import type { Extension, Organization } from "fhir/r4";
import {
  ORGANIZATION_BOOKING_MODE_EXTENSION_URL,
  ORGANIZATION_DEFAULT_APPOINTMENT_DURATION_EXTENSION_URL,
  ORGANIZATION_REQUEST_STYLE_EXTENSION_URL,
  ORGANIZATION_REQUIRE_NEW_PATIENT_EXAM_FIRST_EXTENSION_URL,
  RETIRED_ORGANIZATION_NEW_PATIENT_EXAM_ROLES_EXTENSION_URL,
  getOrganizationPolicyFlags,
  type OrganizationBookingMode,
  type OrganizationRequestStyle,
} from "../config/bookingPolicy";
import { resolveOrgAppointmentPolicy } from "../config/appointmentPolicy";
import { resolveOrgReminderPolicy, type QuietHours, type ReminderPolicy } from "../config/appointmentReminderPolicy";

// Everything the Booking rules panel edits, from its three homes: the organization's booking
// extensions, the appointment-policy route and the reminder route.
export type BookingRulesDraft = {
  telehealthEnabled: boolean;
  bookingMode: OrganizationBookingMode;
  requestStyle: OrganizationRequestStyle;
  requireNewPatientFirst: boolean;
  defaultDurationMinutes: number;
  reminderOffsets: number[];
  maxReminders: number;
  quietHours: QuietHours | null;
};

export type BookingRulesPart = "booking" | "policy" | "reminders";

export const readBookingRules = (org: Organization | null | undefined): BookingRulesDraft => {
  const flags = getOrganizationPolicyFlags(org ?? undefined);
  const reminders = resolveOrgReminderPolicy(org);
  return {
    telehealthEnabled: resolveOrgAppointmentPolicy(org ?? undefined).telehealthEnabled,
    bookingMode: flags.bookingMode,
    requestStyle: flags.requestStyle,
    requireNewPatientFirst: flags.requireNewPatientExamFirst,
    defaultDurationMinutes: flags.defaultAppointmentDurationMinutes,
    // Reminders are on exactly when a time is ticked, so switched-off reminders show none ticked.
    reminderOffsets: reminders.enabled ? [...reminders.offsetsMinutes].sort((a, b) => a - b) : [],
    maxReminders: reminders.maxPerAppointment,
    quietHours: reminders.quietHours,
  };
};

const same = (a: unknown, b: unknown) => JSON.stringify(a) === JSON.stringify(b);

// The parts whose values differ from what is saved, in the order they are written.
export const changedParts = (draft: BookingRulesDraft, saved: BookingRulesDraft): BookingRulesPart[] => {
  const parts: BookingRulesPart[] = [];
  if (
    draft.bookingMode !== saved.bookingMode ||
    draft.requestStyle !== saved.requestStyle ||
    draft.requireNewPatientFirst !== saved.requireNewPatientFirst ||
    draft.defaultDurationMinutes !== saved.defaultDurationMinutes
  ) parts.push("booking");
  if (draft.telehealthEnabled !== saved.telehealthEnabled) parts.push("policy");
  if (
    !same(draft.reminderOffsets, saved.reminderOffsets) ||
    draft.maxReminders !== saved.maxReminders ||
    !same(draft.quietHours, saved.quietHours)
  ) parts.push("reminders");
  return parts;
};

export const bookingRulesProblem = (draft: BookingRulesDraft): string | undefined => {
  if (!Number.isInteger(draft.defaultDurationMinutes) || draft.defaultDurationMinutes <= 0) {
    return "Enter a default appointment length in minutes.";
  }
  return undefined;
};

// The organization with its booking extensions replaced by the draft's; everything else is kept.
export const withBookingRules = (org: Organization, draft: BookingRulesDraft): Organization => {
  const owned = new Set([
    ORGANIZATION_REQUIRE_NEW_PATIENT_EXAM_FIRST_EXTENSION_URL,
    ORGANIZATION_BOOKING_MODE_EXTENSION_URL,
    ORGANIZATION_REQUEST_STYLE_EXTENSION_URL,
    RETIRED_ORGANIZATION_NEW_PATIENT_EXAM_ROLES_EXTENSION_URL,
    ORGANIZATION_DEFAULT_APPOINTMENT_DURATION_EXTENSION_URL,
  ]);
  const extension: Extension[] = [
    ...(org.extension ?? []).filter((e) => !owned.has(e.url)),
    ...(draft.requireNewPatientFirst
      ? [{ url: ORGANIZATION_REQUIRE_NEW_PATIENT_EXAM_FIRST_EXTENSION_URL, valueBoolean: true }]
      : []),
    ...(draft.bookingMode !== "direct" ? [{ url: ORGANIZATION_BOOKING_MODE_EXTENSION_URL, valueCode: draft.bookingMode }] : []),
    ...(draft.bookingMode === "request-only" && draft.requestStyle === "time-window"
      ? [{ url: ORGANIZATION_REQUEST_STYLE_EXTENSION_URL, valueCode: "time-window" }]
      : []),
    { url: ORGANIZATION_DEFAULT_APPOINTMENT_DURATION_EXTENSION_URL, valueInteger: draft.defaultDurationMinutes },
  ];
  return { ...org, extension };
};

// Reminders switch off by leaving every time unticked; the saved times are kept for next time.
export const toReminderPolicy = (draft: BookingRulesDraft, saved: ReminderPolicy): ReminderPolicy => ({
  enabled: draft.reminderOffsets.length > 0,
  offsetsMinutes: draft.reminderOffsets.length > 0 ? draft.reminderOffsets : saved.offsetsMinutes,
  maxPerAppointment: draft.maxReminders,
  quietHours: draft.quietHours,
});