[tepl] FileMetadata: support 'save as'

[Sébastien Wilmet <swilmet src gnome org>]

commit 05f965272336c921fed877c6a0aca245c3869363
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Apr 10 04:10:15 2020 +0200

    FileMetadata: support 'save as'

 tepl/tepl-file-metadata.c      | 221 ++++++++++++++++++++++++++++++++++++-----
 tepl/tepl-file-metadata.h      |   1 +
 testsuite/test-file-metadata.c |   1 +
 3 files changed, 199 insertions(+), 24 deletions(-)
---
diff --git a/tepl/tepl-file-metadata.c b/tepl/tepl-file-metadata.c
index 48fc73e..53b2e84 100644
--- a/tepl/tepl-file-metadata.c
+++ b/tepl/tepl-file-metadata.c
@@ -114,7 +114,8 @@
  * location, then save <emphasis>all</emphasis> the metadata belonging to our
  * document that we are saving.
  *
- * FIXME: currently not well supported by #TeplFileMetadata.
+ * This is supported by tepl_file_metadata_save_async() with the @save_as
+ * parameter.
  *
  * ## Opening a second time the same file in the same application
  *
@@ -515,18 +516,151 @@ tepl_file_metadata_load_finish (TeplFileMetadata  *metadata,
 }
 
 static void
-save_metadata_async_cb (GObject      *source_object,
-                       GAsyncResult *result,
-                       gpointer      user_data)
+save_as__set_attributes_cb (GObject      *source_object,
+                           GAsyncResult *result,
+                           gpointer      user_data)
 {
        GFile *location = G_FILE (source_object);
        GTask *task = G_TASK (user_data);
-       TeplFileMetadata *metadata;
-       TeplFileMetadataPrivate *priv;
+       TeplFileMetadata *metadata = g_task_get_source_object (task);
+       TeplFileMetadataPrivate *priv = tepl_file_metadata_get_instance_private (metadata);
        GError *error = NULL;
 
