#!/usr/bin/env bash
# Convert Mew timeline MP4 clips into small, optimized GIFs for Neocities.
# Requires: ffmpeg, gifsicle
#
# Strategy:
# - Trim to the first few seconds
# - Sample only a few frames per second
# - Scale down to a small width
# - Use a global palette + heavy optimization
# - Aim to keep each GIF under ~5MB
#
# Usage (from this directory):
#   chmod +x mp4-to-gif.sh
#   ./mp4-to-gif.sh /path/to/source/mp4s

set -euo pipefail

SRC_DIR="${1:-.}"
OUT_DIR="${OUT_DIR:-.}"

# Tunables for size/quality tradeoff
FPS="${FPS:-3}"          # frames per second sampled
WIDTH="${WIDTH:-360}"    # output width in pixels
MAX_SECONDS="${MAX_SECONDS:-8}"  # cap duration

if ! command -v ffmpeg &>/dev/null; then
  echo "Error: ffmpeg not found. Install it first." >&2
  exit 1
fi

if ! command -v gifsicle &>/dev/null; then
  echo "Warning: gifsicle not found. Skipping extra optimization (GIFs may be larger)." >&2
fi

convert_one () {
  local name="$1"        # e.g. 2016-12-17_22-42-58
  local in="$SRC_DIR/${name}.mp4"

  # Unique temp files to avoid name clashes if run multiple times
  local pal
  pal="$(mktemp "${OUT_DIR}/${name}-palette-XXXX.png")"
  local out_tmp
  out_tmp="$(mktemp "${OUT_DIR}/${name}-tmp-XXXX.gif")"
  local out_final="${OUT_DIR}/${name}.gif"

  if [[ ! -f "$in" ]]; then
    echo "Skip (missing): $in"
    return
  fi

  echo "Processing $in -> $out_final"

  # 1) Generate palette from trimmed, sparsely sampled, scaled frames
  ffmpeg -y -t "$MAX_SECONDS" -i "$in" \
    -vf "fps=${FPS},scale=${WIDTH}:-1:flags=lanczos,palettegen=stats_mode=single:max_colors=48" \
    -frames:v 1 \
    "$pal"

  # 2) Apply palette to create GIF
  ffmpeg -y -t "$MAX_SECONDS" -i "$in" -i "$pal" \
    -lavfi "fps=${FPS},scale=${WIDTH}:-1:flags=lanczos [x]; [x][1:v] paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle" \
    -loop 0 \
    "$out_tmp"

  # 3) Extra optimization with gifsicle, if available
  if command -v gifsicle &>/dev/null; then
    gifsicle -O3 --lossy=40 "$out_tmp" -o "$out_final"
    rm -f "$out_tmp"
  else
    mv "$out_tmp" "$out_final"
  fi

  rm -f "$pal"

  # 4) Print size
  if command -v du &>/dev/null; then
    echo -n "Final size: "
    du -h "$out_final" | cut -f1
  fi
}

convert_one "2016-12-17_22-42-58"
convert_one "2017-04-01_00-14-00"
convert_one "2018-06-19_06-20-25"

echo "Done. Upload the generated *.gif files to the 'library' folder on Neocities and ensure index.html references the .gif versions."