import { exec } from "node:child_process";

const DEFAULT_TIMEOUT_MS = 5_000;

/** Every environment key owned by HooKit rather than inherited ambiently. */
const MANAGED_ENVIRONMENT_KEYS = [
  "PI_SESSION_ID",
  "PI_SESSION_FILE",
  "PI_SESSION_NAME",
  "PI_SESSION_LEAF_ID",
  "PI_PROVIDER",
  "PI_MODEL",
  "PI_REASONING_LEVEL",
  "PI_MODE",
  "PI_PROJECT_TRUSTED",
  "PI_CONTEXT_TOKENS",
  "PI_CONTEXT_WINDOW",
  "PI_CONTEXT_PERCENT",
  "PI_HOOK_REF",
  "PI_HOOK_EVENT",
  "PI_HOOK_INVOCATION_ID",
  "PI_HOOK_RUN_ID",
  "PI_EVENT",
  "PI_EVENT_PAYLOAD",
  "PI_TOOL_NAME",
  "PI_TOOL_CALL_ID",
  "PI_TOOL_INPUT",
  "PI_TOOL_RESULT",
  "PI_TOOL_IS_ERROR",
  "PI_CWD",
] as const;

export interface ShellResult {
  readonly passed: boolean;
  readonly code: number | null;
  /** Whether the command started for execution accounting (virtual or real). */
  readonly started: boolean;
}

/**
 * Evaluate one command. Exact `true` and `false` are normal, accounted
 * command results that avoid spawning /bin/sh; every other string uses exec.
 */
export function evaluateShell(
  shell: string,
  env: Record<string, string>,
  signal: AbortSignal | undefined,
  cwd: string,
): Promise<ShellResult> {
  if (signal?.aborted) {
    return Promise.resolve({ passed: false, code: null, started: false });
  }
  if (shell === "true") {
    return Promise.resolve({ passed: true, code: 0, started: true });
  }
  if (shell === "false") {
    return Promise.resolve({ passed: false, code: 1, started: true });
  }

  return new Promise<ShellResult>((resolve) => {
    const inherited = { ...process.env };
    for (const key of MANAGED_ENVIRONMENT_KEYS) delete inherited[key];

    try {
      const child = exec(shell, {
        env: { ...inherited, ...env, PWD: cwd },
        timeout: DEFAULT_TIMEOUT_MS,
        signal,
        cwd,
      });

      let started = false;
      child.on("spawn", () => {
        started = true;
      });
      child.on("error", (error: NodeJS.ErrnoException) => {
        if (
          error.name === "AbortError" ||
          signal?.aborted ||
          (error as unknown as { killed?: boolean }).killed
        ) {
          resolve({ passed: false, code: null, started });
          return;
        }
        resolve({ passed: false, code: null, started });
      });
      child.on("close", (code: number | null) => {
        resolve({ passed: code === 0, code, started });
      });
    } catch {
      resolve({ passed: false, code: null, started: false });
    }
  });
}