#!/bin/bash

_help() {
  echo '
Usage: lock-util {lock-file} [-v] [command] [args]
Commands:
  create
  exist                ( return 0 if lock exists )
  old [age in seconds] ( return 0 if file younger than [args] seconds )
  remove
  -v as first argument sets very verbose mode
 
'
}
LOCKFILE="$1"
[[ "$2" = "-v" ]] && { 
    VERBOSE=on
    COMMAND="$3"
    ARG="$4"
} || {
    COMMAND="$2"
    ARG="$3"
}
BOXES=cat
which boxes &>/dev/null && BOXES="boxes -d shell"

_create() {
    LOCKDIR=$( dirname "$LOCKFILE" )
    mkdir -p "$LOCKDIR"
    touch "$LOCKFILE"
}
_exist() {
    test -f "$LOCKFILE"
}
_remove() {
    rm "$LOCKFILE"
}

[[ $COMMAND = "create" ]] && {
    _exist && {
        [[ "$VERBOSE" = "on" ]] && echo "LOCK FILE EXISTS" | $BOXES
        exit 1
    }
    _create
    ec=$?
    [[ "$VERBOSE" = "on" ]] && [[ $ec -eq 0 ]] && echo "LOCK FILE CREATED" | $BOXES
    [[ "$VERBOSE" = "on" ]] && [[ $ec -ne 0 ]] && echo "UNABLE TO CREATE LOCK FILE" | $BOXES
    exit $ec
}

[[ $COMMAND = "exist" ]] && {
    _exist
    ec=$?
    [[ "$VERBOSE" = "on" ]] && [[ $ec -eq 0 ]] && echo "LOCK FILE EXISTS" | $BOXES
    [[ "$VERBOSE" = "on" ]] && [[ $ec -ne 0 ]] && echo "LOCK FILE DOES NOT EXIST" | $BOXES
    exit $ec
}

[[ $COMMAND = "old" ]] && { 
    _exist || {
        [[ "$VERBOSE" = "on" ]] && echo "LOCK FILE MISSING" | $BOXES
        exit 1
    }
    [[ -z "$ARG" ]] && _help && echo "MISSING ARGUMENT" | $BOXES && exit 1
    created=$( stat -c %Y "$LOCKFILE" )
    now=$( date +%s )
    age=$(( $now - $created ))
    test $ARG -lt $age
    ec=$?
    [[ "$VERBOSE" = "on" ]] && [[ $ec -eq 0 ]] && echo "LOCK FILE OLDER THAN $ARG s" | $BOXES
    [[ "$VERBOSE" = "on" ]] && [[ $ec -ne 0 ]] && echo "LOCK FILE YOUNGER THAN $ARG s" | $BOXES
    exit $ec
}

[[ $COMMAND = "remove" ]] && {
    _remove
    ec=$?
    [[ "$VERBOSE" = "on" ]] && [[ $ec -eq 0 ]] && echo "LOCK FILE REMOVED" | $BOXES
    [[ "$VERBOSE" = "on" ]] && [[ $ec -ne 0 ]] && echo "UNABLE TO REMOVE LOCK FILE" | $BOXES
    exit $ec
}

echo Command not recognized
_help