#!/usr/bin/python
# -*- coding: utf-8 -*-

# (c) 2012, Daniel Hokka Zakrisson <daniel@hozac.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

import re
import os
import tempfile

DOCUMENTATION = """
---
module: lineinfile
author: Daniel Hokka Zakrisson
short_description: Ensure a particular line is in a file, or replace an
                   existing line using a back-referenced regular expression.
description:
  - This module will search a file for a line, and ensure that it is present or absent.
  - This is primarily useful when you want to change a single line in a
    file only. For other cases, see the M(copy) or M(template) modules.
version_added: "0.7"
options:
  dest:
    required: true
    aliases: [ name, destfile ]
    description:
      - The file to modify.
  regexp:
    required: true
    description:
      - The regular expression to look for in every line of the file. For
        C(state=present), the pattern to replace if found; only the last line
        found will be replaced. For C(state=absent), the pattern of the line
        to remove.  Uses Python regular expressions; see
        U(http://docs.python.org/2/library/re.html).
  state:
    required: false
    choices: [ present, absent ]
    default: "present"
    aliases: []
    description:
      - Whether the line should be there or not.
  line:
    required: false
    description:
      - Required for C(state=present). The line to insert/replace into the
        file. If backrefs is set, may contain backreferences that will get
        expanded with the regexp capture groups if the regexp matches. The
        backreferences should be double escaped (see examples).
  backrefs:
    required: false
    default: "no"
    choices: [ "yes", "no" ]
    version_added: "1.1"
    description:
      - Used with C(state=present). If set, line can contain backreferences
        (both positional and named) that will get populated if the regexp
        matches. This flag changes the operation of the module slightly;
        insertbefore and insertafter will be ignored, and if the regexp
        doesn't match anywhere in the file, the file will be left unchanged.
        If the regexp does match, the last matching line will be replaced by
        the expanded line parameter.
  insertafter:
    required: false
    default: EOF
    description:
      - Used with C(state=present). If specified, the line will be inserted
        after the specified regular expression. A special value is
        available; C(EOF) for inserting the line at the end of the file.
        May not be used with backrefs.
    choices: [ 'EOF', '*regex*' ]
  insertbefore:
    required: false
    version_added: "1.1"
    description:
      - Used with C(state=present). If specified, the line will be inserted
        before the specified regular expression. A value is available;
        C(BOF) for inserting the line at the beginning of the file.
        May not be used with backrefs.
    choices: [ 'BOF', '*regex*' ]
  create:
    required: false
    choices: [ "yes", "no" ]
    default: "no"
    description:
      - Used with C(state=present). If specified, the file will be created
        if it does not already exist. By default it will fail if the file
        is missing.
  backup:
     required: false
     default: "no"
     choices: [ "yes", "no" ]
     description:
       - Create a backup file including the timestamp information so you can
         get the original file back if you somehow clobbered it incorrectly.
  others:
     description:
       - All arguments accepted by the M(file) module also work here.
     required: false
"""

EXAMPLES = r"""
- lineinfile: dest=/etc/selinux/config regexp=^SELINUX= line=SELINUX=disabled

- lineinfile: dest=/etc/sudoers state=absent regexp="^%wheel"

- lineinfile: dest=/etc/hosts regexp='^127\.0\.0\.1' line='127.0.0.1 localhost' owner=root group=root mode=0644

- lineinfile: dest=/etc/httpd/conf/httpd.conf regexp="^Listen " insertafter="^#Listen " line="Listen 8080"

- lineinfile: dest=/etc/services regexp="^# port for http" insertbefore="^www.*80/tcp" line="# port for http by default"

- lineinfile: dest=/etc/sudoers state=present regexp='^%wheel' line='%wheel ALL=(ALL) NOPASSWD: ALL'

- lineinfile: dest=/opt/jboss-as/bin/standalone.conf regexp='^(.*)Xms(\d+)m(.*)$' line='\1Xms${xms}m\3' backrefs=yes
"""

def write_changes(module,lines,dest):

    tmpfd, tmpfile = tempfile.mkstemp()
    f = os.fdopen(tmpfd,'wb')
    f.writelines(lines)
    f.close()

    module.atomic_move(tmpfile, dest)

def check_file_attrs(module, changed, message):

    file_args = module.load_file_common_arguments(module.params)
    if module.set_file_attributes_if_different(file_args, False):

        if changed:
            message += " and "
        changed = True
        message += "ownership, perms or SE linux context changed"

    return message, changed


def present(module, dest, regexp, line, insertafter, insertbefore, create,
            backup, backrefs):

    if not os.path.exists(dest):
        if not create:
            module.fail_json(rc=257, msg='Destination %s does not exist !' % dest)
        destpath = os.path.dirname(dest)
        if not os.path.exists(destpath):
            os.makedirs(destpath)
        lines = []
    else:
        f = open(dest, 'rb')
        lines = f.readlines()
        f.close()

    msg = ""

    mre = re.compile(regexp)

    if insertafter not in (None, 'BOF', 'EOF'):
        insre = re.compile(insertafter)
    elif insertbefore not in (None, 'BOF'):
        insre = re.compile(insertbefore)
    else:
        insre = None

