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var AWS = require('aws-sdk');
AWS.config.update({region: "us-west-2"});
var doc = require('dynamodb-doc');
var dynamo = new doc.DynamoDB();
var PodcastView = require('./PodcastView');
var DDB_EPISODES_TABLE = 'podcast-episodes';
exports.handleViewUpdate = function(event, context) {
// Handle dynamo event for the views table.
// Each modified view is added as a key in this Object to dedupe multiple
// updates for the same key.
var viewsToUpdate = {};
event.Records.forEach(function(record) {
var eventName = record.eventName;
var viewKey = record.dynamodb.Keys;
switch (eventName) {
case 'INSERT':
case 'MODIFY':
viewsToUpdate[viewKey] = 'update';
break;
case 'REMOVE':
viewsToUpdate[viewKey] = 'remove';
break;
default:
context.fail(new Error('Unrecognized eventName "' + eventname + '"'));
}
});
var viewIds = Object.keys(viewsToUpdate);
var remainingCount = 0;
var errors = [];
var callback = function(error, data) {
// When all are done, call context callback.
remainingCount--;
if (error != null) {
errors.push(error);
}
if (remainingCount == 0) {
if (errors.length == 0) {
context.succeed();
} else {
context.fail(new Error("Failures updating views"), errors);
}
}
};
// Start each update/remove operation.
viewIds.forEach(function(viewId) {
var operation = viewsToUpdate[viewId];
PodcastView.findById(viewId, function(error, view) {
if (operation == 'update') {
remainingCount++;
view.render(callback);
} else if (operation == 'remove') {
remainingCount++;
view.remove(callback);
}
});
});
};
exports.handleEpisodeUpdate = function(event, context) {
// Handle dynamo event for the episodes table.
// Each modified feed is added as a key in this Object to dedupe multiple
// updates for the same feed.
var feedsToUpdate = {};
event.Records.forEach(function(record) {
var eventName = record.eventName;
switch (eventName) {
case 'INSERT':
feedsToUpdate[record.dynamodb.NewImage.feedId] = true;
break;
case 'MODIFY':
var oldImageFeed = record.dynamodb.OldImage.feedId;
var newImageFeed = record.dynamodb.NewImage.feedId;
if (oldImageFeed != newImageFeed) {
feedsToUpdate[oldImageFeed] = true;
}
feedsToUpdate[newImageFeed] = true;
break;
case 'REMOVE':
feedsToUpdate[record.dynamodb.OldImage.feedId] = true;
break;
default:
context.fail(new Error('Unrecognized eventName "' + eventname + '"'));
}
});
var feedIds = Object.keys(feedsToUpdate);
var remainingCount = 0;
var errors = [];
var callback = function(error, data) {
// When all are done, call context callback.
remainingCount--;
if (error != null) {
errors.push(error);
}
if (remainingCount == 0) {
if (errors.length == 0) {
context.succeed();
} else {
context.fail(new Error("Failures updating feeds"), errors);
}
}
};
// Start updates for each feed.
feedIds.forEach(function(feedId) {
remainingCount++;
renderViewsForFeed(feedId, callback);
});
};
function renderViewsForFeed(feedId, callback) {
getEpisodesForFeed(feedId, function(error, episodes) {
if (error) {
callback(error);
return;
}
console.log("Got episodes " + JSON.stringify(episodes));
var remainingCount = 0;
var errors = [];
var renderCallback = function(error, data) {
// When all are done, call context callback.
remainingCount--;
console.log("Remaining is " + remainingCount);
if (error != null) {
errors.push(error);
}
if (remainingCount == 0) {
if (errors.length == 0) {
callback();
} else {
callback(new Error("Failures rendering feeds"), errors);
}
}
};
// Get all of the views for the feed.
PodcastView.forEachView(feedId, function(error, view, last) {
remainingCount++;
if (error != null) {
renderCallback(error);
} else {
view.render(episodes, renderCallback);
}
});
});
}
function getEpisodesForFeed(feedId, callback, startKey, episodes) {
var params = {
TableName: DDB_EPISODES_TABLE,
ConsistentRead: true,
KeyConditionExpression: "feedId = :feedId",
ExpressionAttributeValues: {
':feedId': feedId
}
};
if (startKey) {
params['ExclusiveStartKey'] = startKey;
}
dynamo.query(params, function(error, data) {
if (error != null) {
callback(error);
return;
}
if (!episodes) {
episodes = data.Items;
} else {
episodes = episodes.concat(data.Items);
}
// If this is not the last set of responses, get more.
var lastKey = data.LastEvaluatedKey;
if (lastKey) {
getEpisodesForFeed(feedId, callback, lastKey, episodes);
} else {
callback(null, episodes);
}
});
}
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