famapp/src/lib/llm/mock.ts

import type { ChatCompletionRequest, ChatCompletionResult, LlmClient } from "./types";
import { textFromMessageContent } from "./content";

function hadToolResults(messages: ChatCompletionRequest["messages"]): boolean {
  return messages.some((message) => message.role === "tool");
}

export function createMockLlmClient(): LlmClient {
  return {
    async chatCompletion(request: ChatCompletionRequest): Promise<ChatCompletionResult> {
      const userText = textFromMessageContent(
        [...request.messages].reverse().find((message) => message.role === "user")?.content ?? "",
      ).toLowerCase();

      if (hadToolResults(request.messages)) {
        return {
          message: {
            role: "assistant",
            content: "Done — I updated your household data using the API.",
          },
          finishReason: "stop",
        };
      }

      if (userText.includes("milk") && request.tools?.length) {
        return {
          message: {
            role: "assistant",
            content: null,
            tool_calls: [
              {
                id: "mock_call_add_item",
                type: "function",
                function: {
                  name: "add_list_item",
                  arguments: JSON.stringify({
                    listType: "shopping",
                    text: "milk",
                  }),
                },
              },
            ],
          },
          finishReason: "tool_calls",
        };
      }

      if (userText.includes("calendar") && request.tools?.length) {
        const now = new Date();
        const from = new Date(now);
        from.setDate(from.getDate() - 1);
        const to = new Date(now);
        to.setDate(to.getDate() + 7);

        return {
          message: {
            role: "assistant",
            content: null,
            tool_calls: [
              {
                id: "mock_call_list_events",
                type: "function",
                function: {
                  name: "list_events",
                  arguments: JSON.stringify({
                    from: from.toISOString(),
                    to: to.toISOString(),
                  }),
                },
              },
            ],
          },
          finishReason: "tool_calls",
        };
      }

      return {
        message: {
          role: "assistant",
          content:
            "I'm the famapp assistant (mock provider). Ask me to add items or check the calendar.",
        },
        finishReason: "stop",
      };
    },
  };
}