remix.js

server.method('projects.remix', function(userId, dataToRemix, done) {
  var remixedProject;
  var remixedPages;
  var remixedElements;
  var transaction;
  var transactionErr;

  getTransactionClient().then(function(t) {
    transaction = t;
    return begin(transaction);
  }).then(function() {
    return executeTransaction(transaction, queries.projects.create,
      [
        userId,
        dataToRemix.id,
        server.methods.utils.version(),
        dataToRemix.title,
        dataToRemix.thumbnail
      ]
    );
  }).then(function(result) {
    remixedProject = result.rows[0];
    return Promise.resolve(dataToRemix.pages.map(function(page) {
      return new Promise(function(resolve, reject) {
        var remixPage;
        executeTransaction(transaction, queries.pages.create,
          [
            remixedProject.id,
            page.x,
            page.y,
            page.styles
          ]
        ).then(function(result) {
          remixPage = result.rows[0];
          return Promise.resolve(page.elements.map(function(element) {
            element.attributes.targetProjectId = remixedProject.id;
            element.attributes.targetUserId = userId;
            return executeTransaction(transaction, queries.elements.create,
              [
                remixPage.id,
                element.type,
                element.attributes,
                element.styles
              ]
            );
          }));
        }).then(function(elementPromises) {
          return Promise.all(elementPromises);
        }).then(function(newElements) {
          remixedElements = newElements;
          resolve();
        })
        .catch(reject);
      });
    }));
  }).then(function(pagePromises) {
    return Promise.all(pagePromises);
  }).then(function(newPages) {
    remixedPages = newPages;
    var remixLinks = remixedElements.filter(function(elem) {
      return elem.type === 'link';
    });
    return Promise.resolve(remixLinks.map(function(link) {
      var targetX;
      var targetY;
      var foundTargetPage = dataToRemix.pages.some(function(page) {
        if ( page.id === link.attributes.targetPageId ) {
          targetX = page.x;
          targetY = page.y;
          return true;
        }
        return false;
      });

      if ( !foundTargetPage ) {
        // Link was already broken (i.e. page was deleted and target link was never updated by creator)
        return Promise.resolve();
      }

      remixedPages.some(function(page) {
        if ( page.x === targetX && page.y === targetY ) {
          link.targetPageId = page.id;
          return true;
        }
        return false;
      });

      return executeTransaction(transaction, queries.elements.update,
        [
          link.styles,
          link.attributes,
          link.id
        ]
      );
    }));
  }).then(function(linkPromises) {
    return Promise.all(linkPromises);
  }).then(function() {
    return commit(transaction);
  })
  .then(function() {
    done(null, remixedProject);
  }).catch(function(err) {
    transactionErr = err;
    return rollback(transaction);
  }).then(function() {
    done(transactionErr);
  }).catch(function(err) {
    done(err);
  });
});