#!/usr/bin/env bash
# Stabilize shaky Fujifilm X100V .MOV clips with ffmpeg's 2-pass vidstab
# filter and encode compact 4K HEVC .mp4 output on Intel VAAPI (software
# libx265 fallback when the GPU is unavailable).
#
# Usage:
#   stabilize-video [DIR]                 # stabilize all *.MOV in DIR
#   stabilize-video ~/Videos              # specify a directory
#   stabilize-video clip1.MOV clip2.MOV   # or pass explicit files
#
# Outputs are written next to each source as `stabilised-<base>.mp4`.
# Clips that already have a stabilized output are skipped.

set -euo pipefail

VADEVICE="/dev/dri/renderD128"
trf_dir=""              # set by main; cleaned up by EXIT trap
QUALITY="${QUALITY:-34}"          # HEVC CQP quality (higher = smaller)
SHAKINESS="${SHAKINESS:-5}"       # vidstab shakiness 1..10
ACCURACY="${ACCURACY:-15}"        # vidstab accuracy 1..15
UNSHARP="unsharp=5:5:0.8:3:3:0.4"

# Collect the list of .MOV files to process.
_mov_files=()
if [[ $# -gt 0 ]]; then
  for arg in "$@"; do
    if [[ -d "$arg" ]]; then
      while IFS= read -r -d '' f; do
        _mov_files+=("$f")
      done < <(find "$arg" -maxdepth 1 -type f -iname '*.MOV' -print0)
    elif [[ -f "$arg" ]]; then
      _mov_files+=("$arg")
    else
      echo "stabilize-video: not a file or directory: $arg" >&2
      exit 1
    fi
  done
else
  while IFS= read -r -d '' f; do
    _mov_files+=("$f")
  done < <(find . -maxdepth 1 -type f -iname '*.MOV' -print0)
fi

if [[ ${#_mov_files[@]} -eq 0 ]]; then
  echo "stabilize-video: no .MOV files found" >&2
  exit 0
fi

# Detect whether VAAPI HEVC is usable on the configured device.
_vaapi_ok=no
if [[ -c "$VADEVICE" ]] \
  && ffmpeg -hide_banner -vaapi_device "$VADEVICE" \
       -f lavfi -i color=black:s=320x240:d=0.1 \
       -vf 'format=nv12,hwupload' \
       -c:v hevc_vaapi -f null - 2>/dev/null; then
  _vaapi_ok=yes
fi

# Pass 1: motion detection (all clips in parallel — CPU-bound, read-only).
_pass1() {
  local src="$1" trf="$2"
  ffmpeg -y -i "$src" \
    -vf "vidstabdetect=shakiness=${SHAKINESS}:accuracy=${ACCURACY}:result=${trf}" \
    -f null - 2>&1
}

# Pass 2: transform + sharpen + encode (serial — GPU is the bottleneck).
_pass2() {
  local src="$1" trf="$2" out="$3"
  local vf="vidstabtransform=input=${trf},${UNSHARP}"
  if [[ "$_vaapi_ok" == yes ]]; then
    ffmpeg -y -vaapi_device "$VADEVICE" -i "$src" \
      -map 0:v:0 -map '0:a:0?' \
      -vf "${vf},format=nv12,hwupload" \
      -c:v hevc_vaapi -rc_mode CQP -global_quality "$QUALITY" -tag:v hvc1 \
      -c:a aac -b:a 128k -movflags +faststart "$out" 2>&1
  else
    ffmpeg -y -i "$src" \
      -map 0:v:0 -map '0:a:0?' \
      -vf "$vf" \
      -c:v libx265 -preset medium -crf 28 -tag:v hvc1 \
      -c:a aac -b:a 128k -movflags +faststart "$out" 2>&1
  fi
}

_base() { basename "${1%.MOV}"; }
_outfor() { printf '%s/stabilised-%s.mp4' "$(dirname "$1")" "$(basename "${1%.MOV}")"; }

main() {
  echo "stabilize-video: ${#_mov_files[@]} clip(s) to process"
  echo "  device : $VADEVICE"
  echo "  quality: $QUALITY (vaapi: $_vaapi_ok)"

  # Build the work list, skipping clips whose output already exists.
  local -a todo=()
  trf_dir=$(mktemp -d -t stabilize-video.XXXXXX)
  trap '[[ -n "$trf_dir" ]] && rm -rf "$trf_dir"' EXIT

  for src in "${_mov_files[@]}"; do
    local out
    out=$(_outfor "$src")
    if [[ -f "$out" ]]; then
      echo "  skip (exists): $out"
      continue
    fi
    todo+=("$src")
  done

  if [[ ${#todo[@]} -eq 0 ]]; then
    echo "stabilize-video: nothing to do (all outputs present)" >&2
    exit 0
  fi

  # Pass 1 — parallel motion detection.
  echo ""
  echo "==> Pass 1: motion detection"
  local pids=()
  for src in "${todo[@]}"; do
    local base trf
    base=$(_base "$src")
    trf="${trf_dir}/${base}.trf"
    echo "  [P1] $src"
    _pass1 "$src" "$trf" | sed "s/^/    [$base P1] /" &
    pids+=("$!")
  done
  local fail=0
  for pid in "${pids[@]}"; do
    wait "$pid" || ((++fail))
  done
  if ((fail > 0)); then
    echo "stabilize-video: pass 1 failed for $fail clip(s)" >&2
    exit 1
  fi

  # Pass 2 — serial stabilize + encode.
  echo ""
  echo "==> Pass 2: stabilize + encode ($(_vaapi_label))"
  for src in "${todo[@]}"; do
    local base trf out
    base=$(_base "$src")
    trf="${trf_dir}/${base}.trf"
    out=$(_outfor "$src")
    echo "  [P2] $src -> $out"
    _pass2 "$src" "$trf" "$out" | tail -3 | sed "s/^/    [$base P2] /"
  done

  # Verify outputs decode cleanly and report size reduction.
  echo ""
  echo "==> Verify"
  for src in "${todo[@]}"; do
    local base out src_h out_h dur
    base=$(_base "$src")
    out=$(_outfor "$src")
    src_h=$(du -h "$src" | cut -f1)
    out_h=$(du -h "$out" | cut -f1)
    dur=$(ffprobe -v error -show_entries format=duration \
      -of csv=p=0 "$out")
    if ffmpeg -v error -i "$out" -f null - 2>&1; then
      printf '  %-28s %s -> %s  (%ss, decode OK)\n' \
        "$base" "$src_h" "$out_h" "$dur"
    else
      printf '  %-28s %s -> %s  DECODE ERROR\n' "$base" "$src_h" "$out_h" >&2
    fi
  done

  echo ""
  echo "stabilize-video: done"
}

_vaapi_label() {
  if [[ "$_vaapi_ok" == yes ]]; then
    echo "vaapi hevc"
  else
    echo "software libx265"
  fi
}

main "$@"