import { requireUser } from "#server/utils/context";
import { getProviderById, getModelById } from "#server/service/llm";
import { createOpenAICompatible } from "@ai-sdk/openai-compatible";
import { streamText, type LanguageModelV1 } from "ai";
import log4js from "logger";

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

function resolveModel(
  provider: {
    name: string;
    apiKey: string | null;
    baseUrl: string | null;
    parseMode: string;
  },
  modelId: string,
): LanguageModelV1 {
  const baseUrl = provider.baseUrl?.replace(/\/+$/, "") || undefined;

  if (provider.parseMode === "anthropic") {
    throw createError({
      statusCode: 400,
      statusMessage: "Anthropic 解析模式暂不支持流式对话，请使用 OpenAI 兼容模式",
    });
  }

  const openaiCompatible = createOpenAICompatible({
    name: provider.name,
    apiKey: provider.apiKey || undefined,
    baseURL: baseUrl || "https://api.openai.com/v1",
  });

  return openaiCompatible(modelId) as LanguageModelV1;
}

export default defineEventHandler(async (event) => {
  const user = await requireUser(event);
  if (!user) {
    throw createError({ statusCode: 401, statusMessage: "未登录" });
  }

  const body = await readBody(event);
  const { modelId: llmModelId, messages, enableThinking } = body as {
    modelId: number;
    messages: { role: "user" | "assistant" | "system"; content: string }[];
    enableThinking?: boolean;
  };

  if (!llmModelId || !messages || !Array.isArray(messages) || messages.length === 0) {
    throw createError({ statusCode: 400, statusMessage: "参数无效" });
  }

  const model = await getModelById(llmModelId, user.id);
  if (!model) {
    throw createError({ statusCode: 404, statusMessage: "模型不存在" });
  }

  const provider = await getProviderById(model.providerId, user.id);
  if (!provider) {
    throw createError({ statusCode: 404, statusMessage: "供应商不存在" });
  }

  if (provider.status !== "active") {
    throw createError({ statusCode: 400, statusMessage: "供应商已禁用" });
  }

  if (!provider.apiKey) {
    throw createError({ statusCode: 400, statusMessage: "供应商未配置 API Key" });
  }

  logger.info(
    "[%s] [LLM-CHAT] userId=%d modelId=%d provider=%s parseMode=%s messages=%d thinking=%s",
    event.context.requestId ?? "-",
    user.id,
    llmModelId,
    provider.name,
    provider.parseMode,
    messages.length,
    enableThinking ? "on" : "off",
  );

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

  const result = streamText({
    model: languageModel,
    messages,
    maxTokens: model.maxTokens || undefined,
    ...(enableThinking
      ? {
          providerOptions: {
            openaiCompatible: { reasoningEffort: "high" },
          },
        }
      : {}),
  });

  return result.toDataStreamResponse({ sendReasoning: true });
});