import { generateText } from "ai";
import { createOpenAICompatible } from "@ai-sdk/openai-compatible";
import { type LanguageModel } from "ai";
import { getSystemModelWithProviderById, getModelWithProviderById } from "#server/service/llm";
import { updateSession } from "./session";
import log4js from "logger";

const logger = log4js.getLogger("APP");

function resolveModel(
  provider: {
    name: string;
    apiKey: string | null;
    baseUrl: string | null;
    parseMode: string;
  },
  modelId: string,
): LanguageModel {
  const baseUrl = provider.baseUrl?.replace(/\/+$/, "") || undefined;
  const openaiCompatible = createOpenAICompatible({
    name: provider.name,
    apiKey: provider.apiKey || undefined,
    baseURL: baseUrl || "https://api.openai.com/v1",
  });
  return openaiCompatible(modelId) as LanguageModel;
}

export async function generateSessionTitle(
  sessionId: string,
  firstUserMessage: string,
  firstAssistantMessage: string,
  titleModelId: number,
  userId: number | null,
): Promise<void> {
  try {
    const modelRow = userId
      ? await getModelWithProviderById(titleModelId, userId)
      : await getSystemModelWithProviderById(titleModelId);
    if (!modelRow) {
      logger.warn("[AGENT-TITLE] titleModelId=%d not found, skip", titleModelId);
      return;
    }

    const { model, provider } = modelRow;
    if (!provider.apiKey) {
      logger.warn("[AGENT-TITLE] provider has no apiKey, skip");
      return;
    }

    const languageModel = resolveModel(provider, model.modelId);

    const prompt = `请根据以下对话生成一个简短的标题（不超过20个字，不要加引号、不要加书名号）：

用户: ${firstUserMessage.slice(0, 500)}
助手: ${firstAssistantMessage.slice(0, 500)}

标题:`;

    const result = await generateText({
      model: languageModel,
      prompt,
      maxOutputTokens: 200,
    });

    const title = result.text.trim().slice(0, 100);

    if (title) {
      await updateSession(sessionId, { title });
      logger.info("[AGENT-TITLE] sessionId=%s title=%s", sessionId, title);
    }
  } catch (err) {
    logger.error("[AGENT-TITLE] sessionId=%s error: %s", sessionId, err instanceof Error ? err.message : String(err));
  }
}