Clear hbci KVP from accounts no longer associated with an online one

A reverse hash table is introduced in order to memorize the
matched GnuCash accounts before starting the matching wizard.
This hash table is used within the aai_on_finish callback
to delete only the KVPs of those GnuCash accounts which are
no longer matched with an AqBanking account.
All other GnuCash accounts (previously matched and currently
matched) are just updated with the new assignments.

gnucash/import-export/aqb/assistant-ab-initial.c

@@ -106,7 +106,9 @@ static gboolean find_gnc_acc_cb(gpointer key, gpointer value, gpointer user_data
 static gboolean clear_line_cb(GtkTreeModel *model, GtkTreePath *path, GtkTreeIter *iter, gpointer user_data);
 static void account_list_clicked_cb (GtkTreeView *view, GtkTreePath *path,
                                      GtkTreeViewColumn  *col, gpointer user_data);
-static void clear_kvp_acc_cb(Account *gnc_acc, gpointer user_data);
+static void insert_acc_into_revhash_cb(gpointer ab_acc, gpointer gnc_acc, gpointer revhash);
+static void remove_acc_from_revhash_cb(gpointer ab_acc, gpointer gnc_acc, gpointer revhash);
+static void clear_kvp_acc_cb(gpointer key, gpointer value, gpointer user_data);
 static void save_kvp_acc_cb(gpointer key, gpointer value, gpointer user_data);
 static void aai_close_handler(gpointer user_data);
 
@@ -127,6 +129,8 @@ struct _ABInitialInfo
     AB_BANKING *api;
     /* AB_ACCOUNT* -> Account* -- DO NOT DELETE THE KEYS! */
     GHashTable *gnc_hash;
+    /* Reverse hash table for lookup of matched GnuCash accounts */
+    GHashTable *gnc_revhash;
 };
 
 struct _DeferredInfo
@@ -206,6 +210,12 @@ aai_destroy_cb(GtkWidget *object, gpointer user_data)
         info->gnc_hash = NULL;
     }
 
+    if (info->gnc_revhash)
+    {
+        g_hash_table_destroy(info->gnc_revhash);
+        info->gnc_revhash = NULL;
+    }
+
     if (info->api)
     {
         gnc_AB_BANKING_delete(info->api);
@@ -321,6 +331,20 @@ aai_ab_account_equal (gconstpointer v1, gconstpointer v2)
 }
 #endif
 
+static void
+insert_acc_into_revhash_cb(gpointer ab_acc, gpointer gnc_acc, gpointer revhash)
+{
+    g_return_if_fail(revhash && gnc_acc && ab_acc);
+    g_hash_table_insert((GHashTable *) revhash, gnc_acc, ab_acc);
+}
+
+static void
+remove_acc_from_revhash_cb(gpointer ab_acc, gpointer gnc_acc, gpointer revhash)
+{
+    g_return_if_fail(revhash && gnc_acc);
+    g_hash_table_remove((GHashTable *) revhash, gnc_acc);
+}
+
 void
 aai_match_page_prepare (GtkAssistant *assistant, gpointer user_data)
 {
@@ -349,8 +373,10 @@ aai_match_page_prepare (GtkAssistant *assistant, gpointer user_data)
 #endif
         data.api = info->api;
         data.hash = info->gnc_hash;
-        gnc_account_foreach_descendant(
-            root, (AccountCb) hash_from_kvp_acc_cb, &data);
+        gnc_account_foreach_descendant(root, (AccountCb) hash_from_kvp_acc_cb, &data);
+        /* Memorize initial matches in reverse hash table */
+        info->gnc_revhash = g_hash_table_new(NULL, NULL);
+        g_hash_table_foreach(data.hash, (GHFunc) insert_acc_into_revhash_cb, (gpointer) info->gnc_revhash);
 
         info->match_page_prepared = TRUE;
     }
@@ -365,13 +391,17 @@ void
 aai_on_finish (GtkAssistant *assistant, gpointer user_data)
 {
     ABInitialInfo *info = user_data;
-    Account *root;
 
-    g_return_if_fail(info && info->gnc_hash);
+    g_return_if_fail(info && info->gnc_hash && info->gnc_revhash);
 
+    /* Remove GnuCash accounts from reverse hash table which are still
+     * matched to an AqBanking account. For the remaining GnuCash accounts
+     * the KVPs must be cleared (i.e. deleted).
+     * Please note that the value (i.e. the GnuCash account) stored in info->gnc_hash
+     * is used as key for info->gnc_revhash */
+    g_hash_table_foreach(info->gnc_hash, (GHFunc) remove_acc_from_revhash_cb, info->gnc_revhash);
     /* Commit the changes */
-    root = gnc_book_get_root_account(gnc_get_current_book());
-    gnc_account_foreach_descendant(root, (AccountCb) clear_kvp_acc_cb, NULL);
+    g_hash_table_foreach(info->gnc_revhash, (GHFunc) clear_kvp_acc_cb, NULL);
     g_hash_table_foreach(info->gnc_hash, (GHFunc) save_kvp_acc_cb, NULL);
 
     gtk_widget_destroy(info->window);
@@ -649,14 +679,11 @@ account_list_clicked_cb (GtkTreeView *view, GtkTreePath *path,
 }
 
 static void
-clear_kvp_acc_cb(Account *gnc_acc, gpointer user_data)
+clear_kvp_acc_cb(gpointer gnc_acc, gpointer ab_acc, gpointer user_data)
 {
-    if (gnc_ab_get_account_uid(gnc_acc))
-        gnc_ab_set_account_uid(gnc_acc, 0);
-    if (gnc_ab_get_account_accountid(gnc_acc))
-        gnc_ab_set_account_accountid(gnc_acc, "");
-    if (gnc_ab_get_account_bankcode(gnc_acc))
-        gnc_ab_set_account_bankcode(gnc_acc, "");
+    g_return_if_fail(gnc_acc);
+    /* Delete complete "hbci..." KVPs for GnuCash account */
+    gnc_account_delete_map_entry((Account *) gnc_acc, "hbci", NULL, NULL, FALSE);
 }
 
 static void