lib/replicate/genReplicationId.js

'use strict';

var md5 = require('../deps/md5');

// TODO: check CouchDB's replication id generation
// Generate a unique id particular to this replication
function genReplicationId(src, target, opts) {
  var filterFun = opts.filter ? opts.filter.toString() : '';
  return src.id().then(function (src_id) {
    return target.id().then(function (target_id) {
      var queryData = src_id + target_id + filterFun +
        JSON.stringify(opts.query_params) + opts.doc_ids;
      return md5(queryData).then(function (md5sum) {
        // can't use straight-up md5 alphabet, because
        // the char '/' is interpreted as being for attachments,
        // and + is also not url-safe
        md5sum = md5sum.replace(/\//g, '.').replace(/\+/g, '_');
        return '_local/' + md5sum;
      });
    });
  });
}

module.exports = genReplicationId;