#!/usr/bin/env bash
# Recursively copy non-system dylibs next to a Mach-O binary and rewrite load paths.
set -euo pipefail

find_homebrew_lib() {
  local base="$1"
  find "${HOMEBREW_PREFIX:-/opt/homebrew}/Cellar" "${HOMEBREW_PREFIX:-/opt/homebrew}/opt" \
    -name "${base}" -path '*/lib/*' 2>/dev/null | head -1
}

resolve_dependency_path() {
  local owner="$1"
  local dep="$2"
  local reference="${3:-${owner}}"

  if [[ "${dep}" != @* ]]; then
    [[ -f "${dep}" ]] || return 1
    printf '%s\n' "${dep}"
    return 0
  fi

  local owner_dir reference_dir
  owner_dir="$(cd "$(dirname "${owner}")" && pwd)"
  reference_dir="$(cd "$(dirname "${reference}")" && pwd)"

  case "${dep}" in
    @loader_path/*)
      local candidate="${owner_dir}/${dep#@loader_path/}"
      [[ -f "${candidate}" ]] || return 1
      printf '%s\n' "${candidate}"
      ;;
    @executable_path/*)
      local rel="${dep#@executable_path/}"
      local candidate="${owner_dir}/${rel}"
      if [[ ! -f "${candidate}" ]]; then
        candidate="${reference_dir}/${rel}"
      fi
      if [[ ! -f "${candidate}" ]]; then
        candidate="$(find_homebrew_lib "$(basename "${rel}")")"
      fi
      [[ -f "${candidate}" ]] || return 1
      printf '%s\n' "${candidate}"
      ;;
    @rpath/*)
      local rel="${dep#@rpath/}"
      local rpath candidate
      while IFS= read -r rpath; do
        case "${rpath}" in
          @loader_path/*) candidate="${owner_dir}/${rpath#@loader_path/}/${rel}" ;;
          @executable_path/*) candidate="${owner_dir}/${rpath#@executable_path/}/${rel}" ;;
          *) candidate="${rpath}/${rel}" ;;
        esac
        if [[ -f "${candidate}" ]]; then
          printf '%s\n' "${candidate}"
          return 0
        fi
      done < <(
        otool -l "${owner}" | awk '
          /cmd LC_RPATH/ { want=1; next }
          want && /path / {
            sub(/^.*path /, "", $0)
            sub(/ \(offset.*$/, "", $0)
            print
            want=0
          }
        '
      )
      candidate="${owner_dir}/${rel}"
      [[ -f "${candidate}" ]] || return 1
      printf '%s\n' "${candidate}"
      ;;
    *)
      return 1
      ;;
  esac
}

list_load_dylibs() {
  local target="$1"
  otool -l "${target}" | awk '
    /cmd LC_LOAD_DYLIB/ { want=1; next }
    want && /name / {
      sub(/^.*name /, "", $0)
      sub(/ \(offset.*$/, "", $0)
      print
      want=0
    }
  '
}

bundle_mach_dylibs() {
  local binary="${1:?binary path required}"
  local lib_dir="${2:?lib directory required}"
  local reference_binary="${3:-${binary}}"

  [[ -f "${binary}" ]] || {
    echo "bundle_mach_dylibs: missing binary: ${binary}" >&2
    return 1
  }

  mkdir -p "${lib_dir}"

  local -a queue=("${binary}")
  local seen_list=" "
  local -a sources=()

  is_system_lib() {
    case "$1" in
      /usr/lib/*|/System/*|/Library/*) return 0 ;;
    esac
    return 1
  }

  already_seen() {
    [[ "${seen_list}" == *" $1 "* ]]
  }

  remember() {
    seen_list+=" $1 "
  }

  while ((${#queue[@]} > 0)); do
    local target="${queue[0]}"
    queue=("${queue[@]:1}")
    [[ -f "${target}" ]] || continue

    local dep resolved
    while IFS= read -r dep; do
      [[ -n "${dep}" ]] || continue
      is_system_lib "${dep}" && continue
      already_seen "${dep}" && continue
      remember "${dep}"

      resolved="$(resolve_dependency_path "${target}" "${dep}" "${reference_binary}")" || {
        echo "bundle_mach_dylibs: missing dependency ${dep} for ${target}" >&2
        return 1
      }
      already_seen "${resolved}" || remember "${resolved}"

      if [[ "${resolved}" != "${binary}" ]]; then
        sources+=("${resolved}")
        queue+=("${resolved}")
      fi
    done < <(list_load_dylibs "${target}")
  done

  local src base
  for src in "${sources[@]}"; do
    base="$(basename "${src}")"
    cp -f "${src}" "${lib_dir}/${base}"
    chmod 755 "${lib_dir}/${base}"
  done

  rewrite_dep() {
    local target="$1"
    local dep="$2"
    local new_path="$3"
    install_name_tool -change "${dep}" "${new_path}" "${target}" 2>/dev/null || true
  }

  rewrite_targets() {
    local target="$1"
    local prefix="$2"
    local dep base
    while IFS= read -r dep; do
      [[ -n "${dep}" ]] || continue
      is_system_lib "${dep}" && continue
      [[ "${dep}" == @* ]] && continue
      base="$(basename "${dep}")"
      [[ -f "${lib_dir}/${base}" ]] || continue
      rewrite_dep "${target}" "${dep}" "${prefix}${base}"
    done < <(list_load_dylibs "${target}")
  }

  rewrite_rpath_targets() {
    local target="$1"
    local prefix="$2"
    local dep base
    while IFS= read -r dep; do
      [[ -n "${dep}" ]] || continue
      [[ "${dep}" == @rpath/* ]] || continue
      base="$(basename "${dep}")"
      [[ -f "${lib_dir}/${base}" ]] || continue
      rewrite_dep "${target}" "${dep}" "${prefix}${base}"
    done < <(list_load_dylibs "${target}")
  }

  local changed=1
  while ((changed)); do
    changed=0
    rewrite_targets "${binary}" "@executable_path/../lib/"
    rewrite_rpath_targets "${binary}" "@executable_path/../lib/"
    for staged in "${lib_dir}"/*.dylib; do
      [[ -f "${staged}" ]] || continue
      before="$(list_load_dylibs "${staged}" | { grep -E 'homebrew|^@rpath/' || true; } | wc -l | tr -d ' ')"
      rewrite_targets "${staged}" "@loader_path/"
      rewrite_rpath_targets "${staged}" "@loader_path/"
      after="$(list_load_dylibs "${staged}" | { grep -E 'homebrew|^@rpath/' || true; } | wc -l | tr -d ' ')"
      [[ "${before}" != "${after}" ]] && changed=1
    done
  done

  local remaining
  remaining="$(list_load_dylibs "${binary}" | grep homebrew || true)"
  if [[ -n "${remaining}" ]]; then
    echo "bundle_mach_dylibs: unresolved homebrew dependencies remain:" >&2
    printf '%s\n' "${remaining}" >&2
    return 1
  fi

  install_name_tool -add_rpath "@executable_path/../lib" "${binary}" 2>/dev/null || true

  local staged
  for staged in "${lib_dir}"/*.dylib; do
    [[ -f "${staged}" ]] || continue
    codesign --force --sign - "${staged}" >/dev/null
  done
  codesign --force --sign - "${binary}" >/dev/null
}

if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
  bundle_mach_dylibs "$@"
fi