#!/usr/bin/python

# (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/>.

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, passwd, new_priv):
    cursor.execute("CREATE USER %s@%s IDENTIFIED BY %s", (user,host,passwd))
    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, passwd, new_priv):
    changed = False

    # Handle passwords.
    if passwd 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)", (passwd,))
        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,passwd))
            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()
    for grant in grants:
        res = re.match("GRANT\ (.+)\ ON\ (.+)\ TO", grant[0])
        if res is None:
            module.fail_json(msg="unable to parse the MySQL grant string")
        privileges = res.group(1).split(", ")
        privileges = ['ALL' if x=='ALL PRIVILEGES' else x for x in privileges]
        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)

def privileges_grant(cursor, user,host,db_table,priv):
    priv_string = ",".join(priv)
    query = "GRANT %s ON %s TO '%s'@'%s'" % (priv_string,db_table,user,host)
    cursor.execute(query)

def load_mycnf():
    config = ConfigParser.RawConfigParser()
    mycnf = os.path.expanduser('~/.my.cnf')
    try:
        config.readfp(open(mycnf))
        creds = dict(user=config.get('client', 'user'),passwd=config.get('client', 'pass'))
    except (ConfigParser.NoOptionError, IOError):
        return False
    return creds

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

def main():
    module = AnsibleModule(
        argument_spec = dict(
            loginuser=dict(default=None),
            loginpass=dict(default=None),
            loginhost=dict(default="localhost"),
            user=dict(required=True),
            passwd=dict(default=None),
            host=dict(default="localhost"),
            state=dict(default="present", choices=["absent", "present"]),
            priv=dict(default=None),
        )
    )
    user = module.params["user"]
    passwd = module.params["passwd"]
    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.
    loginpass = module.params["loginpass"]
    loginuser = module.params["loginuser"]
    if loginuser is None and loginpass is None:
        mycnf_creds = load_mycnf()
        if mycnf_creds is False:
            module.fail_json(msg="incomplete login arguments passed and can't find them in ~/.my.cnf")
        else:
            loginuser = mycnf_creds["user"]
            loginpass = mycnf_creds["passwd"]
    elif loginpass is None or loginuser is None:
        module.fail_json(msg="when supplying login arguments, both user and pass must be provided")

    try:
        db_connection = MySQLdb.connect(host=module.params["loginhost"], user=loginuser, passwd=loginpass, db="mysql")
        cursor = db_connection.cursor()
    except Exception as e:
        module.fail_json(msg="unable to connect to database")

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