import { useCallback, useEffect, useState } from "react";
import { InlineNotification, Loading, Theme } from "@carbon/react";
import { api } from "./lib/api";
import type { Settings } from "./lib/types";
import { AppShell, type AppView } from "./components/AppShell";
import Onboarding from "./views/Onboarding";
import NewInvoice from "./views/NewInvoice";
import InvoiceHistory from "./views/InvoiceHistory";
import SeriesSettings from "./views/SeriesSettings";
import AppSettings from "./views/AppSettings";

export default function App() {
  const [settings, setSettings] = useState<Settings | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [view, setView] = useState<AppView>("new");

  const refreshSettings = useCallback(async () => {
    try {
      const next = await api.getSettings();
      setSettings(next);
      setError(null);
    } catch (e) {
      setError(String(e));
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    void refreshSettings();
  }, [refreshSettings]);

  if (loading) {
    return (
      <Theme theme="g10">
        <div className="voiced-empty">
          <Loading description="Loading Voiced" withOverlay={false} small />
        </div>
      </Theme>
    );
  }

  if (error) {
    return (
      <Theme theme="g10">
        <div className="voiced-page">
          <InlineNotification
            kind="error"
            lowContrast
            title="Could not start Voiced"
            subtitle={error}
            hideCloseButton
          />
        </div>
      </Theme>
    );
  }

  if (!settings) return null;

  const theme = settings.theme === "g100" ? "g100" : "g10";

  if (!settings.onboarded) {
    return (
      <Theme theme={theme}>
        <Onboarding
          initial={settings}
          onDone={(next) => {
            setSettings(next);
            setView("new");
          }}
        />
      </Theme>
    );
  }

  const toggleTheme = async () => {
    const next: Settings = { ...settings, theme: settings.theme === "g100" ? "g10" : "g100" };
    setSettings(next);
    try {
      await api.saveSettings(next);
    } catch (e) {
      setError(String(e));
    }
  };

  return (
    <Theme theme={theme}>
      <AppShell view={view} onNavigate={setView} theme={settings.theme} onToggleTheme={toggleTheme}>
        {/* Main views stay mounted so a half-typed invoice survives switching tabs. */}
        <NewInvoice
          settings={settings}
          onSettingsChange={refreshSettings}
          active={view === "new"}
          onActivate={() => setView("new")}
        />
        <div hidden={view !== "invoices"}>
          <InvoiceHistory settings={settings} active={view === "invoices"} />
        </div>
        <div hidden={view !== "series"}>
          <SeriesSettings active={view === "series"} />
        </div>
        {view === "settings" && <AppSettings settings={settings} onSaved={refreshSettings} />}
      </AppShell>
    </Theme>
  );
}