#!/usr/bin/env bash
# Build a minimal, LGPL-2.1-or-later, statically linked FFmpeg (ffmpeg.exe +
# ffprobe.exe) for Windows x64 for Audio Converter.
#
# Run inside an MSYS2 MINGW64 shell (MSYSTEM=MINGW64), from anywhere:
#   bash tools/ffmpeg/build-ffmpeg.sh
# Re-runnable: it reuses out/ffmpeg-src (re-checking out the pinned tag) and
# rebuilds in out/ffmpeg-build. Output goes to tools/bin/ffmpeg/.
#
# Licence rules: no --enable-gpl, no --enable-nonfree, no --enable-version3.
set -euo pipefail

FFMPEG_TAG="n9.0.2"
FFMPEG_SHA="946fcce07b6dcd0331c8cc609192aeff5e1924f8"
FFMPEG_URL="https://github.com/FFmpeg/FFmpeg"

if [ "${MSYSTEM:-}" != "MINGW64" ]; then
  echo "error: run this from an MSYS2 MINGW64 shell (MSYSTEM=MINGW64)" >&2
  exit 1
fi

HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO="$(cd "$HERE/../.." && pwd)"
SRC="$REPO/out/ffmpeg-src"
BUILD="$REPO/out/ffmpeg-build"
DEST="$REPO/tools/bin/ffmpeg"
JOBS="${JOBS:-$(nproc)}"

# --- Dependencies (MSYS2 packages; static .a libraries are used) -----------
PKGS=(mingw-w64-x86_64-toolchain mingw-w64-x86_64-lame mingw-w64-x86_64-libogg
      mingw-w64-x86_64-libvorbis mingw-w64-x86_64-opus mingw-w64-x86_64-zlib
      make pkgconf nasm git diffutils)
if [ "${SKIP_PACMAN:-0}" != "1" ]; then
  pacman -S --noconfirm --needed "${PKGS[@]}"
fi
for lib in libmp3lame.a libogg.a libvorbis.a libvorbisenc.a libopus.a libz.a; do
  [ -f "/mingw64/lib/$lib" ] || { echo "error: missing static /mingw64/lib/$lib" >&2; exit 1; }
done

# --- Source -----------------------------------------------------------------
if [ ! -d "$SRC/.git" ]; then
  git clone --depth 1 --branch "$FFMPEG_TAG" "$FFMPEG_URL" "$SRC"
fi
git -c safe.directory="$SRC" -C "$SRC" -c advice.detachedHead=false checkout -q "$FFMPEG_TAG" 2>/dev/null || {
  git -c safe.directory="$SRC" -C "$SRC" fetch --depth 1 origin "refs/tags/$FFMPEG_TAG:refs/tags/$FFMPEG_TAG"
  git -c safe.directory="$SRC" -C "$SRC" -c advice.detachedHead=false checkout -q "$FFMPEG_TAG"
}
HEAD_SHA="$(git -c safe.directory="$SRC" -C "$SRC" rev-parse HEAD)"
if [ "$HEAD_SHA" != "$FFMPEG_SHA" ]; then
  echo "error: $FFMPEG_TAG resolved to $HEAD_SHA, expected $FFMPEG_SHA" >&2
  exit 1
fi

# --- Component selection ----------------------------------------------------
join() { local IFS=,; echo "$*"; }
# Print a command line readably (quote only args that need it).
showcmd() { local a out=(); for a in "$@"; do
  if [[ "$a" =~ [[:space:]\"\'] ]]; then out+=("'$a'"); else out+=("$a"); fi; done; echo "${out[*]}"; }

DECODERS=(
  mp3float mp3 aac aac_fixed aac_latm alac flac vorbis opus
  wmav1 wmav2 wmapro wmalossless amrnb amrwb ac3 ac3_fixed eac3 gsm
  adpcm_ima_wav adpcm_ms
  pcm_s8 pcm_u8 pcm_s16le pcm_s16be pcm_u16le pcm_u16be pcm_s24le pcm_s24be
  pcm_u24le pcm_u24be pcm_s32le pcm_s32be pcm_u32le pcm_u32be pcm_s64le pcm_s64be
  pcm_f16le pcm_f24le pcm_f32le pcm_f32be pcm_f64le pcm_f64be
  pcm_s16le_planar pcm_s24le_planar pcm_s32le_planar pcm_s8_planar pcm_alaw pcm_mulaw
  mjpeg png bmp
  wrapped_avframe
)
ENCODERS=(
  libmp3lame libopus libvorbis aac flac alac wmav2
  pcm_s16le pcm_s24le pcm_s32le pcm_f32le pcm_s16be pcm_s24be pcm_s32be pcm_u8
  mjpeg
)
# lavfi (sine/testsrc inputs for tests) is an input device in libavdevice: see --enable-indev.
DEMUXERS=(
  mov matroska ogg wav w64 aiff flac mp3 aac asf avi amr amrnb amrwb caf ac3 eac3
  mpegts image2 image2pipe image_jpeg_pipe image_png_pipe image_bmp_pipe mjpeg
  pcm_s16le pcm_s16be pcm_s24le pcm_f32le gsm
)
MUXERS=(
  mp3 ipod mp4 mov wav w64 flac ogg opus aiff asf adts null image2 mjpeg pcm_s16le
)
PARSERS=(
  mpegaudio aac aac_latm flac vorbis opus ac3 amr gsm mjpeg png bmp
)
BSFS=(
  aac_adtstoasc opus_metadata null
)
FILTERS=(
  abuffer abuffersink buffer buffersink
  aresample aformat atrim asetpts volume loudnorm anull apad
  sine anullsrc
  format null trim setpts scale testsrc testsrc2
)

