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package com.oracle.truffle.js.builtins.math;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Cached.Shared;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.profiles.ConditionProfile;
import com.oracle.truffle.js.nodes.function.JSBuiltin;
import com.oracle.truffle.js.runtime.JSContext;
import com.oracle.truffle.js.runtime.JSRuntime;
import com.oracle.truffle.js.runtime.SafeInteger;

Math.floor(x). Returns the greatest (closest to +Infinity) Number value that is not greater than x and is an integer. If x is already an integer, the result is x. The value of Math.floor(x) is the same as the value of -Math.ceil(-x). /**
 * Math.floor(x). Returns the greatest (closest to +Infinity) Number value that is not greater than
 * x and is an integer. If x is already an integer, the result is x.
 *
 * The value of {@code Math.floor(x)} is the same as the value of {@code -Math.ceil(-x)}.
 */
public abstract class FloorNode extends MathOperation {

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

    @Specialization
    protected static int floorInt(int a) {
        return a;
    }

    @Specialization
    protected static SafeInteger floorSafeInt(SafeInteger a) {
        return a;
    }

    @Specialization
    protected static Object floorDouble(double d,
                    @Cached("createBinaryProfile()") @Shared("isZero") ConditionProfile isZero,
                    @Cached("createBinaryProfile()") @Shared("fitsInt") ConditionProfile fitsInt,
                    @Cached("createBinaryProfile()") @Shared("fitsSafeLong") ConditionProfile fitsSafeLong,
                    @Cached("createBinaryProfile()") @Shared("smaller") ConditionProfile smaller) {
        if (isZero.profile(d == 0.0)) {
            // floor(-0.0) => -0.0
            // floor(+0.0) => +0.0
            return d;
        } else if (fitsInt.profile(d >= Integer.MIN_VALUE && d <= Integer.MAX_VALUE)) {
            int i = (int) d;
            return smaller.profile(d < i) ? i - 1 : i;
        } else if (fitsSafeLong.profile(JSRuntime.isSafeInteger(d))) {
            long i = (long) d;
            long result = smaller.profile(d < i) ? i - 1 : i;
            return SafeInteger.valueOf(result);
        } else {
            return mathFloor(d);
        }
    }

    @Specialization(replaces = "floorDouble")
    protected Object floorToDouble(Object a,
                    @Cached("createBinaryProfile()") @Shared("isZero") ConditionProfile isZero,
                    @Cached("createBinaryProfile()") @Shared("fitsInt") ConditionProfile fitsInt,
                    @Cached("createBinaryProfile()") @Shared("fitsSafeLong") ConditionProfile fitsSafeLong,
                    @Cached("createBinaryProfile()") @Shared("smaller") ConditionProfile smaller) {
        double d = toDouble(a);
        return floorDouble(d, isZero, fitsInt, fitsSafeLong, smaller);
    }

    @TruffleBoundary
    private static double mathFloor(double d) {
        return Math.floor(d);
    }
}