-       metadata = g_task_get_source_object (task);
-       priv = tepl_file_metadata_get_instance_private (metadata);
+       g_file_set_attributes_finish (location, result, NULL, &error);
+
+       if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+       {
+               print_fallback_to_metadata_store_warning ();
+               g_clear_error (&error);
+       }
+
+       if (error != NULL)
+       {
+               g_task_return_error (task, error);
+               g_object_unref (task);
+               return;
+       }
+
+       g_clear_object (&priv->file_info_modified);
+
+       g_task_return_boolean (task, TRUE);
+       g_object_unref (task);
+}
+
+static void
+save_as__query_all_previous_metadata_cb (GObject      *source_object,
+                                        GAsyncResult *result,
+                                        gpointer      user_data)
+{
+       GFile *location = G_FILE (source_object);
+       GTask *task = G_TASK (user_data);
+       TeplFileMetadata *metadata = g_task_get_source_object (task);
+       TeplFileMetadataPrivate *priv = tepl_file_metadata_get_instance_private (metadata);
+       GFileInfo *file_info;
+       GError *error = NULL;
+       gchar **attributes;
+       gint attr_num;
+
+       file_info = g_file_query_info_finish (location, result, &error);
+
+       if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+       {
+               print_fallback_to_metadata_store_warning ();
+
+               g_clear_error (&error);
+               g_clear_object (&file_info);
+       }
+
+       if (error != NULL)
+       {
+               /* Ignore error because the purpose is to unset the previous
+                * metadata. If we get an error here we are unable to unset the
+                * metadata, so just do nothing about it.
+                * If we get again an error in save_as__set_attributes_cb(), the
+                * error will be reported there.
+                */
+               g_clear_error (&error);
+               g_clear_object (&file_info);
+       }
+
+       if (file_info == NULL)
+       {
+               file_info = g_file_info_new ();
+               /* After that, take the same code path, so that that code path
+                * is better tested and is written in a general way.
+                * Even though since file_info is empty, it would be possible to
+                * directly call g_file_set_attributes_async() with
+                * priv->file_info_all.
+                */
+       }
+
+       attributes = g_file_info_list_attributes (file_info, "metadata");
+       for (attr_num = 0; attributes != NULL && attributes[attr_num] != NULL; attr_num++)
+       {
+               const gchar *cur_attribute = attributes[attr_num];
+
+               /* Unset. */
+               g_file_info_set_attribute (file_info,
+                                          cur_attribute,
+                                          G_FILE_ATTRIBUTE_TYPE_INVALID,
+                                          NULL);
+       }
+       g_strfreev (attributes);
+
+       attributes = g_file_info_list_attributes (priv->file_info_all, "metadata");
+       for (attr_num = 0; attributes != NULL && attributes[attr_num] != NULL; attr_num++)
+       {
+               const gchar *cur_attribute = attributes[attr_num];
+               GFileAttributeType attribute_type = G_FILE_ATTRIBUTE_TYPE_INVALID;
+               gpointer attribute_value = NULL;
+
+               g_file_info_get_attribute_data (priv->file_info_all,
+                                               cur_attribute,
+                                               &attribute_type,
+                                               &attribute_value,
+                                               NULL);
+
+               g_file_info_set_attribute (file_info,
+                                          cur_attribute,
+                                          attribute_type,
+                                          attribute_value);
+       }
+       g_strfreev (attributes);
+
+       g_file_set_attributes_async (location,
+                                    file_info,
+                                    G_FILE_QUERY_INFO_NONE,
+                                    g_task_get_priority (task),
+                                    g_task_get_cancellable (task),
+                                    save_as__set_attributes_cb,
+                                    task);
+       g_object_unref (file_info);
+}
+
+static void
+start_to_save_as (GTask *task)
+{
+       GFile *location = g_task_get_task_data (task);
+
+       g_file_query_info_async (location,
+                                METADATA_QUERY_ATTRIBUTES,
+                                G_FILE_QUERY_INFO_NONE,
+                                g_task_get_priority (task),
+                                g_task_get_cancellable (task),
+                                save_as__query_all_previous_metadata_cb,
+                                task);
+}
+
+static void
+save_modified_metadata_cb (GObject      *source_object,
+                          GAsyncResult *result,
+                          gpointer      user_data)
+{
+       GFile *location = G_FILE (source_object);
+       GTask *task = G_TASK (user_data);
+       TeplFileMetadata *metadata = g_task_get_source_object (task);
+       TeplFileMetadataPrivate *priv = tepl_file_metadata_get_instance_private (metadata);
+       GError *error = NULL;
 
        g_file_set_attributes_finish (location, result, NULL, &error);
 
@@ -549,10 +683,38 @@ save_metadata_async_cb (GObject      *source_object,
        g_object_unref (task);
 }
 
