import { RunnableSequence, RunnableMap } from '@langchain/core/runnables';
import ListLineOutputParser from '../lib/outputParsers/listLineOutputParser';
import { PromptTemplate } from '@langchain/core/prompts';
import formatChatHistoryAsString from '../utils/formatHistory';
import { BaseMessage } from '@langchain/core/messages';
import { BaseChatModel } from '@langchain/core/language_models/chat_models';
import { ChatOpenAI } from '@langchain/openai';

const suggestionGeneratorPrompt = `
You are an AI suggestion generator for an AI-powered search engine. Based on the conversation provided, generate 4-5 relevant suggestions that the user can use to ask the chat model for more information.

- Ensure each suggestion is relevant to the conversation and provides value to the user.
- The suggestions should be medium-length and informative, offering a path for the user to explore further.

Provide the suggestions in the following format, separated by newlines between the XML tags <suggestions> and </suggestions>:

<suggestions>
Suggestion 1
Suggestion 2
Suggestion 3
</suggestions>

Conversation:
{chat_history}
`;


type SuggestionGeneratorInput = {
  chat_history: BaseMessage[];
};

const outputParser = new ListLineOutputParser({
  key: 'suggestions',
});

const createSuggestionGeneratorChain = (llm: BaseChatModel) => {
  return RunnableSequence.from([
    RunnableMap.from({
      chat_history: (input: SuggestionGeneratorInput) =>
        formatChatHistoryAsString(input.chat_history),
    }),
    PromptTemplate.fromTemplate(suggestionGeneratorPrompt),
    llm,
    outputParser,
  ]);
};

const generateSuggestions = (
  input: SuggestionGeneratorInput,
  llm: BaseChatModel,
) => {
  (llm as unknown as ChatOpenAI).temperature = 0;
  const suggestionGeneratorChain = createSuggestionGeneratorChain(llm);
  return suggestionGeneratorChain.invoke(input);
};

export default generateSuggestions;