package com.horstmann;

import java.io.*;

/**
   A class for formatting numbers that follows <tt>printf</tt> conventions.

   Also implements C-like <tt>atoi</tt> and <tt>atof</tt> functions

   @version 1.21 2000-06-09
   @author Cay Horstmann

   1998-09-14: Fixed a number of bugs.
        1.Formatting the most extreme negative number (-9223372036854775808L) printed with 2 leading minus signs.
        2.Printing 0 with a %e or %g format did not work.
        3.Printing numbers that were closer to 1 than the number of requested decimal places rounded down rather than up, e.g. formatting 1.999 with %.2f printed 1.00. (This one is pretty serious, of course.)
        4.Printing with precision 0 (e.g %10.0f) didn't work.
        5.Printing a string with a precision that exceeded the string length (e.g. print "Hello" with %20.10s) caused a StringIndexOutOfBounds error.
   1998-10-21: Changed method names from print to printf
   2000-06-09: Moved to package com.horstmann; no longer part of
   Core Java
   2000-06-09: Fixed a number of bugs.
        1.Printing 100.0 with %e printed 10.0e1, not 1.0e2
        2.Printing Inf and NaN didn't work.
   2000-06-09: Coding guideline cleanup
*/
public class Format
{
   /**
      Formats the number following <tt>printf</tt> conventions.
      Main limitation: Can only handle one format parameter at a time
      Use multiple Format objects to format more than one number
      @param s the format string following printf conventions
      The string has a prefix, a format code and a suffix. The prefix and suffix
      become part of the formatted output. The format code directs the
      formatting of the (single) parameter to be formatted. The code has the
      following structure
      <ul>
      <li> a % (required)
      <li> a modifier (optional)
      <dl>
      <dt> + <dd> forces display of + for positive numbers
      <dt> 0 <dd> show leading zeroes
      <dt> - <dd> align left in the field
      <dt> space <dd> prepend a space in front of positive numbers
      <dt> # <dd> use "alternate" format. Add 0 or 0x for octal or hexadecimal numbers. Don't suppress trailing zeroes in general floating point format.
      </dl>
      <li> an integer denoting field width (optional)
      <li> a period followed by an integer denoting precision (optional)
      <li> a format descriptor (required)
      <dl>
      <dt>f <dd> floating point number in fixed format
      <dt>e, E <dd> floating point number in exponential notation (scientific format). The E format results in an uppercase E for the exponent (1.14130E+003), the e format in a lowercase e.
      <dt>g, G <dd> floating point number in general format (fixed format for small numbers, exponential format for large numbers). Trailing zeroes are suppressed. The G format results in an uppercase E for the exponent (if any), the g format in a lowercase e.
      <dt>d, i <dd> integer in decimal
      <dt>x <dd> integer in hexadecimal
      <dt>o <dd> integer in octal
      <dt>s <dd> string
      <dt>c <dd> character
      </dl>
      </ul>
      @exception IllegalArgumentException if bad format
   */
   public Format(String s)
   {
      width = 0;
      precision = -1;
      pre = "";
      post = "";
      leadingZeroes = false;
      showPlus = false;
      alternate = false;
      showSpace = false;
      leftAlign = false;
      fmt = ' ';

      int state = 0;
      int length = s.length();
      int parseState = 0;
      // 0 = prefix, 1 = flags, 2 = width, 3 = precision,
      // 4 = format, 5 = end
      int i = 0;

      while (parseState == 0)
      {
         if (i >= length) parseState = 5;
         else if (s.charAt(i) == '%')
         {
            if (i < length - 1)
            {
               if (s.charAt(i + 1) == '%')
               {
                  pre = pre + '%';
                  i++;
               }
               else
                  parseState = 1;
            }
            else throw new java.lang.IllegalArgumentException();
         }
         else
            pre = pre + s.charAt(i);
         i++;
      }
      while (parseState == 1)
      {
         if (i >= length) parseState = 5;
         else if (s.charAt(i) == ' ') showSpace = true;
         else if (s.charAt(i) == '-') leftAlign = true;
         else if (s.charAt(i) == '+') showPlus = true;
         else if (s.charAt(i) == '0') leadingZeroes = true;
         else if (s.charAt(i) == '#') alternate = true;
         else { parseState = 2; i--; }
         i++;
      }
      while (parseState == 2)
      {
         if (i >= length) parseState = 5;
         else if ('0' <= s.charAt(i) && s.charAt(i) <= '9')
         {
            width = width * 10 + s.charAt(i) - '0';
            i++;
         }
         else if (s.charAt(i) == '.')
         {
            parseState = 3;
            precision = 0;
            i++;
         }
         else
            parseState = 4;
      }
      while (parseState == 3)
      {
         if (i >= length) parseState = 5;
         else if ('0' <= s.charAt(i) && s.charAt(i) <= '9')
         {
            precision = precision * 10 + s.charAt(i) - '0';
            i++;
         }
         else
            parseState = 4;
      }
      if (parseState == 4)
      {
         if (i >= length) parseState = 5;
         else fmt = s.charAt(i);
         i++;
      }
      if (i < length)
         post = s.substring(i, length);
   }

