#! /usr/bin/env python

# langgrep: grep for a pattern but only in files written in the
# specified language (as specified by the shebang line).
#
# Copyright 2009 by Akkana Peck.
# Please share, modify and enjoy under the terms of the GPL v2
# or, at your option, any later GPL version.
#
# Bugs: it isn't smart about parsing the grep flags.
# Anything beginning with a - will be considered a flag
# and passed on to grep; the first argument not starting with -
# is taken to be the search pattern, and everything after that
# is the file list.
#

import string, os, sys

def Usage():
    print "langgrep lang [grepflags] pattern files"
    print " e.g. langgrep python -w find *"
    sys.exit(0)

def check_file_lang(filename, lang) :
    try :
        f = open(filename)
        firstline = f.readline(80)
        f.close()
    except IOError, e:
        return False

    if firstline[0:2] == "#!" and string.find(firstline, lang) >= 0 :
        return True
    return False

# main()
if len(sys.argv) < 3 :
    Usage()
lang = sys.argv[1]

args = ""
for i in range(2, len(sys.argv)) :
    if sys.argv[i][0] == '-' :
        args = args + " " + sys.argv[i]
    else :
        args = args + " " + sys.argv[i]
        break

# Now sys.argv[i:] is the file list, if any.
# If none, substitute ~/bin/*
if i >= len(sys.argv) - 1 :
    os.chdir(os.path.join(os.getenv("HOME"), "bin"))
    files = os.listdir(".")
else :
    files = sys.argv[i:]

for fil in files :
    if check_file_lang(fil, lang) :
        os.system("grep -H" + args + " " + fil)