/**
 * Shared helpers for the grok-glance hook scripts and CLI.
 *
 * Deliberately dependency-free and stdlib-only: these run on the critical path of
 * every Grok Build tool call, so they must start fast and never wedge a session.
 */

import fs from "node:fs";
import path from "node:path";
import os from "node:os";
import crypto from "node:crypto";
import { fileURLToPath } from "node:url";

export const PLUGIN_ROOT = path.resolve(fileURLToPath(import.meta.url), "../..");

export const DEFAULT_PORT = 8791;

/**
 * State lives in one fixed place so that hooks (which get GROK_PLUGIN_DATA) and the
 * CLI (which does not) always agree on where config, credentials and events are.
 */
export function glanceHome() {
  if (process.env.GLANCE_HOME) return path.resolve(process.env.GLANCE_HOME);
  return path.join(os.homedir(), ".grok", "glance");
}

export function readConfig() {
  const file = path.join(glanceHome(), "config.json");
  let raw = {};
  try {
    raw = JSON.parse(fs.readFileSync(file, "utf8"));
  } catch {
    // No config yet, or unreadable: defaults are always usable.
  }
  const port = Number(process.env.GLANCE_PORT ?? raw.port ?? DEFAULT_PORT);
  return {
    ...raw,
    port: Number.isFinite(port) ? port : DEFAULT_PORT,
    host: raw.host ?? "127.0.0.1",
  };
}

export function baseUrl(cfg = readConfig()) {
  return `http://127.0.0.1:${cfg.port}`;
}

/** Header the daemon expects on /hook/*; kept in step with server/src/auth.ts. */
export const HOOK_HEADER = "x-glance-hook";

/**
 * The shared secret that admits a caller to /hook/*. Read fresh on every invocation so a
 * regenerated secret is picked up without touching hooks.json.
 *
 * `create` is used by the build-time generator; the hook scripts pass false and simply get
 * null when there is no secret yet. That is deliberate: a hook must never be the thing that
 * creates state, and a missing secret has to degrade to "no telemetry", not "no tool call".
 */
export function hookSecret({ create = false } = {}) {
  const file = path.join(glanceHome(), "hook.secret");
  for (let attempt = 0; attempt < 2; attempt++) {
    try {
      const existing = fs.readFileSync(file, "utf8").trim();
      if (existing) return existing;
    } catch {
      /* fall through */
    }
    if (!create) return null;
    fs.mkdirSync(glanceHome(), { recursive: true, mode: 0o700 });
    const token = crypto.randomBytes(32).toString("base64url");
    try {
      // Exclusive: if the daemon created one a millisecond ago, read theirs instead.
      fs.writeFileSync(file, token + "\n", { mode: 0o600, flag: "wx" });
      return token;
    } catch {
      /* lost the race; loop re-reads */
    }
  }
  try {
    return fs.readFileSync(file, "utf8").trim() || null;
  } catch {
    return null;
  }
}

export function hookHeaders() {
  const token = hookSecret();
  return token ? { [HOOK_HEADER]: token } : {};
}

/**
 * How long the PreToolUse approval hook is allowed to run, in seconds.
 *
 * One formula, two consumers: scripts/gen-hooks.mjs writes it into hooks.json as the hook's
 * `timeout`, and glance-approve.mjs derives its own wait from it. They must agree — if the
 * script outlives its hook timeout, Grok Build kills it and the fail-open path never runs.
 */
export function approvalHookTimeoutSecs(cfg = readConfig()) {
  const ms = Number(cfg.approval?.timeoutMs ?? 90_000);
  const base = Number.isFinite(ms) && ms > 0 ? ms : 90_000;
  return Math.ceil(base / 1000) + 35;
}

/** Read the hook payload that Grok Build writes to stdin. Returns {} if there is none. */
export async function readStdinJson() {
  if (process.stdin.isTTY) return {};
  const chunks = [];
  try {
    for await (const chunk of process.stdin) chunks.push(chunk);
  } catch {
    return {};
  }
  const text = Buffer.concat(chunks).toString("utf8").trim();
  if (!text) return {};
  try {
    return JSON.parse(text);
  } catch {
    return {};
  }
}

/**
 * Grok Build also passes the event in the environment. We merge it in so a payload that
 * is missing fields (or absent entirely) still produces a usable event.
 */
export function envEnvelope(payload) {
  return {
    hookEventName: payload.hookEventName ?? process.env.GROK_HOOK_EVENT ?? "Unknown",
    sessionId: payload.sessionId ?? process.env.GROK_SESSION_ID ?? "unknown",
    workspaceRoot:
      payload.workspaceRoot ?? process.env.GROK_WORKSPACE_ROOT ?? payload.cwd ?? process.cwd(),
    cwd: payload.cwd ?? process.cwd(),
    hookName: process.env.GROK_HOOK_NAME ?? undefined,
    ...payload,
  };
}

export async function postJson(url, body, timeoutMs, extraHeaders = {}) {
  const res = await fetch(url, {
    method: "POST",
    headers: { "content-type": "application/json", ...extraHeaders },
    body: JSON.stringify(body),
    signal: AbortSignal.timeout(timeoutMs),
  });
  const text = await res.text();
  if (!text) return { status: res.status, data: null };
  try {
    return { status: res.status, data: JSON.parse(text) };
  } catch {
    return { status: res.status, data: null };
  }
}

export async function isDaemonUp(cfg = readConfig(), timeoutMs = 400) {
  try {
    const res = await fetch(`${baseUrl(cfg)}/healthz`, {
      signal: AbortSignal.timeout(timeoutMs),
    });
    return res.ok;
  } catch {
    return false;
  }
}

export const sleep = (ms) => new Promise((r) => setTimeout(r, ms));