SkateSpots/android-templates/MainActivity.java

package org.skatespots.app;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import com.getcapacitor.BridgeActivity;

/**
 * Custom MainActivity that lets the WebView hand OFF `intent:` / `nostrsigner:`
 * URLs to the Android OS so Amber's approval screen actually opens.
 *
 * WHY THIS EXISTS
 * ───────────────
 * When the JS signer navigates to an `intent:...;scheme=nostrsigner;...;end`
 * URL, Capacitor's default WebView treats it as a page navigation and silently
 * DROPS it — so Amber never launches and every signing action (delete, accept
 * crew invite, zap, profile edit) hangs forever. Login works only because it
 * goes through the native plugin's startActivityForResult; JS-initiated intents
 * were never reaching the OS. On GrapheneOS this is enforced strictly.
 *
 * The fix: override shouldOverrideUrlLoading. Whenever the WebView tries to load
 * an `intent:` or `nostrsigner:` URL, we parse it and call startActivity()
 * ourselves — a REAL native launch that opens Amber, exactly like login. The
 * result comes back via the app's custom-scheme deep link
 * (org.skatespots.app://amber-callback...), handled by DeepLinkHandler /
 * resolveAmberIntent in the web layer.
 *
 * This file is injected into the generated android/ project at build time by
 * scripts/inject-main-activity.mjs (android/ is not committed).
 */
public class MainActivity extends BridgeActivity {

    private static final String TAG = "SkateSpotsAmber";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        final WebView webView = getBridge().getWebView();
        if (webView == null) {
            return;
        }

        final WebViewClient existing = new WebViewClient();

        webView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                if (handleExternalScheme(url)) {
                    return true;
                }
                return super.shouldOverrideUrlLoading(view, url);
            }

            @Override
            public boolean shouldOverrideUrlLoading(WebView view, android.webkit.WebResourceRequest request) {
                final String url = request.getUrl() != null ? request.getUrl().toString() : null;
                if (url != null && handleExternalScheme(url)) {
                    return true;
                }
                return super.shouldOverrideUrlLoading(view, request);
            }
        });
    }

    /**
     * If the URL is an Amber/signer intent, launch it natively and return true.
     * Returns false for normal in-app URLs so Capacitor handles them as usual.
     */
    private boolean handleExternalScheme(String url) {
        if (url == null) {
            return false;
        }

        try {
            if (url.startsWith("intent:")) {
                // Parse the full Android intent: URI (carries scheme, extras, end).
                Intent intent = Intent.parseUri(url, Intent.URI_INTENT_SCHEME);
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
                return true;
            }

            if (url.startsWith("nostrsigner:")) {
                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
                return true;
            }
        } catch (Exception e) {
            Log.e(TAG, "Failed to launch external signer intent: " + e.getMessage(), e);
            // Fall through — let the WebView try to handle it (will no-op safely).
        }

        return false;
    }
}