// ThinkingSignatureDetector（veridrop detectors/thinking_signature.py）⭐：thinking 块带的 signature 是 Anthropic 服务端
// 生成的加密产物，中转站伪造不了。
//   100 有 thinking（或 redacted_thinking）块，签名非空且够长
//    70 有块、有签名但短得可疑
//    30 有块、没签名
//     0 没有 thinking 块
// 只支持 adaptive 的型号（Opus 4.7 起、本移植加的 Claude 5 系列）发 {type: adaptive, display: summarized} + output_config.effort；
// 两种都支持的（Sonnet 4.6）优先 extended（budget_tokens 好控成本）。都用非流式（原仓库实测流式 + adaptive 会丢 thinking 块）。

import { lookupModel, normalizeModelId } from "../config.js";
import type { DetectorResult } from "../models.js";
import { ActiveDetector, errText, type DetectClient } from "./base.js";

/** 多步辗转相除：难到 adaptive 会决定思考；数字故意不用官方文档那组 1071 / 462。 */
const PROBE_PROMPT = "Find the greatest common divisor of 2378 and 1547 using the Euclidean algorithm.";
const THINKING_BUDGET_TOKENS = 2000;
const MAX_TOKENS = 16000;
const SIGNATURE_MIN_LEN = 50;

export function adaptiveEffortForModel(model: string): string {
  const n = normalizeModelId(model);
  if (n.startsWith("claude-opus-4-7") || n.startsWith("claude-opus-4-8")) return "xhigh";
  return "high";
}

export class ThinkingSignatureDetector extends ActiveDetector {
  readonly name = "thinking_signature";
  readonly displayName = "思维签名验证";
  readonly weight = 25;

  override appliesTo(model: string): boolean {
    const info = lookupModel(model);
    if (info === null) return false;
    return info.supportsExtendedThinking || info.supportsAdaptiveThinking;
  }

  async run(client: DetectClient, model: string): Promise<DetectorResult> {
    const info = lookupModel(model);
    if (info === null) return this.skip("unknown model");

    let thinking: Record<string, unknown>;
    const extra: Record<string, unknown> = {};
    if (info.supportsExtendedThinking) {
      thinking = { type: "enabled", budget_tokens: THINKING_BUDGET_TOKENS };
    } else if (info.supportsAdaptiveThinking) {
      thinking = { type: "adaptive", display: "summarized" };
      extra["output_config"] = { effort: adaptiveEffortForModel(model) };
    } else {
      return this.skip("model lacks thinking support");
    }

    let resp: Record<string, unknown>;
    try {
      ({ resp } = await client.messagesCreate({
        model,
        max_tokens: MAX_TOKENS,
        thinking,
        messages: [{ role: "user", content: PROBE_PROMPT }],
        ...extra,
      }));
    } catch (e) {
      return this.result(
        "error",
        0,
        { thinking_params: thinking, output_config_sent: extra["output_config"] ?? null },
        null,
        errText(e),
      );
    }

    let seen = false;
    let blockType: string | null = null;
    let signature = "";
    let thinkingChars = 0;
    const typesSeen: string[] = [];
    const content = Array.isArray(resp["content"]) ? (resp["content"] as unknown[]) : [];
    for (const block of content) {
      if (!block || typeof block !== "object" || Array.isArray(block)) continue;
      const b = block as Record<string, unknown>;
      const t = b["type"];
      if (typeof t === "string") typesSeen.push(t);
      if (t === "thinking" || t === "redacted_thinking") {
        seen = true;
        blockType = t;
        const sig = b["signature"];
        if (typeof sig === "string" && !signature) signature = sig;
        const text = b["thinking"];
        if (typeof text === "string") thinkingChars += Array.from(text).length;
      }
    }

    const details: Record<string, unknown> = {
      thinking_params: thinking,
      output_config_sent: extra["output_config"] ?? null,
      content_block_types_seen: typesSeen,
      thinking_block_seen: seen,
      thinking_block_type: blockType,
      thinking_text_chars: thinkingChars,
      signature_received: Boolean(signature),
      signature_length: Array.from(signature).length,
      signature_prefix: signature ? Array.from(signature).slice(0, 32).join("") : "",
      stop_reason: resp["stop_reason"] ?? null,
    };

    let score: number;
    let note: string;
    if (!seen) [score, note] = [0, "no_thinking_block"];
    else if (!signature) [score, note] = [30, "thinking_block_but_no_signature"];
    else if (Array.from(signature).length < SIGNATURE_MIN_LEN) [score, note] = [70, "signature_too_short"];
    else [score, note] = [100, "ok"];
    details["evaluation"] = note;
    return this.result(score >= 70 ? "pass" : "fail", score, details);
  }
}