/**
 * @file AgentHub's hooks in Antigravity (`~/.gemini/config/hooks.json`, the
 * global file `agy` and the Antigravity IDE both load), installed and removed
 * only on the user's click. The file maps hook NAMES to their events; ours is
 * the one named `agenthub`, and every other name is left as it is.
 *
 * Only three events, all observational: `PreInvocation` (a model call starts
 * — the first of a run is the user's prompt), `PostToolUse` and `Stop`.
 * NEVER `PreToolUse`: its answer is a permission decision, and agy DENIES the
 * tool when a PreToolUse hook answers `{}` (verified on 1.2.13) — `allow`
 * would skip the user's own permission rules and `ask` would force a prompt,
 * so there is no answer that leaves agy's behaviour alone. agy has no hook
 * for a permission prompt either, so AgentHub cannot show one.
 *
 * The command is a stable path, `'<gemini>/config/agenthub-hook.sh' <Event>`;
 * the script runs this build's `scripts/hook-handler.js <Event> antigravity`
 * with the server's node and CLAUDE_HOME, prints the `{}` agy reads, and every
 * server start rewrites it when stale — same scheme as codex-hooks.js, though
 * agy asks for no trust. A script there that is not ours is never overwritten
 * or removed (`EFOREIGN`), and hooks.json keeps its mode.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("node:fs");
const path = require("node:path");
const { getGeminiDir } = require("./antigravity-home");
const { getClaudeHome } = require("./claude-home");
const { shq, writeAtomic, scriptIsOurs, isLink } = require("./codex-hooks");

const HOOK_NAME = "agenthub";
const HOOK_EVENTS = ["PreInvocation", "PostToolUse", "Stop"];
const TOOL_EVENTS = new Set(["PostToolUse"]); // take {matcher, hooks} groups
const TIMEOUT_S = 5; // the handler gives up after 2.5 s
const HANDLER = path.resolve(__dirname, "..", "..", "scripts", "hook-handler.js");
const MARKER = "# AgentHub's Antigravity hook forwarder.";

const configDir = () => path.join(getGeminiDir(), "config");
const hooksPath = () => path.join(configDir(), "hooks.json");
const scriptPath = () => path.join(configDir(), "agenthub-hook.sh");
const commandFor = (event) => `${shq(scriptPath())} ${event}`;

function scriptBody() {
  return [
    "#!/bin/sh",
    `${MARKER} Rewritten by AgentHub on every start.`,
    `N=${shq(process.execPath)}; [ -x "$N" ] || N=node`,
    `CLAUDE_HOME=${shq(getClaudeHome())} "$N" ${shq(HANDLER)} "$1" antigravity >/dev/null 2>&1`,
    "# agy reads a JSON answer; an empty one changes nothing for these events.",
    "echo '{}'",
    "",
  ].join("\n");
}

function fail(code, message) {
  return Object.assign(new Error(message), { code });
}

/** hooks.json as an object, `{}` when absent; throws EBADJSON otherwise. */
function readHooks() {
  let text;
  try {
    text = fs.readFileSync(hooksPath(), "utf8");
  } catch (err) {
    if (err.code === "ENOENT") return {};
    throw err;
  }
  let file;
  try {
    file = JSON.parse(text);
  } catch {
    file = null;
  }
  if (!file || typeof file !== "object" || Array.isArray(file)) {
    throw fail("EBADJSON", `${hooksPath()} is not a JSON object; fix or move it first`);
  }
  return file;
}

function assertSupported() {
  if (process.platform === "win32") {
    throw fail("EUNSUPPORTED", "Antigravity hooks from AgentHub need a POSIX shell");
  }
}

function ourDefinition() {
  const def = { enabled: true };
  for (const event of HOOK_EVENTS) {
    const handler = { type: "command", command: commandFor(event), timeout: TIMEOUT_S };
    def[event] = TOOL_EVENTS.has(event) ? [{ matcher: ".*", hooks: [handler] }] : [handler];
  }
  return def;
}

/** Install (or reinstall) AgentHub's named hook. @returns the new status. */
function install() {
  assertSupported();
  const file = readHooks();
  if (!scriptIsOurs(scriptPath(), MARKER)) {
    throw fail("EFOREIGN", `${scriptPath()} is not AgentHub's; move it first`);
  }
  file[HOOK_NAME] = ourDefinition();
  fs.mkdirSync(configDir(), { recursive: true });
  writeAtomic(scriptPath(), scriptBody(), 0o755);
  writeAtomic(hooksPath(), JSON.stringify(file, null, 2) + "\n", 0o644, { keepMode: true });
  return status();
}

/** Take AgentHub's named hook out; every other one stays. @returns the new status. */
function remove() {
  const file = readHooks();
  if (HOOK_NAME in file) {
    delete file[HOOK_NAME];
    if (Object.keys(file).length === 0 && !isLink(hooksPath()))
      fs.rmSync(hooksPath(), { force: true });
    else writeAtomic(hooksPath(), JSON.stringify(file, null, 2) + "\n", 0o644, { keepMode: true });
  }
  if (scriptIsOurs(scriptPath(), MARKER)) fs.rmSync(scriptPath(), { force: true });
  return status();
}

/** Whether `list` (a flat handler list, or {matcher, hooks} groups) runs our command. */
function runsOurs(list, event) {
  if (!Array.isArray(list)) return false;
  return list.some((h) =>
    Array.isArray(h?.hooks)
      ? h.hooks.some((x) => x?.command === commandFor(event))
      : h?.command === commandFor(event)
  );
}

/** Per event: is our handler there; plus whether our hook is switched off. */
function status() {
  const base = {
    supported: process.platform !== "win32",
    path: hooksPath(),
    script: scriptPath(),
  };
  let file;
  try {
    file = readHooks();
  } catch (err) {
    return {
      ...base,
      readable: false,
      error: err.message,
      installed: false,
      enabled: false,
      events: {},
    };
  }
  const ours = file[HOOK_NAME] && typeof file[HOOK_NAME] === "object" ? file[HOOK_NAME] : {};
  const events = {};
  for (const event of HOOK_EVENTS) events[event] = { installed: runsOurs(ours[event], event) };
  const installed = HOOK_EVENTS.every((e) => events[e].installed) && fs.existsSync(scriptPath());
  return {
    ...base,
    readable: true,
    installed,
    enabled: installed && ours.enabled !== false,
    events,
  };
}

/**
 * Rewrite the forwarder when it is installed and stale or lost its exec bit.
 * Never creates it, and never touches a file by that name that is not ours.
 * @returns {"absent"|"foreign"|"exists"|"written"|"failed"}
 */
function refreshScript() {
  try {
    const current = fs.readFileSync(scriptPath(), "utf8");
    if (!current.split("\n", 2)[1]?.startsWith(MARKER)) return "foreign";
    const executable = (fs.statSync(scriptPath()).mode & 0o111) !== 0;
    if (current === scriptBody() && executable) return "exists";
    writeAtomic(scriptPath(), scriptBody(), 0o755);
    return "written";
  } catch (err) {
    return err.code === "ENOENT" ? "absent" : "failed";
  }
}

module.exports = { HOOK_NAME, HOOK_EVENTS, commandFor, install, remove, status, refreshScript };