feat: React Native Application using Eppo SDK (#106)

* inital app from create-expo-app
* add Eppo SDK; traditional and precomputed client
* Eppo Client provider and basic flag/bandit display

package-testing/react-native-sdk-relay/.eslintrc.js

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+// https://docs.expo.dev/guides/using-eslint/
+module.exports = {
+  extends: ['expo', 'prettier'],
+  plugins: ['prettier'],
+  rules: {
+    'prettier/prettier': 'error',
+  },
+};

package-testing/react-native-sdk-relay/.gitignore

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+# Learn more https://docs.github.com/en/get-started/getting-started-with-git/ignoring-files
+
+# dependencies
+node_modules/
+
+# Expo
+.expo/
+dist/
+web-build/
+expo-env.d.ts
+
+# Native
+*.orig.*
+*.jks
+*.p8
+*.p12
+*.key
+*.mobileprovision
+
+# Metro
+.metro-health-check*
+
+# debug
+npm-debug.*
+yarn-debug.*
+yarn-error.*
+
+# macOS
+.DS_Store
+*.pem
+
+# local env files
+.env*.local
+
+# typescript
+*.tsbuildinfo
+
+app-example

package-testing/react-native-sdk-relay/README.md

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+# Welcome to your Expo app 👋
+
+This is an [Expo](https://expo.dev) project created with [`create-expo-app`](https://www.npmjs.com/package/create-expo-app).
+
+## Get started
+
+1. Install dependencies
+
+   ```bash
+   npm install
+   ```
+
+2. Start the app
+
+   ```bash
+    npx expo start
+   ```
+
+In the output, you'll find options to open the app in a
+
+- [development build](https://docs.expo.dev/develop/development-builds/introduction/)
+- [Android emulator](https://docs.expo.dev/workflow/android-studio-emulator/)
+- [iOS simulator](https://docs.expo.dev/workflow/ios-simulator/)
+- [Expo Go](https://expo.dev/go), a limited sandbox for trying out app development with Expo
+
+You can start developing by editing the files inside the **app** directory. This project uses [file-based routing](https://docs.expo.dev/router/introduction).
+
+## Get a fresh project
+
+When you're ready, run:
+
+```bash
+npm run reset-project
+```
+
+This command will move the starter code to the **app-example** directory and create a blank **app** directory where you can start developing.
+
+## Learn more
+
+To learn more about developing your project with Expo, look at the following resources:
+
+- [Expo documentation](https://docs.expo.dev/): Learn fundamentals, or go into advanced topics with our [guides](https://docs.expo.dev/guides).
+- [Learn Expo tutorial](https://docs.expo.dev/tutorial/introduction/): Follow a step-by-step tutorial where you'll create a project that runs on Android, iOS, and the web.
+
+## Join the community
+
+Join our community of developers creating universal apps.
+
+- [Expo on GitHub](https://github.com/expo/expo): View our open source platform and contribute.
+- [Discord community](https://chat.expo.dev): Chat with Expo users and ask questions.

package-testing/react-native-sdk-relay/app.json

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+{
+  "expo": {
+    "name": "react-native-sdk-relay",
+    "slug": "react-native-sdk-relay",
+    "version": "1.0.0",
+    "orientation": "portrait",
+    "icon": "./assets/images/icon.png",
+    "scheme": "myapp",
+    "userInterfaceStyle": "automatic",
+    "newArchEnabled": true,
+    "ios": {
+      "supportsTablet": true
+    },
+    "android": {
+      "adaptiveIcon": {
+        "foregroundImage": "./assets/images/adaptive-icon.png",
+        "backgroundColor": "#ffffff"
+      }
+    },
+    "web": {
+      "bundler": "metro",
+      "output": "static",
+      "favicon": "./assets/images/favicon.png"
+    },
+    "plugins": [
+      "expo-router",
+      [
+        "expo-splash-screen",
+        {
+          "image": "./assets/images/splash-icon.png",
+          "imageWidth": 200,
+          "resizeMode": "contain",
+          "backgroundColor": "#ffffff"
+        }
+      ]
+    ],
+    "experiments": {
+      "typedRoutes": true
+    }
+  }
+}

