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import { assert, replaceParams } from './deps.ts';import { Order } from './order.ts';import { Where } from './where.ts';import { Join } from './join.ts';
export class Query {  private _type?: 'select' | 'insert' | 'update' | 'delete';  private _table?: string;  private _where: string[] = [];  private _joins: string[] = [];  private _orders: Order[] = [];  private _fields: string[] = [];  private _groupBy: string[] = [];  private _having: string[] = [];  private _insertValues: any[] = [];  private _updateValue?: any;  private _limit?: { start: number; size: number };
  private get orderSQL() {    if (this._orders && this._orders.length) {      return `ORDER BY ` + this._orders.map((order) => order.value).join(', ');    }  }
  private get whereSQL() {    if (this._where && this._where.length) {      return `WHERE ` + this._where.join(' AND ');    }  }
  private get havingSQL() {    if (this._having && this._having.length) {      return `HAVING ` + this._having.join(' AND ');    }  }
  private get joinSQL() {    if (this._joins && this._joins.length) {      return this._joins.join(' ');    }  }
  private get groupSQL() {    if (this._groupBy && this._groupBy.length) {      return (        'GROUP BY ' +        this._groupBy.map((f) => replaceParams('??', [f])).join(', ')      );    }  }  private get limitSQL() {    if (this._limit) {      return `LIMIT ${this._limit.start}, ${this._limit.size}`;    }  }
  private get selectSQL() {    return [      'SELECT',      this._fields.join(', '),      'FROM',      replaceParams('??', [this._table]),      this.joinSQL,      this.whereSQL,      this.groupSQL,      this.havingSQL,      this.orderSQL,      this.limitSQL,    ]      .filter((str) => str)      .join(' ');  }
  private get insertSQL() {    const len = this._insertValues.length;    const fields = Object.keys(this._insertValues[0]);    const values = this._insertValues.map((row) => {      return fields.map((key) => row[key]!);    });    return replaceParams(      `INSERT INTO ?? ?? VALUES ${values.map((v) => `?`).join(', ')}`,      [this._table, fields, ...values]    );  }
  private get updateSQL() {    assert(!!this._updateValue);    const set = Object.keys(this._updateValue)      .map((key) => {        return replaceParams(`?? = ?`, [key, this._updateValue[key]]);      })      .join(', ');    return [      replaceParams(`UPDATE ?? SET ${set}`, [this._table]),      this.whereSQL,    ].join(' ');  }
  private get deleteSQL() {    return [replaceParams(`DELETE FROM ??`, [this._table]), this.whereSQL].join(      ' '    );  }
  table(name: string) {    this._table = name;    return this;  }
  order(...orders: Order[]) {    this._orders = this._orders.concat(orders);    return this;  }
  groupBy(...fields: string[]) {    this._groupBy = fields;    return this;  }
  where(where: Where | string) {    if (typeof where === 'string') {      this._where.push(where);    } else {      this._where.push(where.value);    }    return this;  }
  having(where: Where | string) {    if (typeof where === 'string') {      this._having.push(where);    } else {      this._having.push(where.value);    }    return this;  }
  limit(start: number, size: number) {    this._limit = { start, size };    return this;  }
  join(join: Join | string) {    if (typeof join === 'string') {      this._joins.push(join);    } else {      this._joins.push(join.value);    }    return this;  }
  select(...fields: string[]) {    this._type = 'select';    assert(fields.length > 0);    this._fields = this._fields.concat(      fields.map((field) => {        if (field.toLocaleLowerCase().indexOf(' as ') > -1) {          return field;        } else if (field.split('.').length > 1) {          return replaceParams('??.??', field.split('.'));        } else {          return replaceParams('??', [field]);        }      })    );    return this;  }
  insert(data: Object[] | Object) {    this._type = 'insert';    if (!(data instanceof Array)) {      data = [data];    }    this._insertValues = data as [];    return this;  }
  update(data: Object) {    this._type = 'update';    this._updateValue = data;    return this;  }
  delete(table?: string) {    if (table) this._table = table;    this._type = 'delete';    return this;  }
  clone() {    const newQuery = new Query();    newQuery._type = this._type;    newQuery._table = this._table;    newQuery._where = this._where;    newQuery._joins = this._joins;    newQuery._orders = this._orders;    newQuery._fields = this._fields;    newQuery._groupBy = this._groupBy;    newQuery._having = this._having;    newQuery._insertValues = this._insertValues;    newQuery._updateValue = this._updateValue;    newQuery._limit = this._limit;    return newQuery;  }
  build(): string {    assert(!!this._table);    switch (this._type) {      case 'select':        return this.selectSQL;      case 'insert':        return this.insertSQL;      case 'update':        return this.updateSQL;      case 'delete':        return this.deleteSQL;      default:        return '';    }  }}