import _ from 'lodash';

const DBDEFINITION = '--db-definition--';

const dbDefinition = {
  _id: DBDEFINITION,
  type: DBDEFINITION,
  version: '0.000001',
};

export const initDb = async (db: any, setDbReady: any) => {
  try {
    await db.get(DBDEFINITION);
    // TODO: support migrations
  } catch (error: any) {
    if (error.status !== 404) {
      console.log(
        `Unexpected error fetching db definition: ${JSON.stringify(error)}`
      );
      return;
    }
  }

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

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

  setDbReady(true);

  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)}`);
};