/**
 * useBranding — White-label branding hook.
 *
 * Fetches white-label settings from /api/enterprise/branding on mount and:
 *   1. Applies --primary-color / --secondary-color CSS variables to :root
 *   2. Updates the page favicon if a custom one is configured
 *   3. Returns the branding object for consumers (Header logo, app name, etc.)
 *
 * This hook is safe to call at the top of the app tree (e.g. App.tsx or
 * AppLayout) — it no-ops when the user is unauthenticated (401 response).
 */

import { useEffect, useState } from 'react';

export interface BrandingSettings {
  logo_url: string;
  primary_color: string;
  secondary_color: string;
  favicon_url: string;
  custom_domain: string;
  app_name: string;
  login_bg_url: string;
}

const DEFAULT_BRANDING: BrandingSettings = {
  logo_url: '',
  primary_color: '#00A846',
  secondary_color: '#008036',
  favicon_url: '',
  custom_domain: '',
  app_name: 'Command Sovereignty',
  login_bg_url: '',
};

/**
 * Apply CSS custom properties to :root so Tailwind / other CSS can reference
 * var(--primary-color) and var(--secondary-color) for theming.
 */
function applyBrandingCssVars(branding: BrandingSettings): void {
  const root = document.documentElement;
  if (branding.primary_color) {
    root.style.setProperty('--primary-color', branding.primary_color);
  }
  if (branding.secondary_color) {
    root.style.setProperty('--secondary-color', branding.secondary_color);
  }
}

/**
 * Swap the page favicon if the company has a custom one configured.
 */
function applyFavicon(faviconUrl: string): void {
  if (!faviconUrl) return;
  const existing = document.querySelector<HTMLLinkElement>('link[rel~="icon"]');
  if (existing) {
    existing.href = faviconUrl;
  } else {
    const link = document.createElement('link');
    link.rel = 'icon';
    link.href = faviconUrl;
    document.head.appendChild(link);
  }
}

export function useBranding(): {
  branding: BrandingSettings;
  loading: boolean;
} {
  const [branding, setBranding] = useState<BrandingSettings>(DEFAULT_BRANDING);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    let cancelled = false;

    fetch('/api/enterprise/branding', { credentials: 'include' })
      .then(async (res) => {
        if (!res.ok) {
          // 401 = not authenticated, 403 = not enterprise tier.
          // In both cases fall back to defaults silently.
          return null;
        }
        return res.json();
      })
      .then((data) => {
        if (cancelled || !data) return;

        const merged: BrandingSettings = { ...DEFAULT_BRANDING, ...data };
        setBranding(merged);
        applyBrandingCssVars(merged);
        applyFavicon(merged.favicon_url);
      })
      .catch(() => {
        // Network error — use defaults, don't crash the app
      })
      .finally(() => {
        if (!cancelled) setLoading(false);
      });

    return () => {
      cancelled = true;
    };
  }, []);

  return { branding, loading };
}