import Handler from '../handlers/Handler.js';
import INode from './INode.js';
import Operator from './types/Operator.js';

/**
 * SqlExpression
 */
class Expression implements INode {
  args: Array<any> = new Array<any>();

  value: string | null | undefined = null;
  operator: Operator | null | undefined = null;
  exps: Array<Expression> = new Array<Expression>();

  constructor(value?: string | null, operator?: Operator, ...expressions: Array<Expression>) {
    this.value = value;
    this.operator = operator;
    this.exps = expressions;
  }

  add(...expressions: Array<Expression>): Expression {
    if (!this.operator || this.operator == Operator.And) {
      this.exps = this.exps.concat(expressions);
      return this;
    } else {
      let exp: Expression = new Expression(null, Operator.And, this);
      expressions.forEach(expr => exp.add(expr));
      return exp;
    }
  }

  // Logical Operators
  and(operand: Expression) {
    return new Expression(null, Operator.And, this, operand);
  }
  or(operand: Expression): Expression {
    return new Expression(null, Operator.Or, this, operand);
  }
  not(): Expression {
    return new Expression(null, Operator.Not, this);
  }

  eval(handler: Handler): string {
    if (this.value) {
      return this.value;
    } else {
      let values = this.exps
        .map(exp => {
          if (exp) {
            let str = exp.eval(handler);
            this.args = this.args.concat(exp.args);
            return str;
          }
        })
        .filter((exp): exp is string => exp != null);

      let val0: string = values[0] ? values[0] : '';
      let val1: string = values[1] ? values[1] : '';

      if (!this.operator) {
        if (this.exps.length == 1) return val0;
        else this.operator = Operator.And;
      }

      let r: string = '';
      switch (this.operator) {
        case Operator.Equal:
          r = handler.eq(val0, val1);
          break;
        case Operator.NotEqual:
          r = handler.neq(val0, val1);
          break;
        case Operator.LessThan:
          r = handler.lt(val0, val1);
          break;
        case Operator.LessThanEqual:
          r = handler.lteq(val0, val1);
          break;
        case Operator.GreaterThan:
          r = handler.gt(val0, val1);
          break;
        case Operator.GreaterThanEqual:
          r = handler.gteq(val0, val1);
          break;
        case Operator.And:
          r = handler.and(values);
          break;
        case Operator.Or:
          r = handler.or(values);
          break;
        case Operator.Not:
          r = handler.not(val0);
          break;
        case Operator.Plus:
          r = handler.plus(val0, val1);
          break;
        case Operator.Minus:
          r = handler.minus(val0, val1);
          break;
        case Operator.Multiply:
          r = handler.multiply(val0, val1);
          break;
        case Operator.Devide:
          r = handler.devide(val0, val1);
          break;
        case Operator.Between:
          r = handler.between(values[0], values[1], values[2]);
          break;
        case Operator.Exists:
          r = handler.exists(val0);
          break;
        case Operator.In:
          r = handler.in(values);
          break;
        case Operator.Like:
          r = handler.like(val0, val1);
          break;
        case Operator.IsNull:
          r = handler.isNull(val0);
          break;
        case Operator.IsNotNull:
          r = handler.isNotNull(val0);
          break;
        case Operator.Asc:
          r = handler.asc(val0);
          break;
        case Operator.Desc:
          r = handler.desc(val0);
          break;
        case Operator.Limit:
          r = handler.limit(val0, val1);
          break;
        case Operator.Count:
          r = handler.count(val0);
          break;
        case Operator.Sum:
          r = handler.sum(val0);
          break;
        case Operator.Min:
          r = handler.min(val0);
          break;
        case Operator.Max:
          r = handler.max(val0);
          break;
        case Operator.Avg:
          r = handler.average(val0);
          break;
        default:
          break;
      }
      return r;
    }
  }
}

export default Expression;