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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 ${"? ".repeat(len)}`, [      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;  }
  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 "";    }  }}