PATCH: local-metadata: Check the user's cache for album art

[Michael Wood <michael g wood intel com>]

Check the user's cache for album art

Implements getting album art according to: 
http://live.gnome.org/MediaArtStorageSpec
https://bugzilla.gnome.org/show_bug.cgi?id=665316

>From aca16d62e23d5f8ae06ea4d7b4165c73e7242f84 Mon Sep 17 00:00:00 2001
From: Michael Wood <michael g wood linux intel com>
Date: Thu, 1 Dec 2011 17:53:25 +0000
Subject: [PATCH] local-metadata:  Check the user's cache for album art

Implements getting album art according to:
http://live.gnome.org/MediaArtStorageSpec
---
 src/metadata/local-metadata/grl-local-metadata.c |  203 ++++++++++++++++++++-
 1 files changed, 193 insertions(+), 10 deletions(-)

diff --git a/src/metadata/local-metadata/grl-local-metadata.c b/src/metadata/local-metadata/grl-local-metadata.c
index 9bcea12..2fd73e2 100644
--- a/src/metadata/local-metadata/grl-local-metadata.c
+++ b/src/metadata/local-metadata/grl-local-metadata.c
@@ -572,22 +572,199 @@ resolve_image (GrlMetadataSource *source,
   }
 }
 
+/* Taken from: http://live.gnome.org/MediaArtStorageSpec/SampleStripCodeInC */
+static gboolean
+strip_find_next_block (const gchar    *original,
+                       const gunichar  open_char,
+                       const gunichar  close_char,
+                       gint           *open_pos,
+                       gint           *close_pos)
+{
+  const gchar *p1, *p2;
+
+  if (open_pos) {
+      *open_pos = -1;
+  }
+
+  if (close_pos) {
+      *close_pos = -1;
+  }
+
+  p1 = g_utf8_strchr (original, -1, open_char);
+  if (p1) {
+      if (open_pos) {
+          *open_pos = p1 - original;
+      }
+
+      p2 = g_utf8_strchr (g_utf8_next_char (p1), -1, close_char);
+      if (p2) {
+          if (close_pos) {
+              *close_pos = p2 - original;
+          }
+
+          return TRUE;
+      }
+  }
+
+  return FALSE;
+}
+
+
+/* Taken from: http://live.gnome.org/MediaArtStorageSpec/SampleStripCodeInC
+ * strips out invalid characters in a album name or artist name before md5sum
+ * to get the unique identifier to find the album art.
+ */
+static gchar *
+albumart_strip_invalid_entities (const gchar *original)
+{
+  GString         *str_no_blocks;
+  gchar          **strv;
+  gchar           *str, *res;
+  gboolean         blocks_done = FALSE;
+  const gchar     *p;
+  const gchar     *invalid_chars = "()[]<>{}_!@#$^&*+=|\\/\"'?~";
+  const gchar     *invalid_chars_delimiter = "*";
+  const gchar     *convert_chars = "\t";
+  const gchar     *convert_chars_delimiter = " ";
+  const gunichar   blocks[5][2] = {
+        { '(', ')' },
+        { '{', '}' },
+        { '[', ']' },
+        { '<', '>' },
+        {  0,   0  }
+  };
+
+  str_no_blocks = g_string_new ("");
+
+  p = original;
+
+  while (!blocks_done) {
+      gint pos1, pos2, i;
+
+      pos1 = -1;
+      pos2 = -1;
+
+      for (i = 0; blocks[i][0] != 0; i++) {
+          gint start, end;
+
+          /* Go through blocks, find the earliest block we can */
+          if (strip_find_next_block (p, blocks[i][0], blocks[i][1], &start,
+                                     &end))
+            {
+              if (pos1 == -1 || start < pos1) {
+                  pos1 = start;
+                  pos2 = end;
+              }
+          }
+      }
+
+      /* If either are -1 we didn't find any */
+      if (pos1 == -1) {
+          /* This means no blocks were found */
+          g_string_append (str_no_blocks, p);
+          blocks_done = TRUE;
+      } else {
+          /* Append the test BEFORE the block */
+          if (pos1 > 0) {
+              g_string_append_len (str_no_blocks, p, pos1);
+          }
+
+          p = g_utf8_next_char (p + pos2);
