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

# Create a universal (arm64+x86_64) .app by merging two already-deployed app bundles
# that have identical layouts, one built on Apple Silicon and one built on Intel.
#
# Usage:
#   ./build_tools/macos/make_universal_app.sh \
#     --arm-app  /path/to/arm64/strawberry.app \
#     --x86-app  /path/to/x86_64/strawberry.app \
#     --out-app  /path/to/output/strawberry.app \
#     [--clean]
#
# Notes:
# - Do NOT sign the per-arch apps first; signatures will be invalidated by lipo anyway.
# - Both inputs must be the same app version/config with the same enabled features,
#   so the file lists match.

ts() { date +"%H:%M:%S"; }

usage() {
  cat <<'EOF'
Usage:
  ./build_tools/macos/make_universal_app.sh --arm-app <path> --x86-app <path> --out-app <path> [--clean]

What it does:
  - Copies the arm64 app to --out-app
  - For every Mach-O file in the copied app, finds the corresponding file in the x86_64 app
  - Uses lipo to combine the two slices into a universal binary at the same relative path

Required:
  --arm-app <path>   Path to arm64 Strawberry.app (built+deployed on Apple Silicon)
  --x86-app <path>   Path to x86_64 Strawberry.app (built+deployed on Intel)
  --out-app <path>   Output path for universal Strawberry.app

Optional:
  --clean            Delete --out-app if it already exists
EOF
}

if [[ "$(uname -s)" != "Darwin" ]]; then
  echo "Error: This script is for macOS only." >&2
  exit 1
fi

arm_app=""
x86_app=""
out_app=""
do_clean=0

while [[ $# -gt 0 ]]; do
  case "$1" in
    --arm-app) arm_app="${2:-}"; shift 2 ;;
    --x86-app) x86_app="${2:-}"; shift 2 ;;
    --out-app) out_app="${2:-}"; shift 2 ;;
    --clean) do_clean=1; shift ;;
    -h|--help) usage; exit 0 ;;
    *) echo "Unknown arg: $1" >&2; usage; exit 2 ;;
  esac
done

if [[ -z "$arm_app" || -z "$x86_app" || -z "$out_app" ]]; then
  echo "Error: missing required args." >&2
  usage
  exit 2
fi
if [[ ! -d "$arm_app" ]]; then
  echo "Error: --arm-app not found: $arm_app" >&2
  exit 2
fi
if [[ ! -d "$x86_app" ]]; then
  echo "Error: --x86-app not found: $x86_app" >&2
  exit 2
fi

for cmd in /usr/bin/file /usr/bin/lipo /usr/bin/ditto; do
  if [[ ! -x "$cmd" ]]; then
    echo "Error: required tool not found: $cmd" >&2
    exit 1
  fi
done

out_parent="$(cd -- "$(dirname -- "$out_app")" && pwd)"
out_name="$(basename -- "$out_app")"
out_app="${out_parent}/${out_name}"

if [[ -e "$out_app" && "$do_clean" -eq 1 ]]; then
  echo "==> [$(ts)] Removing existing output app: $out_app"
  rm -rf "$out_app"
fi
if [[ -e "$out_app" ]]; then
  echo "Error: output already exists: $out_app (use --clean to overwrite)" >&2
  exit 2
fi

echo "==> [$(ts)] Copying arm64 app to output"
/usr/bin/ditto "$arm_app" "$out_app"

# Remove any existing signatures in the copied app; we'll re-sign after creating universal binaries.
echo "==> [$(ts)] Removing existing code signature metadata (will be re-signed later)"
find "$out_app" -type d -name "_CodeSignature" -print0 2>/dev/null | while IFS= read -r -d '' d; do
  rm -rf "$d" || true
done

echo "==> [$(ts)] Merging Mach-O files with lipo"

merged=0
skipped=0

# Traverse output app and lipo-merge any Mach-O file with its counterpart in the x86 app.
while IFS= read -r -d '' f; do
  # Only operate on regular files.
  if [[ ! -f "$f" ]]; then
    continue
  fi

  ft="$(/usr/bin/file -b "$f" 2>/dev/null || true)"
  if [[ "$ft" != *"Mach-O"* ]]; then
    skipped=$((skipped + 1))
    continue
  fi

  rel="${f#"$out_app"/}"
  other="${x86_app}/${rel}"
  if [[ ! -f "$other" ]]; then
    echo "Error: missing matching file in x86 app for:" >&2
    echo "  $rel" >&2
    echo "Expected at:" >&2
    echo "  $other" >&2
    exit 1
  fi

  other_ft="$(/usr/bin/file -b "$other" 2>/dev/null || true)"
  if [[ "$other_ft" != *"Mach-O"* ]]; then
    echo "Error: file is Mach-O in arm app but not Mach-O in x86 app:" >&2
    echo "  $rel" >&2
    echo "arm64: $ft" >&2
    echo "x86_64: $other_ft" >&2
    exit 1
  fi

  # Validate architectures.
  arm_archs="$(/usr/bin/lipo -archs "$f" 2>/dev/null || true)"
  x86_archs="$(/usr/bin/lipo -archs "$other" 2>/dev/null || true)"
  if [[ "$arm_archs" != *"arm64"* ]]; then
    echo "Error: expected arm64 slice in arm app file:" >&2
    echo "  $rel" >&2
    echo "  archs: $arm_archs" >&2
    exit 1
  fi
  if [[ "$x86_archs" != *"x86_64"* ]]; then
    echo "Error: expected x86_64 slice in x86 app file:" >&2
    echo "  $rel" >&2
    echo "  archs: $x86_archs" >&2
    exit 1
  fi

  tmp="$(mktemp -t strawberry-universal.XXXXXX)"
  /usr/bin/lipo -create "$f" "$other" -output "$tmp"
  chmod --reference="$f" "$tmp" 2>/dev/null || true
  mv -f "$tmp" "$f"
  merged=$((merged + 1))
done < <(find "$out_app" -type f -print0 2>/dev/null)

echo "==> [$(ts)] Done"
echo "Merged Mach-O files: $merged"
echo "Non-Mach-O files skipped: $skipped"
echo "Output app:"
echo "  $out_app"