import inherits from 'inherits';
import { EventEmitter } from 'events';
import { each, toArray } from 'lodash'

// Constructor for the builder instance, typically called from
// `knex.builder`, accepting the current `knex` instance,
// and pulling out the `client` and `grammar` from the current
// knex instance.
function SchemaBuilder(client) {
  this.client = client
  this._sequence = []
  this._debug = client.config && client.config.debug
}
inherits(SchemaBuilder, EventEmitter)

// Each of the schema builder methods just add to the
// "_sequence" array for consistency.
each([
  'createTable',
  'createTableIfNotExists',
  'createSchema',
  'createSchemaIfNotExists',
  'dropSchema',
  'dropSchemaIfExists',
  'createExtension',
  'createExtensionIfNotExists',
  'dropExtension',
  'dropExtensionIfExists',
  'table',
  'alterTable',
  'hasTable',
  'hasColumn',
  'dropTable',
  'renameTable',
  'dropTableIfExists',
  'raw'
], function(method) {
  SchemaBuilder.prototype[method] = function() {
    if (method === 'table') method = 'alterTable';
    this._sequence.push({
      method,
      args: toArray(arguments)
    });
    return this;
  }
})

require('../interface')(SchemaBuilder)

SchemaBuilder.prototype.withSchema = function(schemaName) {
  this._schema = schemaName;
  return this;
}

SchemaBuilder.prototype.toString = function() {
  return this.toQuery()
}

SchemaBuilder.prototype.toSQL = function() {
  return this.client.schemaCompiler(this).toSQL()
}

export default SchemaBuilder