clipboard: Add useClipboardHasURL hook

Author: chrisbobbe

src/@react-native-clipboard/clipboard.js

@@ -0,0 +1,74 @@
+/**
+ * Helpers for @react-native-clipboard/clipboard
+ *
+ * @flow strict-local
+ */
+
+import { useState, useCallback, useEffect } from 'react';
+import { AppState, Platform } from 'react-native';
+import Clipboard from '@react-native-clipboard/clipboard';
+
+import * as logging from '../utils/logging';
+import { tryParseUrl } from '../utils/url';
+
+/**
+ * A Hook for the current value of Clipboard.hasURL, when known.
+ *
+ * https://github.com/react-native-clipboard/clipboard#hasurl
+ *
+ * With a hack to simulate Clipboard.hasURL on iOS <14, and on Android.
+ *
+ * Returns the payload of the most recently settled Clipboard.hasURL()
+ * Promise; otherwise `null` if that Promise rejected, or if no such Promise
+ * has settled.
+ *
+ * Re-queries when clipboard value changes, and when app state changes to
+ * "active".
+ *
+ * Subject to subtle races. Don't use for anything critical, and do a
+ * sanity-check in clipboard reads informed by the result of this (e.g.,
+ * check the retrieved string with `tryParseUrl`).
+ */
+export function useClipboardHasURL(): boolean | null {
+  const [result, setResult] = useState<boolean | null>(null);
+
+  const getAndSetResult = useCallback(async () => {
+    try {
+      // TODO(ios-14): Simplify conditional and jsdoc.
+      if (Platform.OS === 'ios' && parseInt(Platform.Version, 10) >= 14) {
+        setResult(await Clipboard.hasURL());
+      } else {
+        // Hack: Simulate Clipboard.hasURL
+        setResult(!!tryParseUrl(await Clipboard.getString()));
+      }
+    } catch (e) {
+      logging.error(e);
+      setResult(null);
+    }
+  }, []);
+
+  useEffect(() => {
+    getAndSetResult();
+
+    const clipboardListener = Clipboard.addListener(() => {
+      getAndSetResult();
+    });
+
+    const appStateChangeListener = AppState.addEventListener('change', s => {
+      if (s === 'active') {
+        getAndSetResult();
+      }
+    });
+
+    return () => {
+      clipboardListener.remove();
+      AppState.removeEventListener('change', appStateChangeListener);
+    };
+  }, [getAndSetResult]);
+
+  return result;
+}
+
+// We probably don't want a useClipboardHasWebURL. The implementation of
+// Clipboard.hasWebURL on iOS is such that it matches when the copied string
+// *has* a URL, not when it *is* a URL.