import type { ForgeTabIcon } from '@cdx-ui/icons/tab-icons';
import type { ForgeNativeBottomTabIcon, ForgeTabBarIcon } from './types';

/**
 * forgeTabIcon — iOS/Android implementation (see `forgeTabIcon.ts` for the
 * full contract and usage example).
 *
 * Returns a `tabBarIcon` function for `createNativeBottomTabNavigator` that
 * resolves the descriptor's pre-rasterized template PNGs: outlined at rest,
 * filled when focused (iOS only — Android tabs use one static icon and
 * express selection via tint). `tinted: true` makes the native tab bar apply
 * `tabBarActiveTintColor` / `tabBarInactiveTintColor` at runtime, so theming
 * and dark mode flow through `useForgeBottomTabScreenOptions` unchanged.
 */
export function forgeTabIcon(icon: ForgeTabIcon): ForgeTabBarIcon {
  const { native } = icon;

  if (!native) {
    const name = icon.Component.displayName ?? 'icon';
    throw new Error(
      `forgeTabIcon: "${name}" has no native tab assets. Use a generated ` +
        `descriptor from '@cdx-ui/icons/tab-icons' (curated in the icon ` +
        `package's tab-icons.config.json), or pass a descriptor with your ` +
        `own template PNGs: { native: { outlined: require(...), filled: ` +
        `require(...) } } at a 24dp base size with @2x/@3x variants.`,
    );
  }

  const resolve = ({ focused }: { focused: boolean }): ForgeNativeBottomTabIcon => ({
    type: 'image',
    source: focused ? native.filled : native.outlined,
    tinted: true,
  });

  return resolve as ForgeTabBarIcon;
}