#!/usr/bin/env bash
# fetch-ffmpeg.sh — populate ./ffmpeg/ with the pinned BtbN LGPL-shared FFmpeg build.
#
# WHY THIS EXISTS: the app used to download ffmpeg from GitHub on first run and execute
# it. That is Windows Store policy 10.2.2 (dynamic code inclusion) and it already cost a
# real failure — the pin aged out of BtbN's 14-day retention and the download 404'd on
# the creator's first recording attempt (2026-09-01). FFmpeg is now BUNDLED, so nothing is
# fetched at runtime. This script is the BUILD-TIME half of that: a fresh clone has no
# ffmpeg/ folder, so it must be filled once before the first build.
#
# The binaries are NOT committed to git (135 MB of incompressible DLLs would tax every
# commit on this 9p-bridged working tree). The URL + SHA-256 below are the audit trail
# that the LGPL written-offer obligation actually needs, and they are reviewable in a diff.
#
# Usage:   ./scripts/fetch-ffmpeg.sh
#          FFMPEG_ZIP=/path/to/already-downloaded.zip ./scripts/fetch-ffmpeg.sh
#
# Idempotent: re-running with ffmpeg/ already populated verifies and exits. Delete
# ffmpeg/ to force a refetch.

set -euo pipefail

# Pinned BtbN lgpl-shared win64 build. A MONTH-END autobuild tag on purpose: BtbN keeps
# ~14 dailies, but month-end builds for ~2 years. Do not "refresh" this to a daily — that
# is the mistake that caused the 404.
URL="https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-08-31-13-27/ffmpeg-N-126342-gf88b741dbf-win64-lgpl-shared.zip"
SHA256="46ea6521ed3877689d2ff0bd03640ac2637104415f6237d42625d13408767146"

# The files we ship. ffplay.exe (18 MB) is deliberately excluded — nothing in the app
# calls it, and shipping an unused player would widen the package and the license surface
# for nothing.
WANT_EXE="ffmpeg.exe ffprobe.exe"

ROOT="$(cd "$(dirname "$0")/.." && pwd)"
DEST="$ROOT/ffmpeg"

if [ -f "$DEST/ffmpeg.exe" ]; then
  echo "✓ ffmpeg/ already populated — nothing to do."
  echo "  (delete $DEST to force a refetch)"
  exit 0
fi

command -v python3 >/dev/null 2>&1 || {
  echo "❌ python3 is required to extract the zip (unzip is not installed in this WSL)."
  echo "   Set FFMPEG_ZIP to a pre-downloaded archive, or install python3."
  exit 1
}

ZIP="${FFMPEG_ZIP:-}"
if [ -z "$ZIP" ]; then
  ZIP="$(mktemp -t ffmpeg-pin-XXXXXX.zip)"
  trap 'rm -f "$ZIP"' EXIT
  echo "══ Downloading the pinned FFmpeg build (~65 MB, one time) ══"
  curl -fsSL --retry 3 -o "$ZIP" "$URL"
fi

echo "══ Verifying SHA-256 ══"
GOT="$(sha256sum "$ZIP" | cut -d' ' -f1)"
if [ "$GOT" != "$SHA256" ]; then
  echo "❌ SHA-256 mismatch — refusing to extract."
  echo "   expected $SHA256"
  echo "   actual   $GOT"
  exit 1
fi
echo "✓ $GOT"

echo "══ Extracting into ffmpeg/ ══"
python3 - "$ZIP" "$DEST" "$WANT_EXE" <<'PY'
import os, sys, zipfile

archive_path, dest, want = sys.argv[1], sys.argv[2], set(sys.argv[3].split())
wanted_exe = {n for n in want}

os.makedirs(dest, exist_ok=True)
found = []
with zipfile.ZipFile(archive_path) as z:
    for name in z.namelist():
        if '/bin/' not in name or name.endswith('/'):
            continue
        base = os.path.basename(name)
        if not (base.endswith('.dll') or base in wanted_exe):
            continue
        with z.open(name) as src, open(os.path.join(dest, base), 'wb') as out:
            out.write(src.read())
        found.append(base)

missing = wanted_exe - set(found)
if missing:
    sys.exit(f"❌ archive is missing required binaries: {sorted(missing)}")

print(f"✓ extracted {len(found)} files")
for base in sorted(found):
    print(f"    {base}")
PY

echo ""
echo "✓ Bundled FFmpeg ready. The build copies ffmpeg/ → bin/<config>/<tfm>/ffmpeg/."
echo "  Nothing is downloaded at runtime any more (Store policy 10.2.2 satisfied)."