bsky-social-app/src/components/PolicyUpdateOverlay/Overlay.tsx

import {type ReactNode} from 'react'
import {ScrollView, View} from 'react-native'
import {
  useSafeAreaFrame,
  useSafeAreaInsets,
} from 'react-native-safe-area-context'
import {LinearGradient} from 'expo-linear-gradient'
import {utils} from '@bsky.app/alf'

import {useA11y} from '#/state/a11y'
import {atoms as a, useBreakpoints, useTheme, web} from '#/alf'
import {FocusScope} from '#/components/FocusScope'
import {LockScroll} from '#/components/LockScroll'
import {IS_ANDROID, IS_NATIVE} from '#/env'

const GUTTER = 24

export function Overlay({
  children,
  label,
}: {
  children: ReactNode
  label: string
}) {
  const t = useTheme()
  const {gtPhone} = useBreakpoints()
  const {reduceMotionEnabled} = useA11y()
  const insets = useSafeAreaInsets()
  const frame = useSafeAreaFrame()

  return (
    <>
      <LockScroll />

      <View style={[a.fixed, a.inset_0, !reduceMotionEnabled && a.fade_in]}>
        {gtPhone ? (
          <View style={[a.absolute, a.inset_0, {opacity: 0.8}]}>
            <View
              style={[
                a.fixed,
                a.inset_0,
                {backgroundColor: t.palette.black},
                !reduceMotionEnabled && a.fade_in,
              ]}
            />
          </View>
        ) : (
          <LinearGradient
            colors={[
              utils.alpha(t.atoms.bg.backgroundColor, 0),
              t.atoms.bg.backgroundColor,
              t.atoms.bg.backgroundColor,
            ]}
            start={[0.5, 0]}
            end={[0.5, 1]}
            style={[a.absolute, a.inset_0]}
          />
        )}
      </View>

      <ScrollView
        showsVerticalScrollIndicator={false}
        style={[
          a.z_10,
          gtPhone &&
            web({
              paddingHorizontal: GUTTER,
              paddingVertical: '10vh',
            }),
        ]}
        contentContainerStyle={[a.align_center]}>
        {/**
         * This is needed to prevent centered dialogs from overflowing
         * above the screen, and provides a "natural" centering so that
         * stacked dialogs appear relatively aligned.
         */}
        <View
          style={[
            a.w_full,
            a.z_20,
            a.align_center,
            !gtPhone && [a.justify_end, {minHeight: frame.height}],
            IS_NATIVE && [
              {
                paddingBottom: Math.max(insets.bottom, a.p_2xl.padding),
              },
            ],
          ]}>
          {!gtPhone && (
            <View
              style={[
                a.flex_1,
                a.w_full,
                {
                  minHeight: Math.max(insets.top, a.p_2xl.padding),
                },
              ]}>
              <LinearGradient
                colors={[
                  utils.alpha(t.atoms.bg.backgroundColor, 0),
                  t.atoms.bg.backgroundColor,
                ]}
                start={[0.5, 0]}
                end={[0.5, 1]}
                style={[a.absolute, a.inset_0]}
              />
            </View>
          )}

          <FocusScope>
            <View
              accessible={IS_ANDROID}
              role="dialog"
              aria-role="dialog"
              aria-label={label}
              style={[
                a.relative,
                a.w_full,
                a.p_2xl,
                t.atoms.bg,
                !reduceMotionEnabled && a.zoom_fade_in,
                gtPhone && [
                  a.rounded_md,
                  a.border,
                  t.atoms.shadow_lg,
                  t.atoms.border_contrast_low,
                  web({
                    maxWidth: 420,
                  }),
                ],
              ]}>
              {children}
            </View>
          </FocusScope>
        </View>
      </ScrollView>
    </>
  )
}