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package com.oracle.truffle.js.builtins;

import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.js.builtins.BigIntFunctionBuiltinsFactory.JSBigIntAsIntNNodeGen;
import com.oracle.truffle.js.builtins.BigIntFunctionBuiltinsFactory.JSBigIntAsUintNNodeGen;
import com.oracle.truffle.js.nodes.cast.JSToBigIntNode;
import com.oracle.truffle.js.nodes.cast.JSToIndexNode;
import com.oracle.truffle.js.nodes.function.JSBuiltin;
import com.oracle.truffle.js.nodes.function.JSBuiltinNode;
import com.oracle.truffle.js.runtime.BigInt;
import com.oracle.truffle.js.runtime.Errors;
import com.oracle.truffle.js.runtime.JSContext;
import com.oracle.truffle.js.runtime.JSRuntime;
import com.oracle.truffle.js.runtime.builtins.BuiltinEnum;
import com.oracle.truffle.js.runtime.builtins.JSBigInt;

Contains builtins for JSBigInt function (constructor). /**
 * Contains builtins for {@linkplain JSBigInt} function (constructor).
 */
public final class BigIntFunctionBuiltins extends JSBuiltinsContainer.SwitchEnum<BigIntFunctionBuiltins.BigIntFunction> {

    public static final JSBuiltinsContainer BUILTINS = new BigIntFunctionBuiltins();

    protected BigIntFunctionBuiltins() {
        super(JSBigInt.CLASS_NAME, BigIntFunction.class);
    }

    public enum BigIntFunction implements BuiltinEnum<BigIntFunction> {
        asUintN(2),
        asIntN(2);

        private final int length;

        BigIntFunction(int length) {
            this.length = length;
        }

        @Override
        public int getLength() {
            return length;
        }

        @Override
        public int getECMAScriptVersion() {
            return 9;
        }
    }

    @Override
    protected Object createNode(JSContext context, JSBuiltin builtin, boolean construct, boolean newTarget, BigIntFunction builtinEnum) {
        switch (builtinEnum) {
            case asUintN:
                return JSBigIntAsUintNNodeGen.create(context, builtin, args().fixedArgs(2).createArgumentNodes(context));
            case asIntN:
                return JSBigIntAsIntNNodeGen.create(context, builtin, args().fixedArgs(2).createArgumentNodes(context));
        }
        return null;
    }

    public abstract static class JSBigIntAsUintNNode extends JSBuiltinNode {

        public JSBigIntAsUintNNode(JSContext context, JSBuiltin builtin) {
            super(context, builtin);
        }

        @Specialization
        protected BigInt doIt(Object bitsObj, Object bigIntObj,
                        @Cached("create()") JSToIndexNode toIndexNode,
                        @Cached("create()") JSToBigIntNode toBigIntNode) {

            long bits = toIndexNode.executeLong(bitsObj);
            BigInt bigint = toBigIntNode.executeBigInteger(bigIntObj);
            if (bits > JSRuntime.MAX_BIG_INT_EXPONENT) {
                if (bigint.signum() >= 0) {
                    return bigint;
                } else {
                    throw Errors.createRangeErrorBigIntMaxSizeExceeded();
                }
            } else {
                return bigint.mod((BigInt.TWO).pow((int) bits));
            }
        }
    }

    public abstract static class JSBigIntAsIntNNode extends JSBuiltinNode {

        public JSBigIntAsIntNNode(JSContext context, JSBuiltin builtin) {
            super(context, builtin);
        }

        @Specialization
        protected BigInt doIt(Object bitsObj, Object bigIntObj,
                        @Cached("create()") JSToIndexNode toIndexNode,
                        @Cached("create()") JSToBigIntNode toBigIntNode) {

            long bits = toIndexNode.executeLong(bitsObj);
            BigInt bigint = toBigIntNode.executeBigInteger(bigIntObj);
            if (bits > JSRuntime.MAX_BIG_INT_EXPONENT) {
                return bigint;
            }
            BigInt twoPowBits = BigInt.TWO.pow((int) bits);
            BigInt mod = bigint.mod(twoPowBits);
            if (bits > 0) {
                if (mod.compareTo(BigInt.TWO.pow((int) bits - 1)) >= 0) {
                    return mod.subtract(twoPowBits);
                } else {
                    return mod;
                }
            } else {
                return BigInt.ZERO;
            }

        }
    }
}