Extract rn dir finding logic to function

android/build.gradle

@@ -38,6 +38,42 @@ def isNewArchitectureEnabled() {
     return project.hasProperty("newArchEnabled") && project.newArchEnabled == "true"
 }
 
+def resolveReactNativeDirectory() {
+    def userDefinedRnDirPath = safeAppExtGet("REACT_NATIVE_NODE_MODULES_DIR", null)
+    if (userDefinedRnDirPath != null) {
+        return file(userDefinedRnDirPath)
+    }
+
+    File standardRnDirFile = file("$rootDir/../node_modules/react-native/")
+    if (standardRnDirFile.exists()) {
+        return standardRnDirFile
+    }
+
+    // This is legacy code, I'm not sure why it works in certain scenarios but it was reported that one of our
+    // projects needs this.
+    File legacyRnDirFile = file("$projectDir/../node_modules/react-native/")
+    if (legacyRnDirFile.exists()) {
+        return legacyRnDirFile
+    }
+
+    // We're in non standard setup, e.g. monorepo - try to use node resolver to locate the react-native package.
+    String maybeRnPackagePath = ["node", "--print", "require.resolve('react-native/package.json')"].execute(null, rootDir).text.trim()
+
+    File nodeResolverRnDirFile = null
+    // file() constructor fails in case string is null or blank
+    if (maybeRnPackagePath != null && !maybeRnPackagePath.isBlank()) {
+        File maybeRnPackageFile = file(maybeRnPackagePath)
+        nodeResolverRnDirFile = maybeRnPackageFile.parentFile
+        if (nodeResolverRnDirFile.exists()) {
+            return nodeResolverRnDirFile
+        }
+    }
+
+    throw new Exception("[RNScreens] Failed to resolve react-native directory. " +
+            "Attempted locations: ${standardRnDirFile}, ${legacyRnDirFile} and ${nodeResolverRnDirFile}. " +
+            "You should set project extension property (in `app/build.gradle`) `REACT_NATIVE_NODE_MODULES_DIR` with path to react-native.")
+}
+
 // spotless is only accessible within react-native-screens repo
 if (isRunningInContextOfScreensRepo()) {
     apply from: 'spotless.gradle'
@@ -151,43 +187,7 @@ android {
 
 repositories {
     maven {
-        // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
-
-        // First look for the standard location of react-native, as in RN Hello World template
-        // https://github.com/facebook/react-native/blob/1e8f3b11027fe0a7514b4fc97d0798d3c64bc895/local-cli/templates/HelloWorld/android/build.gradle#L21
-        // TODO(kkafar): Note, that in latest template app https://github.com/react-native-community/template/blob/0f4745b7a9d84232aeedec2def8d75ab9b050d11/template/android/build.gradle
-        // this is not specified at all.
-        File standardRnAndroidDirLocation = file("$rootDir/../node_modules/react-native/android")
-        if (standardRnAndroidDirLocation.exists()) {
-            url standardRnAndroidDirLocation
-            return
-        }
-
-        // This is legacy code, I'm not sure why it works in certain scenarios but it was reported that one of our
-        // projects needs this.
-        File secondStandardRnAndroidDirLocation = file("$projectDir/../node_modules/react-native/android")
-        if (secondStandardRnAndroidDirLocation.exists()) {
-            url secondStandardRnAndroidDirLocation
-            return
-        }
-
-        // We're in non standard setup - try to use node resolver to locate the react-native package.
-        String searchResult = ["node", "--print", "require.resolve('react-native/package.json')"].execute(null, rootDir).text.trim()
-
-        // file() constructor fails in case string is null or blank
-        if (searchResult == null || searchResult.isBlank()) {
-            println "[RNScreens] Failed to resolve react-native directory. Attempted locations: ${standardRnAndroidDirLocation}, ${secondStandardRnAndroidDirLocation} and search with node resolution algorithm failed."
-            return
-        }
-
-        File reactNativePackage = file(searchResult)
-        def rnAndroidDirLocation = "$reactNativePackage.parentFile/android"
-        if (reactNativePackage.exists()) {
-            url rnAndroidDirLocation
-            return
-        }
-
-        println "[RNScreens] Failed to resolve react-native directory. Attempted locations: ${standardRnAndroidDirLocation}, ${secondStandardRnAndroidDirLocation}, ${rnAndroidDirLocation}"
+        url "${resolveReactNativeDirectory()}/android"
     }
 
     mavenCentral()