package-testing/react-native-sdk-relay/app/(tabs)/_layout.tsx

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+import { Tabs } from 'expo-router';
+import React from 'react';
+import { Platform } from 'react-native';
+
+import { HapticTab } from '@/components/HapticTab';
+import { IconSymbol } from '@/components/ui/IconSymbol';
+import TabBarBackground from '@/components/ui/TabBarBackground';
+import { Colors } from '@/constants/Colors';
+import { useColorScheme } from '@/hooks/useColorScheme';
+
+export default function TabLayout() {
+  const colorScheme = useColorScheme();
+
+  return (
+    <Tabs
+      screenOptions={{
+        tabBarActiveTintColor: Colors[colorScheme ?? 'light'].tint,
+        headerShown: false,
+        tabBarButton: HapticTab,
+        tabBarBackground: TabBarBackground,
+        tabBarStyle: Platform.select({
+          ios: {
+            // Use a transparent background on iOS to show the blur effect
+            position: 'absolute',
+          },
+          default: {},
+        }),
+      }}
+    >
+      <Tabs.Screen
+        name="index"
+        options={{
+          title: 'Home',
+          tabBarIcon: ({ color }) => <IconSymbol size={28} name="house.fill" color={color} />,
+        }}
+      />
+      <Tabs.Screen
+        name="bandits"
+        options={{
+          title: 'Bandits',
+          tabBarIcon: ({ color }) => <IconSymbol size={28} name="paperplane.fill" color={color} />,
+        }}
+      />
+      <Tabs.Screen
+        name="eppo-flags"
+        options={{
+          title: 'Flags',
+          tabBarIcon: ({ color }) => <IconSymbol size={28} name="flag.fill" color={color} />,
+        }}
+      />
+    </Tabs>
+  );
+}

package-testing/react-native-sdk-relay/app/(tabs)/bandits.tsx

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+import { StyleSheet } from 'react-native';
+
+import { Collapsible } from '@/components/Collapsible';
+import ParallaxScrollView from '@/components/ParallaxScrollView';
+import { ThemedText } from '@/components/ThemedText';
+import { ThemedView } from '@/components/ThemedView';
+import { IconSymbol } from '@/components/ui/IconSymbol';
+import { useEffect, useState } from 'react';
+import { getInstance } from '@eppo/react-native-sdk';
+import { useSubjectAttributes } from '@/hooks/useSubjectAttributes';
+import { useEppoPrecomputedClient } from '@/hooks/useEppoPrecomputedClient';
+
+export default function BanditTabScreen() {
+  const [updateHighlightsBanditVariation, setUpdateHighlightsBanditVariation] = useState<string>('LOADING...');
+  const [updateHighlightsBanditAction, setUpdateHighlightsBanditAction] = useState<string>('');
+
+  const [updateHighlightsFlagValue, setUpdateHighlightsFlagValue] = useState<string>('LOADING...');
+  const [precomputedFlagValue, setPrecomputedFlagValue] = useState<string>('LOADING...');
+
+  const subjectAttributes = useSubjectAttributes();
+  const client = useEppoPrecomputedClient();
+
+  // const client = useEppoPrecomputedClient();
+
+  useEffect(() => {
+    try {
+      const result = client.getBanditAction('update-highlights-bandit', 'NONE');
+
+      setUpdateHighlightsBanditVariation(result?.variation ?? 'ERROR');
+      setUpdateHighlightsBanditAction(result?.action ?? 'ERROR');
+
+      const flagResult = getInstance().getStringAssignment(
+        'update-highlights-bandit',
+        'user123',
+        subjectAttributes,
+        'NONE',
+      );
+      setUpdateHighlightsFlagValue(flagResult);
+
+      const precomputedFlagResult = client.getStringAssignment('update-highlights-bandit', 'NONE');
+      setPrecomputedFlagValue(precomputedFlagResult);
+    } catch (error) {
+      console.error('Error in bandit effect:', error);
+      setUpdateHighlightsBanditVariation('ERROR');
+      setUpdateHighlightsBanditAction('ERROR');
+    }
+  }, [client, subjectAttributes]);
+
+  return (
+    <ParallaxScrollView
+      headerBackgroundColor={{ light: '#D0D0D0', dark: '#353636' }}
+      headerImage={
+        <IconSymbol
+          size={310}
+          color="#808080"
+          name="chevron.left.forwardslash.chevron.right"
+          style={styles.headerImage}
+        />
+      }
+    >
+      <ThemedView style={styles.titleContainer}>
+        <ThemedText type="title">Bandits</ThemedText>
+      </ThemedView>
+      <ThemedText>Here we are seeing the first bandits on a mobile app!</ThemedText>
+      <Collapsible title="update-highlights-bandit">
+        <ThemedText>
+          <ThemedText type="defaultSemiBold">VariationValue</ThemedText>{' '}
+          <ThemedText>{updateHighlightsBanditVariation}</ThemedText>
+        </ThemedText>
+        <ThemedText>
+          <ThemedText type="defaultSemiBold">Bandit Value</ThemedText>{' '}
+          <ThemedText>{updateHighlightsBanditAction}</ThemedText>
+        </ThemedText>
+      </Collapsible>
+      <Collapsible title="update-highlights-bandit Flag Value">
+        <ThemedText>
+          <ThemedText type="defaultSemiBold">Traditional Client</ThemedText>{' '}
+          <ThemedText>{updateHighlightsFlagValue}</ThemedText>
+        </ThemedText>
+        <ThemedText>
+          <ThemedText type="defaultSemiBold">Precomputed Client</ThemedText>{' '}
+          <ThemedText>{precomputedFlagValue}</ThemedText>
+        </ThemedText>
+      </Collapsible>
+    </ParallaxScrollView>
+  );
+}
+
+const styles = StyleSheet.create({
+  headerImage: {
+    color: '#808080',
+    bottom: -90,
+    left: -35,
+    position: 'absolute',
+  },
+  titleContainer: {
+    flexDirection: 'row',
+    gap: 8,
+  },
+});

