library-ts/browser/date/DateHelper.ts

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

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() );
    
    // console.log( "\n\n>>", expression, ">>>", query.tokens.map( tk => tk.isDoneOrError ?  "" : ( "[" + tk.type + ":" + tk.match + "]" ) ).join( ", " ) );
    let now = query.find( le => le.isMatcher( DateExpressionLexer.Now ) );

    if ( now )
    {
      // console.log( "is 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() + 1;
    let day   = DateHelper.now().getDate();

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

    if ( ! date )
    { 
      let currentDate = DateHelper.createYMD( year, month, day, hours, minutes, seconds );

      if ( DateMath.isInThePast( currentDate ) )
      {
        currentDate = DateMath.addDays( currentDate, 1 );
      }

      return currentDate;
    }

    
    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 ];
      day = values[ 2 ];
    }
    else
    {
      day = values[ 0 ];
      month = values[ 1 ];

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

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

    

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

  } 
}