#!/usr/bin/python
#
#  Scan potential external strings from Ecmascript and C files.
#
#  Very simplistic example with a lot of limitations:
#
#    - Doesn't handle multiple variables in a variable declaration
#
#    - Only extracts strings from C files, these may correspond to
#      Duktape/C bindings (but in many cases don't)
#

import os
import sys
import re
import json

strmap = {}

# Ecmascript function declaration
re_funcname = re.compile(r'function\s+(\w+)', re.UNICODE)

# Ecmascript variable declaration
# XXX: doesn't handle multiple variables
re_vardecl = re.compile(r'var\s+(\w+)', re.UNICODE)

# Ecmascript variable assignment
re_varassign = re.compile(r'(\w+)\s*=\s*', re.UNICODE)

# Ecmascript dotted property reference (also matches numbers like
# '4.0', which are separately rejected below)
re_propref = re.compile(r'(\w+(?:\.\w+)+)', re.UNICODE)
re_digits = re.compile(r'^\d+$', re.UNICODE)

# Ecmascript or C string literal
re_strlit_dquot = re.compile(r'("(?:\\"|\\\\|[^"])*")', re.UNICODE)
re_strlit_squot = re.compile(r'(\'(?:\\\'|\\\\|[^\'])*\')', re.UNICODE)

def strDecode(x):
	# Need to decode hex, unicode, and other escapes.  Python syntax
	# is close enough to C and Ecmascript so use eval for now.

	try:
		return eval('u' + x)  # interpret as unicode string
	except:
		sys.stderr.write('Failed to parse: ' + repr(x) + ', ignoring\n')
		return None

def scan(f, fn):
	global strmap

	# Scan rules depend on file type
	if fn[-2:] == '.c':
		use_funcname = False
		use_vardecl = False
		use_varassign = False
		use_propref = False
		use_strlit_dquot = True
		use_strlit_squot = False
	else:
		use_funcname = True
		use_vardecl = True
		use_varassign = True
		use_propref = True
		use_strlit_dquot = True
		use_strlit_squot = True

	for line in f:
		# Assume input data is UTF-8
		line = line.decode('utf-8')

		if use_funcname:
			for m in re_funcname.finditer(line):
				strmap[m.group(1)] = True

		if use_vardecl:
			for m in re_vardecl.finditer(line):
				strmap[m.group(1)] = True

		if use_varassign:
			for m in re_varassign.finditer(line):
				strmap[m.group(1)] = True

		if use_propref:
			for m in re_propref.finditer(line):
				parts = m.group(1).split('.')
				if re_digits.match(parts[0]) is not None:
					# Probably a number ('4.0' or such)
					pass
				else:
					for part in parts:
						strmap[part] = True

		if use_strlit_dquot:
			for m in re_strlit_dquot.finditer(line):
				s = strDecode(m.group(1))
				if s is not None:
					strmap[s] = True

		if use_strlit_squot:
			for m in re_strlit_squot.finditer(line):
				s = strDecode(m.group(1))
				if s is not None:
					strmap[s] = True

def main():
	for fn in sys.argv[1:]:
		f = open(fn, 'rb')
		scan(f, fn)
		f.close()

	strs = []
	strs_base64 = []
	doc = {
		# Strings as Unicode strings
		'scanned_strings': strs,

		# Strings as base64-encoded UTF-8 data, which should be ready
		# to be used in C code (Duktape internal string representation
		# is UTF-8)
		'scanned_strings_base64': strs_base64
	}
	k = strmap.keys()
	k.sort()
	for s in k:
		strs.append(s)
		t = s.encode('utf-8').encode('base64')
		if len(t) > 0 and t[-1] == '\n':
			t = t[0:-1]
		strs_base64.append(t)

	print(json.dumps(doc, indent=4, ensure_ascii=True, sort_keys=True))

if __name__ == '__main__':
	main()