/* globals openDatabase:false */

// WebSQL
// -------
import inherits from 'inherits';

import Transaction from './transaction';
import Client_SQLite3 from '../sqlite3';
import Promise from 'bluebird';
import { assign, map, uniqueId, clone } from 'lodash'

function Client_WebSQL(config) {
  Client_SQLite3.call(this, config);
  this.name = config.name || 'knex_database';
  this.version = config.version || '1.0';
  this.displayName = config.displayName || this.name;
  this.estimatedSize = config.estimatedSize || 5 * 1024 * 1024;
}
inherits(Client_WebSQL, Client_SQLite3);

assign(Client_WebSQL.prototype, {

  transaction() {
    return new Transaction(this, ...arguments)
  },

  dialect: 'websql',

  // Get a raw connection from the database, returning a promise with the connection object.
  acquireConnection() {
    return new Promise((resolve, reject) => {
      try {
        /*jslint browser: true*/
        const db = openDatabase(
          this.name, this.version, this.displayName, this.estimatedSize
        );
        db.transaction(function(t) {
          t.__knexUid = uniqueId('__knexUid');
          resolve(t);
        });
      } catch (e) {
        reject(e);
      }
    });
  },

  // Used to explicitly close a connection, called internally by the pool
  // when a connection times out or the pool is shutdown.
  releaseConnection() {
    return Promise.resolve()
  },

  // Runs the query on the specified connection,
  // providing the bindings and any other necessary prep work.
  _query(connection, obj) {
    return new Promise((resolver, rejecter) => {
      if (!connection) return rejecter(new Error('No connection provided.'));
      connection.executeSql(obj.sql, obj.bindings, (trx, response) => {
        obj.response = response;
        return resolver(obj);
      }, (trx, err) => {
        rejecter(err);
      });
    });
  },

  _stream(connection, sql, stream) {
    const client = this;
    return new Promise(function(resolver, rejecter) {
      stream.on('error', rejecter)
      stream.on('end', resolver)
      return client._query(connection, sql).then(obj =>
        client.processResponse(obj)
      ).map(row => {
        stream.write(row)
      }).catch(err => {
        stream.emit('error', err)
      }).then(() => {
        stream.end()
      })
    })
  },

  processResponse(obj, runner) {
    const resp = obj.response;
    if (obj.output) return obj.output.call(runner, resp);
    switch (obj.method) {
      case 'pluck':
      case 'first':
      case 'select': {
        let results = [];
        for (let i = 0, l = resp.rows.length; i < l; i++) {
          results[i] = clone(resp.rows.item(i));
        }
        if (obj.method === 'pluck') results = map(results, obj.pluck);
        return obj.method === 'first' ? results[0] : results;
      }
      case 'insert':
        return [resp.insertId];
      case 'delete':
      case 'update':
      case 'counter':
        return resp.rowsAffected;
      default:
        return resp;
    }
  }

})

export default Client_WebSQL;