+
+          /* Do same again for position AFTER block */
+          if (*p == '\0') {
+              blocks_done = TRUE;
+          }
+      }
+  }
+
+  str = g_string_free (str_no_blocks, FALSE);
+
+  /* Now strip invalid chars */
+  g_strdelimit (str, invalid_chars, *invalid_chars_delimiter);
+  strv = g_strsplit (str, invalid_chars_delimiter, -1);
+  g_free (str);
+  str = g_strjoinv (NULL, strv);
+  g_strfreev (strv);
+
+  /* Now convert chars */
+  g_strdelimit (str, convert_chars, *convert_chars_delimiter);
+  strv = g_strsplit (str, convert_chars_delimiter, -1);
+  g_free (str);
+  str = g_strjoinv (convert_chars_delimiter, strv);
+  g_strfreev (strv);
+
+  /* Now remove double spaces */
+  strv = g_strsplit (str, "  ", -1);
+  g_free (str);
+  str = g_strjoinv (" ", strv);
+  g_strfreev (strv);
+
+  /* Now strip leading/trailing white space */
+  g_strstrip (str);
+
+  res = g_utf8_strdown (str, -1);
+  g_free (str);
+
+  return res;
+}
+
 static void
 resolve_album_art (GrlMetadataSource *source,
                    GrlMetadataSourceResolveSpec *rs,
                    resolution_flags_t flags)
 {
-  /* FIXME: implement this, according to
-   * http://live.gnome.org/MediaArtStorageSpec
-   *
-   * When this is implemented, _may_resolve() should be modified to accept
-   * GrlMediaAudio.
+  const gchar *artist_value, *album_value;
+  gchar *artist, *album, *artist_md5, *album_md5, *file_path;
+  GRegex *regex;
+
+  artist_value = grl_media_audio_get_artist (GRL_MEDIA_AUDIO (rs->media));
+  album_value = grl_media_audio_get_album (GRL_MEDIA_AUDIO (rs->media));
+
+  if (!artist_value || !album_value)
+    return;
+
+  /* regex to find if we need to strip invalid chars
+   * ()[]<>{}_!@#$^&*+=|\\/\"'?~" and 2 or more spaces
    */
-  GError *error;
-  error = g_error_new (GRL_CORE_ERROR, GRL_CORE_ERROR_RESOLVE_FAILED,
-    "Thumbnail resolution for GrlMediaAudio not implemented in local-metadata");
-  rs->callback (rs->source, rs->resolve_id, rs->media, rs->user_data, error);
-  g_error_free (error);
+
+  regex =
+    g_regex_new ("([\\(\\)\\[\\]\\<\\>\\{\\}_!@#$\\^&\\*"
+                 "\\+=\\|\\\\/\\\"\\'\?~]|\\s{2,})",
+                 0, 0, NULL);
+
+  if ((g_regex_match (regex, artist_value, 0, NULL)))
+    artist = albumart_strip_invalid_entities (artist_value);
+  else
+    artist = g_utf8_strdown (artist_value, -1);
+
+  if (g_regex_match (regex, album_value, 0, NULL))
+    album = albumart_strip_invalid_entities (album_value);
+  else
+    album = g_utf8_strdown (album_value,  -1);
+
+  g_regex_unref (regex);
+
+  artist_md5 = g_compute_checksum_for_string (G_CHECKSUM_MD5, artist, -1);
+  album_md5 = g_compute_checksum_for_string (G_CHECKSUM_MD5, album, -1);
+
+  file_path = g_strdup_printf ("%s/media-art/album-%s-%s.jpeg",
+                               g_get_user_cache_dir (),
+                               artist_md5,
+                               album_md5);
+  g_free (album_md5);
+  g_free (artist_md5);
+
+  if (g_file_test (file_path, G_FILE_TEST_EXISTS))
+    {
+      gchar *thumbnail_uri = g_filename_to_uri (file_path, NULL, NULL);
+      grl_media_set_thumbnail (rs->media, thumbnail_uri);
+      g_free (thumbnail_uri);
+      g_free (file_path);
+
+      rs->callback (rs->source, rs->resolve_id, rs->media, rs->user_data, NULL);
+      return;
+    }
 }
 
 static gboolean
@@ -683,6 +860,12 @@ grl_local_metadata_source_may_resolve (GrlMetadataSource *source,
           return TRUE;
       }
     }
+
+   if (GRL_IS_MEDIA_AUDIO (media)) {
+      if (has_compatible_media_url (media) &&
+          (key_id == GRL_METADATA_KEY_THUMBNAIL))
+        return TRUE;
+   }
   }
 
   if (missing_keys)
-- 
1.7.8.rc0