#!/bin/bash

MYCNF=$HOME/.my.cnf
DBHOST=mysql0
GRANTHOST='%'

[ -f /etc/egscripts/egmakedb.cnf ] && . /etc/egscripts/egmakedb.cnf

SIMULATE=0

usage() {
  cat <<EOT

Usage: `basename $0` [ OPTIONS ] user dbname

Create a MySQL database.  As well as creating the database, this script will
grant access to the database to the specified user, which must be a real user
on the system, and create an additional MySQL user with the same name as the
database.

OPTIONS

  -h            - Show this help
  -H host       - Set database host (Default: $DBHOST)
  -c mycnf      - Use specified my.cnf file for access and database creation 
                  (Default: $MYCNF)
  -g hostspec   - Specify the hostname part of the GRANT specification for
                  user, e.g. GRANT ... TO user@'$GRANTHOST'
  -s            - Simulate.  Just output the SQL to be run to STDOUT.

The script outputs a set of variables on stdout which can be eval'd for
use from other shell commands.  These variables are DBHOST DBNAME DBOWNER
DBUSER and DBPASS

EOT
}

# MySQL only allows 16 character user names
make_mysql_username() {
  prefix=$1
  suffix=$2
  
  # Suffix is optional
  if [ -n "$suffix" ] ; then
    let comp="15 - ${#suffix}"
    echo "${prefix:0:$comp}_${suffix}"
  else
    echo "${prefix:0:16}"
  fi
}

get_next_username() {

  user=$1

  if [ -z "$user" ] ; then
    return
  fi

  # Only try 99 times
  for i in `seq 1 99` ; do
    username=`make_mysql_username $user $i`
    count=`printf "SELECT COUNT(*) FROM mysql.user WHERE USER = '%s'" $username | $mysql_select`
    if [ "$count" -eq 0 ] ; then
      echo "${username}"
      return
    fi
  done
}

create_db() {
  db=$1
  user=$2

  if [ -z "$db" ] || [ -z "$user" ] ; then
    echo "Err: invalid call to grant_privs() function" >&2
    exit 1
  fi

  # In addition to granting all privileges for $user, create a user
  # specific for this db.  This will be in the format $user_1, $user_2
  # up to $user_99, with the lowest available number being chosen.
  dbuser=`get_next_username $user`

  if [ -z "$dbuser" ] ; then
    echo "Unable to generate a new username for db $db" >&2
    exit 1
  fi

  printf 'CREATE DATABASE `%s`;' $dbname | $mysql

  # If a .my.cnf file exists for the main user, assume they
  # already have a password set.  Otherwise create a new MySQL user
  # and a .my.cnf in their home directory.
  if [ ! -e /home/${user}/.my.cnf ] ; then
    passwd=`pwgen -B 10 1`
    extra_grants=" IDENTIFIED BY '$passwd'"
    if [ $SIMULATE -eq 1 ] ; then
      echo "Create /home/${user}/.my.cnf"
    else
      if [ "$LOGNAME" != "$user" ] ; then
        runasuser="sudo -u $user"
      fi
      $runasuser egcreatemycnf /home/${user}/.my.cnf $DBHOST $user $passwd
    fi
  fi

  # Grant all privileges on the database to the main user
  $mysql <<EOT
    GRANT ALL PRIVILEGES ON \`$dbname\`.* TO '$user'@'$GRANTHOST'$extra_grants;
EOT

  passwd=`pwgen -B 10 1`
  $mysql <<EOT
    GRANT ALL PRIVILEGES ON \`$dbname\`.* TO '$dbuser'@'$GRANTHOST' IDENTIFIED BY '$passwd';
EOT
  echo "DBHOST=$DBHOST"
  echo "DBNAME=$dbname"
  echo "DBOWNER=$user"
  echo "DBUSER=$dbuser"
  echo "DBPASS=$passwd"
}

while getopts "c:H:g:hs" OPT ; do
  case $OPT in
    c)  MYCNF=$OPTARG ;;
    g)  GRANTHOST=$OPTARG ;;
    H)  DBHOST=$OPTARG ;;
    s)  SIMULATE=1 ;;
    h)  usage ; exit 0 ;;
    *)  usage ; exit 1 ;;
  esac
done

shift $(($OPTIND - 1))

if [ $# -ne 2 ] ; then
  usage
  exit 1
fi

user=$1
dbname=$2

if [ $SIMULATE -eq 1 ] ; then
  mysql="cat"
else
  mysql="mysql --defaults-file=$MYCNF -h $DBHOST -s"
fi

# In simulate mode, we still need to do real selects to set up
# variables
mysql_select="mysql --defaults-file=$MYCNF -h $DBHOST -s"

# Do some sanity checks
if ! id $user > /dev/null ; then
  exit 1
fi

# Exit on any error
set -e

create_db $dbname $user