Replace ChatGPT with Google Gemini

README.md

@@ -1,10 +1,10 @@
 # TweetBot - AI-Powered Twitter Bot
 
-An automated Twitter bot that generates and posts tweets using OpenAI's ChatGPT API. This Java application allows you to create engaging social media content with custom prompts.
+An automated Twitter bot that generates and posts tweets using Google Gemini's free API. This Java application allows you to create engaging social media content with custom prompts.
 
 ## Features
 
-- Generate tweet content using ChatGPT (GPT-3.5-turbo)
+- Generate tweet content using Google Gemini (gemini-2.0-flash-exp) - **Free Tier**
 - **Three operation modes:**
   - Interactive mode with manual approval
   - Auto-post mode for one-time tweets
@@ -22,17 +22,24 @@ An automated Twitter bot that generates and posts tweets using OpenAI's ChatGPT
 
 - Java 17 or higher
 - Maven 3.6 or higher
-- OpenAI API key
+- Google Gemini API key (free tier available)
 - Twitter Developer Account with API credentials
 
 ## Setup Instructions
 
-### 1. Get OpenAI API Key
+### 1. Get Google Gemini API Key (Free)
 
-1. Go to [OpenAI Platform](https://platform.openai.com/)
-2. Sign up or log in to your account
-3. Navigate to API keys section
-4. Create a new API key and save it securely
+1. Go to [Google AI Studio](https://aistudio.google.com/app/apikey)
+2. Sign in with your Google account
+3. Click "Create API Key"
+4. Select or create a Google Cloud project
+5. Copy the API key and save it securely
+
+**Note:** The free tier of Google Gemini includes:
+- 15 requests per minute
+- 1 million tokens per minute
+- 1,500 requests per day
+- More than enough for a tweet bot!
 
 ### 2. Get Twitter API Credentials
 
@@ -44,7 +51,6 @@ An automated Twitter bot that generates and posts tweets using OpenAI's ChatGPT
    - API Secret (Consumer Secret)
    - Access Token
    - Access Token Secret
-   - Bearer Token
 
 **Important:** Ensure your Twitter app has **Read and Write** permissions:
 - Go to your app settings
@@ -60,12 +66,11 @@ An automated Twitter bot that generates and posts tweets using OpenAI's ChatGPT
 
 2. Edit `.env` and add your API credentials:
    ```
-   OPENAI_API_KEY=sk-your-openai-api-key-here
+   GEMINI_API_KEY=your-gemini-api-key-here
    TWITTER_API_KEY=your-twitter-api-key
    TWITTER_API_SECRET=your-twitter-api-secret
    TWITTER_ACCESS_TOKEN=your-twitter-access-token
    TWITTER_ACCESS_TOKEN_SECRET=your-twitter-access-token-secret
-   TWITTER_BEARER_TOKEN=your-twitter-bearer-token
    TWEET_PROMPT=Write a short, engaging tweet about technology trends
    IMAGE_PATH=/path/to/your/image.jpg
    ```
@@ -80,7 +85,7 @@ An automated Twitter bot that generates and posts tweets using OpenAI's ChatGPT
    - Supported formats: JPEG, PNG, GIF
    - Maximum file size: 5MB (Twitter limit)
 
-### 5. Build the Project
+### 4. Build the Project
 
 ```bash
 mvn clean package
@@ -216,7 +221,7 @@ tweetbot/
         │               ├── config/
         │               │   └── Config.java            # Configuration loader
         │               └── service/
-        │                   ├── OpenAIService.java     # ChatGPT integration
+        │                   ├── GeminiService.java     # Google Gemini integration
         │                   └── TwitterService.java    # Twitter API integration
         └── resources/
             └── logback.xml          # Logging configuration
@@ -228,12 +233,11 @@ tweetbot/
 
 | Variable | Required | Description |
 |----------|----------|-------------|
-| `OPENAI_API_KEY` | Yes | Your OpenAI API key |
+| `GEMINI_API_KEY` | Yes | Your Google Gemini API key (free tier available) |
 | `TWITTER_API_KEY` | Yes | Twitter API Key (Consumer Key) |
 | `TWITTER_API_SECRET` | Yes | Twitter API Secret (Consumer Secret) |
 | `TWITTER_ACCESS_TOKEN` | Yes | Twitter Access Token |
 | `TWITTER_ACCESS_TOKEN_SECRET` | Yes | Twitter Access Token Secret |
-| `TWITTER_BEARER_TOKEN` | Yes | Twitter Bearer Token |
 | `TWEET_PROMPT` | No | Default prompt for tweet generation |
 | `IMAGE_PATH` | No | Path to image file to attach to every tweet (jpg, png, gif) |
 
@@ -371,9 +375,10 @@ Ensure your `.env` file exists and contains all required variables.
 
 ### "Failed to generate tweet"
 
-1. Verify your OpenAI API key is valid
-2. Check that you have sufficient API credits
+1. Verify your Gemini API key is valid
+2. Check that you're within the free tier rate limits (15 RPM, 1500 RPD)
 3. Review the error message in logs
+4. Ensure your Google Cloud project is properly configured
 
 ### Twitter API Rate Limits
 
@@ -385,9 +390,7 @@ Twitter API has rate limits:
 
 ## Dependencies
 
-- **Twitter API Java SDK** (2.0.3) - Twitter API client
-- **OpenAI GPT-3 Java** (0.18.2) - OpenAI API client
-- **OkHttp** (4.12.0) - HTTP client
+- **OkHttp** (4.12.0) - HTTP client for API requests
 - **Jackson** (2.16.1) - JSON processing
 - **SLF4J & Logback** (2.0.9) - Logging
 - **Dotenv** (3.0.0) - Environment variable management
@@ -406,7 +409,6 @@ private static final int SCHEDULE_INTERVAL_MINUTES = 30; // Change this value
 
 ### Other Enhancement Ideas
 
-- Add support for images and media attachments
 - Implement tweet threading for longer content
 - Add sentiment analysis before posting
 - Create multiple prompt templates with rotation
@@ -429,4 +431,4 @@ For issues or questions:
 1. Check the troubleshooting section
 2. Review application logs in `tweetbot.log`
 3. Verify API credentials and permissions
-4. Check Twitter and OpenAI API status pages
+4. Check Twitter and Google AI Studio status pages