#!/usr/local/bin/ruby
#
# parse filename
#

# ^field: value
#
# ^field:
# [\t ]value...

# fields[fieldname] = fieldvalue

# Open file for reading
# infield=false
# curfield=""
# curvalue=""
# for each line ll in file do
#   switch ll:
#     /^[^\t ]/   :  if infield? close and add field to fields
#                    begin new field
#     /^[\t ]/    :  append to curvalue
#     eof         :  if infield? close and add field to fields
#   done
# done
# 

if ARGV[0] == nil then
	print "Usage: parse filename\n"
	exit 1
end

def parse_form( formdata, fieldnames )
	fields = {}
	infield=false
	curfield=nil
	curvalue=nil

	formdata.each do |line|
		line.chomp!
		case line
			when /^[\t ]*#/
				# ignore comment lines
			when /^[^\t ]/
				# begin field
				if infield then
					fields[curfield] = curvalue
					fieldnames << curfield
				end
				infield=true
				curfield = line[/^[^:]*/].strip
				curvalue = line.sub(/^[^:]*:[\t ]*/, "")
			when /^[\t ]/
				# continue field
				if infield then
					curvalue = "#{curvalue}\n#{line}"
				else
					# unknown
				end
			else
				# unknown
		end
	end
	
	if infield then
		fields[curfield] = curvalue
		fieldnames << curfield
	end
	return fields
end

a_fieldnames = []
a_file = File.new(ARGV[0])
a_fields = parse_form(a_file, a_fieldnames)
a_file.close
	
b_fieldnames = []
b_file = File.new(ARGV[1])
b_fields = parse_form(b_file, b_fieldnames)
b_file.close
	
in_both = a_fieldnames & b_fieldnames
deleted = a_fieldnames - b_fieldnames
added = b_fieldnames - a_fieldnames
changed = []

for f in in_both
	if a_fields[f] != b_fields[f] then
		changed << f
	end
end

same = in_both - changed

printf "Unchanged fields: %s\n", same.join(", ")
printf "Deleted fields: %s\n", deleted.join(", ")
printf "Added fields: %s\n", added.join(", ")
printf "Changed fields: %s\n", changed.join(", ")