completion: Add an api to complete columns

The new function, flatpak_compete_columns, takes an array
of Column structs and completes a --columns= option.

Unfortunately, bash completion does not let us do better
than repeating the entire list of columns for every
possible completion. This is not ideal, but at least
it gives good results for the first column.

Closes: #2445
Approved by: alexlarsson

app/flatpak-complete.c

@@ -36,7 +36,10 @@ flatpak_completion_debug (const gchar *format, ...)
   static FILE *f = NULL;
 
   va_start (var_args, format);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
   s = g_strdup_vprintf (format, var_args);
+#pragma GCC diagnostic pop
   if (f == NULL)
     f = fopen ("/tmp/flatpak-completion-debug.txt", "a+");
   fprintf (f, "%s\n", s);
@@ -400,6 +403,69 @@ flatpak_complete_options (FlatpakCompletion *completion,
     }
 }
 
+static void
+flatpak_complete_column (FlatpakCompletion *completion,
+                         char **used,
+                         const char *column)
+{
+  g_autoptr(GString) s = NULL;
+
+  s = g_string_new ("");
+
+  if (used[0] != NULL)
+    {
+      int i;
+
+      if (g_strv_contains ((const char * const *)used, column))
+        return;
+
+      const char *last = NULL;
+      last = used[g_strv_length (used) - 1];
+      if (!g_str_has_prefix (column, last))
+        return;
+
+      for (i = 0; used[i + 1]; i++)
+        {
+          g_string_append (s, used[i]);
+          g_string_append_c (s, ',');
+        }
+    }
+
+  g_string_append (s, column);
+  flatpak_completion_debug ("completing column: %s", s->str);
+
+  g_print ("%s\n", s->str);
+}
+
+void
+flatpak_complete_columns (FlatpakCompletion *completion,
+                          Column            *columns)
+{
+  int i;
+  const char *list = NULL;
+  g_auto(GStrv) used = NULL;
+
+  if (!g_str_has_prefix (completion->cur, "--columns="))
+    return;
+
+  list = completion->cur + strlen ("--columns=");
+  if (strcmp (list, "all") == 0 ||
+      strcmp (list, "help") == 0)
+    return;
+
+  used = g_strsplit (list, ",", 0);
+  flatpak_completion_debug ("complete columns, used: '%s'", list);
+
+  if (g_strv_length (used) <= 1)
+    {
+      flatpak_complete_column (completion, used, "all");
+      flatpak_complete_column (completion, used, "help");
+    }
+
+  for (i = 0; columns[i].name; i++)
+    flatpak_complete_column (completion, used, columns[i].name);
+}
+
 void
 flatpak_complete_context (FlatpakCompletion *completion)
 {

app/flatpak-complete.h

@@ -23,6 +23,7 @@
 
 #include <ostree.h>
 #include "flatpak-dir-private.h"
+#include "flatpak-builtins-utils.h"
 
 typedef struct FlatpakCompletion FlatpakCompletion;
 
@@ -60,6 +61,8 @@ void               flatpak_complete_file (FlatpakCompletion *completion,
 void               flatpak_complete_dir (FlatpakCompletion *completion);
 void               flatpak_complete_options (FlatpakCompletion *completion,
                                              GOptionEntry      *entries);
+void               flatpak_complete_columns (FlatpakCompletion *completion,
+                                             Column            *columns);
 void               flatpak_completion_free (FlatpakCompletion *completion);
 void               flatpak_complete_context (FlatpakCompletion *completion);