    # index[0] is the line num where regexp has been found
    # index[1] is the line num where insertafter/inserbefore has been found
    index = [-1, -1]
    m = None
    for lineno, cur_line in enumerate(lines):
        match_found = mre.search(cur_line)
        if match_found:
            index[0] = lineno
            m = match_found
        elif insre is not None and insre.search(cur_line):
            if insertafter:
                # + 1 for the next line
                index[1] = lineno + 1
            if insertbefore:
                # + 1 for the previous line
                index[1] = lineno

    msg = ''
    changed = False
    # Regexp matched a line in the file
    if index[0] != -1:
        if backrefs:
            new_line = m.expand(line)
        else:
            # Don't do backref expansion if not asked.
            new_line = line

        if lines[index[0]] != new_line + os.linesep:
            lines[index[0]] = new_line + os.linesep
            msg = 'line replaced'
            changed = True
    elif backrefs:
        # Do absolutely nothing, since it's not safe generating the line
        # without the regexp matching to populate the backrefs.
        pass
    # Add it to the beginning of the file
    elif insertbefore == 'BOF' or insertafter == 'BOF':
        lines.insert(0, line + os.linesep)
        msg = 'line added'
        changed = True
    # Add it to the end of the file if requested or
    # if insertafter=/insertbefore didn't match anything
    # (so default behaviour is to add at the end)
    elif insertafter == 'EOF':
        lines.append(line + os.linesep)
        msg = 'line added'
        changed = True
    # Do nothing if insert* didn't match
    elif index[1] == -1:
        pass
    # insert* matched, but not the regexp
    else:
        lines.insert(index[1], line + os.linesep)
        msg = 'line added'
        changed = True

    if changed and not module.check_mode:
        if backup and os.path.exists(dest):
            module.backup_local(dest)
        write_changes(module, lines, dest)

    msg, changed = check_file_attrs(module, changed, msg)
    module.exit_json(changed=changed, msg=msg)


def absent(module, dest, regexp, backup):

    if not os.path.exists(dest):
        module.exit_json(changed=False, msg="file not present")

    msg = ""

    f = open(dest, 'rb')
    lines = f.readlines()
    f.close()
    cre = re.compile(regexp)
    found = []

    def matcher(line):
        if cre.search(line):
            found.append(line)
            return False
        else:
            return True

    lines = filter(matcher, lines)
    changed = len(found) > 0
    if changed and not module.check_mode:
        if backup:
            module.backup_local(dest)
        write_changes(module, lines, dest)

    if changed:
        msg = "%s line(s) removed" % len(found)

    msg, changed = check_file_attrs(module, changed, msg)
    module.exit_json(changed=changed, found=len(found), msg=msg)


def main():
    module = AnsibleModule(
        argument_spec=dict(
            dest=dict(required=True, aliases=['name', 'destfile']),
            state=dict(default='present', choices=['absent', 'present']),
            regexp=dict(required=True),
            line=dict(aliases=['value']),
            insertafter=dict(default=None),
            insertbefore=dict(default=None),
            backrefs=dict(default=False, type='bool'),
            create=dict(default=False, type='bool'),
            backup=dict(default=False, type='bool'),
        ),
        mutually_exclusive=[['insertbefore', 'insertafter']],
        add_file_common_args=True,
        supports_check_mode=True
    )

    params = module.params
    create = module.params['create']
    backup = module.params['backup']
    backrefs = module.params['backrefs']
    dest = os.path.expanduser(params['dest'])


    if os.path.isdir(dest):
        module.fail_json(rc=256, msg='Destination %s is a directory !' % dest)

    if params['state'] == 'present':
        if 'line' not in params:
            module.fail_json(msg='line= is required with state=present')

        # Deal with the insertafter default value manually, to avoid errors
        # because of the mutually_exclusive mechanism.
        ins_bef, ins_aft = params['insertbefore'], params['insertafter']
        if ins_bef is None and ins_aft is None:
            ins_aft = 'EOF'

        present(module, dest, params['regexp'], params['line'],
                ins_aft, ins_bef, create, backup, backrefs)
    else:
        absent(module, dest, params['regexp'], backup)

# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>

main()
