Moving episode handling to PodcastEpisode.HEADmaster

1 files changed, 107 insertions, 0 deletions

diff --git a/lib/PodcastEpisode.js b/lib/PodcastEpisode.js
new file mode 100644
index 0000000..ebe7b26
--- /dev/null
+++ b/lib/PodcastEpisode.js
@@ -0,0 +1,107 @@
+var doc = require('dynamodb-doc');
+var dynamo = new doc.DynamoDB();
+
+var DDB_EPISODES_TABLE = 'podcast-episodes';
+
+/**
+ * PodcastEpisode represents a single podcast episode.
+ *
+ * @param {Object} episode - properties to set on the episode.
+ * @constructor
+ */
+var PodcastEpisode = module.exports = function PodcastEpisode(episode) {
+  for (var property in episode) {
+    if (episode.hasOwnProperty(property)) {
+      this[property] = episode[property];
+    }
+  }
+};
+
+/**
+ * Find an episode in DynamoDB by Id.
+ *
+ * @param {Object} id - The episode id.
+ * @param {Function} - Callback to call with an error or episode.
+ */
+PodcastEpisode.findById = function(id, callback) {
+  var params = {
+    TableName: DDB_EPISODES_TABLE,
+    Key: id
+  };
+
+  dynamo.getItem(params, function(error, data) {
+    if (error) {
+      callback(error);
+      return;
+    }
+
+    var episode = new PodcastEpisode(data.Item);
+    callback(null, episode);
+  });
+}
+
+/**
+ * Find all episodes for a given feed.
+ *
+ * @param {Object} feedId - The feed id.
+ * @param {Function} - Callback with signature function(error, episode, last)
+ */
+PodcastEpisode.forEachEpisode = function(feedId, callback) {
+  forEachEpisode(feedId, callback);
+};
+
+function forEachEpisode(feedId, callback, startKey) {
+  var params = {
+    TableName: DDB_EPISODES_TABLE,
+    KeyConditionExpression: "feedId = :feedId",
+    ExpressionAttributeValues: {
+      ':feedId': feedId
+    }
+  };
+
+  if (startKey) {
+    params['ExclusiveStartKey'] = startKey;
+  }
+
+  dynamo.query(params, function(error, data) {
+    if (error != null) {
+      callback(error);
+      return;
+    }
+
+    var lastResponse = !data.LastEvaluatedKey;
+
+    data.Items.forEach(function(episodeData, index, array) {
+      var episode = new PodcastEpisode(episodeData);
+      var last = lastResponse && index == (array.length - 1);
+      callback(null, episode, last);
+    });
+
+    // If this is not the last set of responses, get more.
+    if (!lastResponse) {
+      forEachEpisode(feedId, callback, data.LastEvaluatedKey);
+    }
+  });
+}
+
+/**
+ * Find all episodes for a given feed and return them as a collection.
+ *
+ * @param {Object} feedId - The feed id.
+ * @param {Function} - Callback with signature function(error, episodes)
+ */
+PodcastEpisode.getEpisodesForFeed = function(feedId, callback) {
+  var episodes = [];
+  PodcastEpisode.forEachEpisode(feedId, function(error, episode, last) {
+    if (error) {
+      callback(error);
+      return;
+    }
+
+    episodes.append(episode);
+
+    if (last) {
+      callbacK(null, episodes);
+    }
+  });
+};