#!/usr/bin/python3

# Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com/>

# This file is part of GlusterFS.

#

# This file is licensed to you under your choice of the GNU Lesser

# General Public License, version 3 or any later version (LGPLv3 or

# later), or the GNU General Public License, version 2 (GPLv2), in all

# cases as published by the Free Software Foundation.

import sys

import os

import xattr

import uuid

import re

import errno

CHANGELOG_SEARCH_MAX_TRY = 31

DEC_CTIME_START = 5

ROOT_GFID = "00000000-0000-0000-0000-000000000001"

MAX_NUM_CHANGELOGS_TRY = 2

def output_not_found(gfid):

    # Write GFID to stderr

    sys.stderr.write("%s\n" % gfid)

def output_success(path):

    # Write converted Path to Stdout

    sys.stdout.write("%s\n" % path)

def full_dir_path(gfid):

    out_path = ""

    while True:

        path = os.path.join(".glusterfs", gfid[0:2], gfid[2:4], gfid)

        path_readlink = os.readlink(path)

        pgfid = os.path.dirname(path_readlink)

        out_path = os.path.join(os.path.basename(path_readlink), out_path)

        if pgfid == "../../00/00/%s" % ROOT_GFID:

            out_path = os.path.join("./", out_path)

            break

        gfid = os.path.basename(pgfid)

    return out_path

def find_path_from_changelog(fd, gfid):

    """

    In given Changelog File, finds using following pattern

    <T><GFID>\x00<TYPE>\x00<MODE>\x00<UID>\x00<GID>\x00<PARGFID>/<BASENAME>

    Pattern search finds PARGFID and BASENAME, Convert PARGFID to Path

    Using readlink and add basename to form Full path.

    """

    content = fd.read()

    pattern = "E%s" % gfid

    pattern += "\x00(3|23)\x00\d+\x00\d+\x00\d+\x00([^\x00]+)/([^\x00]+)"

    pat = re.compile(pattern)

    match = pat.search(content)

    if match:

        pgfid = match.group(2)

        basename = match.group(3)

        if pgfid == ROOT_GFID:

            return os.path.join("./", basename)

        else:

            full_path_parent = full_dir_path(pgfid)

            if full_path_parent:

                return os.path.join(full_path_parent, basename)

    return None

def gfid_to_path(gfid):

    """

    Try readlink, if it is directory it succeeds.

    Get ctime of the GFID file, Decrement by 5 sec

    Search for Changelog filename, Since Changelog file generated

    every 15 sec, Search and get immediate next Changelog after the file

    Creation. Get the Path by searching in Changelog file.

    Get the resultant file's GFID and Compare with the input, If these

    GFIDs are different then Some thing is changed(May be Rename)

    """

    gfid = gfid.strip()

    gpath = os.path.join(".glusterfs", gfid[0:2], gfid[2:4], gfid)

    try:

        output_success(full_dir_path(gfid))

        return

    except OSError:

        # Not an SymLink

        pass

    try:

        ctime = int(os.stat(gpath).st_ctime)

        ctime -= DEC_CTIME_START

    except (OSError, IOError):

        output_not_found(gfid)

        return

    path = None

    found_changelog = False

    changelog_parse_try = 0

    for i in range(CHANGELOG_SEARCH_MAX_TRY):

        cl = os.path.join(".glusterfs/changelogs", "CHANGELOG.%s" % ctime)

        try:

            with open(cl, "rb") as f:

                changelog_parse_try += 1

                found_changelog = True

                path = find_path_from_changelog(f, gfid)

                if not path and changelog_parse_try < MAX_NUM_CHANGELOGS_TRY:

                    ctime += 1

                    continue

            break

        except (IOError, OSError) as e:

            if e.errno == errno.ENOENT:

                ctime += 1

            else:

                break

    if not found_changelog:

        output_not_found(gfid)

        return

    if not path:

        output_not_found(gfid)

        return

    gfid1 = str(uuid.UUID(bytes=xattr.get(path, "trusted.gfid")))

    if gfid != gfid1:

        output_not_found(gfid)

        return

    output_success(path)

def main():

    num_arguments = 3

    if not sys.stdin.isatty():

        num_arguments = 2

    if len(sys.argv) != num_arguments:

        sys.stderr.write("Invalid arguments\nUsage: "

                         "%s <BRICK_PATH> <GFID_FILE>\n" % sys.argv[0])

        sys.exit(1)

    path = sys.argv[1]

    if sys.stdin.isatty():

        gfid_list = os.path.abspath(sys.argv[2])

        os.chdir(path)

        with open(gfid_list) as f:

            for gfid in f:

                gfid_to_path(gfid)

    else:

        os.chdir(path)

        for gfid in sys.stdin:

            gfid_to_path(gfid)

if __name__ == "__main__":

    main()