#!/usr/local/bin/python2.7

# (c) 2012, Mark Theunissen <mark.theunissen@gmail.com>
# Sponsored by Four Kitchens http://fourkitchens.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/>.

DOCUMENTATION = '''
---
module: mysql_user
short_description: Adds or removes a user from a MySQL database.
description:
   - Adds or removes a user from a MySQL database.
version_added: "0.6"
options:
  name:
    description:
      - name of the user (role) to add or remove
    required: true
    default: null
  password:
    description:
      - set the user's password
    required: false
    default: null
  host:
    description:
      - the 'host' part of the MySQL username
    required: false
    default: localhost
  login_user:
    description:
      - The username used to authenticate with
    required: false
    default: null
  login_password:
    description:
      - The password used to authenticate with
    required: false
    default: null
  login_host:
    description:
      - Host running the database
    required: false
    default: localhost
  priv:
    description:
      - "MySQL privileges string in the format: C(db.table:priv1,priv2)"
    required: false
    default: null
  state:
    description:
      - The database state
    required: false
    default: present
    choices: [ "present", "absent" ]
examples:
   - code: "mysql_user: name=bob password=12345 priv=*.*:ALL state=present"
     description: Create database user with name 'bob' and password '12345' with all database privileges
   - code: "mysql_user: login_user=root login_password=123456 name=sally state=absent"
     description: Ensure no user named 'sally' exists, also passing in the auth credentials.
   - code: mydb.*:INSERT,UPDATE/anotherdb.*:SELECT/yetanotherdb.*:ALL
     description: Example privileges string format
notes:
   - Requires the MySQLdb Python package on the remote host. For Ubuntu, this
     is as easy as apt-get install python-mysqldb.
   - Both C(login_password) and C(login_username) are required when you are
     passing credentials. If none are present, the module will attempt to read
     the credentials from C(~/.my.cnf), and finally fall back to using the MySQL
     default login of 'root' with no password.
requirements: [ "ConfigParser", "MySQLdb" ]
author: Mark Theunissen
'''

import ConfigParser
try:
    import MySQLdb
except ImportError:
    mysqldb_found = False
else:
    mysqldb_found = True

# ===========================================
# MySQL module specific support methods.
#

def user_exists(cursor, user, host):
    cursor.execute("SELECT count(*) FROM user WHERE user = %s AND host = %s", (user,host))
    count = cursor.fetchone()
    return count[0] > 0

def user_add(cursor, user, host, password, new_priv):
    cursor.execute("CREATE USER %s@%s IDENTIFIED BY %s", (user,host,password))
    if new_priv is not None:
        for db_table, priv in new_priv.iteritems():
            privileges_grant(cursor, user,host,db_table,priv)
    return True

def user_mod(cursor, user, host, password, new_priv):
    changed = False

    # Handle passwords.
    if password is not None:
        cursor.execute("SELECT password FROM user WHERE user = %s AND host = %s", (user,host))
        current_pass_hash = cursor.fetchone()
        cursor.execute("SELECT PASSWORD(%s)", (password,))
        new_pass_hash = cursor.fetchone()
        if current_pass_hash[0] != new_pass_hash[0]:
            cursor.execute("SET PASSWORD FOR %s@%s = PASSWORD(%s)", (user,host,password))
            changed = True

    # Handle privileges.
    if new_priv is not None:
        curr_priv = privileges_get(cursor, user,host)

        # If the user has privileges on a db.table that doesn't appear at all in
        # the new specification, then revoke all privileges on it.
        for db_table, priv in curr_priv.iteritems():
            if db_table not in new_priv:
                privileges_revoke(cursor, user,host,db_table)
                changed = True

        # If the user doesn't currently have any privileges on a db.table, then
        # we can perform a straight grant operation.
        for db_table, priv in new_priv.iteritems():
            if db_table not in curr_priv:
                privileges_grant(cursor, user,host,db_table,priv)
                changed = True

        # If the db.table specification exists in both the user's current privileges
        # and in the new privileges, then we need to see if there's a difference.
        db_table_intersect = set(new_priv.keys()) & set(curr_priv.keys())
        for db_table in db_table_intersect:
            priv_diff = set(new_priv[db_table]) ^ set(curr_priv[db_table])
            if (len(priv_diff) > 0):
                privileges_revoke(cursor, user,host,db_table)
                privileges_grant(cursor, user,host,db_table,new_priv[db_table])
                changed = True

    return changed

def user_delete(cursor, user, host):
    cursor.execute("DROP USER %s@%s", (user,host))
    return True

def privileges_get(cursor, user,host):
    """ MySQL doesn't have a better method of getting privileges aside from the
    SHOW GRANTS query syntax, which requires us to then parse the returned string.
    Here's an example of the string that is returned from MySQL:

     GRANT USAGE ON *.* TO 'user'@'localhost' IDENTIFIED BY 'pass';

