import { useRef, useState } from "react";

import type { AssistantReply } from "../../services/AssistantService.tsx";

export interface Turn {
  question: string;
  reply?: AssistantReply;
  failed?: boolean;
}

export interface Conversation {
  id: number;
  subject: string;
  turns: Turn[];
  draft: string;
  asking: boolean;
  showingTicket: boolean;
}

let lastId = 0;
const fresh = (subject: string): Conversation =>
  ({ id: ++lastId, subject, turns: [], draft: "", asking: false, showingTicket: false });

export interface AssistantConversation {
  conversation: Conversation;
  update: (change: (current: Conversation) => Partial<Conversation>, id?: number) => void;
  isLive: (id: number) => boolean;
}

// The path, query and hash, which carry any patient or encounter id the route names.
export const assistantSubject = ({ pathname, search, hash }: { pathname: string; search: string; hash: string }) =>
  pathname + search + hash;

// A new subject replaces the conversation before it paints; a write for a replaced one is dropped.
export const useAssistantConversation = (subject: string): AssistantConversation => {
  const [stored, setStored] = useState(() => fresh(subject));
  let conversation = stored;
  if (stored.subject !== subject) {
    conversation = fresh(subject);
    setStored(conversation);
  }
  const live = useRef(conversation.id);
  live.current = conversation.id;
  const update: AssistantConversation["update"] = (change, id = conversation.id) =>
    setStored((previous) => (previous.id === id ? { ...previous, ...change(previous) } : previous));
  return { conversation, update, isLive: (id) => live.current === id };
};