# shellcheck shell=bash
# Portable resolver for the pinned LLVM build tree.
#
# The out-of-tree LLVM pass (-fpass-plugin) must load into the *exact* LLVM it
# was built against (clang has no stable plugin ABI). That LLVM is the
# from-source pin described in toolchain/llvm-from-source.md (commit 60513b8d,
# clang 22), built with the dylib + plugin flags. This helper locates its build
# directory (the one containing bin/clang and lib/cmake/llvm) without baking in
# any machine-specific absolute path.
#
# Search order (first hit wins):
#   1. $HWJS_LLVM_BUILD                    — explicit override
#   2. <repo>/llvm-project/build           — the LLVM this repo pins as a
#                                            submodule, and the default
#                                            libexec/config.sh resolves to
#   3. $HOME/toolchains/llvm-pin/build     — where llvm-from-source.md installs
#   4. <repo>/../llvm-project/build        — a sibling checkout, or the sibling
#      <repo>/../../toolchains/llvm-project/build   submodule in a super-repo
#
# Candidate 2 was added when the LLVM fork became a submodule of this repo, and
# it deliberately outranks the $HOME candidate: this repo pins its own LLVM, and
# a build tree in someone's home directory is a DIFFERENT LLVM whose plugin load
# fails as a crash or a miscompile rather than a clean version error. Everything
# below the explicit override is a guess; prefer the guess the repo itself pins.
#
# Callers that go through bin/ never reach the guesses at all —
# libexec/config.sh resolves BRINTIUM_LLVM and exports WASMLD_HWJS_LLVM_BIN,
# which hwjs_llvm_bin honors first.
#
# Usage:
#   source libexec/find-llvm.sh
#   build="$(hwjs_find_llvm_build "$SOME_DIR_INSIDE_THE_REPO")" || exit 1

hwjs_find_llvm_build() {
  # $1: any directory inside this checkout (used to locate the repo root and
  #     its sibling llvm-project). Falls back to this file's own location.
  local anchor="${1:-}"
  local self_dir
  self_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"   # repo root
  local candidates=(
    "${HWJS_LLVM_BUILD:-}"
    "$self_dir/llvm-project/build"
    "$HOME/toolchains/llvm-pin/build"
    "$self_dir/../llvm-project/build"
    "$self_dir/../../toolchains/llvm-project/build"
  )
  [ -n "$anchor" ] && candidates+=(
    "$anchor/../../../llvm-project/build"
    "$anchor/../../../../toolchains/llvm-project/build"
  )
  local c
  for c in "${candidates[@]}"; do
    [ -n "$c" ] && [ -x "$c/bin/clang" ] && { (cd "$c" && pwd); return 0; }
  done
  return 1
}

# hwjs_llvm_bin: echo the pinned LLVM `bin/` directory (clang, wasm-ld, opt,
# llvm-nm, llvm-ar, llvm-link). Honors $WASMLD_HWJS_LLVM_BIN / $HWJS_LLVM_BIN
# first (the driver override interface the distro sets), else resolves the build
# tree via hwjs_find_llvm_build. Non-zero exit if nothing resolves.
hwjs_llvm_bin() {
  local anchor="${1:-}"
  if [ -n "${WASMLD_HWJS_LLVM_BIN:-}" ]; then printf '%s\n' "$WASMLD_HWJS_LLVM_BIN"; return 0; fi
  if [ -n "${HWJS_LLVM_BIN:-}" ]; then printf '%s\n' "$HWJS_LLVM_BIN"; return 0; fi
  local build; build="$(hwjs_find_llvm_build "$anchor")" || return 1
  printf '%s\n' "$build/bin"
}