#!/bin/sed -nrf

#log-filter.sed
#this is part of the program "propogate"

#rearrange input into the format that the command parser expects: property_name,value

#I tried to prevent any potential security flaws from crafted input by:
# - exactly matching allowable properties, instead of removing all the possible invalid ones that I could think of
# - restricting the allowed characters to the minimum required to do their jobs

# - first field: property name, without any leading or trailing whitespace, and without a colon at the end
#   allowed characters:
#   - uppercase letters
#   - lowercase letters
#   - underscores
#   - dashes

# - second field: the value of the property, stripped of quotes and leading and trailing white space
#   allowed characters:
#   - uppercase letters
#   - lowercase letters
#   - numbers
#   - underscores
#   - dashes
#   - periods
#   - colons
#   - spaces

#to prevent any invalid input from getting past, I had this script by default output nothing
#in addition, I placed the "d" command (delete current buffer, move on to next line) 
#before the "p" command (print contents of pattern buffer), and the script only jumps
#to the "p" command if the input is validly formatted

#trim white space

s/^[ 	]*(.*)[ 	]*$/\1/

#handle opening and closing curly braces, and skip to the print command if they're found

/^[\{\}]$/ b print

#main substitution line: if the line matches an acceptable format for an input, extract the property 
#name and its value, and put them into a comma-separated list
s/^([A-Za-z_\-]*)\:[ 	]*\"([A-Za-z0-9 _\-\.\:\/]*)\"\,?/\1,\2/

#if the previous substitution succeeded, skip to the print command
t print

#if the previous substitution failed, output an error message

#s/.*/error,&/

#delete the contents of the pattern space, thus implicitly moving on to the next line

d

#the script should only get to this point if the previous substitution was a success

:print
p