#!/bin/bash
# Merge all *_condensed.mkv files into a rolling accumulator via stream copy
# Usage: ipcam-merge.sh [output.mkv]
# The accumulator file is prepended (oldest first), new condensed files appended in order
DIR="$(cd "$(dirname "$0")" && pwd)"
OUT="${1:-$DIR/ipcam/motion.mkv}"
TMP=$(mktemp -d)
trap "rm -rf $TMP" EXIT

# collect condensed files sorted by name (timestamp order)
CONDENSED=($(ls "$DIR"/ipcam/*_condensed.mkv 2>/dev/null | sort))

if [ ${#CONDENSED[@]} -eq 0 ]; then
  echo "no condensed files to merge"
  exit 0
fi

# build concat list: existing accumulator first, then new condensed files
if [ -f "$OUT" ]; then
  echo "file '$OUT'" > "$TMP/concat.txt"
fi
for f in "${CONDENSED[@]}"; do
  echo "file '$f'" >> "$TMP/concat.txt"
done

echo "merging ${#CONDENSED[@]} condensed files"

ffmpeg -y -loglevel error -f concat -safe 0 -i "$TMP/concat.txt" -c copy "$TMP/merged.mkv"
mv "$TMP/merged.mkv" "$OUT"

# remove merged condensed files
for f in "${CONDENSED[@]}"; do
  rm "$f"
done

echo "wrote $OUT ($(du -h "$OUT" | cut -f1))"