#!/bin/sh
# Builds one Koh release binary into build/releases/koh-<target>.
#
#   KOH_TARGET=linux-x86_64 sh build.sh
#
# `koh build` sets KOH_TARGET for each platform in koh.build; run by hand, the
# target defaults to the machine running the script. Runs on macOS and Linux.
#
# macOS targets need macOS: they link against the Apple SDK and are ad-hoc
# signed with codesign. Linux targets are static musl binaries built with
# `zig cc`. Every target needs its own OS and CPU: the pinned V disables
# garbage collection when cross-compiling. Linux VMs work from a Mac.
set -eu

die() {
  echo "build.sh: $*" >&2
  exit 1
}

# Paths below are relative to the repository, wherever the script is run from.
cd "$(dirname "$0")"

# The pin is the only compiler Koh is verified against; see AGENTS.md.
command -v v >/dev/null 2>&1 || die 'V is not on PATH; install V 0.5.2 b9a2d87 (see AGENTS.md)'
[ "$(v version)" = 'V 0.5.2 b9a2d87' ] || die "Koh requires V 0.5.2 b9a2d87, found: $(v version)"

host_target() {
  case "$(uname -s)" in
    Darwin) os=macos ;;
    Linux) os=linux ;;
    *) die "unsupported host OS: $(uname -s)" ;;
  esac
  case "$(uname -m)" in
    arm64|aarch64) cpu=aarch64 ;;
    x86_64|amd64) cpu=x86_64 ;;
    *) die "unsupported host CPU: $(uname -m)" ;;
  esac
  echo "$os-$cpu"
}

native=$(host_target)
target=${KOH_TARGET:-$native}
case "$target" in
  macos-aarch64|macos-x86_64|linux-aarch64|linux-x86_64) ;;
  *) die "unsupported release target: $target (want macos-aarch64, macos-x86_64, linux-x86_64 or linux-aarch64)" ;;
esac
[ "$target" = "$native" ] || die "$target requires a native $target host or VM to retain garbage collection (this host is $native)"
out="build/releases/koh-$target"
mkdir -p build/releases

case "$target" in
  macos-aarch64|macos-x86_64)
    [ "$(uname -s)" = Darwin ] || die "$target needs the Apple SDK; build it on macOS"
    case "$target" in
      macos-aarch64) arch=arm64; cpu=arm64 ;;
      *) arch=x64; cpu=x86_64 ;;
    esac
    v -prod -gc boehm -d use_bundled_libgc -arch "$arch" \
      -cflags "-arch $cpu -mmacosx-version-min=11.0" -o "$out" src/koh.v
    # Apple Silicon refuses to run an unsigned binary.
    codesign -f -s - "$out"
    ;;
  linux-aarch64|linux-x86_64)
    command -v zig >/dev/null 2>&1 || die 'Linux builds need Zig on PATH (zig cc provides the musl toolchain)'
    case "$target" in
      linux-aarch64) arch=arm64; triple=aarch64-linux-musl ;;
      *) arch=x64; triple=x86_64-linux-musl ;;
    esac
    # V's -cc takes a single program, not `zig cc -target …`, so wrap it.
    # musl has neither getcontext nor ARM64's expected __data_start symbol.
    # libgc can scan the stack and discover the data segment without them.
    compiler="$PWD/build/cc-$target"
    printf '#!/bin/sh\nexec zig cc -target %s "$@"\n' "$triple" > "$compiler"
    chmod 755 "$compiler"
    v -prod -gc boehm -d use_bundled_libgc -os linux -arch "$arch" \
      -musl -cc "$compiler" -cflags "-DNO_GETCONTEXT -DSEARCH_FOR_DATA_START" \
      -ldflags "-s" -o "$out" src/koh.v
    ;;
esac

echo "built $out"