Add Android support

plugin/android/app-build-gradle.js

@@ -0,0 +1,54 @@
+const { AndroidConfig, withDangerousMod } = require('@expo/config-plugins');
+const {
+  createGeneratedHeaderComment,
+  removeContents,
+} = require('@expo/config-plugins/build/utils/generateCode');
+const codeModAndroid = require('@expo/config-plugins/build/android/codeMod');
+const fs = require('fs');
+
+const withAppAuthAppBuildGradle = (rootConfig, options) =>
+  withDangerousMod(rootConfig, [
+    'android',
+    config => {
+      // detauls to app scheme
+      const authScheme = options?.authScheme ?? config.scheme ?? '';
+
+      // find the app/build.gradle file and checks its format
+      const appBuildGradlePath = AndroidConfig.Paths.getAppBuildGradleFilePath(
+        config.modRequest.projectRoot
+      );
+
+      // BEWARE: we update the app/build.gradle file *outside* of the standard Expo config procedure !
+      let contents = fs.readFileSync(appBuildGradlePath, 'utf-8');
+
+      if (contents.includes('manifestPlaceholders')) {
+        throw new Error(
+          'app/build.gradle already contains manifestPlaceholders, cannot update automatically !'
+        );
+      }
+
+      // let's add the manifestPlaceholders section !
+      contents = removeContents({
+        src: contents,
+        tag: 'react-native-app-auth',
+      }).contents;
+      contents = codeModAndroid.appendContentsInsideDeclarationBlock(
+        contents,
+        'defaultConfig',
+        `
+        ${createGeneratedHeaderComment(contents, 'react-native-app-auth', '//')}
+        manifestPlaceholders = [
+          'appAuthRedirectScheme': '${authScheme}',
+        ]
+        // @generated end react-native-app-auth
+`
+      );
+
+      // and finally we write the file back to the disk
+      fs.writeFileSync(appBuildGradlePath, contents, 'utf-8');
+
+      return config;
+    },
+  ]);
+
+module.exports = { withAppAuthAppBuildGradle };

plugin/android/index.js

@@ -0,0 +1,5 @@
+const { withAppAuthAppBuildGradle } = require('./app-build-gradle');
+
+module.exports = {
+  withAppAuthAppBuildGradle,
+};

plugin/index.js

@@ -1,11 +1,15 @@
 const { withPlugins, createRunOncePlugin } = require('@expo/config-plugins');
 const { withAppAuthAppDelegate, withAppAuthAppDelegateHeader } = require('./ios');
+const { withAppAuthAppBuildGradle } = require('./android');
 
 const withAppAuth = config => {
   return withPlugins(config, [
     // iOS
     withAppAuthAppDelegate,
     withAppAuthAppDelegateHeader, // 👈 ️this one uses withDangerousMod !
+
+    // Android
+    withAppAuthAppBuildGradle, // 👈 ️this one uses withDangerousMod !
   ]);
 };