import { dateToString } from "../../../utils/utils";
import { Injectable } from "@angular/core";
import { DateDatatype } from "../date/date.datatype";
import { EntitySchemaField } from "../../entity/schema/entity-schema-field";

/**
 * Datatype for the EntitySchemaService transforming Date values to/from a date string format ("YYYY-mm-dd").
 *
 * Throws an exception if the property is set to something that is not a Date instance and cannot be cast to Date either.
 * Uses the import value mapping properties of the general DateDatatype.
 *
 * For example:
 * `@DatabaseField({dataType: 'date-only'}) myDate: Date = new Date('2020-01-15'); // will be "2020-01-15" (without time) in the database`
 */
@Injectable()
export class DateOnlyDatatype extends DateDatatype<string> {
  static override dataType = "date-only";
  static override label: string = $localize`:datatype-label:date`;

  override transformToDatabaseFormat(value: Date) {
    if (!(value instanceof Date)) {
      return undefined;
    }
    return dateToString(value);
  }

  override transformToObjectFormat(
    value: any,
    schemaField?: EntitySchemaField,
    parent?: any,
  ): Date {
    if (typeof value !== "string") {
      return undefined;
    }

    value = migrateIsoDatesToInferredDateOnly(value);

    // new Date("2022-01-01") is interpreted as UTC time whereas new Date(2022, 0, 1) is local time
    // -> we want local time to represent the same day wherever used.
    const values = value.split("-").map((v) => Number(v));
    let date: Date = new Date(values[0], values[1] - 1, values[2]);
    if (isNaN(date.getTime())) {
      // fallback to legacy date parsing if format is not "YYYY-mm-dd"
      date = new Date(value);
    }

    // re-use error logging and basic return logic from base type
    return super.transformToObjectFormat(date, schemaField, parent);
  }
}

function migrateIsoDatesToInferredDateOnly(value: string): string {
  if (!value.match(/\d\d\d\d-\d\d-\d\dT\d\d:\d\d:\d\d\.\d\d\dZ/)) {
    // not ISO Date format (2023-01-06T10:03:35.726Z)
    return value;
  }

  const date = new Date(value);
  if (
    date.getMinutes() % 15 === 0 &&
    date.getSeconds() === 0 &&
    date.getMilliseconds() === 0
  ) {
    // this date was originally created without time information
    // -> infer the time zone and adjust its offset
    if (date.getHours() > 12) {
      // adjust because these are showing the previous day due to timezone offset
      date.setDate(date.getDate() + 1);
    }
    return dateToString(date);
  }

  // not a clean offset but a custom date => cannot reliably infer timezone here
  // cut off the time details and use the UTC date
  return value.substring(0, 10);
}