package-testing/react-native-sdk-relay/app/(tabs)/eppo-flags.tsx

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+import { StyleSheet, Image, Platform } from 'react-native';
+
+import { Collapsible } from '@/components/Collapsible';
+import { ExternalLink } from '@/components/ExternalLink';
+import ParallaxScrollView from '@/components/ParallaxScrollView';
+import { ThemedText } from '@/components/ThemedText';
+import { ThemedView } from '@/components/ThemedView';
+import { IconSymbol } from '@/components/ui/IconSymbol';
+import React from 'react';
+import { TypeCompiler } from '@sinclair/typebox/compiler';
+import Code = TypeCompiler.Code;
+import EppoFlagKeyDump from '@/components/EppoFlagKeyDump';
+
+export default function EppoFlagsScreen() {
+  return (
+    <ParallaxScrollView
+      headerBackgroundColor={{ light: '#D0D0D0', dark: '#353636' }}
+      headerImage={
+        <IconSymbol
+          size={310}
+          color="#808080"
+          name="chevron.left.forwardslash.chevron.right"
+          style={styles.headerImage}
+        />
+      }
+    >
+      <ThemedView style={styles.titleContainer}>
+        <ThemedText type="title">Eppo Flag Assignments</ThemedText>
+      </ThemedView>
+      <ThemedText>Get dynamic values for your app based on your Eppo Experiments and Feature Flags.</ThemedText>
+      <Collapsible title="Assignment Methods">
+        <ThemedText>
+          <ThemedText>
+            getBooleanAssignment(...) getNumericAssignment(...) getIntegerAssignment(...) getStringAssignment(...)
+            getJSONAssignment(...)
+          </ThemedText>
+        </ThemedText>
+        <ExternalLink href="https://docs.geteppo.com/sdks/client-sdks/react-native/" target="_blank">
+          <ThemedText type="link">Learn more</ThemedText>
+        </ExternalLink>
+      </Collapsible>
+      <Collapsible title="Flag Keys">
+        <ThemedText>These flags have been loaded by the traditional Eppo SDK.</ThemedText>
+        <ThemedText type="defaultSemiBold">They are probably hashed.</ThemedText>
+        <EppoFlagKeyDump></EppoFlagKeyDump>
+      </Collapsible>
+    </ParallaxScrollView>
+  );
+}
+
+const styles = StyleSheet.create({
+  headerImage: {
+    color: '#808080',
+    bottom: -90,
+    left: -35,
+    position: 'absolute',
+  },
+  titleContainer: {
+    flexDirection: 'row',
+    gap: 8,
+  },
+});