import type { ApiEvent, CalendarEvent, EventStatus } from "@/lib/types";

const STATUSES: readonly EventStatus[] = ["PUBLIC", "PRIVATE", "DRAFT", "DELETED"];

const parseDate = (value: string | null | undefined): Date | null => {
  if (!value) {
    return null;
  }
  const date = new Date(value);
  return Number.isNaN(date.getTime()) ? null : date;
};

/**
 * Turns one row of the API's JSON into a `CalendarEvent`, or null for a row
 * the list should not show.
 *
 * Null covers deleted events - the admin feed returns them, because deleting
 * only appends a version with `status = 'DELETED'` - and anything without a
 * usable start and end, which a deleted row also is (all its other columns are
 * null). The Angular app filtered on status alone and would have rendered such
 * a row as "Invalid Date".
 *
 * A missing status (the anonymous public listing omits it) means PUBLIC, since
 * that listing only returns published events. An unknown one is treated as
 * PRIVATE (and saved back as such) - "not public" is the safe reading; it is
 * never silently promoted to PUBLIC.
 */
export const parseApiEvent = (row: ApiEvent): CalendarEvent | null => {
  const status: EventStatus =
    row.status == null ? "PUBLIC" : STATUSES.includes(row.status as EventStatus) ? (row.status as EventStatus) : "PRIVATE";
  if (status === "DELETED") {
    return null;
  }

  const start = parseDate(row.startDateTime);
  const end = parseDate(row.endDateTime);
  if (!start || !end) {
    return null;
  }

  return {
    eventId: row.eventId,
    calendarId: row.calendarId,
    uuid: row.uuid ?? "",
    name: row.name ?? "",
    description: row.description ?? "",
    start,
    end,
    created: parseDate(row.createdDate),
    lastModified: parseDate(row.lastModifiedDate),
    location: row.location ?? "",
    createdBy: row.createdBy ?? "",
    lastModifiedBy: row.lastModifiedBy ?? "",
    url: row.url ?? "",
    wholeDay: Boolean(row.wholeDay),
    repeatFrequency: row.repeatFrequency ?? "",
    status,
  };
};

export const parseApiEvents = (rows: ApiEvent[]): CalendarEvent[] =>
  rows.map(parseApiEvent).filter((e): e is CalendarEvent => e !== null);