// The human transport (lead decision 70): run
// `packages/bus/src/human-cli.mjs <socket>` as a child, write
// `{business, verb, args}` on its stdin, read the JSON reply on its stdout,
// or one bus error code on its stderr. The bus does the proof: the child
// re-executes itself with a nonce and the broker checks the process and its
// ancestry for agent markers. Nothing here carries a capability.

import { spawnSync } from "node:child_process";
import { fileURLToPath } from "node:url";
import { CliError } from "./errors.mjs";

export const HUMAN_CLI = fileURLToPath(new URL("../../bus/src/human-cli.mjs", import.meta.url));

// The broker's markers (packages/bus/src/human.mjs). The broker checks the
// whole ancestry; this check is only the clear early message for the case
// it would refuse anyway.
export const AGENT_MARKERS = Object.freeze([
  "MOSAIC_BUS_CAP",
  "MOSAIC_RUN_ID",
  "MOSAIC_AGENT_RUN",
  "CLAUDECODE",
  "CLAUDE_CODE_ENTRYPOINT",
  "CODEX_THREAD_ID",
  "PI_AGENT_DIR",
]);

export function refuseInsideAgent(env = process.env) {
  const found = AGENT_MARKERS.filter((k) => env[k]);
  if (found.length > 0) {
    throw new CliError(`refused: this runs only from a human shell, outside any agent run (found ${found.join(", ")} in the environment)`, 3);
  }
}

// Exit codes by bus error code; anything else is invalid input (2).
const EXIT = {
  "human-required": 3,
  unauthenticated: 3,
  "unknown-business": 3,
  "read-only": 3,
  "outcome-unknown": 1,
  "response-too-large": 1,
  "invalid-response": 1,
};

export function busExit(code) {
  return EXIT[code] ?? 2;
}

// Returns a call(verb, args) for one business. `cli` and `spawn` exist for
// the tests; the command line never sets them.
export function humanTransport({ socket, business, env = process.env, cli = HUMAN_CLI, spawn = spawnSync, timeoutMs = 30000 }) {
  return async function call(verb, args = {}) {
    const proc = spawn(process.execPath, [cli, socket], {
      input: `${JSON.stringify({ business, verb, args })}\n`,
      encoding: "utf8",
      env,
      timeout: timeoutMs,
      maxBuffer: 8 * 1024 * 1024,
    });
    if (proc.error || proc.status === null) throw new CliError("outcome-unknown: the bus transport did not finish", 1);
    if (proc.status !== 0) {
      const code = String(proc.stderr ?? "").trim().split("\n").reverse().find((l) => /^[a-z-]{1,64}$/.test(l)) ?? "invalid-response";
      const error = new CliError(code, busExit(code));
      error.code = code;
      throw error;
    }
    try {
      return JSON.parse(proc.stdout);
    } catch {
      const error = new CliError("invalid-response", 1);
      error.code = "invalid-response";
      throw error;
    }
  };
}