// Library for converting numbers to various Chinese representations.
// See:
// http://www.mandarintools.com/numbers.html
// http://en.wikipedia.org/wiki/Chinese_numerals
//
class ChineseNumbers
{
   // Dictionaries that store the styles.
   class var casual = ChineseNumbers.initializeCasual[]
   class var formal = ChineseNumbers.initializeFormal[]

   // Initialize the casual dictionary
   class initializeCasual[] :=
   {
      casual = new dict
      
      casual@"0" = "\u96F6"
      casual@"1" = "\u4e00"
      casual@"2" = "\u4e8c"
      casual@"3" = "\u4e09"
      casual@"4" = "\u56db"
      casual@"5" = "\u4e94"
      casual@"6" = "\u516d"
      casual@"7" = "\u4e03"
      casual@"8" = "\u516b"
      casual@"9" = "\u4e5d"
      casual@"10"= "\u5341"
      casual@"100" = "\u767e"
      casual@"1000" = "\u5343"
      casual@"10000" = "\u4e07"

      return casual
   }

   // Initialize the formal dictionary
   class initializeFormal[] :=
   {
      formal = new dict
      
      formal@"0" = "\u96F6"
      formal@"1" = "\u58F9"
      formal@"2" = "\u8cb3"
      formal@"3" = "\u53c4"
      formal@"4" = "\u8086"
      formal@"5" = "\u4f0d"
      formal@"6" = "\u9678"
      formal@"7" = "\u67D2"
      formal@"8" = "\u634C"
      formal@"9" = "\u7396"
      formal@"10"= "\u62fe"
      formal@"100" = "\u4f70"
      formal@"1000" = "\u4edf"
      formal@"10000" = "\u842c"
      return formal
   }

   // Get string corresponding to casual Chinese writing.
   class formatCasual[num is dimensionless] :=
   {
      return format[num, casual]
   }

   // Get string corresponding to formal Chinese writing.
   class formatFormal[num is dimensionless] :=
   {
      return format[num, formal]
   }
   
   // Function to format according to style.
   class format[num, dict, hasLeading=false] :=
   {
      ret = formatTenThousands[num, dict, false]

      re = subst["(.)" + dict@"0" + "+$", "$1"] // Remove trailing zeroes
      ret =~ re

      re = subst[dict@"0" + "{2,}", dict@"0"] // Remove doubled zeroes
      ret =~ re
   }

   // Format ten-thousands place
   class formatTenThousands[num, dict, hasLeading] :=
   {
      digits = num div 10000
      remainder = num mod 10000

      if digits == 0
         if !hasLeading
            return formatThousands[remainder, dict, false]
         else
            return dict@"0" + formatThousands[remainder, dict, true]

      return format[digits,dict,true] + dict@"10000" + formatThousands[remainder, dict, true]
   }
   
   // Format thousands place
   class formatThousands[num, dict, hasLeading] :=
   {
      digit = num div 1000
      remainder = num mod 1000

      if digit == 0
         if !hasLeading
            return formatHundreds[remainder, dict, false]
         else
            return dict@"0" + formatHundreds[remainder, dict, true]

      return dict@"$digit" + dict@"1000" + formatHundreds[remainder, dict, true]
   }
   
   // Format hundreds place
   class formatHundreds[num, dict, hasLeading] :=
   {
      digit = num div 100
      remainder = num mod 100

      if digit == 0
         if !hasLeading
            return formatTens[remainder, dict, false]
         else
            return dict@"0" + formatTens[remainder, dict, true]

      return dict@"$digit" + dict@"100" + formatTens[remainder, dict, true]
   }   

   // Format tens place
   class formatTens[num, dict, hasLeading] :=
   {
      digit = num div 10
      remainder = num mod 10

      if digit == 0
         if !hasLeading
            return formatOnes[remainder, dict, false]
         else
            return dict@"0" + formatOnes[remainder, dict, true]
         
      
      if digit == 1             // Special case for 11-99
         if !hasLeading
            return dict@"10" + formatOnes[remainder, dict, true]

      return dict@"$digit" + dict@"10" + formatOnes[remainder, dict, true]
   }   

   // Format ones place
   class formatOnes[num, dict, hasLeading] :=
   {
      if num == 0
         if !hasLeading         // No leading, return zero character
            return dict@"0"
         else                   // Has leading, skip if zero
            return ""

      return dict@"$num"        // Normal case
   }
}