feat: Added Ollama engine via OpenAI api (#51)

* feat: Added Ollama engine via OpenAI api

* fix: Added PR remarks and test

Author: AtakanTekparmak

Diff for: README.md

@@ -384,6 +384,20 @@ We are grateful for all the help we got from our contributors!
                     <br />
                     <sub><b>tboen1</b></sub>
                 </a>
+            </td>
+            <td align="center">
+                <a href="https://github.com/nihalnayak">
+                    <img src="https://avatars.githubusercontent.com/u/5679782?v=4" width="100;" alt="nihalnayak"/>
+                    <br />
+                    <sub><b>Nihal Nayak</b></sub>
+                </a>
+            </td>
+            <td align="center">
+                <a href="https://github.com/AtakanTekparmak">
+                    <img src="https://avatars.githubusercontent.com/u/59488384?v=4" width="100;" alt="AtakanTekparmak"/>
+                    <br />
+                    <sub><b>Atakan Tekparmak</b></sub>
+                </a>
             </td>
 		</tr>
 	<tbody>

Diff for: tests/test_engines.py

@@ -0,0 +1,15 @@
+import pytest
+
+from textgrad.engine import get_engine
+
+def test_ollama_engine():
+    # Declare test constants
+    OLLAMA_BASE_URL = 'http://localhost:11434/v1'
+    MODEL_STRING = "test-model-string"
+
+    # Initialise the engine
+    engine = get_engine("ollama-" + MODEL_STRING)
+
+    assert engine
+    assert engine.model_string == MODEL_STRING
+    assert engine.base_url == OLLAMA_BASE_URL

Diff for: textgrad/engine/__init__.py

@@ -55,6 +55,14 @@ def get_engine(engine_name: str, **kwargs) -> EngineLM:
     elif engine_name in ["command-r-plus", "command-r", "command", "command-light"]:
         from .cohere import ChatCohere
         return ChatCohere(model_string=engine_name, **kwargs)
+    elif engine_name.startswith("ollama"):
+        from .openai import ChatOpenAI, OLLAMA_BASE_URL
+        model_string = engine_name.replace("ollama-", "")
+        return ChatOpenAI(
+            model_string=model_string,
+            base_url=OLLAMA_BASE_URL,
+            **kwargs
+        )
     elif "vllm" in engine_name:
         from .vllm import ChatVLLM
         engine_name = engine_name.replace("vllm-", "")

Diff for: textgrad/engine/openai.py

@@ -17,6 +17,12 @@
 from .base import EngineLM, CachedEngine
 from .engine_utils import get_image_type_from_bytes
 
+# Default base URL for OLLAMA
+OLLAMA_BASE_URL = 'http://localhost:11434/v1'
+
+# Check if the user set the OLLAMA_BASE_URL environment variable
+if os.getenv("OLLAMA_BASE_URL"):
+    OLLAMA_BASE_URL = os.getenv("OLLAMA_BASE_URL")
 
 class ChatOpenAI(EngineLM, CachedEngine):
     DEFAULT_SYSTEM_PROMPT = "You are a helpful, creative, and smart assistant."
@@ -26,23 +32,36 @@ def __init__(
         model_string: str="gpt-3.5-turbo-0613",
         system_prompt: str=DEFAULT_SYSTEM_PROMPT,
         is_multimodal: bool=False,
+        base_url: str=None,
         **kwargs):
         """
         :param model_string:
         :param system_prompt:
+        :param base_url: Used to support Ollama
         """
         root = platformdirs.user_cache_dir("textgrad")
         cache_path = os.path.join(root, f"cache_openai_{model_string}.db")
 
         super().__init__(cache_path=cache_path)
 
         self.system_prompt = system_prompt
-        if os.getenv("OPENAI_API_KEY") is None:
-            raise ValueError("Please set the OPENAI_API_KEY environment variable if you'd like to use OpenAI models.")
+        self.base_url = base_url
 
-        self.client = OpenAI(
-            api_key=os.getenv("OPENAI_API_KEY"),
-        )
+        if not base_url:
+            if os.getenv("OPENAI_API_KEY") is None:
+                raise ValueError("Please set the OPENAI_API_KEY environment variable if you'd like to use OpenAI models.")
+            
+            self.client = OpenAI(
+                api_key=os.getenv("OPENAI_API_KEY")
+            )
+        elif base_url and base_url == OLLAMA_BASE_URL:
+            self.client = OpenAI(
+                base_url=base_url,
+                api_key="ollama"
+            )
+        else:
+            raise ValueError("Invalid base URL provided. Please use the default OLLAMA base URL or None.")
+
         self.model_string = model_string
         self.is_multimodal = is_multimodal