/* eslint-disable no-undef, no-var, vars-on-top, no-restricted-globals, regex/invalid, import/extensions */
// ignore lint error because this file is js as mongoshell

/**
 * @typedef {import('./types').MigrationModule} MigrationModule
 * @typedef {import('./types').ReplaceLatestRevisions} ReplaceLatestRevisions
 */

var pagesCollection = db.getCollection('pages');
var revisionsCollection = db.getCollection('revisions');

var batchSize = process.env.BATCH_SIZE ?? 100; // default 100 revisions in 1 bulkwrite
var batchSizeInterval = process.env.BATCH_INTERVAL ?? 3000; // default 3 sec

var migrationModule = process.env.MIGRATION_MODULE;

/** @type {MigrationModule[]} */
var migrationModules = require(`./migrations/${migrationModule}`);

if (migrationModules.length === 0) {
  throw Error('No valid migrationModules found. Please enter a valid environment variable');
}

/** @type {ReplaceLatestRevisions} */
function replaceLatestRevisions(body, migrationModules) {
  var replacedBody = body;
  migrationModules.forEach((migrationModule) => {
    replacedBody = migrationModule(replacedBody);
  });
  return replacedBody;
}

var operations = [];
pagesCollection.find({}).forEach((doc) => {
  if (doc.revision) {
    var revision = revisionsCollection.findOne({ _id: doc.revision });
    var replacedBody = replaceLatestRevisions(revision.body, [...migrationModules]);
    var operation = {
      updateOne: {
        filter: { _id: revision._id },
        update: {
          $set: { body: replacedBody },
        },
      },
    };
    operations.push(operation);

    // bulkWrite per 100 revisions
    if (operations.length > (batchSize - 1)) {
      revisionsCollection.bulkWrite(operations);
      // sleep time can be set from env var
      sleep(batchSizeInterval);
      operations = [];
    }
  }
});
revisionsCollection.bulkWrite(operations);

print('migration complete!');