library-ts/browser/date/DateHelper.ts

import { DateExpressionLexer } from "../text/lexer/DateExpressionLexer";
import { LexerQuery } from "../text/lexer/LexerQuery";

export class DateHelper
{
  static now()
  {
    let date = new Date();

    return date;
  }

  static nowMS()
  {
    return this.now().getTime();
  }

  static today()
  {
    let date = new Date();
    date.setHours( 0, 0, 0 );

    return date;
  }

  static createYMD( year:number, month:number = 1, day:number = 1, hours:number = 0, minutes:number = 0, seconds:number = 0  )
  {
    let date = new Date();
    
    date.setFullYear( year );
    date.setMonth( month - 1 );
    date.setDate( day );
    date.setHours( hours, minutes, seconds );

    return date;
  }

  static parseDateExpression( expression:string ):Date
  {
    let query = LexerQuery.from( expression, new DateExpressionLexer() );
    
    let now = query.find( le => le.isMatcher( DateExpressionLexer.Now ) );

    if ( now )
    {
      return DateHelper.now();
    }

    let time = query.find( le => le.isMatcher( DateExpressionLexer.Time ) );    
    let hourMinutesSeconds = ( time?.match || "9:00" ).split( ":" ).map( s => parseInt( s ) );

    let hours = hourMinutesSeconds[ 0 ];
    let minutes = hourMinutesSeconds[ 1 ];
    let seconds = hourMinutesSeconds.length == 3 ? hourMinutesSeconds[ 2 ] : 0;
    
    let year  = DateHelper.now().getFullYear();
    let month = DateHelper.now().getMonth();
    let day   = DateHelper.now().getDate();

    let date = query.find( le => /date/i.test( le.type ) );

    if ( date )
    {
      let seperator = /slash/i.test( date.type ) ? "/" : /dot/i.test( date.type ) ? "." : "-"; 
      
      let values = date.match.replace( /(\/|\.|\-)$/, "" ).split( seperator ).map( s => parseInt( s ) );

      if ( /reverse/i.test( date.type ) )
      {
        year = values[ 0 ];
        month = values[ 1 ] - 1;
        day = values[ 2 ];
      }
      else
      {
        day = values[ 0 ];
        month = values[ 1 ] - 1;

        if ( values.length == 3 )
        {
          year = values[ 2 ];

          if ( year < 100 )
          {
            year += 2000;
          }
        }
      }

    }

    return DateHelper.createYMD( year, month, day, hours, minutes, seconds );

  } 
}