package liblet.util;
         

         
import nova.envir.ComputeCompare;
         
import nova.envir.ComputeElem;
         
import nova.Machine;
         
import nova.Special;
         
import nova.Store;
         

         
import java.util.Locale;
         

         
public final class strlib {
         

         

         
    private static boolean test_sys_float_atom(Object[] args) {
         
        Object value = Machine.deref(Machine.exec_build(args[0]));
         
        Special.check_number(value);
         
        Object spec = Machine.deref(Machine.exec_build(args[1]));
         
        Special.check_atom(spec);
         
        Object alpha = Machine.deref(Machine.exec_build(args[2]));
         
        Special.check_integer(alpha);
         
        if (ComputeCompare.integer_signum((Number) alpha) < 0)
         
            throw Machine.make_error(new Store.Compound("domain_error",
         
                    new Object[]{"not_less_than_zero", alpha}));
         
        if (Special.is_bigint(alpha))
         
            throw Machine.make_error(new Store.Compound("representation_error",
         
                    new Object[]{"int"}));
         
        int digs = ((Integer)alpha).intValue();
         
        String res;
         
        value = value instanceof Double ? value :
         
                Double.valueOf(ComputeElem.narrow_float((Number)value));
         
        if ("f".equals(spec)) {
         
            res = String.format(Locale.UK, "%." + Integer.toString(digs) + "f", value);
         
            res = shapeFloat(res, 0);
         
        } else if ("e".equals(spec)) {
         
            res = String.format(Locale.UK, "%." + Integer.toString(digs) + "e", value);
         
            res = shapeFloat(res, 0);
         
        } else if ("g".equals(spec)) {
         
            res = String.format(Locale.UK, "%." + Integer.toString(digs) + "g", value);
         
            res = shapeFloat(res, 2);
         
        } else {
         
            throw Machine.make_error(new Store.Compound("domain_error",
         
                    new Object[]{"illegal_format", spec}));
         
        }
         
        return Machine.exec_unify(args[3], res);
         
    }
         

         
    public static String shapeFloat(String res, int flag) {
         
        int peek = res.indexOf('e');
         
        if (peek != -1) {
         
            res = shapeFloatMantissa(res.substring(0, peek), flag) +
         
                    "e" + shapeFloatExponent(res.substring(peek + 1));
         
        } else {
         
            res = shapeFloatMantissa(res, flag);
         
        }
         
        return res;
         
    }
         

         
    private static String shapeFloatMantissa(String res, int flag) {
         
        if ((flag & 2) != 0) {
         
            if (res.indexOf('.') != -1) {
         
                int pos = res.length();
         
                while (res.charAt(pos - 1) == '0')
         
                    pos--;
         
                if (res.charAt(pos - 1) == '.')
         
                    pos--;
         
                if (pos != res.length())
         
                    res = res.substring(0, pos);
         
            }
         
        }
         
        if ((flag & 1) != 0) {
         
            if (res.indexOf('.') == -1)
         
                res += ".0";
         
        }
         
        return res;
         
    }
         

         
    private static String shapeFloatExponent(String res) {
         
        if (0 < res.length() && res.charAt(0) == '+')
         
            res = res.substring(1);
         
        if (res.startsWith("0") && 1 < res.length())
         
            res = res.substring(1);
         
        else if (res.startsWith("-0") && 2 < res.length())
         
            res = "-" + res.substring(2);
         
        return res;
         
    }
         

         

         
    public static void main() {
         
        Store.add("sys_float_atom", 4, Special.make_check(strlib::test_sys_float_atom));
         
    }
         

         
}