# Builds a dev-shell shellHook that links a project's selected skills into its
# own `.claude/skills/` as direct-child symlinks into the Nix store.
skills:
let
  storeDir = builtins.storeDir;
  links = builtins.concatStringsSep "\n" (
    map (skill: "    _mkskills_link '${skill.skillName}' '${skill}'") skills
  );
in
''
  # Places this project's Nix-delivered skills into ./.claude/skills/ on shell
  # entry.
  # Each run first drops every direct-child symlink pointing into the store,
  # then relinks the current selection.
  # Those store symlinks are unambiguously ours, so this removes deselected
  # skills for free and needs no manifest.
  # A real (non-symlink) skill directory is a hand-authored, project-private
  # skill and is left untouched.
  # The whole hook runs in a subshell so it leaks no names into the interactive
  # shell.
  (
    _mkskills_dir=".claude/skills"
    mkdir -p "$_mkskills_dir"

    for _mkskills_entry in "$_mkskills_dir"/*; do
      [ -L "$_mkskills_entry" ] || continue
      case "$(readlink "$_mkskills_entry")" in
        ${storeDir}/*) rm -f "$_mkskills_entry" ;;
      esac
    done

    # A real path at a selected skill's name is a hand-authored skill.
    # It is left in place and left out of the managed set, so the .gitignore
    # below keeps tracking it rather than the skill that would have been linked.
    _mkskills_managed=""
    _mkskills_link() {
      _mkskills_dest="$_mkskills_dir/$1"
      if [ -e "$_mkskills_dest" ] && [ ! -L "$_mkskills_dest" ]; then
        printf 'mkSkillsShellHook: skipping %s: a non-symlink path already exists\n' "$1" >&2
      else
        # At most a non-store symlink remains at this name, so removing it first
        # keeps the link step to a plain POSIX `ln -s` with no overwrite flag.
        rm -f "$_mkskills_dest"
        ln -s "$2" "$_mkskills_dest"
        _mkskills_managed="$_mkskills_managed $1"
      fi
    }
${links}

    # Regenerate the self-ignoring .gitignore from the current selection, so the
    # store symlinks stay out of git while hand-authored skills, absent from this
    # list, remain tracked.
    {
      printf '%s\n' "# Generated by mkSkillsShellHook. Nix-delivered skill symlinks, kept out of git."
      printf '%s\n' "/.gitignore"
      # Disable pathname expansion so a managed name is never glob-expanded.
      set -f
      for _mkskills_name in $_mkskills_managed; do
        printf '/%s\n' "$_mkskills_name"
      done
    } > "$_mkskills_dir/.gitignore"
  )
''