Add cohere chat generator (#88)

* add cohere chat generator

Signed-off-by: sunilkumardash9 <[email protected]>

* remove chat_message.py

Signed-off-by: sunilkumardash9 <[email protected]>

* add unit and integration tests

Signed-off-by: sunilkumardash9 <[email protected]>

* improve tests

Signed-off-by: sunilkumardash9 <[email protected]>

* fix lint errors

Signed-off-by: sunilkumardash9 <[email protected]>

* fix lint errors(1)

Signed-off-by: sunilkumardash9 <[email protected]>

* 1. add releasenote
2. add doc strings
3. change metadata to match other chat generators

Signed-off-by: sunilkumardash9 <[email protected]>

* 1. Adds ChatRole and convert default role to Cohere compliant role
2. Adds a unit test for 1

Signed-off-by: sunilkumardash9 <[email protected]>

* remove releasenotes

Signed-off-by: sunilkumardash9 <[email protected]>

---------

Signed-off-by: sunilkumardash9 <[email protected]>
Co-authored-by: Massimiliano Pippi <[email protected]>

integrations/cohere/pyproject.toml

@@ -174,7 +174,9 @@ ignore_missing_imports = true
 addopts = "--strict-markers"
 markers = [
   "integration: integration tests",
+  "unit: unit tests",
   "embedders: embedders tests",
   "generators: generators tests",
+  "chat_generators: chat_generators tests",
 ]
 log_cli = true

