// MySQL Column Compiler
// -------
import inherits from 'inherits';
import ColumnCompiler from '../../../schema/columncompiler';

import { assign } from 'lodash'

function supportsPreciseTimestamps(client) {
  if (!client.version) {
    const message = 'To get rid of this warning you should specify the mysql dialect version in ' +
                    'your knex configuration. Currently this defaults to 5.5, but in a future ' +
                    'release it will default to 5.6 which supports high precision timestamps. ' +
                    'See http://knexjs.org/#Schema-timestamps for more information.'
    client.logger.warn(message)
  }

  return client.version && parseFloat(client.version) > 5.5
}

function ColumnCompiler_MySQL() {
  ColumnCompiler.apply(this, arguments);
  this.modifiers = ['unsigned', 'nullable', 'defaultTo', 'comment', 'collate', 'first', 'after']
}
inherits(ColumnCompiler_MySQL, ColumnCompiler);

// Types
// ------

assign(ColumnCompiler_MySQL.prototype, {

  increments: 'int unsigned not null auto_increment primary key',

  bigincrements: 'bigint unsigned not null auto_increment primary key',

  bigint: 'bigint',

  double(precision, scale) {
    if (!precision) return 'double'
    return `double(${this._num(precision, 8)}, ${this._num(scale, 2)})`
  },

  integer(length) {
    length = length ? `(${this._num(length, 11)})` : ''
    return `int${length}`
  },

  mediumint: 'mediumint',

  smallint: 'smallint',

  tinyint(length) {
    length = length ? `(${this._num(length, 1)})` : ''
    return `tinyint${length}`
  },

  text(column) {
    switch (column) {
      case 'medium':
      case 'mediumtext':
        return 'mediumtext';
      case 'long':
      case 'longtext':
        return 'longtext'
      default:
        return 'text';
    }
  },

  mediumtext() {
    return this.text('medium')
  },

  longtext() {
    return this.text('long')
  },

  enu(allowed) {
    return `enum('${allowed.join("', '")}')`
  },

  datetime() {
    return supportsPreciseTimestamps(this.client) ? 'datetime(6)' : 'datetime'
  },

  timestamp() {
    return supportsPreciseTimestamps(this.client) ? 'timestamp(6)' : 'timestamp'
  },

  bit(length) {
    return length ? `bit(${this._num(length)})` : 'bit'
  },

  binary(length) {
    return length ? `varbinary(${this._num(length)})` : 'blob'
  },

  json() {
    return 'json';
  },

  // Modifiers
  // ------

  defaultTo(value) {
    const defaultVal = ColumnCompiler_MySQL.super_.prototype.defaultTo.apply(this, arguments);
    if (this.type !== 'blob' && this.type.indexOf('text') === -1) {
      return defaultVal
    }
    return ''
  },

  unsigned() {
    return 'unsigned'
  },

  comment(comment) {
    if (comment && comment.length > 255) {
      this.client.logger.warn('Your comment is longer than the max comment length for MySQL')
    }
    return comment && `comment '${comment}'`
  },

  first() {
    return 'first'
  },

  after(column) {
    return `after ${this.formatter.wrap(column)}`
  },

  collate(collation) {
    return collation && `collate '${collation}'`
  }

})

export default ColumnCompiler_MySQL;