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 InvoiceDetail from "./views/InvoiceDetail";
import Clients from "./views/Clients";
import { ToastProvider, useToast } from "./components/ToastProvider";
import AppSettings from "./views/AppSettings";
import { requestSettingsTab } from "./lib/settingsTab";
import { applyDocumentTheme, cachedTheme, normalizeTheme } from "./lib/theme";

export default function App() {
  return (
    <ToastProvider>
      <AppInner />
    </ToastProvider>
  );
}

function AppInner() {
  const toast = useToast();
  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 [detailId, setDetailId] = useState<number | null>(null);
  // A draft made by "Duplicate" that the New invoice form should open once it is shown.
  const [openDraftId, setOpenDraftId] = useState<number | null>(null);

  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]);

  // Before settings load (and on the error screen) use the cached theme so the window never flashes white.
  const theme = settings ? normalizeTheme(settings.theme) : cachedTheme();
  useEffect(() => {
    applyDocumentTheme(theme);
  }, [theme]);

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

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

  if (!settings) return null;

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

  const openIntegrations = () => {
    requestSettingsTab("integrations");
    setView("settings");
  };

  const toggleTheme = async () => {
    const next: Settings = { ...settings, theme: settings.theme === "g100" ? "g10" : "g100" };
    setSettings(next);
    try {
      await api.saveSettings(next);
    } catch (e) {
      toast.error("Could not save the theme", String(e));
    }
  };

  return (
    <Theme theme={theme} className="voiced-theme">
      <AppShell view={view} onNavigate={setView} theme={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")}
          openDraftId={openDraftId}
          onDraftOpened={() => setOpenDraftId(null)}
          theme={theme}
          onToggleTheme={toggleTheme}
        />
        <div hidden={view !== "invoices"}>
          <InvoiceHistory
            settings={settings}
            active={view === "invoices"}
            onOpenSettings={openIntegrations}
            onOpen={(id) => {
              setDetailId(id);
              setView("invoice");
            }}
          />
        </div>
        {view === "invoice" && detailId !== null ? (
          <InvoiceDetail
            key={detailId}
            invoiceId={detailId}
            settings={settings}
            onBack={() => setView("invoices")}
            onOpenSettings={openIntegrations}
            onDuplicated={(draftId) => {
              setOpenDraftId(draftId);
              setView("new");
            }}
          />
        ) : null}
        <div hidden={view !== "clients"}>
          <Clients active={view === "clients"} />
        </div>
        {view === "settings" && <AppSettings settings={settings} onSaved={refreshSettings} />}
      </AppShell>
    </Theme>
  );
}