integrations/cohere/src/cohere_haystack/chat/chat_generator.py

@@ -0,0 +1,203 @@
+import logging
+import os
+from typing import Any, Callable, Dict, List, Optional
+
+from haystack import component, default_from_dict, default_to_dict
+from haystack.components.generators.utils import deserialize_callback_handler, serialize_callback_handler
+from haystack.dataclasses import ChatMessage, ChatRole, StreamingChunk
+from haystack.lazy_imports import LazyImport
+
+with LazyImport(message="Run 'pip install cohere'") as cohere_import:
+    import cohere
+logger = logging.getLogger(__name__)
+
+
+class CohereChatGenerator:
+    """Enables text generation using Cohere's chat endpoint. This component is designed to inference
+    Cohere's chat models.
+
+    Users can pass any text generation parameters valid for the `cohere.Client,chat` method
+    directly to this component via the `**generation_kwargs` parameter in __init__ or the `**generation_kwargs`
+    parameter in `run` method.
+
+    Invocations are made using 'cohere' package.
+    See [Cohere API](https://docs.cohere.com/reference/chat) for more details.
+    """
+
+    def __init__(
+        self,
+        api_key: Optional[str] = None,
+        model_name: str = "command",
+        streaming_callback: Optional[Callable[[StreamingChunk], None]] = None,
+        api_base_url: Optional[str] = None,
+        generation_kwargs: Optional[Dict[str, Any]] = None,
+        **kwargs,
+    ):
+        """
+        Initialize the CohereChatGenerator instance.
+
+        :param api_key: The API key for the Cohere API. If not set, it will be read from the COHERE_API_KEY env var.
+        :param model_name: The name of the model to use. Available models are: [command, command-light, command-nightly,
+            command-nightly-light]. Defaults to "command".
+        :param streaming_callback: A callback function to be called with the streaming response. Defaults to None.
+        :param api_base_url: The base URL of the Cohere API. Defaults to "https://api.cohere.ai".
+        :param generation_kwargs: Additional model parameters. These will be used during generation. Refer to
+            https://docs.cohere.com/reference/chat for more details.
+            Some of the parameters are:
+            - 'chat_history': A list of previous messages between the user and the model, meant to give the model
+               conversational context for responding to the user's message.
+            - 'preamble_override': When specified, the default Cohere preamble will be replaced with the provided one.
+            - 'conversation_id': An alternative to chat_history. Previous conversations can be resumed by providing
+               the conversation's identifier. The contents of message and the model's response will be stored
+               as part of this conversation.If a conversation with this id does not already exist,
+               a new conversation will be created.
+            - 'prompt_truncation': Defaults to AUTO when connectors are specified and OFF in all other cases.
+               Dictates how the prompt will be constructed.
+            - 'connectors': Accepts {"id": "web-search"}, and/or the "id" for a custom connector, if you've created one.
+                When specified, the model's reply will be enriched with information found by
+                quering each of the connectors (RAG).
+            - 'documents': A list of relevant documents that the model can use to enrich its reply.
+            - 'search_queries_only': Defaults to false. When true, the response will only contain a
+               list of generated search queries, but no search will take place, and no reply from the model to the
+               user's message will be generated.
+            - 'citation_quality': Defaults to "accurate". Dictates the approach taken to generating citations
+                as part of the RAG flow by allowing the user to specify whether they want
+                "accurate" results or "fast" results.
+            - 'temperature': A non-negative float that tunes the degree of randomness in generation. Lower temperatures
+                mean less random generations.
+        """
+        cohere_import.check()
+
+        if not api_key:
+            api_key = os.environ.get("COHERE_API_KEY")
+        if not api_key:
+            error = "CohereChatGenerator needs an API key to run. Either provide it as init parameter or set the env var COHERE_API_KEY."  # noqa: E501
+            raise ValueError(error)
+
+        if not api_base_url:
+            api_base_url = cohere.COHERE_API_URL
+        if generation_kwargs is None:
+            generation_kwargs = {}
+        self.api_key = api_key
+        self.model_name = model_name
+        self.streaming_callback = streaming_callback
+        self.api_base_url = api_base_url
+        self.generation_kwargs = generation_kwargs
+        self.model_parameters = kwargs
+        self.client = cohere.Client(api_key=self.api_key, api_url=self.api_base_url)
+
+    def _get_telemetry_data(self) -> Dict[str, Any]:
+        """
+        Data that is sent to Posthog for usage analytics.
+        """
+        return {"model": self.model_name}
+
+    def to_dict(self) -> Dict[str, Any]:
+        """
+        Serialize this component to a dictionary.
+        :return: The serialized component as a dictionary.
+        """
+        callback_name = serialize_callback_handler(self.streaming_callback) if self.streaming_callback else None
+        return default_to_dict(
+            self,
+            model_name=self.model_name,
+            streaming_callback=callback_name,
+            api_base_url=self.api_base_url,
+            generation_kwargs=self.generation_kwargs,
+        )
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any]) -> "CohereChatGenerator":
+        """
+        Deserialize this component from a dictionary.
+        :param data: The dictionary representation of this component.
+        :return: The deserialized component instance.
+        """
+        init_params = data.get("init_parameters", {})
+        serialized_callback_handler = init_params.get("streaming_callback")
+        if serialized_callback_handler:
+            data["init_parameters"]["streaming_callback"] = deserialize_callback_handler(serialized_callback_handler)
+        return default_from_dict(cls, data)
+
+    def _message_to_dict(self, message: ChatMessage) -> Dict[str, str]:
+        if message.role == ChatRole.USER:
+            role = "User"
+        elif message.role == ChatRole.ASSISTANT:
+            role = "Chatbot"
+        chat_message = {"user_name": role, "text": message.content}
+        return chat_message
+
+    @component.output_types(replies=List[ChatMessage])
+    def run(self, messages: List[ChatMessage], generation_kwargs: Optional[Dict[str, Any]] = None):
+        """
+        Invoke the text generation inference based on the provided messages and generation parameters.
+
+        :param messages: A list of ChatMessage instances representing the input messages.
+        :param generation_kwargs: Additional keyword arguments for text generation. These parameters will
+        potentially override the parameters passed in the __init__ method.
+        For more details on the parameters supported by the Cohere API, refer to the
+        Cohere [documentation](https://docs.cohere.com/reference/chat).
+        :return: A list containing the generated responses as ChatMessage instances.
+        """
+        # update generation kwargs by merging with the generation kwargs passed to the run method
+        generation_kwargs = {**self.generation_kwargs, **(generation_kwargs or {})}
+        chat_history = [self._message_to_dict(m) for m in messages[:-1]]
+        response = self.client.chat(
+            message=messages[-1].content,
+            model=self.model_name,
+            stream=self.streaming_callback is not None,
+            chat_history=chat_history,
+            **generation_kwargs,
+        )
+        if self.streaming_callback:
+            for chunk in response:
+                if chunk.event_type == "text-generation":
+                    stream_chunk = self._build_chunk(chunk)
+                    self.streaming_callback(stream_chunk)
+            chat_message = ChatMessage.from_assistant(content=response.texts)
+            chat_message.metadata.update(
+                {
+                    "model": self.model_name,
+                    "usage": response.token_count,
+                    "index": 0,
+                    "finish_reason": response.finish_reason,
+                    "documents": response.documents,
+                    "citations": response.citations,
+                }
+            )
+        else:
+            chat_message = self._build_message(response)
+        return {"replies": [chat_message]}
+
+    def _build_chunk(self, chunk) -> StreamingChunk:
+        """
+        Converts the response from the Cohere API to a StreamingChunk.
+        :param chunk: The chunk returned by the OpenAI API.
+        :param choice: The choice returned by the OpenAI API.
+        :return: The StreamingChunk.
+        """
+        # if chunk.event_type == "text-generation":
+        chat_message = StreamingChunk(
+            content=chunk.text, metadata={"index": chunk.index, "event_type": chunk.event_type}
+        )
+        return chat_message
+
+    def _build_message(self, cohere_response):
+        """
+        Converts the non-streaming response from the Cohere API to a ChatMessage.
+        :param cohere_response: The completion returned by the Cohere API.
+        :return: The ChatMessage.
+        """
+        content = cohere_response.text
+        message = ChatMessage.from_assistant(content=content)
+        message.metadata.update(
+            {
+                "model": self.model_name,
+                "usage": cohere_response.token_count,
+                "index": 0,
+                "finish_reason": None,
+                "documents": cohere_response.documents,
+                "citations": cohere_response.citations,
+            }
+        )
+        return message