import { readdirSync, readFileSync } from "node:fs";
import { join } from "node:path";

/** Pi 会话里的 research_check：请求和结果按 toolCallId 配对，不把超限请求算成执行。 */
export function lightCheckUsage(sessionDir: string, maxCount: number) {
  type Part = { type: string; id?: string; name?: string; text?: string };
  type Message = {
    role: string;
    toolCallId?: string;
    toolName?: string;
    isError?: boolean;
    content: Part[];
  };
  const requests: Array<{ id: string; file: string; line: number }> = [];
  const results = new Map<
    string,
    { file: string; line: number; message: Message }
  >();
  const files = readdirSync(sessionDir)
    .filter((f) => f.endsWith(".jsonl"))
    .sort();
  if (files.length === 0) throw new Error(`没有会话文件：${sessionDir}`);
  for (const file of files) {
    readFileSync(join(sessionDir, file), "utf8")
      .split("\n")
      .forEach((line, index) => {
        if (!line.trim()) return;
        const entry = JSON.parse(line) as { type: string; message?: Message };
        const m = entry.message;
        if (entry.type !== "message" || m === undefined) return;
        if (m.role === "assistant") {
          for (const p of m.content)
            if (p.type === "toolCall" && p.name === "research_check")
              requests.push({ id: p.id!, file, line: index + 1 });
        } else if (m.role === "toolResult" && m.toolName === "research_check")
          results.set(m.toolCallId!, { file, line: index + 1, message: m });
      });
  }
  const checks = requests.map((request) => {
    const result = results.get(request.id);
    if (result === undefined)
      return { request, result: null, status: "missingResult", used: null };
    const text = result.message.content
      .filter((p) => p.type === "text")
      .map((p) => p.text)
      .join("\n");
    const source = { file: result.file, line: result.line, text };
    if (result.message.isError)
      return { request, result: source, status: "toolError", used: null };
    if (text.startsWith("本次调用的轻量检查已用完"))
      return { request, result: source, status: "deniedLimit", used: null };
    const value = JSON.parse(text) as {
      used: number;
      maxCount: number;
      seconds: number;
      result: unknown;
    };
    return { request, result: source, status: "executed", used: value.used };
  });
  const used = checks.flatMap((c) => (c.used === null ? [] : [c.used]));
  const unresolved = checks.some(
    (c) => c.status === "missingResult" || c.status === "toolError",
  );
  return {
    sessionDir,
    maxCount,
    requested: checks.length,
    executed: used.length,
    deniedLimit: checks.filter((c) => c.status === "deniedLimit").length,
    // 工具报错或缺结果时不能猜实际执行量，也不当作 0 次通过。
    pass:
      !unresolved &&
      used.length <= maxCount &&
      used.every((n, i) => n === i + 1),
    checks,
  };
}