# Hello World with Apigee LLM

This sample demonstrates how to use the Agent Development Kit (ADK) with an LLM fronted by an Apigee proxy. It showcases the flexibility of the `ApigeeLlm` class in configuring the target LLM provider (Gemini or Vertex AI) and API version through the model string.

## Setup

Before running the sample, you need to configure your environment with the necessary credentials.

1. **Create a `.env` file:**
   Copy the sample environment file to a new file named `.env` in the same directory.

   ```bash
   cp .env-sample .env
   ```

1. **Set Environment Variables:**
   Open the `.env` file and provide values for the following variables:

   - `GOOGLE_API_KEY`: Your API key for the Google AI services (Gemini).
   - `APIGEE_PROXY_URL`: The full URL of your Apigee proxy endpoint.

   Example `.env` file:

   ```
   GOOGLE_API_KEY="your-google-api-key"
   APIGEE_PROXY_URL="https://your-apigee-proxy.net/basepath"
   ```

   The `main.py` script will automatically load these variables when it runs.

## Run the Sample

Once your `.env` file is configured, you can run the sample with the following command:

```bash
python main.py
```

## Configuring the Apigee LLM

The `ApigeeLlm` class is configured using a special model string format in `agent.py`. This string determines which backend provider (Vertex AI or Gemini) and which API version to use.

### Model String Format

The supported format is:

`apigee/[<provider>/][<version>/]<model_id>`

- **`provider`** (optional): Can be `vertex_ai` or `gemini`.

  - If specified, it forces the use of that provider.
  - If omitted, the provider is determined by the `GOOGLE_GENAI_USE_VERTEXAI` environment variable. If this variable is set to `true` or `1`, Vertex AI is used; otherwise, `gemini` is used by default.

- **`version`** (optional): The API version to use (e.g., `v1`, `v1beta`).

  - If omitted, the default version for the selected provider is used.

- **`model_id`** (required): The identifier for the model you want to use (e.g., `gemini-2.5-flash`).

### Configuration Examples

Here are some examples of how to configure the model string in `agent.py` to achieve different behaviors:

1. **Implicit Provider (determined by environment variable):**

   - `model="apigee/gemini-2.5-flash"`

     - Uses the default API version.
     - Provider is Vertex AI if `GOOGLE_GENAI_USE_VERTEXAI` is true; otherwise, Gemini.

   - `model="apigee/v1/gemini-2.5-flash"`

     - Uses API version `v1`.
     - Provider is determined by the environment variable.

1. **Explicit Provider (ignores environment variable):**

   - `model="apigee/vertex_ai/gemini-2.5-flash"`

     - Uses Vertex AI with the default API version.

   - `model="apigee/gemini/gemini-2.5-flash"`

     - Uses Gemini with the default API version.

   - `model="apigee/gemini/v1/gemini-2.5-flash"`

     - Uses Gemini with API version `v1`.

   - `model="apigee/vertex_ai/v1beta/gemini-2.5-flash"`

     - Uses Vertex AI with API version `v1beta`.

By modifying the `model` string in `agent.py`, you can test various configurations without changing the core logic of the agent.