+static void
+start_to_save_modified_metadata (GTask *task)
+{
+       TeplFileMetadata *metadata = g_task_get_source_object (task);
+       TeplFileMetadataPrivate *priv = tepl_file_metadata_get_instance_private (metadata);
+       GFile *location = g_task_get_task_data (task);
+
+       if (priv->file_info_modified == NULL)
+       {
+               g_task_return_boolean (task, TRUE);
+               g_object_unref (task);
+               return;
+       }
+
+       /* The g_file_set_attributes_async() implementation calls
+        * g_file_info_dup(), so no need to take care about data races ourself
+        * (save_async() -> set() -> save_finish()).
+        */
+       g_file_set_attributes_async (location,
+                                    priv->file_info_modified,
+                                    G_FILE_QUERY_INFO_NONE,
+                                    g_task_get_priority (task),
+                                    g_task_get_cancellable (task),
+                                    save_modified_metadata_cb,
+                                    task);
+}
+
 /**
  * tepl_file_metadata_save_async:
  * @metadata: a #TeplFileMetadata.
  * @location: a #GFile.
+ * @save_as: whether it's for a 'save as' operation.
  * @io_priority: the I/O priority of the request. E.g. %G_PRIORITY_LOW,
  *   %G_PRIORITY_DEFAULT or %G_PRIORITY_HIGH.
  * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
@@ -566,6 +728,25 @@ save_metadata_async_cb (GObject      *source_object,
  *
  * @location must exist on the filesystem, otherwise an error is returned.
  *
+ * If @save_as is %FALSE, only the <emphasis>modified</emphasis> metadata is
+ * saved. A call to tepl_file_metadata_set() marks that metadata as modified. A
+ * successful call to tepl_file_metadata_load_async() deletes all previous
+ * metadata stored in the #TeplFileMetada object, including modified metadata. A
+ * successful call to tepl_file_metadata_save_async() marks the modified
+ * metadata as saved, so those metadata will no longer be marked as modified
+ * (but will still be part of #TeplFileMetadata).
+ *
+ * If @save_as is %TRUE, this function:
+ * 1. Erases all previously stored metadata for @location.
+ * 2. Then saves <emphasis>all</emphasis> the metadata of @metadata for
+ *    @location.
+ *
+ * @save_as can be set to %TRUE in two different situations: (1) save a new
+ * document for the first time; (2) open a file, possibly modify it, then save
+ * it to another location. In both cases, a #GFile needs to be chosen by the
+ * user, and if it replaces an existing file, the user needs to confirm to
+ * overwrite it.
+ *
  * See the #GAsyncResult documentation to know how to use this function.
  *
  * Since: 5.0
@@ -573,6 +754,7 @@ save_metadata_async_cb (GObject      *source_object,
 void
 tepl_file_metadata_save_async (TeplFileMetadata    *metadata,
                               GFile               *location,
+                              gboolean             save_as,
                               gint                 io_priority,
                               GCancellable        *cancellable,
                               GAsyncReadyCallback  callback,
@@ -592,25 +774,16 @@ tepl_file_metadata_save_async (TeplFileMetadata    *metadata,
 
        task = g_task_new (metadata, cancellable, callback, user_data);
        g_task_set_priority (task, io_priority);
+       g_task_set_task_data (task, g_object_ref (location), g_object_unref);
 
-       if (priv->file_info_modified == NULL)
+       if (save_as)
        {
-               g_task_return_boolean (task, TRUE);
-               g_object_unref (task);
-               return;
+               start_to_save_as (task);
+       }
+       else
+       {
+               start_to_save_modified_metadata (task);
        }
-
-       /* The g_file_set_attributes_async() implementation calls
-        * g_file_info_dup(), so no need to take care about data races ourself
-        * (save_async() -> set() -> save_finish()).
-        */
-       g_file_set_attributes_async (location,
-                                    priv->file_info_modified,
-                                    G_FILE_QUERY_INFO_NONE,
-                                    io_priority,
-                                    cancellable,
-                                    save_metadata_async_cb,
-                                    task);
 }
 
 /**
diff --git a/tepl/tepl-file-metadata.h b/tepl/tepl-file-metadata.h
index 83f0ffb..ddb1e77 100644
--- a/tepl/tepl-file-metadata.h
+++ b/tepl/tepl-file-metadata.h
@@ -62,6 +62,7 @@ gboolean              tepl_file_metadata_load_finish                  (TeplFileMetadata  
*metadata,
 
 void                   tepl_file_metadata_save_async                   (TeplFileMetadata    *metadata,
                                                                         GFile               *location,
+                                                                        gboolean             save_as,
                                                                         gint                 io_priority,
                                                                         GCancellable        *cancellable,
                                                                         GAsyncReadyCallback  callback,
diff --git a/testsuite/test-file-metadata.c b/testsuite/test-file-metadata.c
index f64e757..2cec64c 100644
--- a/testsuite/test-file-metadata.c
+++ b/testsuite/test-file-metadata.c
@@ -66,6 +66,7 @@ save_sync (TeplFileMetadata *metadata,
 {
        tepl_file_metadata_save_async (metadata,
                                       location,
+                                      FALSE,
                                       G_PRIORITY_DEFAULT,
                                       NULL,
                                       save_sync_cb,