// SQLite3
// -------
import Promise from 'bluebird';

import inherits from 'inherits';
import { isUndefined, map, assign } from 'lodash'

import Client from '../../client';
import * as helpers from '../../helpers';

import QueryCompiler from './query/compiler';
import SchemaCompiler from './schema/compiler';
import ColumnCompiler from './schema/columncompiler';
import TableCompiler from './schema/tablecompiler';
import SQLite3_DDL from './schema/ddl';

function Client_SQLite3(config) {
  Client.call(this, config)
  if (isUndefined(config.useNullAsDefault)) {
    helpers.warn(
      'sqlite does not support inserting default values. Set the ' +
      '`useNullAsDefault` flag to hide this warning. ' +
      '(see docs http://knexjs.org/#Builder-insert).'
    );
  }
}
inherits(Client_SQLite3, Client)

assign(Client_SQLite3.prototype, {

  dialect: 'sqlite3',

  driverName: 'sqlite3',

  _driver() {
    return require('sqlite3')
  },

  SchemaCompiler,

  QueryCompiler,

  ColumnCompiler,

  TableCompiler,

  ddl(compiler, pragma, connection) {
    return new SQLite3_DDL(this, compiler, pragma, connection)
  },

  // Get a raw connection from the database, returning a promise with the connection object.
  acquireRawConnection() {
    const client = this;
    return new Promise(function(resolve, reject) {
      const db = new client.driver.Database(client.connectionSettings.filename, function(err) {
        if (err) return reject(err)
        resolve(db)
      })
    })
  },

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

  // Runs the query on the specified connection, providing the bindings and any
  // other necessary prep work.
  _query(connection, obj) {
    const { method } = obj;
    let callMethod;
    switch (method) {
      case 'insert':
      case 'update':
      case 'counter':
      case 'del':
        callMethod = 'run';
        break;
      default:
        callMethod = 'all';
    }
    return new Promise(function(resolver, rejecter) {
      if (!connection || !connection[callMethod]) {
        return rejecter(new Error(`Error calling ${callMethod} on connection.`))
      }
      connection[callMethod](obj.sql, obj.bindings, function(err, response) {
        if (err) return rejecter(err)
        obj.response = response;

        // We need the context here, as it contains
        // the "this.lastID" or "this.changes"
        obj.context = this;
        return resolver(obj)
      })
    })
  },

  _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 => obj.response).map(function(row) {
        stream.write(row)
      }).catch(function(err) {
        stream.emit('error', err)
      }).then(function() {
        stream.end()
      })
    })
  },

  // Ensures the response is returned in the same format as other clients.
  processResponse(obj, runner) {
    const ctx = obj.context;
    let { response } = obj;
    if (obj.output) return obj.output.call(runner, response)
    switch (obj.method) {
      case 'select':
      case 'pluck':
      case 'first':
        response = helpers.skim(response)
        if (obj.method === 'pluck') response = map(response, obj.pluck)
        return obj.method === 'first' ? response[0] : response;
      case 'insert':
        return [ctx.lastID];
      case 'del':
      case 'update':
      case 'counter':
        return ctx.changes;
      default:
        return response;
    }
  },

  poolDefaults(config) {
    return assign(Client.prototype.poolDefaults.call(this, config), {
      min: 1,
      max: 1
    })
  },

  ping(resource, callback) {
    resource.each('SELECT 1', callback);
  }

})

export default Client_SQLite3