import type { Address, Location, Organization } from "fhir/r4";
import { normalizeFhirAddress } from "./fhirAddress";
import { withTimezoneExtension } from "./practiceTimezone";
import { LOCATION_PHYSICAL_TYPE_SYSTEM, SITE_PHYSICAL_TYPE_CODE } from "./roomLocation";
import { isUsStateCode } from "./usStates";

export type SiteLocationDraft = {
  name: string;
  street: string;
  city: string;
  state: string;
  postalCode: string;
  timezone: string;
};

export type SiteLocationField = keyof SiteLocationDraft;

export const EMPTY_SITE_LOCATION: SiteLocationDraft = {
  name: "",
  street: "",
  city: "",
  state: "",
  postalCode: "",
  timezone: "",
};

const US_CORE_LOCATION_PROFILE = "http://hl7.org/fhir/us/core/StructureDefinition/us-core-location";

export const siteLocationAddress = (draft: SiteLocationDraft): Address => ({
  use: "work",
  type: "physical",
  line: [draft.street.trim()],
  city: draft.city.trim(),
  state: draft.state,
  postalCode: draft.postalCode.trim(),
  country: "US",
});

// An existing site at the draft's address, which a primary-location step resumes instead of
// creating a second one.
export const findSameAddress = (draft: SiteLocationDraft, existing: Location[]): Location | undefined => {
  const address = normalizeFhirAddress(siteLocationAddress(draft));
  return existing.find((l) => normalizeFhirAddress(l.address) === address);
};

// Field-specific messages, in form order, so the first one is the field to focus.
export const validateSiteLocation = (
  draft: SiteLocationDraft,
  existing: Location[],
): Partial<Record<SiteLocationField, string>> => {
  const errors: Partial<Record<SiteLocationField, string>> = {};
  if (!draft.name.trim()) errors.name = "Name this location.";
  if (!draft.street.trim()) errors.street = "Enter the street address.";
  if (!draft.city.trim()) errors.city = "Enter the city.";
  if (!isUsStateCode(draft.state)) errors.state = "Choose the state.";
  if (!/^\d{5}(-\d{4})?$/.test(draft.postalCode.trim())) errors.postalCode = "Enter a 5-digit ZIP code.";
  if (!draft.timezone.trim()) errors.timezone = "Choose the time zone.";
  if (!errors.street && !errors.city && !errors.state && !errors.postalCode) {
    const duplicate = findSameAddress(draft, existing);
    if (duplicate) errors.street = `This address already exists for ${duplicate.name || "another location"}.`;
  }
  return errors;
};

export const buildSiteLocation = (draft: SiteLocationDraft, org: Organization): Location => ({
  resourceType: "Location",
  meta: { profile: [US_CORE_LOCATION_PROFILE] },
  status: "active",
  mode: "instance",
  name: draft.name.trim(),
  physicalType: {
    coding: [{ system: LOCATION_PHYSICAL_TYPE_SYSTEM, code: SITE_PHYSICAL_TYPE_CODE, display: "Site" }],
  },
  address: siteLocationAddress(draft),
  managingOrganization: { reference: `Organization/${org.id}`, display: org.name },
  extension: withTimezoneExtension(undefined, draft.timezone),
});