import random, time
from google import genai
from google.genai import errors, types

client = genai.Client(http_options=types.HttpOptions(
    retry_options=types.HttpRetryOptions(attempts=4, initial_delay=1.0, max_delay=60.0, exp_base=2.0, jitter=1.0)))

def generate(model: str, prompt: str) -> str:
    try:
        r = client.models.generate_content(model=model, contents=prompt,
                                           config=types.GenerateContentConfig(max_output_tokens=256))
    except errors.ClientError as e:            # 4xx (SDK already retried 429)
        if e.code == 404 and "no longer available to new users" in str(e):
            return generate("gemini-3.5-flash-lite", prompt)   # 2.5 family closed to new keys
        if e.code == 429:                        # free tier limit 0 / quota: back off or upgrade tier
            time.sleep(min(60, random.uniform(1, 5)))
        raise
    except errors.ServerError:                 # 5xx after retries -> fall back
        return generate("gemini-3.5-flash-lite", prompt)
    if r.prompt_feedback and r.prompt_feedback.block_reason:
        raise RuntimeError(f"prompt blocked: {r.prompt_feedback.block_reason}")
    cand = r.candidates[0]
    if cand.finish_reason and cand.finish_reason.name not in ("STOP", "MAX_TOKENS"):
        raise RuntimeError(f"generation stopped: {cand.finish_reason.name}")
    return r.text or ""

import { GoogleGenAI, ApiError } from "@google/genai";
const ai = new GoogleGenAI({ httpOptions: { timeout: 60_000 } });

const sleep = (ms: number) => new Promise(r => setTimeout(r, ms));
export async function generate(model: string, prompt: string, attempt = 0): Promise<string> {
  try {
    const r = await ai.models.generateContent({ model, contents: prompt, config: { maxOutputTokens: 256 } });
    if (r.promptFeedback?.blockReason) throw new Error(`prompt blocked: ${r.promptFeedback.blockReason}`);
    const fr = r.candidates?.[0]?.finishReason;
    if (fr && !["STOP", "MAX_TOKENS"].includes(fr)) throw new Error(`generation stopped: ${fr}`);
    return r.text ?? "";
  } catch (e) {
    if (e instanceof ApiError) {
      const retryable = [429, 500, 503, 504].includes(e.status);
      if (retryable && attempt < 4) {
        const m = /retry in ([\d.]+)s/.exec(e.message);              // 429 message carries the delay
        await sleep(m ? Number(m[1]) * 1000 : 2 ** attempt * 1000 + Math.random() * 500);
        return generate(model, prompt, attempt + 1);
      }
      if (e.status === 404 && e.message.includes("no longer available to new users"))
        return generate("gemini-3.5-flash-lite", prompt, attempt);
    }
    throw e;
  }
}