#!/usr/bin/env bash
#
# Kill the virtual machines, take a snapshot, and start the virtual machines up again.
set -euo pipefail
IFS=$'\n\t'
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

: ${VMS:="poudriere controller0 controller1 controller2 worker0 worker1 worker2"}

############## Setup #########################

function die {
    local status_code="$1"
    shift
    (>&2 echo "${@}")
    exit "$status_code"
}

function log {
    (>&2 echo "${@}")
}

############## Program #########################

function main {
    VMS=($(convert_ifs "$VMS" ' ' "$IFS"))
    local snapshot_name="$1"

    local rollback_targets=$(doas zfs list -t snapshot -p -o name | grep -E "@${snapshot_name}\$")
    log "Rolling back to the following snapshots:"
    while read target; do
        log "    $target"
    done<<<"$rollback_targets"
    sanity_check_targets "$rollback_targets"

    kill_all_bhyve
    log "Rolling back to snapshot $1"
    while read target; do
        zfs rollback "$target"
    done<<<"$rollback_targets"
    launch_all_bhyve
    log "Done."
}

function kill_all_bhyve {
    log "Killing all virtual machines."
    doas killall bhyve; while true; do tmux ls || break; sleep 2; done;
}

function launch_all_bhyve {
    log "Launching all virtual machines."
    for vm in $VMS[@]; do tmux new -d -s $vm doas bhyve_netgraph_bridge start $vm zdata/vm/$vm /vm/$vm; sleep 5; done
}

function sanity_check_targets {
    local rollback_targets="$1"
    local targets_length=$(wc -l <<<"$rollback_targets")
    if [ $targets_length -ne 7 ]; then
        die 1 "Expecting the snapshot to exist for each k8s vm and the k8s persistent storage space. Only found $targets_length targets."
    fi
    while read rollback_target; do
        if [[ ! $rollback_target = "zdata/vm"[/@]* ]] && [[ ! $rollback_target = "zdata/k8spersistent"[/@]* ]]; then
            die 1 "Rollback target not in k8s-vm-related zfs datasets: $rollback_target"
        fi
    done<<<"$rollback_targets"
}

function convert_ifs {
    # Converts a string from one internal field separator to another. For example "foo bar baz" to "foo:bar:baz". This is useful for parsing a string as an array (for example, to read the value from environment variables like $PATH) while using a different IFS
    #
    # TODO: It would be a lot better if we could just convert from string to array directly using a temporarily different IFS variable without converting to a different string format first.
    local string_to_convert="$1"
    local ifs_in_string="$2"
    local target_ifs="$3"
    local current_ifs="$IFS"
    IFS="$ifs_in_string"
    local split_to_array=($string_to_convert)
    local expanded_string=$(IFS="$target_ifs"; printf '%s' "${split_to_array[*]}")
    # Restore IFS to the original value in case this function is not run inside a subshell
    IFS="$current_ifs"
    cat <<<"$expanded_string"
}

main "$@"