export const ticketPattern = /^Ticket#\d{6}$/;
export const trackableTicketPattern = /^(Ticket#\d{6}|Fix#\d+)$/;
export const monthPattern = /^\d{4}-\d{2}$/;
export const dayPattern = /^\d{4}-\d{2}-\d{2}$/;
export const usernamePattern = /^\S{3,40}$/u;

export function requireString(value: unknown, field: string) {
  if (typeof value !== "string" || value.trim().length === 0) {
    throw badRequest(`${field} is required`);
  }

  return value.trim();
}

export function parseTicketNumber(value: unknown) {
  const ticketNumber = requireString(value, "ticketNumber");

  if (!ticketPattern.test(ticketNumber)) {
    throw badRequest("ticketNumber must match Ticket#XXXXXX");
  }

  return ticketNumber;
}

export function parseTrackableTicketNumber(value: unknown) {
  const ticketNumber = requireString(value, "ticketNumber");

  if (!trackableTicketPattern.test(ticketNumber)) {
    throw badRequest("ticketNumber must match Ticket#XXXXXX or Fix#ID");
  }

  return ticketNumber;
}

export function parseUsername(value: unknown) {
  const username = requireString(value, "username");

  if (!usernamePattern.test(username)) {
    throw badRequest("username must be 3-40 characters without spaces");
  }

  return username;
}

export function parseMonth(value: string) {
  if (!monthPattern.test(value)) {
    throw badRequest("month must use YYYY-MM");
  }

  const monthStart = `${value}-01`;
  const date = new Date(`${monthStart}T00:00:00.000Z`);

  if (Number.isNaN(date.getTime()) || date.getUTCMonth() + 1 !== Number(value.slice(5, 7))) {
    throw badRequest("month is invalid");
  }

  const next = new Date(date);
  next.setUTCMonth(next.getUTCMonth() + 1);

  return {
    label: value,
    start: monthStart,
    startIso: date.toISOString(),
    endIso: next.toISOString()
  };
}

export function parseDay(value: string) {
  if (!dayPattern.test(value)) {
    throw badRequest("day must use YYYY-MM-DD");
  }

  const date = new Date(`${value}T00:00:00.000Z`);

  if (Number.isNaN(date.getTime()) || date.toISOString().slice(0, 10) !== value) {
    throw badRequest("day is invalid");
  }

  const next = new Date(date);
  next.setUTCDate(next.getUTCDate() + 1);

  return {
    label: value,
    start: value,
    startIso: date.toISOString(),
    endIso: next.toISOString()
  };
}

export function parsePositiveInteger(value: unknown, field: string) {
  const number = Number(value);

  if (!Number.isInteger(number) || number < 0) {
    throw badRequest(`${field} must be a positive integer`);
  }

  return number;
}

export function parseWorkType(value: unknown) {
  if (value !== "support" && value !== "consulting") {
    throw badRequest("workType must be support or consulting");
  }

  return value;
}

export function parseBillingStatus(value: unknown) {
  if (value === null) {
    return null;
  }

  if (value !== "billable" && value !== "billed" && value !== "non_billable") {
    throw badRequest("billingStatus must be billable, billed, non_billable or null");
  }

  return value;
}

export function parseIsoDate(value: unknown, field: string) {
  const raw = requireString(value, field);
  const date = new Date(raw);

  if (Number.isNaN(date.getTime())) {
    throw badRequest(`${field} must be an ISO date`);
  }

  return date;
}

export function badRequest(message: string) {
  const error = new Error(message) as Error & { status?: number };
  error.status = 400;
  return error;
}