#!/usr/bin/env bash

TMP_FILE=/tmp/ensure_running.json
BOOT_ID=$(cat  /proc/sys/kernel/random/boot_id)
data=$(cat "$TMP_FILE")


prep_tmp_if_needed() {
    if [ ! -f "$TMP_FILE" ]; then
        echo "{ \"boot_id\": \"$BOOT_ID\", \"entries\": [], \"running_pids\": {} }" > "$TMP_FILE"
    fi
    data=$(cat "$TMP_FILE")
    data_bid=$(jq -r '.boot_id' <<< $data)
    if [[ "$data_bid" == "" || "$data_bid" != "$BOOT_ID" ]]; then
        rm $TMP_FILE
        prep_tmp_if_needed
        return
    fi
}

run() {
    prep_tmp_if_needed

    while read -r e; do
        existing_pid=$(jq -r --arg k "$e" '.running_pids[($k)]?' <<< "$data")
        if [[ $existing_pid != "null" && "$(ps -p $existing_pid -o pid --no-headers)" != "" ]]; then
            continue
        fi;

        bash -lc "$e" &
        pid=$!

        data=$(jq --arg k "$e" --arg v "$pid" \
            '.running_pids += {($k): $v}' <<< "$data")
    done < <(jq -r '.entries[]' <<< "$data")
    echo "$data" > "$TMP_FILE"
}

register() {
    prep_tmp_if_needed

    data=$(jq --arg val "$*" '.entries += [$val]' <<< "$data")
    data=$(jq '.entries |= unique' <<< "$data")
    echo "$data" > "$TMP_FILE"
}

remove() {
    prep_tmp_if_needed

    diff=$data
    data=$(jq --arg val "$*" '.entries -= [$val]' <<< "$data")
    if [ "$diff" = "$data" ]; then
        echo "Element to remove was not found"
        exit 1
    fi
    echo "$data" > "$TMP_FILE"
}

list() {
    jq -C <<< "$data"
}

i=1
for arg in "$@"; do
    i=( $i+1 )
    case $arg in
        run) run; exit 0; ;;
        register)
            register "${@:i}"; exit 0; ;;
        remove)
            remove "${@:i}"; exit 0; ;;
        list) list; exit 0; ;;
        *)
            echo "Unsuported: $arg"; exit 1 ;;
    esac
done