import { Platform, useWindowDimensions } from "react-native";
import { useSafeAreaFrame, useSafeAreaInsets } from "react-native-safe-area-context";

import { spacing } from "@/constants/theme";

/** Standard UITabBar content height (home indicator is separate). */
const IOS_TAB_BAR_HEIGHT = 49;

/** Slightly less than measured inset so content sits closer to the tab bar. */
const TAB_BAR_PADDING_TRIM = spacing.sm;

/**
 * Pixels between the bottom of the safe-area layout frame and the window bottom.
 */
function useBelowLayoutFrame(): number {
  const { height: windowHeight } = useWindowDimensions();
  const frame = useSafeAreaFrame();

  return Math.max(0, windowHeight - frame.y - frame.height);
}

/** Native tab bar height excluding the home-indicator inset. */
export function useNativeTabBarHeight(): number {
  const belowLayoutFrame = useBelowLayoutFrame();
  const { bottom: homeIndicator } = useSafeAreaInsets();
  const measured = Math.max(0, belowLayoutFrame - homeIndicator);

  if (measured > 0) return measured;
  return Platform.OS === "ios" ? IOS_TAB_BAR_HEIGHT : 0;
}

/**
 * Bottom padding so scroll content can clear the floating native tab bar.
 * Uses layout-frame measurement when available, otherwise tab bar + home indicator.
 */
export function useTabBarScrollPadding(): number {
  const belowLayoutFrame = useBelowLayoutFrame();
  const { bottom: homeIndicator } = useSafeAreaInsets();
  const tabBar = useNativeTabBarHeight();

  const raw =
    belowLayoutFrame > 0 ? belowLayoutFrame : tabBar + homeIndicator;

  return Math.max(tabBar + homeIndicator - TAB_BAR_PADDING_TRIM, raw - TAB_BAR_PADDING_TRIM);
}

/** @deprecated Use useTabBarScrollPadding */
export function useTabBarInset() {
  return useTabBarScrollPadding();
}