import { Injectable } from '@angular/core';
import { DatePipe } from '@angular/common';
import { Observable ,  Observer } from 'rxjs';
import { ITypeaheadItem } from '../models/typeahead.item';

@Injectable({
  providedIn: 'root',
})
export class TimespanService {
  constructor(private datePipe: DatePipe) {
  }
  unitScales: number[] = [1, 1000, 1000 * 60, 1000 * 60 * 60, 1000 * 60 * 60 * 24, 1000 * 60 * 60 * 24 * 7, 1000 * 60 * 60 * 24 * 31, 1000 * 60 * 60 * 24 * 31 * 3, 1000 * 60 * 60 * 24 * 365.25];
  units: string[] = ['millisecond', 'second', 'minute', 'hour', 'day', 'week', 'month', 'quarter', 'year'];
  quarters: string[] = ['KW1', 'KW2', 'KW3', 'KW4'];

  getStartEndCaption(date: Date, otherDate: Date, unitScale: number, suffix = false, extended = true): string {
    const showSuffix = false;
    otherDate = new Date(otherDate.getTime() - 1); // fix year edge case
    if (unitScale == 3) {
      let format = "HH:00";
      if (extended) {
        if (suffix || date.getFullYear() != otherDate.getFullYear())
          format = "d MMM yyyy:HH:00";
        else if (date.getMonth() !== otherDate.getMonth())
          format = "d MMM HH:00";
      }
      return this.datePipe.transform(date, format);

    }
    if (unitScale == 4) {
      let format = "d";
      if (extended) {
        if (suffix || date.getFullYear() != otherDate.getFullYear())
          format = "d MMM yyyy";
        else if (date.getMonth() !== otherDate.getMonth())
          format = "d MMM"
      }
      return this.datePipe.transform(date, format);

    }
    if (unitScale == 6) {
      let format = "MMM";
      if (extended) {
        if (suffix || date.getFullYear() != otherDate.getFullYear())
          format = "MMM yyyy";
      }
      return this.datePipe.transform(date, format);
    }
    if (unitScale == 7) {
      const q = Math.trunc(date.getMonth() / 3);
      return this.quarters[q];
    }
    if (unitScale == 8) {
      return this.datePipe.transform(date, "yyyy");
    }
    return "";
  }

  getStartCaption(startDate: Date, endDate: Date, unitScale: number, suffix = false, extended = true): string {
    return this.getStartEndCaption(new Date(startDate.getTime() + (this.unitScales[unitScale] / 2)), endDate, unitScale, suffix, extended);
  }

  getEndCaption(startDate: Date,endDate: Date, unitScale: number, suffix = true): string {
    return this.getStartEndCaption(new Date(endDate.getTime() - (this.unitScales[unitScale] / 2)), startDate, unitScale, suffix);
  }

  getCaption(startDate: Date, endDate: Date, unitScale?: number): string {
    let scale = unitScale;
    if(unitScale==null) {
        scale=4;
        if(startDate.getUTCMonth() == 0 && startDate.getUTCDate() == 1 && startDate.getUTCHours() == 0 && startDate.getUTCMinutes() ==0 && startDate.getUTCSeconds() ==0 &&
           endDate.getUTCMonth() == 0 && endDate.getUTCDate() == 1 && endDate.getUTCHours() == 0 && endDate.getUTCMinutes() ==0 && endDate.getUTCSeconds() ==0) {
           scale=8;
        } else if (startDate.getUTCHours() > 0 && startDate.getUTCMinutes() >0) {
          scale =3
        }
    }
    const startCaption = this.getStartCaption(startDate, endDate, scale);
    const endCaption = this.getEndCaption(startDate,endDate, scale);
    if ((endDate.getTime() - startDate.getTime()) < (1.5 * this.unitScales[scale]))
      return endCaption;
    return `${startCaption}-${endCaption}`;
  }  
}