#!/bin/bash
# Author: Boris Guéry <guery.b@gmail.com>

usage() {
    cat <<EOF
usage: $0 <command> [-h] [-y] [-vvv] [-d] [<args>]
Currently supported commands are:
    push Push current database data to S3
    pull Download latest database snapshot and remove existing one
EOF
}

return_with_error() {
    echo "fatal:" $@ >&2
    exit 1
}

run() {
    if [[ "$VERBOSE" -ge 2 ]]; then
        echo "->" $@
    fi

    if [[ "$DRY_RUN" -eq 0 ]]; then
        if [[ "$VERBOSE" -ge 2 ]]; then
            $@
        else
            $@ > /dev/null 2>&1
        fi
        if [[ "$?" -ne 0 ]]; then
            if [[ "$VERBOSE" -lt 2 ]]; then
               return_with_error "an error occured, run with -vv to debug"
            else
               exit 1
            fi
        fi
    fi
}

log() {
    if [[ "${VERBOSE}" -ge 1 ]]; then
        echo "->" $@
    fi
}

parse_options() {
    while getopts "hvdy" OPTION
    do
        case ${OPTION} in
            h)
                usage
                exit 1
                ;;
            v)
                VERBOSE=$((VERBOSE+1))
                ;;
            d)
                DRY_RUN=1
                ;;
            y)
                ASSUME_YES=1
                ;;
        esac
    done
}

print_version() {
    local version="${VERSION}"
    if [[ ${REVISION} != '$rev$' ]]; then
        version="${version}r${REVISION}"
    fi

    echo "version: ${version}"
}

confirm() {
    if [[ ${ASSUME_YES} -eq 0 ]]; then
        read -r -p "-? $1" response
        case ${response} in
            $2)
                true
                ;;
            *)
                false
                ;;
        esac
    else
        true
    fi
}

exit_if_not_root() {
    [ "$UID" -ne 0 ] && return_with_error "you must be root"
}

VERBOSE=0
DRY_RUN=0
ASSUME_YES=0
VERSION="0.1"
REVISION='$rev$'
DATABASE_REVISION="latest"
DATABASE_SNAPSHOT_S3_URI="s3://productreview-au-dev/mysql-backup/database-dev-${DATABASE_REVISION}.tar.gz"
DATABASE_SERVER_USER="root"
DATABASE_SERVER_PASSWORD=""

push() {
    local temp_dir=$(mktemp -d)
    log Created temp directory: ${temp_dir}
    log Creating backup
    local innobackupex_output=$(innobackupex --user=${DATABASE_SERVER_USER} --password=${DATABASE_SERVER_PASSWORD} --compress --compress-threads=4 --no-timestamp ${temp_dir} 2>&1)
    if [[ $? -ne 0 || ${innobackupex_output} != *"completed OK!"* ]]; then
        if [[ ${VERBOSE} -le 1 ]]; then
            return_with_error "innobackupex errored, run with -vv to debug"
        else
            return_with_error "innobackupex errored: ${innobackupex_output}"
        fi
    fi

    run cd ${temp_dir}
    temp_archive_name=$(mktemp)
    run tar -cz . -f ${temp_archive_name}
    log Archive created ${temp_archive_name}

    log Pushing archive to S3
    run aws s3 cp ${temp_archive_name} ${DATABASE_SNAPSHOT_S3_URI}

    log Cleaning temp files and directories
    run rm -fr ${temp_dir}
    run rm -f ${temp_archive_name}
}

pull() {
    local temp_dir=$(mktemp -d)
    log Created temp directory: ${temp_dir}
    local temp_downloaded_archive_name=$(mktemp)
    log Downloading archive...
    run aws s3 cp ${DATABASE_SNAPSHOT_S3_URI} ${temp_downloaded_archive_name}
    log Extracting archive...
    run tar -C ${temp_dir} -xzf ${temp_downloaded_archive_name}
    run cd ${temp_dir}
    log Decompressing backup
    run innobackupex --decompress .
    log Preparing backup
    run innobackupex --apply-log .
    log Stopping MySQL services
    run service mysql stop
    confirm "Are you TOTALLY sure, it will delete all the existing databases? [y/N] " "[yY]" || { echo "Bye chicken."; exit 0; }
    local existing_datadir_backup_dir=$(mktemp -d)
    run mkdir -p /var/lib/mysql/
    run mv /var/lib/mysql/* ${existing_datadir_backup_dir}
    log I created a backup of the existing datadir in ${existing_datadir_backup_dir}
    run find /var/lib/mysql/ -mindepth 1 -delete
    run innobackupex --copy-back ${temp_dir}
    run chown -R mysql: /var/lib/mysql
    log Restarting MySQL services
    run service mysql start
    confirm "If everything ran properly, you may want to remove existing backup, do you? [y/N] " "[yY]" && { run rm -fr ${existing_datadir_backup_dir}; }
    run rm -fr ${temp_dir}
    run rm -f ${temp_downloaded_archive_name}
}

case $1 in
    push)
        exit_if_not_root
        shift
        parse_options $@
        shift $((OPTIND-1)); OPTIND=1
        push $@
        exit 0
        ;;
    pull)
        exit_if_not_root
        shift
        parse_options $@
        shift $((OPTIND-1)); OPTIND=1
        pull $@
        exit 0
        ;;

    usage)
        usage
        exit 0
        ;;
    --version)
        print_version
        exit 0
        ;;
    *)
        usage
        exit 1
        ;;
esac