CONFIGURE=(
  "$SRC/configure"
  --arch=x86_64 --target-os=mingw32
  --pkg-config-flags=--static
  --extra-cflags=-static
  --extra-ldflags=-static
  --disable-shared --enable-static
  --disable-autodetect
  --disable-everything
  --disable-programs --enable-ffmpeg --enable-ffprobe
  --disable-doc --disable-debug --disable-network
  --disable-devices --disable-hwaccels
  --enable-indev=lavfi
  --enable-small
  --enable-zlib
  --enable-libmp3lame --enable-libopus --enable-libvorbis
  --enable-protocol=file,pipe
  --enable-decoder="$(join "${DECODERS[@]}")"
  --enable-encoder="$(join "${ENCODERS[@]}")"
  --enable-demuxer="$(join "${DEMUXERS[@]}")"
  --enable-muxer="$(join "${MUXERS[@]}")"
  --enable-parser="$(join "${PARSERS[@]}")"
  --enable-bsf="$(join "${BSFS[@]}")"
  --enable-filter="$(join "${FILTERS[@]}")"
)

echo "=== configure line ==="
showcmd "${CONFIGURE[@]}"
echo "======================"

rm -rf "$BUILD"
mkdir -p "$BUILD" "$DEST"
cd "$BUILD"
"${CONFIGURE[@]}" || { tail -50 ffbuild/config.log; exit 1; }

# Licence guard: refuse to ship anything that is not LGPL-2.1-or-later.
grep -q '^#define CONFIG_GPL 0' config.h
grep -q '^#define CONFIG_NONFREE 0' config.h
grep -q '^#define CONFIG_VERSION3 0' config.h
grep -q 'FFMPEG_LICENSE "LGPL version 2.1 or later"' config.h

make -j"$JOBS" ffmpeg.exe ffprobe.exe

# make already strips ffmpeg.exe/ffprobe.exe (the *_g.exe files keep symbols);
# strip again to be explicit. Only the stripped exes are shipped.
rm -f "$DEST"/*-unstripped.exe
strip -o "$DEST/ffmpeg.exe" ffmpeg.exe
strip -o "$DEST/ffprobe.exe" ffprobe.exe
echo "--- sizes (bytes): unstripped *_g.exe vs shipped"
stat -c '%n %s' ffmpeg_g.exe ffprobe_g.exe "$DEST/ffmpeg.exe" "$DEST/ffprobe.exe"

# Imports must be Windows system DLLs only.
for exe in ffmpeg.exe ffprobe.exe; do
  echo "--- imports of $exe"
  objdump -p "$DEST/$exe" | grep 'DLL Name' | tee "$BUILD/$exe.imports"
  if grep -Eiq 'libgcc|libwinpthread|libstdc|libmp3lame|libogg|libvorbis|libopus|zlib1|libz' "$BUILD/$exe.imports"; then
    echo "error: $exe imports a non-system DLL" >&2; exit 1
  fi
done

# --- Licence and provenance files --------------------------------------------
cp "$SRC/COPYING.LGPLv2.1" "$DEST/LICENSE.txt"
"$DEST/ffmpeg.exe" -hide_banner -buildconf > "$DEST/buildconf.txt"
"$DEST/ffmpeg.exe" -hide_banner -L | grep -q 'GNU Lesser General Public'
if grep -Eq -- '--enable-(gpl|nonfree|version3)' "$DEST/buildconf.txt"; then
  echo "error: buildconf contains a non-LGPL-2.1 flag" >&2; exit 1
fi

{
  echo "Audio Converter - bundled FFmpeg (LGPL-2.1-or-later)"
  echo
  echo "FFmpeg $FFMPEG_TAG"
  echo "  commit:  $HEAD_SHA"
  echo "  source:  $FFMPEG_URL/tree/$FFMPEG_TAG"
  echo "  tarball: https://ffmpeg.org/releases/ffmpeg-${FFMPEG_TAG#n}.tar.xz"
  echo "  licence: LGPL-2.1-or-later (see LICENSE.txt, COPYING.LGPLv2.1 from the source tree)"
  echo
  echo "Statically linked libraries (MSYS2 MINGW64 packages, https://packages.msys2.org/):"
  for p in mingw-w64-x86_64-lame mingw-w64-x86_64-libogg mingw-w64-x86_64-libvorbis \
           mingw-w64-x86_64-opus mingw-w64-x86_64-zlib mingw-w64-x86_64-gcc \
           mingw-w64-x86_64-crt-git mingw-w64-x86_64-winpthreads; do
    v="$(pacman -Q "$p" 2>/dev/null || echo "$p (not installed)")"
    echo "  $v"
  done
  echo "  upstream: LAME (LGPL-2.0-or-later) https://lame.sourceforge.io/"
  echo "            libogg, libvorbis (BSD-3-Clause) https://xiph.org/downloads/"
  echo "            libopus (BSD-3-Clause) https://opus-codec.org/"
  echo "            zlib (zlib licence) https://zlib.net/"
  echo "            MinGW-w64 runtime / winpthreads (ZPL/MIT/BSD), libgcc (GPL + runtime exception)"
  echo "  package sources: https://github.com/msys2/MINGW-packages"
  echo
  echo "Configure line:"
  showcmd "${CONFIGURE[@]}" | sed "s#$SRC#./ffmpeg-src#"
} > "$DEST/SOURCE.txt"

ls -l "$DEST"
echo "BUILD OK"