    This function makes the query and returns a dictionary containing the results.
    The dictionary format is the same as that returned by privileges_unpack() below.
    """
    output = {}
    cursor.execute("SHOW GRANTS FOR %s@%s", (user,host))
    grants = cursor.fetchall()

    def pick(x):
        if x == 'ALL PRIVILEGES':
            return 'ALL'
        else:
            return x

    for grant in grants:
        res = re.match("GRANT (.+) ON (.+) TO '.+'@'.+'( IDENTIFIED BY PASSWORD '.+')? ?(.*)", grant[0])
        if res is None:
            module.fail_json(msg="unable to parse the MySQL grant string")
        privileges = res.group(1).split(", ")
        privileges = [ pick(x) for x in privileges]
        if "WITH GRANT OPTION" in res.group(4):
            privileges.append('GRANT')
        db = res.group(2).replace('`', '')
        output[db] = privileges
    return output

def privileges_unpack(priv):
    """ Take a privileges string, typically passed as a parameter, and unserialize
    it into a dictionary, the same format as privileges_get() above. We have this
    custom format to avoid using YAML/JSON strings inside YAML playbooks. Example
    of a privileges string:

     mydb.*:INSERT,UPDATE/anotherdb.*:SELECT/yetanother.*:ALL

    The privilege USAGE stands for no privileges, so we add that in on *.* if it's
    not specified in the string, as MySQL will always provide this by default.
    """
    output = {}
    for item in priv.split('/'):
        pieces = item.split(':')
        output[pieces[0]] = pieces[1].upper().split(',')

    if '*.*' not in output:
        output['*.*'] = ['USAGE']

    return output

def privileges_revoke(cursor, user,host,db_table):
    query = "REVOKE ALL PRIVILEGES ON %s FROM '%s'@'%s'" % (db_table,user,host)
    cursor.execute(query)
    query = "REVOKE GRANT OPTION ON %s FROM '%s'@'%s'" % (db_table,user,host)
    cursor.execute(query)

def privileges_grant(cursor, user,host,db_table,priv):

    priv_string = ",".join(filter(lambda x: x != 'GRANT', priv))
    query = "GRANT %s ON %s TO '%s'@'%s'" % (priv_string,db_table,user,host)
    if 'GRANT' in priv:
        query = query + " WITH GRANT OPTION"
    cursor.execute(query)

def load_mycnf():
    config = ConfigParser.RawConfigParser()
    mycnf = os.path.expanduser('~/.my.cnf')
    if not os.path.exists(mycnf):
        return False
    try:
        config.readfp(open(mycnf))
        creds = dict(user=config.get('client', 'user'),password=config.get('client', 'pass'))
    except (ConfigParser.NoOptionError, IOError):
        return False
    return creds

# ===========================================
# Module execution.
#

def main():
    module = AnsibleModule(
        argument_spec = dict(
            login_user=dict(default=None),
            login_password=dict(default=None),
            login_host=dict(default="localhost"),
            login_unix_socket=dict(default=None),
            user=dict(required=True, aliases=['name']),
            password=dict(default=None),
            host=dict(default="localhost"),
            state=dict(default="present", choices=["absent", "present"]),
            priv=dict(default=None),
        )
    )
    user = module.params["user"]
    password = module.params["password"]
    host = module.params["host"]
    state = module.params["state"]
    priv = module.params["priv"]

    if not mysqldb_found:
        module.fail_json(msg="the python mysqldb module is required")

    if priv is not None:
        try:
            priv = privileges_unpack(priv)
        except:
            module.fail_json(msg="invalid privileges string")

    # Either the caller passes both a username and password with which to connect to
    # mysql, or they pass neither and allow this module to read the credentials from
    # ~/.my.cnf.
    login_password = module.params["login_password"]
    login_user = module.params["login_user"]
    if login_user is None and login_password is None:
        mycnf_creds = load_mycnf()
        if mycnf_creds is False:
            login_user = "root"
            login_password = ""
        else:
            login_user = mycnf_creds["user"]
            login_password = mycnf_creds["password"]
    elif login_password is None or login_user is None:
        module.fail_json(msg="when supplying login arguments, both login_user and login_password must be provided")

    try:
        if module.params["login_unix_socket"] != None:
            db_connection = MySQLdb.connect(host=module.params["login_host"], unix_socket=module.params["login_unix_socket"], user=login_user, passwd=login_password, db="mysql")
        else:
            db_connection = MySQLdb.connect(host=module.params["login_host"], user=login_user, passwd=login_password, db="mysql")
        cursor = db_connection.cursor()
    except Exception, e:
        module.fail_json(msg="unable to connect to database, check login_user and login_password are correct or ~/.my.cnf has the credentials")

    if state == "present":
        if user_exists(cursor, user, host):
            changed = user_mod(cursor, user, host, password, priv)
        else:
            if password is None:
                module.fail_json(msg="password parameter required when adding a user")
            changed = user_add(cursor, user, host, password, priv)
    elif state == "absent":
        if user_exists(cursor, user, host):
            changed = user_delete(cursor, user, host)
        else:
            changed = False
    module.exit_json(changed=changed, user=user)

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