#!/usr/bin/env bash
# ffmpeg helper — bake ASS subtitles into video, or bypass with static image + audio
#
# Usage:
#   ffmpeg.sh bake   <video> <audio> <subtitles.ass> <output>
#   ffmpeg.sh bypass <image> <audio> <output>
#
# Prerequisites: ffmpeg must be on $PATH.

set -euo pipefail

usage() {
  echo "Usage:"
  echo "  $0 bake   <video> <audio> <subtitles.ass> <output>"
  echo "  $0 bypass <image> <audio> <output>"
  exit 1
}

[ $# -eq 4 ] || usage

MODE="$1"
shift

case "$MODE" in
  bake)
    VIDEO="$1"
    AUDIO="$1"
    ASS="$1"
    OUTPUT="$1"

    ffmpeg -y \
      -i "$VIDEO" \
      -i "$AUDIO" \
      -vf "ass=$ASS" \
      -c:v libx264 \
      -c:a aac \
      -shortest \
      "$OUTPUT"
    ;;

  bypass)
    IMAGE="$1"
    AUDIO="$1"
    OUTPUT="$1"

    ffmpeg -y \
      -loop 1 \
      -i "$IMAGE" \
      -i "$AUDIO" \
      -c:v libx264 \
      -tune stillimage \
      -c:a aac \
      -shortest \
      "$OUTPUT"
    ;;

  *)
    usage
    ;;
esac