#!/usr/bin/env bash
set -euo pipefail

FFMPEG_VERSION="8.1.2"
FFMPEG_SHA256="464beb5e7bf0c311e68b45ae2f04e9cc2af88851abb4082231742a74d97b524c"
NASM_VERSION="2.16.03"
NASM_SHA256="1412a1c760bbd05db026b6c0d1657affd6631cd0a63cddb6f73cc6d4aa616148"

# Ubuntu 20.04 on purpose: it pins the .so to glibc 2.31, the same floor as docker/linux-builder and
# therefore as the shipped AppImage. Building on anything newer produces libraries the AppImage cannot
# load on the older distros we claim to support.
BUILD_IMAGE="ubuntu:20.04"
PLATFORM="linux/amd64"

HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
DEST="${HERE}/ffmpeg"

echo "==================================================="
echo " Building LGPL ffmpeg ${FFMPEG_VERSION} (x86_64, decode-only)"
echo " image: ${BUILD_IMAGE} (${PLATFORM})"
echo " dest : ${DEST}"
echo "==================================================="

command -v docker >/dev/null || { echo "ERROR: docker not found"; exit 1; }

rm -rf "$DEST"
mkdir -p "$DEST"

docker run --rm --platform "$PLATFORM" -v "${DEST}:/out" "$BUILD_IMAGE" bash -eu -c "
export DEBIAN_FRONTEND=noninteractive
apt-get update -qq
apt-get install -y -qq --no-install-recommends ca-certificates curl xz-utils build-essential >/dev/null

# 20.04 ships nasm 2.14, which chokes on ffmpeg 8's AVX macros (\"error: expecting ')'\" in
# libswscale/x86/ops_float.asm). Build a current nasm rather than reaching for --disable-x86asm: that
# would drop the SIMD decode paths and slow every frame down, on the machines least able to afford it.
cd /tmp
curl -sSL -o nasm.tar.xz https://www.nasm.us/pub/nasm/releasebuilds/${NASM_VERSION}/nasm-${NASM_VERSION}.tar.xz
echo '${NASM_SHA256}  nasm.tar.xz' | sha256sum -c -
tar -xf nasm.tar.xz
cd nasm-${NASM_VERSION}
./configure --prefix=/usr/local >/dev/null && make -j\$(nproc) >/dev/null && make install >/dev/null
nasm -v

cd /tmp
curl -sSL -o ffmpeg.tar.xz https://ffmpeg.org/releases/ffmpeg-${FFMPEG_VERSION}.tar.xz
echo '${FFMPEG_SHA256}  ffmpeg.tar.xz' | sha256sum -c -
tar -xf ffmpeg.tar.xz
cd ffmpeg-${FFMPEG_VERSION}

# Same LGPL, decode-only configuration as the macOS build (see ../macos/build_ffmpeg.sh); only the
# platform bits differ. Keep the two in step: a codec enabled on one platform and not the other is a
# file that previews on a Mac and fails on Linux.
./configure \
    --prefix=/tmp/stage \
    --enable-shared \
    --disable-static \
    --enable-pic \
    --disable-programs \
    --disable-doc \
    --disable-autodetect \
    --disable-everything \
    --disable-avdevice \
    --disable-avfilter \
    --disable-swresample \
    --disable-network \
    --disable-gpl \
    --disable-nonfree \
    --enable-decoder=h264,hevc,mjpeg,mjpegb \
    --enable-parser=h264,hevc,mjpeg \
    --enable-demuxer=mov,matroska,avi,flv,mpegts,h264,hevc,mjpeg,image2 \
    --enable-protocol=file \
    --enable-bsf=h264_mp4toannexb,hevc_mp4toannexb,extract_extradata \
    >/tmp/configure.log 2>&1 || { tail -30 /tmp/configure.log; exit 1; }

make -j\$(nproc) >/dev/null
make install >/dev/null

mkdir -p /out/include /out/lib
cp -R /tmp/stage/include/* /out/include/
# Copy the real .so under its soname: the unversioned symlinks make install leaves behind do not
# survive a git checkout, and the soname is what the loader actually resolves.
for f in /tmp/stage/lib/*.so.*; do
    [ -L \"\$f\" ] && continue
    soname=\$(objdump -p \"\$f\" | awk '/SONAME/ {print \$2}')
    cp \"\$f\" \"/out/lib/\$soname\"
done
chmod -R a+rX /out
chown -R \$(stat -c '%u:%g' /out) /out
"

echo ""
echo "Verifying..."
FAIL=0
for f in "${DEST}/lib/"*.so*; do
    [[ -f "$f" ]] || { echo "ERROR: no shared library produced"; exit 1; }
done
for f in "${DEST}/lib/"*.so*; do
    printf '  %-28s %s\n' "$(basename "$f")" "$(du -h "$f" | cut -f1)"
done
[[ "$FAIL" -eq 0 ]] || exit 1

echo ""
echo "Done. Next: rebuild the AppImage and check that no libav* resolves outside the bundle."