Deduplicate code in lookup CLI

src/pyobo/cli/lookup.py

@@ -113,52 +113,34 @@ def metadata(**kwargs: Unpack[LookupKwargs]) -> None:
 def ids(**kwargs: Unpack[LookupKwargs]) -> None:
     """Page through the identifiers of entities in the given namespace."""
     id_list = get_ids(**kwargs)
-    click.echo_via_pager("\n".join(id_list))
+    if not id_list:
+        click.secho("no data", fg="red")
+    else:
+        click.echo_via_pager("\n".join(id_list))
 
 
 @lookup_annotate
 @identifier_option
 def names(identifier: str | None, **kwargs: Unpack[LookupKwargs]) -> None:
     """Page through the identifiers and names of entities in the given namespace."""
     id_to_name = get_id_name_mapping(**kwargs)
-    if identifier is None:
-        _help_page_mapping(id_to_name)
-    else:
-        name = id_to_name.get(identifier)
-        if name is None:
-            click.secho(f"No name available for {identifier}", fg="red")
-        else:
-            click.echo(name)
+    _help_page_mapping(id_to_name, identifier=identifier)
 
 
 @lookup_annotate
 @identifier_option
 def species(identifier: str | None, **kwargs: Unpack[LookupKwargs]) -> None:
     """Page through the identifiers and species of entities in the given namespace."""
     id_to_species = get_id_species_mapping(**kwargs)
-    if identifier is None:
-        _help_page_mapping(id_to_species)
-    else:
-        species = id_to_species.get(identifier)
-        if species is None:
-            click.secho(f"No species available for {identifier}", fg="red")
-        else:
-            click.echo(species)
+    _help_page_mapping(id_to_species, identifier=identifier)
 
 
 @lookup_annotate
 @identifier_option
 def definitions(identifier: str | None, **kwargs: Unpack[LookupKwargs]) -> None:
     """Page through the identifiers and definitions of entities in the given namespace."""
     id_to_definition = get_id_definition_mapping(**kwargs)
-    if identifier is None:
-        _help_page_mapping(id_to_definition)
-    else:
-        definition = id_to_definition.get(identifier)
-        if definition is None:
-            click.secho(f"No definition available for {identifier}", fg="red")
-        else:
-            click.echo(definition)
+    _help_page_mapping(id_to_definition, identifier=identifier)
 
 
 @lookup_annotate
@@ -168,9 +150,15 @@ def typedefs(**kwargs: Unpack[LookupKwargs]) -> None:
     echo_df(df)
 
 
-def _help_page_mapping(id_to_name: Mapping[str, str]) -> None:
+def _help_page_mapping(id_to_name: Mapping[str, str], *, identifier: str | None = None) -> None:
     if not id_to_name:
         click.secho("no data", fg="red")
+    elif identifier:
+        value = id_to_name.get(identifier)
+        if value:
+            click.echo(value)
+        else:
+            click.secho(f"no data for {identifier}", fg="red")
     else:
         click.echo_via_pager("\n".join("\t".join(item) for item in id_to_name.items()))
 
@@ -248,7 +236,10 @@ def hierarchy(
         include_has_member=include_has_member,
         **kwargs,
     )
-    click.echo_via_pager("\n".join("\t".join(row) for row in h.edges()))
+    if h.number_of_edges() == 0:
+        click.secho("no data", fg="red")
+    else:
+        click.echo_via_pager("\n".join("\t".join(row) for row in h.edges()))
 
 
 @lookup_annotate
@@ -258,6 +249,7 @@ def ancestors(
     **kwargs: Unpack[LookupKwargs],
 ) -> None:
     """Look up ancestors."""
+    # note, prefix is passed via kwargs
     curies = get_ancestors(identifier=identifier, **kwargs)
     for curie in sorted(curies or []):
         click.echo(f"{curie}\t{get_name_by_curie(curie, version=kwargs['version'])}")
@@ -270,6 +262,7 @@ def descendants(
     **kwargs: Unpack[LookupKwargs],
 ) -> None:
     """Look up descendants."""
+    # note, prefix is passed via kwargs
     curies = get_descendants(identifier=identifier, **kwargs)
     for curie in sorted(curies or []):
         click.echo(f"{curie}\t{get_name_by_curie(curie, version=kwargs['version'])}")
@@ -297,15 +290,4 @@ def alts(
 ) -> None:
     """Page through alt ids in a namespace."""
     id_to_alts = get_id_to_alts(**kwargs)
-    if identifier is None:
-        click.echo_via_pager(
-            "\n".join(
-                f"{identifier}\t{alt}" for identifier, alts in id_to_alts.items() for alt in alts
-            )
-        )
-    else:
-        _alts = id_to_alts.get(identifier)
-        if _alts is None:
-            click.secho(f"No alternate identifiers for {identifier}", fg="red")
-        else:
-            click.echo("\n".join(_alts))
+    _help_page_mapping(id_to_alts, identifier=identifier)