#!/bin/zsh
# vg-interp — RIFE frame interpolation (rife-ncnn-vulkan, Metal via MoltenVK).
# Usage: vg-interp CLIP [--factor 2|4] [--slowmo] [--out FILE] [--model rife-v4.6]
#   default: smooth motion (fps × factor, audio kept)
#   --slowmo: same fps, clip runs factor× longer (audio dropped)
# Output: ProRes LT .mov next to the input (CLIP_interp.mov / CLIP_slowmo.mov)
export PATH=/opt/homebrew/bin:/usr/bin:/bin:/usr/sbin:/sbin
set -u
VG="$(cd "$(dirname "$0")/.." && pwd)"
RIFE="$VG/tools/rife/rife-ncnn-vulkan"
[[ -x "$RIFE" ]] || { echo "rife not installed — run setup/fetch_phase2.sh" >&2; exit 1; }

IN="${1:?usage: vg-interp CLIP [--factor N] [--slowmo] [--out FILE] [--model NAME]}"
shift
FACTOR=2; SLOWMO=0; OUT=""; MODEL="rife-v4.6"
while [[ $# -gt 0 ]]; do
  case "$1" in
    --factor) FACTOR="$2"; shift 2 ;;
    --slowmo) SLOWMO=1; shift ;;
    --out) OUT="$2"; shift 2 ;;
    --model) MODEL="$2"; shift 2 ;;
    *) echo "unknown arg: $1" >&2; exit 1 ;;
  esac
done
IN="${IN:A}"
[[ -f "$IN" ]] || { echo "no such file: $IN" >&2; exit 1; }

fps=$(ffprobe -v error -select_streams v:0 -show_entries stream=avg_frame_rate -of csv=p=0 "$IN")
fps_num="${fps%%/*}"; fps_den="${fps##*/}"
in_fps=$(( fps_num * 1.0 / fps_den ))

W=$(mktemp -d "${TMPDIR:-/tmp}/vginterp.XXXXXX")
trap "rm -rf $W" EXIT
mkdir -p "$W/in" "$W/out"

echo "extracting frames ..."
ffmpeg -hide_banner -loglevel error -y -i "$IN" "$W/in/%08d.png" </dev/null
n_in=$(ls "$W/in" | wc -l | tr -d " ")
n_out=$(( n_in * FACTOR ))
echo "$n_in frames in -> $n_out frames (${MODEL})"

"$RIFE" -i "$W/in" -o "$W/out" -m "$VG/tools/rife/$MODEL" -n "$n_out" -f "%08d.png" || exit 1
n_got=$(ls "$W/out" | wc -l | tr -d " ")
echo "rife produced $n_got frames"

if [[ $SLOWMO -eq 1 ]]; then
  out_fps=$in_fps
  DEF="${IN%.*}_slowmo.mov"
else
  out_fps=$(( in_fps * FACTOR ))
  DEF="${IN%.*}_interp.mov"
fi
OUT="${OUT:-$DEF}"
out_fps=$(printf "%g" "$out_fps")

echo "encoding ProRes at ${out_fps}fps ..."
if [[ $SLOWMO -eq 1 ]]; then
  ffmpeg -hide_banner -loglevel error -y -framerate "$out_fps" -i "$W/out/%08d.png" \
    -c:v prores_ks -profile:v 1 -pix_fmt yuv422p10le "$OUT" </dev/null
else
  ffmpeg -hide_banner -loglevel error -y -framerate "$out_fps" -i "$W/out/%08d.png" -i "$IN" \
    -map 0:v:0 -map '1:a:0?' -c:v prores_ks -profile:v 1 -pix_fmt yuv422p10le \
    -c:a pcm_s16le -shortest "$OUT" </dev/null
fi
echo "done: $OUT"