#!/usr/bin/env bash

set -euo pipefail

# Add zeros to epoch-timestamped streams.  For example, with interval=100:
#
# Input:
# 10000400 3
# 10000500 4
# 10000800 2
#
# Output:
# 10000400 3
# 10000500 4
# 10000600 0
# 10000700 0
# 10000800 2
#
# This is helpful for feeding such streams to gnuplot.

interval=${1:-3600}
zero=${2:-0}

read -r prevt rest
echo "$prevt $rest"
while read -r t rest;do
  while (( t - prevt > interval ));do
    prevt=$(( prevt + interval))
    echo "$prevt $zero"
  done
  echo "$t $rest"
  prevt=$t
done