#!/usr/bin/env bash
# build_ffmpeg_lgpl.sh <dest-prefix> [--tarball <ffmpeg-8.1.1.tar.xz>] [--jobs N]
#
# Builds the FFmpeg the Enchant mac app ships, exactly: the source tarball and configure line in
# ffmpeg_lgpl.conf (next to this script), shared dylibs with @rpath install names, installed to
# <dest-prefix>. Used by scripts/fetch_deps_mac.sh (--ffmpeg-lgpl) and shipped unchanged in the
# LGPL source package (make_ffmpeg_source_package.sh) — so anyone holding that package rebuilds
# the same libraries and can drop them into Enchant.app/Contents/Frameworks (see its README).
#
# Needs: macOS arm64, Xcode command line tools, Homebrew pkgconf + dav1d + libvpx + opus.
# Without --tarball it downloads FFmpeg from ffmpeg.org; either way the sha256 must match.
set -euo pipefail
HERE="$(cd "$(dirname "$0")" && pwd)"
# shellcheck source=ffmpeg_lgpl.conf
. "$HERE/ffmpeg_lgpl.conf"

DEST=""; TARBALL=""; JOBS="${FF_JOBS:-8}"
while [ $# -gt 0 ]; do
  case "$1" in
    --tarball) shift; TARBALL="${1:?}";;
    --jobs) shift; JOBS="${1:?}";;
    -h|--help) sed -n '2,11p' "$0"; exit 0;;
    *) [ -z "$DEST" ] && DEST="$1" || { echo "unknown argument: $1" >&2; exit 2; };;
  esac; shift
done
[ -n "$DEST" ] || { echo "usage: $0 <dest-prefix> [--tarball file] [--jobs N]" >&2; exit 2; }
case "$DEST" in /*) ;; *) DEST="$(pwd)/$DEST";; esac

WORK="$(mktemp -d "${TMPDIR:-/tmp}/enchant-ffmpeg.XXXXXX")"
trap 'rm -rf "$WORK"' EXIT
export PATH="/opt/homebrew/bin:/opt/homebrew/sbin:/usr/bin:/bin:/usr/sbin:/sbin"   # arm64 brew, never /usr/local

for b in "${FF_LGPL_BREW_DEPS[@]}"; do
  brew list --versions "$b" >/dev/null 2>&1 || { echo "[ffmpeg] brew install $b"; brew install "$b"; }
done

if [ -z "$TARBALL" ]; then
  echo "[ffmpeg] download $FF_LGPL_URL"
  curl -fSL --retry 3 -o "$WORK/ffmpeg.tar.xz" "$FF_LGPL_URL"
  TARBALL="$WORK/ffmpeg.tar.xz"
fi
got="$(shasum -a 256 "$TARBALL" | cut -d' ' -f1)"
[ "$got" = "$FF_LGPL_SHA" ] || { echo "[ffmpeg] ERROR: sha256 $got != $FF_LGPL_SHA ($TARBALL)" >&2; exit 1; }

mkdir -p "$WORK/src" "$WORK/root"
tar -xf "$TARBALL" -C "$WORK/src" --strip-components=1
echo "[ffmpeg] configure: ${FF_LGPL_CONFIGURE[*]}"
( cd "$WORK/src" && ./configure "${FF_LGPL_CONFIGURE[@]}" > "$WORK/configure.log" 2>&1 ) \
  || { tail -30 "$WORK/configure.log"; echo "[ffmpeg] ERROR: configure failed" >&2; exit 1; }
grep -q "^License: LGPL version 2.1 or later" "$WORK/configure.log" \
  || { echo "[ffmpeg] ERROR: configure did not come out LGPL 2.1+ — refusing to build" >&2; exit 1; }
echo "[ffmpeg] make -j$JOBS (~5 min on M-series)"
( cd "$WORK/src" && make -j"$JOBS" > "$WORK/make.log" 2>&1 && make install DESTDIR="$WORK/root" > "$WORK/install.log" 2>&1 ) \
  || { tail -30 "$WORK/make.log"; echo "[ffmpeg] ERROR: build failed" >&2; exit 1; }

STAGE="$WORK/root/enchant/ffmpeg-lgpl"
# Relocatable pkg-config: nothing inside may name the fake prefix or this machine.
for pc in "$STAGE"/lib/pkgconfig/*.pc; do
  sed -i '' -e 's|^prefix=.*|prefix=${pcfiledir}/../..|' \
            -e 's|^libdir=.*|libdir=${prefix}/lib|' \
            -e 's|^includedir=.*|includedir=${prefix}/include|' "$pc"
done
mkdir -p "$STAGE/share/ffmpeg-licenses"
cp "$WORK/src/LICENSE.md" "$WORK/src/COPYING.LGPLv2.1" "$STAGE/share/ffmpeg-licenses/"
{
  echo "FFmpeg $FF_LGPL_VER, LGPL version 2.1 or later"
  echo "source:    $FF_LGPL_URL"
  echo "sha256:    $FF_LGPL_SHA"
  echo "configure: ${FF_LGPL_CONFIGURE[*]}"
  echo "built by:  scripts/build_ffmpeg_lgpl.sh (Enchant), $(date -u +%Y-%m-%d)"
} > "$STAGE/share/ffmpeg-licenses/BUILD_INFO.txt"
rm -rf "$DEST"; mkdir -p "$(dirname "$DEST")"
mv "$STAGE" "$DEST"
echo "[ffmpeg] OK -> $DEST"