObjectGenericR")
    @Megamorphic
    Object callObjectRMegamorphic(VirtualFrame frame, Object left, Object right,
                    @Cached("create(slot)") LookupSpecialMethodSlotNode getattr,
                    @Cached("create(rslot)") LookupSpecialMethodSlotNode getattrR,
                    @Cached GetClassNode getLeftClassNode,
                    @Cached GetClassNode getRightClassNode,
                    @Cached TypeNodes.IsSameTypeNode isSameTypeNode,
                    @Cached IsSubtypeNode isSubtype,
                    @Cached ConditionProfile hasLeftCallable,
                    @Cached ConditionProfile hasRightCallable,
                    @Cached ConditionProfile notImplementedProfile,
                    @Cached BranchProfile noLeftBuiltinClassType,
                    @Cached BranchProfile noRightBuiltinClassType,
                    @Cached BranchProfile gotResultBranch,
                    @Cached("createAreSameCallables()") AreSameCallables areSameCallables,
                    @Cached GetEnclosingType getEnclosingType) {
        return doCallObjectR(frame, left, right, getattr, getattrR, getLeftClassNode, getRightClassNode, isSameTypeNode, isSubtype, hasLeftCallable, hasRightCallable, notImplementedProfile,
                        noLeftBuiltinClassType, noRightBuiltinClassType, gotResultBranch, areSameCallables, getEnclosingType);
    }

    private Object doCallObjectR(VirtualFrame frame, Object left, Object right, LookupSpecialMethodSlotNode getattr, LookupSpecialMethodSlotNode getattrR, GetClassNode getLeftClassNode,
                    GetClassNode getRightClassNode, TypeNodes.IsSameTypeNode isSameTypeNode, IsSubtypeNode isSubtype, ConditionProfile hasLeftCallable, ConditionProfile hasRightCallable,
                    ConditionProfile notImplementedProfile, BranchProfile noLeftBuiltinClassType, BranchProfile noRightBuiltinClassType,
                    BranchProfile gotResultBranch, AreSameCallables areSameCallables, GetEnclosingType getEnclosingType) {
        // This specialization implements the logic from cpython://Objects/abstract.c#binary_op1
        // (the structure is modelled closely on it), as well as the additional logic in
        // cpython://Objects/typeobject.c#SLOT1BINFULL. The latter has the addition that it swaps
        // the arguments around. The swapping of arguments is undone when the call ends up in a
        // builtin function using a wrapper in CPython. We implement this reversal in our
        // BuiltinFunctionRootNode. This is opposite to what CPython does (and more in line with
        // what PyPy does), in that CPython always dispatches with the same argument order and has
        // slot wrappers for heap types __r*__ methods to swap the arguments, but we don't wrap heap
        // types' methods and instead have our swapping for the builtin types.

        Object result = PNotImplemented.NOT_IMPLEMENTED;
        Object leftClass = getLeftClassNode.execute(left);
        Object leftCallable;
        try {
            leftCallable = getattr.execute(frame, leftClass, left);
        } catch (PException e) {
            if (ignoreDescriptorException) {
                leftCallable = PNone.NO_VALUE;
            } else {
                throw e;
            }
        }
        Object rightClass = getRightClassNode.execute(right);
        Object rightCallable;
        try {
            rightCallable = getattrR.execute(frame, rightClass, right);
        } catch (PException e) {
            if (ignoreDescriptorException) {
                rightCallable = PNone.NO_VALUE;
            } else {
                throw e;
            }
        }

        if (!alwaysCheckReverse && areSameCallables.execute(leftCallable, rightCallable)) {
            rightCallable = PNone.NO_VALUE;
        }

        if (hasLeftCallable.profile(leftCallable != PNone.NO_VALUE)) {
            if (hasRightCallable.profile(rightCallable != PNone.NO_VALUE) &&
                            (!isSameTypeNode.execute(leftClass, rightClass) && isSubtype.execute(frame, rightClass, leftClass) ||
                                            isFlagSequenceCompat(leftClass, rightClass, slot, noLeftBuiltinClassType, noRightBuiltinClassType))) {
                result = dispatch(frame, ensureReverseDispatch(), rightCallable, right, left, rightClass, rslot, isSubtype, getEnclosingType);
                if (result != PNotImplemented.NOT_IMPLEMENTED) {
                    return result;
                }
                gotResultBranch.enter();
                rightCallable = PNone.NO_VALUE;
            }
            result = dispatch(frame, ensureDispatch(), leftCallable, left, right, leftClass, slot, isSubtype, getEnclosingType);
            if (result != PNotImplemented.NOT_IMPLEMENTED) {
                return result;
            }
            gotResultBranch.enter();
        }
        if (notImplementedProfile.profile(rightCallable != PNone.NO_VALUE)) {
            result = dispatch(frame, ensureReverseDispatch(), rightCallable, right, left, rightClass, rslot, isSubtype, getEnclosingType);
        }
        if (handlerFactory != null && result == PNotImplemented.NOT_IMPLEMENTED) {
            return runErrorHandler(frame, left, right);
        }
        return result;
    }

    protected AreSameCallables createAreSameCallables() {
        return !alwaysCheckReverse ? AreSameCallablesNodeGen.create() : null;
    }

