import { browser } from "$app/environment";
import { listAccounts } from "$lib/api/endpoints";
import type { Account } from "$lib/api/types";

const STORAGE_KEY = "bg.account";

function readSelected(): number | null {
  if (!browser) {
    return null;
  }
  const stored = localStorage.getItem(STORAGE_KEY);
  return stored === null ? null : Number(stored);
}

function createAccounts() {
  let list = $state<Account[]>([]);
  let selectedId = $state<number | null>(readSelected());
  let loaded = $state(false);

  const selected = $derived(
    list.find((account) => account.account_id === selectedId) ?? null
  );

  function persist(id: number | null) {
    if (!browser) {
      return;
    }
    if (id === null) {
      localStorage.removeItem(STORAGE_KEY);
    } else {
      localStorage.setItem(STORAGE_KEY, String(id));
    }
  }

  return {
    get list() {
      return list;
    },
    get selectedId() {
      return selectedId;
    },
    get selected() {
      return selected;
    },
    get loaded() {
      return loaded;
    },
    async load() {
      list = await listAccounts();
      loaded = true;
      const exists = list.some((account) => account.account_id === selectedId);
      if (!exists) {
        const fallback =
          list.find((account) => account.is_active) ?? list.at(0) ?? null;
        selectedId = fallback ? fallback.account_id : null;
        persist(selectedId);
      }
    },
    select(id: number) {
      selectedId = id;
      persist(id);
    },
  };
}

export const accounts = createAccounts();