import _ from 'lodash';
import PouchDB from 'pouchdb';
import PouchDBFind from 'pouchdb-find';
import uri from '../lib/ids';
import changeHandler from './change-handler';

PouchDB.plugin(PouchDBFind);

const dbDefinitionId = uri('dbdef', {});

const currentDbDefinition = {
  _id: dbDefinitionId,
  type: dbDefinitionId,
  def: { version: '0.000001' },
};

declare global {
  var db: any;
  var dbReady: boolean;
}

export const initDb = async (params: any) => {
  console.log({ caller: 'initDb' });

  if (globalThis.db === undefined) {
    globalThis.db = new PouchDB('dyomedea', {
      auto_compaction: false,
      revs_limit: 10,
    });
  }
  const db = globalThis.db;
  var previousDbDefinition = {
    _id: dbDefinitionId,
    type: dbDefinitionId,
    def: { version: '0' },
  };
  try {
    previousDbDefinition = await db.get(dbDefinitionId);
  } catch (error: any) {
    if (error.status !== 404) {
      console.log(
        `Unexpected error fetching db definition: ${JSON.stringify(error)}`
      );
      return;
    }
  }

  if (previousDbDefinition.def.version < currentDbDefinition.def.version) {
    previousDbDefinition.def = currentDbDefinition.def;
    db.put(previousDbDefinition);
    // TODO: support migrations
  }
  //await await db.compact();
  await db.viewCleanup();

  // WARNING: defs must use the canonical form and be identical to what will be returned by db.getIndexes
  const requiredIndexes: any = [
    {
      name: 'type',
      def: {
        fields: [{ type: 'desc' }, { id: 'desc' }],
      },
    },
  ];

  const existingIndexes = (await db.getIndexes()).indexes;

  const pruneIndex = ({ name, def }: any) => ({ name, def });

  const isSameIndex = (idx1: any, idx2: any) => {
    return _.isEqual(pruneIndex(idx1), pruneIndex(idx2));
  };

  const findIndex = (targetIndexes: any, index: any) =>
    targetIndexes.find((targetIndex: any) => {
      return isSameIndex(targetIndex, index);
    });

  for (var index of existingIndexes) {
    if (index.type === 'json') {
      // Non system indexes
      //      console.log(`Checking existing index :${JSON.stringify(index)}`);
      if (!findIndex(requiredIndexes, index)) {
        //        console.log(`db.deleteIndex(${JSON.stringify(index)})`);
        await db.deleteIndex(index);
      }
    }
  }

  for (index of requiredIndexes) {
    if (!findIndex(existingIndexes, index)) {
      //      console.log(`db.createIndex(${JSON.stringify(index)})`);
      await db.createIndex({ name: index.name, ...index.def });
    }
  }

  globalThis.dbReady = true;

  console.log({ caller: 'initDb / before db.changes' });

  const changes = db
    .changes({ since: 'now', live: true, include_docs: false })
    .on('change', changeHandler)
    .on('complete', (info: any) => {
      console.log({ caller: 'changes / complete', info });
    })
    .on('error', (error: any) => {
      console.log({ caller: 'changes / complete', error });
    });

  // console.log({ caller: 'initDb / back from db.changes', changes });

  //  changes.cancel();

  /*   const indexes = await db.getIndexes();
  console.log(`indexes: ${JSON.stringify(indexes)}`);

  const explain1 = await db.explain({
    selector: {
      type: 'trkpt',
      gpx: 'xxxx',
    },
    //   sort: ['trkpt.time'],
    // use_index: 'type-trkpt-gpx-time',
  });
  console.log(`explain1: ${JSON.stringify(explain1)}`);
  const explain2 = await db.explain({
    selector: {
      type: 'gpx',
    },
    //   sort: ['trkpt.time'],
    // use_index: 'type-trkpt-gpx-time',
  });
  console.log(`explain2: ${JSON.stringify(explain2)}`);
 */
};