[libgames-support] scores: Add support for importing old Nibbles scores

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 40b8617447cb401f8ddbf36855b20b69f3806d37
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Fri Feb 12 21:53:04 2016 -0600

    scores: Add support for importing old Nibbles scores

 games/Makefile.am          |    1 +
 games/scores/context.vala  |    9 +++
 games/scores/importer.vala |  127 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 137 insertions(+), 0 deletions(-)
---
diff --git a/games/Makefile.am b/games/Makefile.am
index 1380acb..c34a444 100644
--- a/games/Makefile.am
+++ b/games/Makefile.am
@@ -6,6 +6,7 @@ libgames_support_la_SOURCES = \
        scores/category.vala    \
        scores/context.vala     \
        scores/dialog.vala      \
+       scores/importer.vala    \
        scores/score.vala
 
 libgames_support_la_CFLAGS = \
diff --git a/games/scores/context.vala b/games/scores/context.vala
index 9f445ec..d18ec25 100644
--- a/games/scores/context.vala
+++ b/games/scores/context.vala
@@ -85,6 +85,15 @@ public class Context : Object
 
         try
         {
+            Importer.run (user_score_dir);
+        }
+        catch (Error e)
+        {
+            warning ("Score importer failed: %s", e.message);
+        }
+
+        try
+        {
             load_scores_from_files ();
         }
         catch (Error e)
diff --git a/games/scores/importer.vala b/games/scores/importer.vala
new file mode 100644
index 0000000..4b94989
--- /dev/null
+++ b/games/scores/importer.vala
@@ -0,0 +1,127 @@
+/* -*- Mode: vala; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * Copyright © 2016 Michael Catanzaro <mcatanzaro gnome org>
+ *
+ * This file is part of libgames-scores.
+ *
+ * libgames-scores is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * libgames-scores is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with libgames-scores.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Games {
+namespace Scores {
+
+/* Time for a history lesson. Once upon a time, scores were stored under
+ * /var/games in a format basically the same as what we use now, split into
+ * different files based on category. Games were installed setgid for the games
+ * group, allowing scores to be shared between users (fun in a computer lab or
+ * shared machine) while preventing cheating, since editing the scores file
+ * would require some privilege escalation exploit.
+ *
+ * When Robert started rewriting games in Vala, he changed the scores format so
+ * that all scores for a game would be saved in one file, in the home directory.
+ * Placing the file in the home directory has an important advantage in that you
+ * do not lose your scores if you copy your home directory to another computer.
+ * Of course, this had the one-time cost that scores were lost upon upgrading
+ * to the new Vala version of the game, as there was no score importer. It also
+ * makes importing a bit tricky, because the columns in the scores file are
+ * different for each game.
+ *
+ * Then, for GNOME 3.12, I (Michael) changed all the remaining C games to store
+ * scores in the home directory, without changing the format except for removing
+ * the player name column, since it didn't seem relevant if all scores were in
+ * the home directory. Again, all users' scores were lost in this transition.
+ * Currently, scores use this same format, except the player name column is back
+ * because it turns out people share user accounts and want to record scores
+ * separately.
+ *
+ * This importer exists so that we don't delete everyone's scores a second time.
+ *
+ * Some users have complained that scores are now saved in the home directory.
+ * Using /var/games was a clever setup and it's a bit of a shame to see it go;
+ * bug #749682 exists to restore that old behavior. It has been suggested that
+ * we could hardlink scores files from the home directory to /var/games to get
+ * the best of both worlds. I don't see why not, except some distro folks really
+ * don't like using the setgid bit. Another possibility would be to make this
+ * some configurable option. Few enough people have been complaining that I
+ * don't plan to spend more time on this, though.
+ */
+
+/* Note that all file I/O here is performed synchronously, because the importer
+ * is only used before scores are loaded, and the library ensures scores are
+ * always loaded before showing the main window.
+ */
+
+/* TODO: Support importing scores from Vala games, bug #745489. */
+namespace Importer
+{
+    /* This scores format is mostly-compatible with the current format, the only
+     * differences are (a) the scores file nowadays has a column for the player
+     * name, (b) scores nowadays are kept under ~/.local/share/APPNAME/scores
+     * whereas they used to be saved one level up, and (c) some category names
+     * have changed. All we have to do here is copy the files from the parent
+     * directory to the subdirectory, and rename them according to the new
+     * category names. Context.load_scores_from_file handles the missing player
+     * name column by assuming it matches the current UNIX account if missing.
+     * Notice that we are importing only home directory scores, not any scores
+     * from /var/games, since it's been several years since scores were removed
+     * from there and most players will have lost them by now anyway.
+     *
+     * TODO: Use this for Five or More, Four-in-a-row, Klotski, Robots, and Tali.
+     */
+    private static void importOldScoresFromCGame (File new_scores_dir,
+                                                  Gee.Map<string, string> category_map) throws GLib.Error
+    {
+        var original_scores_dir = new_scores_dir.get_parent ();
+        if (original_scores_dir == null)
+            return;
+
+        foreach (var entry in category_map.entries)
+        {
+            var original_file = original_scores_dir.get_child (entry.key);
+            if (original_file.query_exists ())
+            {
+                var new_file = new_scores_dir.get_child (entry.value);
+                original_file.copy (new_file, FileCopyFlags.NONE);
+                original_file  delete ();
+                debug ("Moved scores from %s to %s", original_file.get_path (), new_file.get_path ());
+            }
+        }
+    }
+
+    private static void run (string new_scores_dir) throws GLib.Error
+    {
+        var new_dir = File.new_for_path (new_scores_dir);
+        if (new_dir.query_exists ())
+            return;
+        new_dir.make_directory ();
+
+        /* TODO: Add API so that the mapping can be done by the games themselves. */
+        if (Environment.get_prgname () == "org.gnome.Nibbles")
+        {
+            var category_map = new Gee.HashMap<string, string> ();
+            category_map  set ("1.0", "beginner");
+            category_map  set ("2.0", "slow");
+            category_map  set ("3.0", "medium");
+            category_map  set ("4.0", "fast");
+            category_map  set ("1.1", "beginner-fakes");
+            category_map  set ("2.1", "slow-fakes");
+            category_map  set ("3.1", "medium-fakes");
+            category_map  set ("4.1", "fast-fakes");
+            importOldScoresFromCGame (new_dir, category_map);
+        }
+    }
+} /* namespace Importer */
+
+} /* namespace Scores */
+} /* namespace Games */