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;
      if (precision < 0) precision = 6;
      int s = 1;
      if (x < 0) { x = -x; s = -1; }
      if (Double.isNaN(x)) r = "NaN";
      else if (x == Double.POSITIVE_INFINITY) r = "Inf";
      else if (fmt == 'f')
         r = fixedFormat(x);
      else if (fmt == 'e' || fmt == 'E' || fmt == 'g' || fmt == 'G')
         r = expFormat(x);
      else throw new java.lang.IllegalArgumentException();

      return pad(sign(s, r));
   }

   /**
      Formats an integer into a string (like sprintf in C)
      @param x the number to format
      @return the formatted string
   */
   public String format(int x)
   {
      long lx = x;
      if (fmt == 'o' || fmt == 'x' || fmt == 'X')
         lx &= 0xFFFFFFFFL;
      return format(lx);
   }

   /**
      Formats a long integer into a string (like sprintf in C)
      @param x the number to format
      @return the formatted string
   */
   public String format(long x)
   {
      String r;
      int s = 0;
      if (fmt == 'd' || fmt == 'i')
      {
         if (x < 0)
         {
            r = ("" + x).substring(1);
            s = -1;
         }
         else
         {
            r = "" + x;
            s = 1;
         }
      }
      else if (fmt == 'o')
         r = convert(x, 3, 7, "01234567");
      else if (fmt == 'x')
         r = convert(x, 4, 15, "0123456789abcdef");
      else if (fmt == 'X')
         r = convert(x, 4, 15, "0123456789ABCDEF");
      else throw new java.lang.IllegalArgumentException();

      return pad(sign(s, r));
   }

   /**
      Formats a character into a string (like sprintf in C)
      @param x the value to format
      @return the formatted string
   */
   public String format(char c)
   {
      if (fmt != 'c')
         throw new java.lang.IllegalArgumentException();

      String r = "" + c;
      return pad(r);
   }

   /**
      Formats a string into a larger string (like sprintf in C)
      @param x the value to format
      @return the formatted string
   */
   public String format(String s)
   {
      if (fmt != 's')
         throw new java.lang.IllegalArgumentException();
      if (precision >= 0 && precision < s.length())
         s = s.substring(0, precision);
      return pad(s);
   }


   /**
      a test stub for the format class
   */
   public static void main(String[] a)
   {
      double x = 1.23456789012;
      double y = 123;
      double z = 1.2345e30;
      double w = 1.02;
      double u = 1.234e-5;
      int d = 0xCAFE;
      Format.printf("x = |%f|\n", x);
      Format.printf("u = |%20f|\n", u);
      Format.printf("x = |% .5f|\n", x);
      Format.printf("w = |%20.5f|\n", w);
      Format.printf("x = |%020.5f|\n", x);
      Format.printf("x = |%+20.5f|\n", x);
      Format.printf("x = |%+020.5f|\n", x);
      Format.printf("x = |% 020.5f|\n", x);
      Format.printf("y = |%#+20.5f|\n", y);
      Format.printf("y = |%-+20.5f|\n", y);
      Format.printf("z = |%20.5f|\n", z);

      Format.printf("x = |%e|\n", x);
      Format.printf("u = |%20e|\n", u);
      Format.printf("x = |% .5e|\n", x);
      Format.printf("w = |%20.5e|\n", w);
      Format.printf("x = |%020.5e|\n", x);
      Format.printf("x = |%+20.5e|\n", x);
      Format.printf("x = |%+020.5e|\n", x);
      Format.printf("x = |% 020.5e|\n", x);
      Format.printf("y = |%#+20.5e|\n", y);
      Format.printf("y = |%-+20.5e|\n", y);

      Format.printf("x = |%g|\n", x);
      Format.printf("z = |%g|\n", z);
      Format.printf("w = |%g|\n", w);
      Format.printf("u = |%g|\n", u);
      Format.printf("y = |%.2g|\n", y);
      Format.printf("y = |%#.2g|\n", y);

      Format.printf("d = |%d|\n", d);
      Format.printf("d = |%20d|\n", d);
      Format.printf("d = |%020d|\n", d);
      Format.printf("d = |%+20d|\n", d);
      Format.printf("d = |% 020d|\n", d);
      Format.printf("d = |%-20d|\n", d);
      Format.printf("d = |%20.8d|\n", d);
      Format.printf("d = |%x|\n", d);
      Format.printf("d = |%20X|\n", d);
      Format.printf("d = |%#20x|\n", d);
      Format.printf("d = |%020X|\n", d);
      Format.printf("d = |%20.8x|\n", d);
      Format.printf("d = |%o|\n", d);
      Format.printf("d = |%020o|\n", d);
      Format.printf("d = |%#20o|\n", d);
      Format.printf("d = |%#020o|\n", d);
      Format.printf("d = |%20.12o|\n", d);

