#!/usr/bin/env bash
# Cross-compiles the service inside a container, for hosts that cannot run the
# NDK directly. The openlgtv buildroot SDK is a Linux toolchain, so on macOS or
# Windows this is the only way to build the native part.
#
#   ./tools/docker-build.sh          # build the service into build/native/
#   ./tools/docker-build.sh shell    # a prompt inside the SDK, for poking about
#   ./tools/docker-build.sh clean    # drop the image
#
# The SDK is baked into an image, so it is downloaded once (~350 MB) and every
# build after the first starts instantly. There are aarch64 and x86_64 builds
# of the SDK and the image picks the one matching the container, so this runs
# natively on Apple Silicon rather than under emulation.
#
# NDK_RELEASE pins the SDK release; DOCKER is podman if you prefer.
set -euo pipefail

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

DOCKER="${DOCKER:-docker}"
NDK_RELEASE="${NDK_RELEASE:-webos-a38c582}"
IMAGE="${IMAGE:-lgtv-audiocap-sdk:$NDK_RELEASE}"
SDK=/opt/webos-sdk
TOOLCHAIN="$SDK/share/buildroot/toolchainfile.cmake"
BUILD_DIR=build/native

say() { printf '%s\n' "$*"; }
step() { printf '\n== %s\n' "$*"; }
die() { printf 'error: %s\n' "$*" >&2; exit 1; }

command -v "$DOCKER" >/dev/null 2>&1 || die "$DOCKER is not installed"

build_image() {
  if "$DOCKER" image inspect "$IMAGE" >/dev/null 2>&1; then
    return
  fi
  step "Building the SDK image (once, ~350 MB download)"
  # The arch is resolved inside the build so the image is right for whatever
  # the daemon runs, without the caller having to know.
  "$DOCKER" build --tag "$IMAGE" - <<EOF
FROM debian:bookworm-slim
RUN apt-get update \\
 && apt-get install -y --no-install-recommends \\
      ca-certificates curl cmake make file python3 \\
 && rm -rf /var/lib/apt/lists/*
RUN case "\$(uname -m)" in \\
      aarch64|arm64) arch=aarch64 ;; \\
      x86_64|amd64)  arch=x86_64 ;; \\
      *) echo "no webOS SDK for \$(uname -m)" >&2; exit 1 ;; \\
    esac \\
 && mkdir -p $SDK \\
 && curl -fL "https://github.com/openlgtv/buildroot-nc4/releases/download/$NDK_RELEASE/arm-webos-linux-gnueabi_sdk-buildroot-\$arch.tar.gz" \\
    | tar xz -C $SDK --strip-components=1 \\
 && $SDK/relocate-sdk.sh
EOF
}

# --user keeps build/ owned by the caller instead of root. HOME has to point
# somewhere writable or cmake complains about its package registry.
run() {
  "$DOCKER" run --rm \
    --volume "$ROOT:/src" \
    --workdir /src \
    --user "$(id -u):$(id -g)" \
    --env HOME=/tmp \
    "$@"
}

compile() {
  build_image

  # A cache from a differently placed toolchain cannot be reused.
  if [ -f "$BUILD_DIR/CMakeCache.txt" ] \
     && ! grep -q "CMAKE_TOOLCHAIN_FILE:.*=$TOOLCHAIN" "$BUILD_DIR/CMakeCache.txt"; then
    say "discarding a cmake cache from a different toolchain"
    rm -rf "$BUILD_DIR"
  fi

  step "Cross-compiling the service"
  run --interactive=false "$IMAGE" sh -c "
    set -e
    cmake -S native -B $BUILD_DIR \
      -DCMAKE_TOOLCHAIN_FILE=$TOOLCHAIN \
      -DCMAKE_BUILD_TYPE=Release
    cmake --build $BUILD_DIR --parallel
    file $BUILD_DIR/audiocap-service
  "

  [ -f "$BUILD_DIR/audiocap-service" ] || die "the build produced no binary"
  say ""
  say "built $BUILD_DIR/audiocap-service"
  say "now: ./tools/build.sh package"
}

case "${1:-build}" in
  build) compile ;;
  shell)
    build_image
    step "A shell in the SDK image; the toolchain is at $SDK"
    run --interactive --tty "$IMAGE" bash
    ;;
  clean)
    "$DOCKER" image rm "$IMAGE" 2>/dev/null && say "removed $IMAGE" || say "no image to remove"
    ;;
  -h|--help)
    awk 'NR == 1 { next } /^#/ { sub(/^# ?/, ""); print; next } { exit }' "$0" ;;
  *) die "unknown command '$1' (try --help)" ;;
esac