refactor: don't hardcode nix subcommands in run-help-nix

misc/zsh/run-help-nix

@@ -18,80 +18,25 @@ emulate -L zsh
 #
 #     bindkey '^[h' run-help
 
-if (( $# == 0 )); then
-  man nix
-  return
-fi
-
 while [[ "$#" != 0 && "$1" == -* ]]; do
   shift
 done
 
-case "$1" in
-  flake)
-    case "$2" in
-      archive|check|clone|info|init|lock|metadata|new|prefetch|show|update)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  hash)
-    case "$2" in
-      file|path|to-base16|to-base32|to-base64|to-sri)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  key)
-    case "$2" in
-      convert-secret-to-public|generate-secret)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  nar)
-    case "$2" in
-      cat|dump-path|ls)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  profile)
-    case "$2" in
-      diff-closures|history|install|list|remove|rollback|upgrade|wipe-history)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  realisation)
-    case "$2" in
-      info)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  registry)
-    case "$2" in
-      add|list|pin|remove)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  store)
-    case "$2" in
-      add-file|add-path|cat|copy-sigs|delete|diff-closures|dump-path|gc|ls)
-        ;& # fallthrough
-      make-content-addressed|optimise|ping|prefetch-file|repair|sign|verify)
-        man "nix3-$1-$2" ;;
-      *)
-        man "nix3-$1" ;;
-    esac ;;
-  *)
-    if man -w "nix3-$1" >/dev/null 2>&1; then
-      man "nix3-$1"
-    else
-      man nix
-    fi ;;
-esac
+local -a subcommands; subcommands=( nix3 )
+
+local arg
+for arg in "$@"; do
+  if man -w "${(j:-:)subcommands}-$arg" >/dev/null 2>&1; then
+    subcommands+="$arg"
+  else
+    break
+  fi
+done
+
+if (( $#subcommands > 1 )); then
+  man "${(j:-:)subcommands}"
+else
+  man nix
+fi
 
 return $?