/**
 * POST /.netlify/functions/chat-claude
 * Body: { messages: [{role:"user"|"assistant"|"system", content:"..."}], system?: string, max_tokens?: number }
 * Env: ANTHROPIC_API_KEY, ANTHROPIC_MODEL (optional, defaults to claude-3-5-sonnet-latest)
 */
export async function handler(event) {
  if (event.httpMethod === "OPTIONS") {
    return {
      statusCode: 204,
      headers: {
        "Access-Control-Allow-Origin": "*",
        "Access-Control-Allow-Headers": "Content-Type",
        "Access-Control-Allow-Methods": "POST, OPTIONS",
      },
    };
  }
  if (event.httpMethod !== "POST") {
    return { statusCode: 405, body: "Method Not Allowed" };
  }

  const headers = {
    "Content-Type": "application/json",
    "Access-Control-Allow-Origin": "*",
  };

  const key = process.env.ANTHROPIC_API_KEY;
  if (!key) {
    return {
      statusCode: 200,
      headers,
      body: JSON.stringify({
        ok: false,
        error: "Missing ANTHROPIC_API_KEY in Netlify environment.",
      }),
    };
  }

  let payload = {};
  try {
    payload = JSON.parse(event.body || "{}");
  } catch {}

  const model = process.env.ANTHROPIC_MODEL || "claude-3-5-sonnet-latest";
  const max_tokens = Math.min(1024, Math.max(128, payload.max_tokens || 512));
  const system = payload.system || "You are Volt, a concise, helpful assistant.";

  const body = {
    model,
    max_tokens,
    system,
    messages: payload.messages || [],
  };

  try {
    const resp = await fetch("https://api.anthropic.com/v1/messages", {
      method: "POST",
      headers: {
        "content-type": "application/json",
        "x-api-key": key,
        "anthropic-version": "2023-06-01",
      },
      body: JSON.stringify(body),
    });
    const data = await resp.json();
    if (!resp.ok) {
      return {
        statusCode: 200,
        headers,
        body: JSON.stringify({ ok: false, error: data.error || data }),
      };
    }

    const text =
      (data.content && data.content[0] && data.content[0].text) ||
      JSON.stringify(data);
    return {
      statusCode: 200,
      headers,
      body: JSON.stringify({ ok: true, text, raw: data }),
    };
  } catch (err) {
    return {
      statusCode: 200,
      headers,
      body: JSON.stringify({ ok: false, error: String(err) }),
    };
  }
}