const DEEPSEEK_BASE = process.env.DEEPSEEK_BASE_URL || "https://api.deepseek.com";
const DEEPSEEK_KEY = process.env.DEEPSEEK_API_KEY || "";
const DEEPSEEK_MODEL = process.env.DEEPSEEK_MODEL || "deepseek-chat";
const DEEPSEEK_ANTHROPIC = process.env.DEEPSEEK_ANTHROPIC === "true";

export async function aiChat(
  systemPrompt: string,
  userMessage: string
): Promise<string> {
  if (!DEEPSEEK_KEY) throw new Error("DeepSeek API key not configured");

  let url: string;
  let headers: Record<string, string>;
  let body: Record<string, unknown>;

  if (DEEPSEEK_ANTHROPIC) {
    // Anthropic Messages API
    url = `${DEEPSEEK_BASE}/v1/messages`;
    headers = {
      "Content-Type": "application/json",
      "x-api-key": DEEPSEEK_KEY,
      "anthropic-version": "2023-06-01",
    };
    body = {
      model: DEEPSEEK_MODEL,
      max_tokens: 2048,
      system: systemPrompt,
      messages: [{ role: "user", content: userMessage }],
    };
  } else {
    // OpenAI-compatible API (default)
    url = `${DEEPSEEK_BASE}/v1/chat/completions`;
    headers = {
      "Content-Type": "application/json",
      Authorization: `Bearer ${DEEPSEEK_KEY}`,
    };
    body = {
      model: DEEPSEEK_MODEL,
      temperature: 0.7,
      max_tokens: 2048,
      messages: [
        { role: "system", content: systemPrompt },
        { role: "user", content: userMessage },
      ],
    };
  }

  const res = await fetch(url, { method: "POST", headers, body: JSON.stringify(body) });

  if (!res.ok) {
    const err = await res.json().catch(() => ({}));
    throw new Error((err as { error?: { message?: string } }).error?.message || `API error: ${res.status}`);
  }

  const data = await res.json();
  // Anthropic format or OpenAI format
  const text = data?.content?.[0]?.text || data?.choices?.[0]?.message?.content || "";
  if (!text) throw new Error("AI returned empty response");
  return text;
}

export const AI_PROMPTS = {
  polish: "你是一个文字润色助手。请润色以下文字，使其更流畅、更有文采，但保持原意和语气不变。直接返回润色后的文字，不要加任何解释。",
  expand: "你是一个写作助手。请扩写以下文字，增加更多细节和论述，使其更充实。保持原风格和语气。直接返回扩写后的文字，不要加任何解释。",
  shorten: "你是一个写作助手。请缩写以下文字，保留核心信息，删除冗余。直接返回缩写后的文字，不要加任何解释。",
  fix: "你是一个文字校对助手。请修正以下文字中的错别字、语法错误和标点问题。直接返回修正后的文字，不要加任何解释。",
  summary: "根据以下文章标题和内容，生成一个简短的摘要（100字以内）。直接返回摘要，不要加任何解释。\n\n标题：{title}\n\n内容片段：{content}",
  tags: "根据以下文章标题和内容，提取3-5个中文标签（用顿号分隔）。只返回标签，不要加解释。\n\n标题：{title}\n\n内容片段：{content}",
};