# Builds a dev-shell shellHook that links a project's selected skills into its
# own `.agents/skills/` as direct-child symlinks into the Nix store, with
# `.claude/skills` as a compatibility symlink when that path is free.
# Generated ignores live in the project root so agent skill scanners still see
# the linked skills.
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 ./.agents/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.
  # When ./.claude/skills is free, it is kept as a compatibility symlink to the
  # canonical ./.agents/skills directory so Claude Code sees the same skills.
  # The whole hook runs in a subshell so it leaks no names into the interactive
  # shell.
  (
    _mkskills_dir=".agents/skills"
    mkdir -p "$_mkskills_dir"

    _mkskills_claude_skills_managed=0
    mkdir -p .claude
    if [ ! -e .claude/skills ] && [ ! -L .claude/skills ]; then
      ln -s ../.agents/skills .claude/skills
      _mkskills_claude_skills_managed=1
    elif [ -L .claude/skills ]; then
      case "$(readlink .claude/skills)" in
        ../.agents/skills) _mkskills_claude_skills_managed=1 ;;
        ${storeDir}/*) rm -f .claude/skills && ln -s ../.agents/skills .claude/skills && _mkskills_claude_skills_managed=1 ;;
      esac
    else
      printf 'mkSkillsShellHook: leaving existing non-symlink .claude/skills in place; Claude Code compatibility link not installed\n' >&2
    fi

    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 generated
    # ignore block 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}

    if [ -f "$_mkskills_dir/.gitignore" ] \
      && grep -qx '# Generated by mkSkillsShellHook. Nix-delivered skill symlinks, kept out of git.' "$_mkskills_dir/.gitignore"; then
      rm -f "$_mkskills_dir/.gitignore"
    fi

    # Regenerate the project-root ignore block from the current selection.
    # Skill scanners read ignore files under .agents/skills, so the block must
    # live above the scanned tree.
    _mkskills_gitignore=".gitignore"
    _mkskills_gitignore_tmp=".gitignore.mkskills.$$"
    if [ -f "$_mkskills_gitignore" ]; then
      awk '
        $0 == "# BEGIN mkSkillsShellHook" { skip = 1; next }
        $0 == "# END mkSkillsShellHook" { skip = 0; next }
        !skip { lines[++n] = $0 }
        END {
          while (n > 0 && lines[n] == "") n--
          for (i = 1; i <= n; i++) print lines[i]
        }
      ' "$_mkskills_gitignore" > "$_mkskills_gitignore_tmp"
    else
      : > "$_mkskills_gitignore_tmp"
    fi
    {
      if [ -s "$_mkskills_gitignore_tmp" ]; then
        cat "$_mkskills_gitignore_tmp"
        printf '\n'
      fi
      printf '%s\n' "# BEGIN mkSkillsShellHook"
      printf '%s\n' "# Generated by mkSkillsShellHook. Nix-delivered skill symlinks, kept out of git."
      if [ "$_mkskills_claude_skills_managed" = 1 ]; then
        printf '%s\n' ".claude/skills"
      fi
      # Disable pathname expansion so a managed name is never glob-expanded.
      set -f
      for _mkskills_name in $_mkskills_managed; do
        printf '.agents/skills/%s\n' "$_mkskills_name"
      done
      printf '%s\n' "# END mkSkillsShellHook"
    } > "$_mkskills_gitignore"
    rm -f "$_mkskills_gitignore_tmp"
  )
''