  /**
     prints a formatted number following printf conventions
     @param fmt the format string
     @param x the double to print
   */
   public static void printf(String fmt, double x)
   {
      System.out.print(new Format(fmt).format(x));
   }

   /**
      prints a formatted number following printf conventions
      @param fmt the format string
      @param x the int to print
   */
   public static void printf(String fmt, int x)
   {
      System.out.print(new Format(fmt).format(x));
   }

   /**
      prints a formatted number following printf conventions
      @param fmt the format string
      @param x the long to print
   */
   public static void printf(String fmt, long x)
   {
      System.out.print(new Format(fmt).format(x));
   }

   /**
      prints a formatted number following printf conventions
      @param fmt the format string
      @param x the character to print
   */
   public static void printf(String fmt, char x)
   {
      System.out.print(new Format(fmt).format(x));
   }

   /**
      prints a formatted number following printf conventions
      @param fmt the format string
      @param x a string to print
   */
   public static void printf(String fmt, String x)
   {
      System.out.print(new Format(fmt).format(x));
   }

   /**
      Converts a string of digits (decimal, octal or hex) to an integer
      @param s a string
      @return the numeric value of the prefix of s representing a base 10 integer
   */
   public static int atoi(String s)
   {
      return (int)atol(s);
   }

  /**
     Converts a string of digits (decimal, octal or hex) to a long integer
     @param s a string
     @return the numeric value of the prefix of s representing a base 10 integer
  */
   public static long atol(String s)
   {
      int i = 0;

      while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++;
      if (i < s.length() && s.charAt(i) == '0')
      {
         if (i + 1 < s.length() && (s.charAt(i + 1) == 'x' || s.charAt(i + 1) == 'X'))
            return parseLong(s.substring(i + 2), 16);
         else return parseLong(s, 8);
      }
      else return parseLong(s, 10);
   }

   private static long parseLong(String s, int base)
   {
      int i = 0;
      int sign = 1;
      long r = 0;

      while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++;
      if (i < s.length() && s.charAt(i) == '-') { sign = -1; i++; }
      else if (i < s.length() && s.charAt(i) == '+') { i++; }
      while (i < s.length())
      {
         char ch = s.charAt(i);
         if ('0' <= ch && ch < '0' + base)
            r = r * base + ch - '0';
         else if ('A' <= ch && ch < 'A' + base - 10)
            r = r * base + ch - 'A' + 10 ;
         else if ('a' <= ch && ch < 'a' + base - 10)
            r = r * base + ch - 'a' + 10 ;
         else
            return r * sign;
         i++;
      }
      return r * sign;
   }

   /**
      Converts a string of digits to a <tt>double</tt>
      @param s a string
   */
   public static double atof(String s)
   {
      int i = 0;
      int sign = 1;
      double r = 0; // integer part
      double f = 0; // fractional part
      double p = 1; // exponent of fractional part
      int state = 0; // 0 = int part, 1 = frac part

      while (i < s.length() && Character.isWhitespace(s.charAt(i))) i++;
      if (i < s.length() && s.charAt(i) == '-') { sign = -1; i++; }
      else if (i < s.length() && s.charAt(i) == '+') { i++; }
      while (i < s.length())
      {
         char ch = s.charAt(i);
         if ('0' <= ch && ch <= '9')
         {
            if (state == 0)
               r = r * 10 + ch - '0';
            else if (state == 1)
            {
               p = p / 10;
               r = r + p * (ch - '0');
            }
         }
         else if (ch == '.')
         {
            if (state == 0) state = 1;
            else return sign * r;
         }
         else if (ch == 'e' || ch == 'E')
         {
            long e = (int)parseLong(s.substring(i + 1), 10);
            return sign * r * Math.pow(10, e);
         }
         else return sign * r;
         i++;
      }
      return sign * r;
   }

   /**
      Formats a <tt>double</tt> into a string (like sprintf in C)
      @param x the number to format
      @return the formatted string
      @exception IllegalArgumentException if bad argument
   */
   public String format(double x)
   {
      String r;