      Format.printf("s = |%-20s|\n", "Hello");
      Format.printf("s = |%-20c|\n", '!');

      // regression test to confirm fix of reported bugs

      Format.printf("|%i|\n", Long.MIN_VALUE);

      Format.printf("|%6.2e|\n", 0.0);
      Format.printf("|%6.2g|\n", 0.0);

      Format.printf("|%6.2f|\n", 9.99);
      Format.printf("|%6.2f|\n", 9.999);
      Format.printf("|%.2f|\n", 1.999);

      Format.printf("|%6.0f|\n", 9.999);
      Format.printf("|%20.10s|\n", "Hello");
      d = -1;
      Format.printf("-1 = |%X|\n", d);

      Format.printf("100 = |%e|\n", 100.0); // 2000-06-09
      Format.printf("1/0 = |%f|\n", 1.0 / 0.0);
      Format.printf("-1/0 = |%e|\n", -1.0 / 0.0);
      Format.printf("0/0 = |%g|\n", 0.0 / 0.0);
   }

   private static String repeat(char c, int n)
   {
      if (n <= 0) return "";
      StringBuffer s = new StringBuffer(n);
      for (int i = 0; i < n; i++) s.append(c);
      return s.toString();
   }

   private static String convert(long x, int n, int m, String d)
   {
      if (x == 0) return "0";
      String r = "";
      while (x != 0)
      {
         r = d.charAt((int)(x & m)) + r;
         x = x >>> n;
      }
      return r;
   }

   private String pad(String r)
   {
      String p = repeat(' ', width - r.length());
      if (leftAlign) return pre + r + p + post;
      else return pre + p + r + post;
   }

   private String sign(int s, String r)
   {
      String p = "";
      if (s < 0) p = "-";
      else if (s > 0)
      {
         if (showPlus) p = "+";
         else if (showSpace) p = " ";
      }
      else
      {
         if (fmt == 'o' && alternate && r.length() > 0 && r.charAt(0) != '0') p = "0";
         else if (fmt == 'x' && alternate) p = "0x";
         else if (fmt == 'X' && alternate) p = "0X";
      }
      int w = 0;
      if (leadingZeroes)
         w = width;
      else if ((fmt == 'd' || fmt == 'i' || fmt == 'x' || fmt == 'X' || fmt == 'o')
         && precision > 0) w = precision;

      return p + repeat('0', w - p.length() - r.length()) + r;
   }

   private String fixedFormat(double d)
   {
      boolean removeTrailing
         = (fmt == 'G' || fmt == 'g') && !alternate;
         // remove trailing zeroes and decimal point

      if (d > 0x7FFFFFFFFFFFFFFFL) return expFormat(d);
      if (precision == 0)
         return (long)(d + 0.5) + (removeTrailing ? "" : ".");

      long whole = (long)d;
      double fr = d - whole; // fractional part
      if (fr >= 1 || fr < 0) return expFormat(d);

      double factor = 1;
      String leadingZeroes = "";
      for (int i = 1; i <= precision && factor <= 0x7FFFFFFFFFFFFFFFL; i++)
      {
         factor *= 10;
         leadingZeroes = leadingZeroes + "0";
      }
      long l = (long) (factor * fr + 0.5);
      if (l >= factor) { l = 0; whole++; } // CSH 10-25-97

      String z = leadingZeroes + l;
      z = "." + z.substring(z.length() - precision, z.length());

      if (removeTrailing)
      {
         int t = z.length() - 1;
         while (t >= 0 && z.charAt(t) == '0') t--;
         if (t >= 0 && z.charAt(t) == '.') t--;
         z = z.substring(0, t + 1);
      }

      return whole + z;
   }

   private String expFormat(double d)
   {
      String f = "";
      int e = 0;
      double dd = d;
      double factor = 1;
      if (d != 0)
      {
         while (dd >= 10) { e++; factor /= 10; dd = dd / 10; } // 2000-06-09
         while (dd < 1) { e--; factor *= 10; dd = dd * 10; }
      }
      if ((fmt == 'g' || fmt == 'G') && e >= -4 && e < precision)
         return fixedFormat(d);

      d = d * factor;
      f = f + fixedFormat(d);

      if (fmt == 'e' || fmt == 'g')
         f = f + "e";
      else
         f = f + "E";

      String p = "000";
      if (e >= 0)
      {
         f = f + "+";
         p = p + e;
      }
      else
      {
         f = f + "-";
         p = p + (-e);
      }

      return f + p.substring(p.length() - 3, p.length());
   }

   private int width;
   private int precision;
   private String pre;
   private String post;
   private boolean leadingZeroes;
   private boolean showPlus;
   private boolean alternate;
   private boolean showSpace;
   private boolean leftAlign;
   private char fmt; // one of cdeEfgGiosxXos
}
