#!/usr/bin/env bash

usage="

script to convert MySQL/MariaDB charset and collation on one database, all tables and columns

/!\ Use at your own risk, data loss can occur !

USAGE
$(basename "$0") [options] [action] db_name db_user db_password

The db_password is optional

EXAMPLE
$(basename "$0") --db-host=127.0.0.1 --charset=utf8 --collation=utf8_unicode_ci my_database root rootpassword

ACTION
    display             Display sql only
    execute             Run generated sql

OPTIONS
    --help -h           show this help
    --version -v        Display the script version
    --db-host           database host(default: localhost)
    --charset           set the seed value (default: utf8mb4)
    --collation         set the collation to use (default: utf8mb4_unicode_ci)
    --execute           if you pass this argument you indicate that you want to execute the sql (by default this script only display generated sql)

LICENSE

The MIT License

Copyright 2017 Sylvain COMBES

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the \"Software\"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED \"AS IS\", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"

version='0.0.1'
host='localhost'
password=''
charset='utf8mb4'
collation='utf8mb4_unicode_ci'
execute=false
sql=''

for i in "$@"
do
case $i in
    -h|--help)
    echo "$usage";
    shift
    exit;
    ;;
    -v|--version)
    echo "$version";
    shift
    exit;
    ;;
    --db-host=*)
    host="${i#*=}"
    shift
    ;;
    --charset=*)
    charset="${i#*=}"
    shift
    ;;
    --collation=*)
    collation="${i#*=}"
    shift
    ;;
    --execute)
    execute=true
    echo "SQL will be executed ..."
    shift
    ;;
    --default)
    DEFAULT=YES
    shift
    ;;
#    *)
#    echo "${i#*=}";
#    ;;
esac
done

if [ -z "$1" ]
  then
    echo "Missing database name as first argument"
    exit 1
fi

name="\`$1\`"

if [ -z "$2" ]
  then
    echo "Missing database user as second argument"
    exit 1
fi

user="$2"

if [ ! -z "$3" ]
  then
    password="--password=$3"
fi

mysql_command="mysql -s --host=$host --user=$user $password"

sql="${sql}ALTER DATABASE $name CHARACTER SET $charset COLLATE $collation;\n"

sql=${sql}$(echo "USE $name; SHOW TABLES;" | eval "${mysql_command}" | (
    while read TABLE; do
        echo "ALTER TABLE $name.\`$TABLE\` CONVERT TO CHARACTER SET $charset COLLATE $collation;"
    done
))


if [ ${execute} = true ]
    then
        read -p "Are you sure? " -n 1 -r
        echo
        if [[ $REPLY =~ ^[Yy]$ ]]
            then
                echo -e "${sql}" | eval "${mysql_command}"
                echo 'done !'
                exit 0;
            else
                echo "Operation cancelled"
                exit 1;
        fi
    else
        echo -e "${sql}"
        exit 0;
fi

exit 0;