    @ImportStatic(PGuards.class)
    protected abstract static class AreSameCallables extends Node {
        public abstract boolean execute(Object left, Object right);

        @Specialization(guards = "a == b")
        static boolean areIdenticalFastPath(@SuppressWarnings("unused") Object a, @SuppressWarnings("unused") Object b) {
            return true;
        }

        @Specialization(guards = "isNone(a) || isNone(b)")
        static boolean noneFastPath(@SuppressWarnings("unused") Object a, @SuppressWarnings("unused") Object b) {
            return a == b;
        }

        @Specialization(replaces = "areIdenticalFastPath")
        static boolean doDescrs(BuiltinMethodDescriptor a, BuiltinMethodDescriptor b) {
            return a == b;
        }

        @Specialization(replaces = "areIdenticalFastPath")
        static boolean doDescrFun1(BuiltinMethodDescriptor a, PBuiltinFunction b) {
            return a.isDescriptorOf(b);
        }

        @Specialization(replaces = "areIdenticalFastPath")
        static boolean doDescrFun2(PBuiltinFunction a, BuiltinMethodDescriptor b) {
            return b.isDescriptorOf(a);
        }

        @Specialization(replaces = "areIdenticalFastPath")
        static boolean doDescrMeth1(BuiltinMethodDescriptor a, PBuiltinMethod b) {
            return doDescrFun1(a, b.getFunction());
        }

        @Specialization(replaces = "areIdenticalFastPath")
        static boolean doDescrMeth2(PBuiltinMethod a, BuiltinMethodDescriptor b) {
            return doDescrFun2(a.getFunction(), b);
        }

        @Fallback
        static boolean doGenericRuntimeObjects(Object a, Object b) {
            return a == b;
        }
    }

    @ImportStatic(PGuards.class)
    protected abstract static class GetEnclosingType extends Node {
        public abstract Object execute(Object callable);

        @Specialization
        static Object doDescrs(BuiltinMethodDescriptor descriptor) {
            return descriptor.getEnclosingType();
        }

        @Specialization
        static Object doBuiltinFun(PBuiltinFunction fun) {
            return fun.getEnclosingType();
        }

        @Specialization
        static Object doBuiltinMethod(PBuiltinMethod a) {
            return doBuiltinFun(a.getFunction());
        }

        @Fallback
        static Object doOthers(@SuppressWarnings("unused") Object callable) {
            return null;
        }
    }

    private Object dispatch(VirtualFrame frame, CallBinaryMethodNode dispatch, Object callable, Object leftValue, Object rightValue, Object leftClass, SpecialMethodSlot op, IsSubtypeNode isSubtype,
                    GetEnclosingType getEnclosingType) {
        // see descrobject.c/wrapperdescr_call()
        Object enclosing = getEnclosingType.execute(callable);
        if (enclosing != null && !isSubtype.execute(leftClass, enclosing)) {
            throw ensureRaiseNode().raise(TypeError, ErrorMessages.DESCRIPTOR_REQUIRES_OBJ, op.getName(), ensureGetNameNode().execute(leftClass), leftValue);
        }
        return dispatch.executeObject(frame, callable, leftValue, rightValue);
    }

    private static boolean isFlagSequenceCompat(Object leftClass, Object rightClass, SpecialMethodSlot slot, BranchProfile gotLeftBuiltinClassType, BranchProfile gotRightBuiltinClassType) {
        if (PGuards.isNativeClass(leftClass) || PGuards.isNativeClass(rightClass)) {
            return false;
        }
        // see pypy descroperation.py#_make_binop_impl()
        boolean isSeqBugCompatOperation = (slot == SpecialMethodSlot.Add || slot == SpecialMethodSlot.Mul);
        return isSeqBugCompatOperation && isFlagSequenceBugCompat(leftClass, gotLeftBuiltinClassType) && !isFlagSequenceBugCompat(rightClass, gotRightBuiltinClassType);
    }

    private static boolean isFlagSequenceBugCompat(Object clazz, BranchProfile gotBuiltinClassType) {
        PythonBuiltinClassType type = null;
        if (clazz instanceof PythonBuiltinClassType) {
            type = (PythonBuiltinClassType) clazz;
        } else if (clazz instanceof PythonBuiltinClass) {
            type = ((PythonBuiltinClass) clazz).getType();
        } else {
            return false;
        }
        gotBuiltinClassType.enter();
        return type == PythonBuiltinClassType.PString ||
                        type == PythonBuiltinClassType.PByteArray ||
                        type == PythonBuiltinClassType.PBytes ||
                        type == PythonBuiltinClassType.PList ||
                        type == PythonBuiltinClassType.PTuple;
    }

    public String getName() {
        return slot.getName();
    }

    public String getRname() {
        return rslot.getName();
    }

}
