#! /bin/bash

SEG="${SEG:-300}"

function main() {
   if [ "$#" -eq 0 ]; then
      log "USAGE: $0 ip ip ip..." >&2
      return 1
   fi

   function clean() {
      kill -9 $(jobs -p)
   }
   if [ "$(hostname)" == "Scratch" ]; then
      trap clean EXIT ERR
   fi
   watchman "$@" &
   for ip in "$@"; do
      log recording from $ip... 
      record "$ip" &
   done
   
   for i in "$@"; do
      if ! wait -n 1; then
         log "Something died: $?" 
         exit 1
      fi
      exit 0
   done
}

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

function mkdirs() {
   mkdir -p "${OUT_DIR:-/tmp/ffmpeg_cap}/$(date +%Y)/$(date +%m)/$(date +%d)"
}

function watchman() {
   log watchman starting on $@
   local max_last=$SEG
   max_last=$((max_last*3))
   function finder() {
      local suffix="${1:-"*"}"
      find "${OUT_DIR:-/tmp/ffmpeg_cap}" -type f -name "*_${suffix}.m*"
   }
   function mark_last_file() {
      local now="$(date +%s)"
      local suffix="$1"
      local min=$((max_last-1))
      for f in $(finder "$suffix"); do
         local ts="$(stat -c '%X' "$f")"
         if ((now-ts<min)); then
            min=$((now-ts))
         fi
      done
      echo $min
   }
   function check_disk() {
      if du -s "${OUT_DIR:-/tmp/ffmpeg_cap}" | grep -E '^[6-9][0-9]{5}'; then
         return 1
      fi
   }
   while sleep 10; do
      mkdirs
      for suffix in "$@"; do
         local seconds=$(mark_last_file "$suffix")
         log "$suffix: $seconds s"
         if ((seconds>max_last)); then
            log "no new videos in $seconds seconds for $suffix, panicking"
            exit 1
         fi
      done
      until check_disk; do
         local f="$(finder | sort | head -n 1)"
         log "high disk usage, pruning $f"
         rm -f "$f"
      done
   done
}

function record() {
   log "starting record for $@"
   _record "$@"
   tail -n 50 /tmp/ffmpegs.log
}

function _record() {
   local out="${OUT_DIR:-/tmp/ffmpeg_cap}/%Y/%m/%d/%H-%M-%S_${1}.mp4"
   mkdirs
   ffmpeg \
      -threads 0 \
      -nostdin \
      -nostats \
      -loglevel error \
      -i rtsp://192.168.0.$1:8554/unicast \
      -an \
      -map 0 \
      -force_key_frames "expr:gte(t,n_forced*9)" \
      -f segment \
      -segment_time $SEG \
      -segment_format mp4 \
      -strftime 1 \
      -minrate .05k \
      -vcodec copy \
      "$out" \
      -vf "select=gt(scene\,0.003),setpts=N/(15*TB)" \
   < /dev/null \
   >> /tmp/ffmpegs.log \
   2>&1 
}

if [ "$0" == "$BASH_SOURCE" ]; then
   main "$@"
fi