#!/usr/local/bin/python

# csh2sh.py - convert csh scripts to sh script.
#             The input filename should be in the form
#             x.csh, and the output file will be x.sh
#
# WARNING: This script only does some very crude 
# substitutions. Code generated by this script
# should be considered as a starting point for
# manual translation to sh.

# Version  11/15/09

# Synopsis:
#   csh2sh.py infile 
#        infile - csh script



import sys
import os
import string
import re
import shutil

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
class Parameters :
      "Wrapper class for command line parameters"
      def __init__(self) :
          self.IFN = ""
	  self.OFN = ""
	  
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
def READARGS(P) :
    "Read command line arguments into a Parameter object"
    "Right now, only IFN is supported."
    NUMARGS = len(sys.argv)
    if NUMARGS >= 1 :
       P.IFN = sys.argv[1]

    P.OFN = P.IFN
    if P.OFN.endswith('.csh') :
       P.OFN = P.OFN[0:-4]
    P.OFN = P.OFN + '.sh'

#    I = 2
#    while (I < NUMARGS)  :
#          # This code is here as a placeholder for
#          # future command line switches
#	  if sys.argv[I] == "-dummy1" :
#             I = I + 1
#             if I < NUMARGS :
#		I = I + 1
#	  elif sys.argv[I] == "-dummy2" :
#             I = I + 1
#             if I < NUMARGS :
#		I = I + 1
#	  else :
#             P.OFN = sys.argv[I]
#             I = NUMARGS	             	
    return


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
class scriptfile :
      "Contents of the file"

      def __init__(self) :
	  self.text = ""

      def readFile(self,IFN) :         
	  INFILE = open(IFN,'r')
          self.text = INFILE.read()
	  INFILE.close()
          return

      def writeFile(self,OFN) :         
	  OUTFILE = open(OFN,'w')
	  OUTFILE.write(self.text)
	  OUTFILE.close()
          return

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
def CONVERT(SCRIPT) :
    "Iterate through the script replacing csh syntax with" 
    "sh syntax."
    SCRIPT.text = re.sub('#!/bin/csh','#!/bin/sh',SCRIPT.text)
    
    # arguments
    SCRIPT.text = re.sub('\$#argv','$#',SCRIPT.text)
    SCRIPT.text = re.sub('\$argv','$*',SCRIPT.text)
    # We still need to handle the usage:  $argv[n]
    
    # Convert $home, $path to $HOME, $PATH
    SCRIPT.text = re.sub('\$home','$HOME',SCRIPT.text)
    SCRIPT.text = re.sub('\$path','$PATH',SCRIPT.text)

    #------ File name manipulations -----------

    # Basename: $FILE:t
    EXP1='(\$)(.+)(:t)'
    EXP2='`basename \g<1>\g<2>`'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)
   
    # File extension: $FILE:e
    EXP1='(\$)(.+)(:e)'
    EXP2='\g<1>{\g<2>##*.}'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)

    # Filename minus file extension: $FILE:r
    EXP1='(\$)(.+)(:r)'
    EXP2='\g<1>{\g<2>%.*}'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)

    # ----------  Flow of control statements ---------------------
    
    # if then
    EXP1='([\t ]*)(if[\t ]+)(.+)([\t ]+then)'
    EXP2='\g<1>if [ \g<3> ]\n\g<1>\tthen'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)
    EXP1='(if \[)([\t ]+)(\()(.*)(\))([\t ]*)(\])'
    EXP2='if [ \g<4> ]'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)
    SCRIPT.text = re.sub('endif','fi',SCRIPT.text)
    
    
    # set, setenv 
    EXP1 = '(set[\t ]+)(\S+)([\t ]+=[\t ]+)(\()(\s)(.*)(\s)(\))'
    EXP2 = '\g<1>\g<2>\g<3>"\g<6>"'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)
    SCRIPT.text = re.sub('(set[\t ]+)(\S+)([\t ]+=[\t ]+)','\g<2>=',SCRIPT.text)
    SCRIPT.text = re.sub('([\t ]*)(setenv[\t ]+)(\S+)([\t ]+)(\S+)','\g<1>\g<3>=\g<5>\n\g<1>export \g<3>',SCRIPT.text) 
       
    # switch
    SCRIPT.text = re.sub('(switch[\t ]+\()(\S+)([\t ]*\)[\t ]*)','case \g<2> in',SCRIPT.text)
    SCRIPT.text = re.sub('(case[\t ]+)(\S+)([\t ]*\:[\t ]*)','\g<2>)',SCRIPT.text) 
    SCRIPT.text = re.sub('breaksw',';;',SCRIPT.text)
    SCRIPT.text = re.sub('default:','*)',SCRIPT.text)
    SCRIPT.text = re.sub('endsw','esac',SCRIPT.text) 
      
    # while
    EXP1 = '(while[\t ]+)(\()(.*)(\)[\t ]*\n)'
    EXP2 = 'while [ \g<3> ]\n\tdo\n'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)	
    SCRIPT.text = re.sub('(\n[\t ]*)(end)','\g<1>done',SCRIPT.text)
    
    # foreach
    #this doesn't seem to work and I can't figure out why.
    EXP1 = '([\t ]*)(foreach[\t ]+)(\S+)([\t ]+)(.*)'
    EXP2 = '\g<1>for \g<3> in \g<5>\n\g<1>    do\n'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)	
    # Also replace parentheses with double quotes, for lists in a for expression
    EXP1 = '(for[\t ]+\S+[\t ]+in[\t ])(\()(.*)(\))'
    EXP2 = '\g<1>"\g<3>"'    
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)	

    #Lists
    EXP1 = re.compile('(\S+=)(\()(.*?)(\))',re.DOTALL |re.MULTILINE)
    EXP2 = '\g<1>"\g<3>"'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text,re.DOTALL |re.MULTILINE)	    

    # boolean tests
    EXP1 = '(\$\{\?)(\S+)(\})'
    EXP2 = '! -z "$\g<2>"'
    SCRIPT.text = re.sub(EXP1,EXP2,SCRIPT.text)  
      
    return    
        
#======================== MAIN PROCEDURE ==========================
P = Parameters ()

READARGS(P)

# Read the csh file
SCRIPT = scriptfile()
SCRIPT.readFile(P.IFN)

# Replace csh syntax with sh syntax. 
CONVERT(SCRIPT)

# WARNING: this is currently a very simple-minded replacement.
SCRIPT.writeFile(P.OFN)
os.chmod(P.OFN,0755)