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package com.oracle.graal.python.parser.sst;

import java.math.BigInteger;

public abstract class NumberLiteralSSTNode extends SSTNode {

    private NumberLiteralSSTNode(int startIndex, int endIndex) {
        super(startIndex, endIndex);
    }

    public static final class IntegerLiteralSSTNode extends NumberLiteralSSTNode {

        protected long value;

        protected IntegerLiteralSSTNode(long value, int startIndex, int endIndex) {
            super(startIndex, endIndex);
            this.value = value;
        }

        @Override
        public <T> T accept(SSTreeVisitor<T> visitor) {
            return visitor.visit(this);
        }

        @Override
        public void negate() {
            assert value != Long.MIN_VALUE;
            value = -value;
        }

        @Override
        public boolean isNegative() {
            return value < 0;
        }
    }

    public static final class BigIntegerLiteralSSTNode extends NumberLiteralSSTNode {

        protected BigInteger value;

        protected BigIntegerLiteralSSTNode(BigInteger value, int startIndex, int endIndex) {
            super(startIndex, endIndex);
            this.value = value;
        }

        @Override
        public <T> T accept(SSTreeVisitor<T> visitor) {
            return visitor.visit(this);
        }

        @Override
        public void negate() {
            value = value.negate();
        }

        @Override
        public boolean isNegative() {
            return value.signum() < 0;
        }
    }

    private static int digitValue(char ch) {
        if (ch >= '0' && ch <= '9') {
            return ch - '0';
        } else if (ch >= 'a' && ch <= 'f') {
            return ch - 'a' + 10;
        } else {
            assert ch >= 'A' && ch <= 'f';
            return ch - 'A' + 10;
        }
    }

    public static NumberLiteralSSTNode create(String rawValue, int start, int base, int startIndex, int endIndex) {
        String value = rawValue.replace("_", "");

        final long max = Long.MAX_VALUE;
        final long moltmax = max / base;
        int i = start;
        long result = 0;
        int lastD;
        boolean overunder = false;
        while (i < value.length()) {
            lastD = digitValue(value.charAt(i));

            long next = result;
            if (next > moltmax) {
                overunder = true;
            } else {
                next *= base;
                if (next > (max - lastD)) {
                    overunder = true;
                } else {
                    next += lastD;
                }
            }
            if (overunder) {
                // overflow
                BigInteger bigResult = BigInteger.valueOf(result);
                BigInteger bigBase = BigInteger.valueOf(base);
                while (i < value.length()) {
                    bigResult = bigResult.multiply(bigBase).add(BigInteger.valueOf(digitValue(value.charAt(i))));
                    i++;
                }
                return new BigIntegerLiteralSSTNode(bigResult, startIndex, endIndex);
            }
            result = next;
            i++;
        }

        return new IntegerLiteralSSTNode(result, startIndex, endIndex);
    }

    public abstract void negate();

    public abstract boolean isNegative();
}
