#!/usr/bin/env python
import sys, re, os, os.path, fnmatch, codecs, locale
from optparse import OptionParser
desc = """Walk the current directory and its subdirectories, opening '*.txt' 
files and reporting the changes needed for the new, post version 845, format. 
If the option '-m' is used, changes will be made and and the results saved with 
the file extension changed to '.text' provided this file does not already 
exist."""

encoding = "UTF-8"
file_encoding = locale.getdefaultlocale()[1]

def make_xlat(d):
    adict = d
    rx = re.compile('|'.join(adict))
    def one_xlat(match):
        return adict[match.group(0)]
    def xlat(text):
        return rx.sub(one_xlat, text)
    return xlat

def walkdir(make_changes=False):
    global numfiles, numlines, numchanges
    numfiles = 0
    numlines = 0
    numchanges = 0
    amper = re.compile(r'^&')
    under = re.compile(r'^(_+)')
    period = re.compile(r'^(\.+)')
    # to remove any any white space following '@e +'
    extent = re.compile(r'@e \+\s+')
    sdict = {
        '@l' : '@+', # include list
        '@x' : '@-', # exclude list
        '@p' : '@e +', # action period -> +extent
            }
    translate = make_xlat(sdict)

    cwd = os.getcwd()
    all_changes = []
    num_skipped = 0
    num_changed = 0
    for path, subdirs, names in os.walk(cwd):
        for name in names:
            level = 1
            if fnmatch.fnmatch(name, '[!.]*.txt'):
                file_changes = []
                numfiles += 1
                changed = False
                f = os.path.join(path,name)
                newf = "%s.text" % os.path.splitext(f)[0]
                if make_changes and os.path.isfile(newf):
                    print """
    Skipping 
        %s 
    to avoid overwriting an existing file. Remove or rename 
        %s 
    before running this program to process this file.
                    """ % (f, newf)
                    num_skipped += 1
                    continue
                sf = f[len(path)+1:]
                # use the relative path as the key
                fo = codecs.open(f, 'r', file_encoding)
                lines = fo.readlines()
                fo.close()
                for i in range(len(lines)):
                    numlines += 1
                    old_line = lines[i].rstrip()
                    if not old_line:
                        continue
                    new_line = translate(old_line)
                    new_line = extent.sub('@e +', new_line)
                    new_line = amper.sub('*', new_line)     # old rem -> event
                    m = under.match(new_line)
                    if m:
                        new_line = under.sub('+'*len(m.group(0)), new_line)
                    m = period.match(new_line)
                    if m:
                        new_line = period.sub('-'*len(m.group(0)), new_line)
                    if new_line != old_line:
                        numchanges += 1
                        changed = True
                        file_changes.append("  line %s: " % i)
                        file_changes.append("  [-] '%s'" % old_line)
                        file_changes.append("  [+] '%s'" % new_line) 
                        if make_changes:
                            lines[i] = "%s\n" % new_line
                if changed:
                    num_changed += 1
                    file_changes.insert(0, "file: '%s'" % f)
                    all_changes.extend(file_changes)
                    if make_changes:
                        newf = "%s.text" % os.path.splitext(f)[0]
                        fo = codecs.open(newf, 'w', file_encoding)
                        fo.writelines(lines)
                        fo.close()

    if num_skipped: 
        print """
%s files with the extension '.txt' were found. Of these %s were skipped
because matching files with the extension '.text' were found. The
remaining %s files were examined for needed changes.
        """ % (numfiles, num_skipped, numfiles - num_skipped)
    else:
        print """
%s files with the extension '.txt' were found and examined for needed 
changes.
        """ % numfiles 

    if numchanges:
        if make_changes:
            v = "Made"
            p = ''
        else:
            v = "You need to make"
            p = "\nAppend '-m' to the command line to make these changes and save the results\nto new files with the extension '.text'.\n\nANY EXISTING FILES WITH THE EXTENSION '.text' WILL NOT BE OVERWRITTEN.\n"
        print("%s the following %s changes in %s file(s):\n" % 
                (v, numchanges, num_changed))
        print("\n".join(all_changes))
        print(p)
    else:
        print("There are no changes to be made in the %s files which were examined." 
                % (numfiles - num_skipped))


def main():
    usage = "%prog [options]"

    parser = OptionParser(usage=usage, 
    description = desc)
    parser.add_option("-m", "--make_changes", 
                      action="store_true", dest="make_changes",  
                      help="Actually make changes and save the result with the file's extension changed to .text." )
    options, args= parser.parse_args()
    walkdir(options.make_changes)

if __name__ == '__main__':
    main()