#!/usr/bin/python2.7

import os, sys
import getopt
import fnmatch, re

class Usage(Exception):
    def __init__(self, msg=None):
        if msg:
            self.msg = "Error: " + str(msg) + "\n\n"
        else:
            self.msg = ""
        self.msg = self.msg + "Usage: find_newer.py [options] dir...\n\n"
        self.msg = self.msg + "Options:\n"
	self.msg = self.msg + "   --name glob  find files matching glob\n"
        self.msg = self.msg + "   --newer ref  find files newer than a reference file"
        self.msg = self.msg + "   -c           compare ctimes (the time the file status was last changed)\n"
        self.msg = self.msg + "                This is the default.\n"
        self.msg = self.msg + "   -m           compare mtimes (the time the file was last modified)\n"
        self.msg = self.msg + "   -a           compare atimes (the time the file was last accessed)\n"
        self.msg = self.msg + "   -f           follow symlinks\n"
        self.msg = self.msg + "\nNote: if more than one of -c -m and -a are specified, find_newer will\n"
        self.msg = self.msg + "compare the most recent of the given times\n"


def get_file_time(stat, type):
    time = None
    if "c" in type:
        time = stat.st_ctime;
    if "m" in type:
        if time:
            if time < stat.st_mtime:
                time = stat.st_mtime
        else:
            time = stat.st_mtime;
    elif "a" in type:
        if time:
            if time < stat.st_atime:
                time = stat.st_atime
        else:
            time = stat.st_atime;
    return time

dirs_seen = []
def find_newer_files(dir, comp_time, ref_time, reobj, follow_links):
    dir = os.path.abspath(dir)
    if dir in dirs_seen:
        print >>sys.stderr, "Warning: infinite loop of symlinks"
        return
    dirs_seen.append(dir)
    for root, dirs, files in os.walk(dir):
        for file in files:
            try:
                file = os.path.abspath(os.path.join(root, file))
                stat = os.stat (file)
                if ref_time:
                    if get_file_time (stat, comp_time) > ref_time:
                        if reobj:
                            if reobj.match (file):
                                print file
                        else:
                            print file
                else:
                    # no reference time, print all files that match the regex
                    if reobj:
                        if reobj.match (file):
                            print file
                    else:
                        print file
            except:
                pass
        if follow_links:
            # descend into subdirectories that are really symlinks
            for d in dirs:
                d = os.path.join(root, d)
                if os.path.islink(d) and os.path.lexists(d):
                    d = os.path.abspath(os.path.join(root, os.readlink(d)))
                    find_newer_files(d, comp_time, ref_time, reobj, follow_links)
    

def main(argv=None):
    comp_time = []
    follow_links = False
    glob = None
    ref_file = None

    # parse the command line args
    if argv is None:
        argv = sys.argv
    try:
        try:
            opts, args = getopt.getopt(argv[1:], "hcmaf", ["help", "newer=", "name="])
        except getopt.error, msg:
            raise Usage(msg)
        for o, a in opts:
            if o == "-c":
                comp_time.append("c")
            elif o == "-m":
                comp_time.append("m")
            elif o == "-a":
                comp_time.append("a")
            elif o in ("-h", "--help"):
                raise Usage()
            elif o in "-f":
                follow_links = True
            elif o in "--name":
                glob = a
            elif o in "--newer":
                ref_file = a
        if len(args) < 1:
            raise Usage("invalid arguments")

    except Usage, err:
        print >>sys.stderr, err.msg
        print >>sys.stderr, "Use --help for usage information"
        return 2

    # default: compare ctime
    if not comp_time:
        comp_time = ["c"]

    # return stat time as floats
    os.stat_float_times (True)

    if ref_file:
        try:
            ref_stat = os.stat(ref_file)
        except:
            print >>sys.stderr, "Cannot stat reference file: %s" % ref_file
            return 1
        ref_time = get_file_time (ref_stat, comp_time)
    else:
        ref_time = None

    for dir in args:
        if not os.path.isdir(dir):
            print >>sys.stderr, "Directory not found: %s" % dir
            return 1

        if glob:
            regex = fnmatch.translate(glob)
            reobj = re.compile (regex)
        else:
            reobj = None

        find_newer_files(dir, comp_time, ref_time, reobj, follow_links)

if __name__ == "__main__":
    sys.exit(main())