// ProtocolDetector（veridrop detectors/protocol.py）：被动，看所有应答是否符合 Messages API 的字段形状。
// 每一种问题只扣一次（10 分），衡量的是合不合规，不是出现了几次。

import type { Body } from "../client.js";
import type { DetectorResult } from "../models.js";
import { isInt, pyRepr } from "../py.js";
import { PassiveDetector } from "./base.js";

const VALID_STOP_REASONS = new Set<unknown>(["end_turn", "max_tokens", "stop_sequence", "tool_use", null, undefined]);
const VALID_CONTENT_BLOCK_TYPES = new Set([
  "text",
  "tool_use",
  "thinking",
  "redacted_thinking",
  "server_tool_use",
  "web_search_tool_result",
]);
const ISSUE_PENALTY = 10;

function nonNegInt(v: unknown): boolean {
  return isInt(v) && v >= 0;
}

export class ProtocolDetector extends PassiveDetector {
  readonly name = "protocol";
  readonly displayName = "协议规范性";
  readonly weight = 5;
  private readonly issues = new Set<string>();
  private observations = 0;

  override observe(_request: Body, response: Record<string, unknown>): void {
    this.observations++;
    const rid = response["id"];
    if (typeof rid !== "string" || !rid) this.issues.add("id_missing_or_not_string");
    if (response["type"] !== "message") this.issues.add(`type_invalid:${pyRepr(response["type"])}`);
    if (response["role"] !== "assistant") this.issues.add(`role_invalid:${pyRepr(response["role"])}`);
    const model = response["model"];
    if (typeof model !== "string" || !model) this.issues.add("model_missing_or_not_string");

    const content = response["content"];
    if (!Array.isArray(content)) {
      this.issues.add("content_not_array");
    } else {
      for (const block of content) {
        if (!block || typeof block !== "object" || Array.isArray(block)) {
          this.issues.add("content_block_not_object");
          continue;
        }
        const t = (block as Record<string, unknown>)["type"];
        if (typeof t !== "string") this.issues.add("content_block_missing_type");
        else if (!VALID_CONTENT_BLOCK_TYPES.has(t)) this.issues.add(`content_block_unknown_type:${pyRepr(t)}`);
      }
    }

    if (!VALID_STOP_REASONS.has(response["stop_reason"])) {
      this.issues.add(`stop_reason_invalid:${pyRepr(response["stop_reason"])}`);
    }
    const ss = response["stop_sequence"];
    if (!(ss === null || ss === undefined || typeof ss === "string")) this.issues.add("stop_sequence_wrong_type");

    const usage = response["usage"];
    if (!usage || typeof usage !== "object" || Array.isArray(usage)) {
      this.issues.add("usage_missing_or_not_object");
    } else {
      const u = usage as Record<string, unknown>;
      if (!nonNegInt(u["input_tokens"])) this.issues.add("usage_input_tokens_invalid");
      if (!nonNegInt(u["output_tokens"])) this.issues.add("usage_output_tokens_invalid");
      for (const opt of ["cache_read_input_tokens", "cache_creation_input_tokens"]) {
        if (opt in u && !nonNegInt(u[opt])) this.issues.add(`${opt}_wrong_type`);
      }
    }
    // 不查 anthropic-request-id 头：原仓库实测 api.anthropic.com 的 /v1/messages 也不回它。
  }

  finalize(): DetectorResult {
    if (this.observations === 0) return this.skip("no observations");
    const score = Math.max(0, 100 - this.issues.size * ISSUE_PENALTY);
    return this.result(score >= 70 ? "pass" : "fail", score, {
      observation_count: this.observations,
      issue_count: this.issues.size,
      issues: [...this.issues].sort(),
    });
  }
}