import { chmodSync, copyFileSync, existsSync, mkdirSync, renameSync } from 'node:fs';
import { homedir } from 'node:os';
import { join } from 'node:path';
import { locateBinary } from '@@/plugins/os-deps';

// The iris sidecar: a builder wearing a supervisor's clothes.
//
// The install pipeline installs packages and fetches release binaries, but deliberately runs no build
// step — so compiling a Rust crate is this plugin's own job, and the sidecar is the only process the
// platform starts for a plugin. First start pays for the build (minutes — watch `pm2 logs officer-iris`);
// every later start finds the binary and settles into a heartbeat.
//
// Everything lands where the platform already looks: `~/.local/bin` is first on the probe path in
// os-deps.ts, so `iris` and `iris-browser` are found by whoever asks, without anyone's PATH changing.

const name = 'officer-iris';
const CRATE = 'iris-screenshot';
// Upstream's declared rust-version. Distro cargo lags real Rust by a year or more, so this is checked
// BEFORE building — a clear refusal with instructions beats cargo's own MSRV error buried in build spam.
const MSRV: readonly [number, number] = [1, 88];

const home = homedir();
const localBin = join(home, '.local', 'bin');

// The platform's own resolver, not a copy of it. It asks the OWNER's login shell where a binary is,
// which is the only source that knows about rustup's `~/.cargo/bin`, or anything else a per-user
// installer added — this file used to guess that list and disagreed with the manifest probe, so a
// rustup-only machine was refused the install and then built fine.
const which = (binary: string): string | null => locateBinary(binary);

const log = (message: string): void => console.log(`[${name}] ${message}`);

/**
 * The wrapper ships in this repository; agents need it on a path they can name. Overwrite = upgrade.
 *
 * Written to a temporary name and RENAMED over the target, because `copyFileSync` truncates in place: a
 * restart during a capture would have the running shell read a half-written script, which fails in
 * whatever way the truncation happens to produce. Rename is atomic within a filesystem, so a reader
 * holds either the old file or the new one. Same reasoning as `installRelease` in os-deps.ts.
 */
function installWrapper(): void {
  const source = join(import.meta.dir, '..', 'bin', 'iris-browser');
  const target = join(localBin, 'iris-browser');
  const staging = `${target}.new`;
  mkdirSync(localBin, { recursive: true });
  copyFileSync(source, staging);
  chmodSync(staging, 0o755);
  renameSync(staging, target);
  log(`iris-browser installed to ${target}`);
}

/** `cargo 1.75.0 (…)` → [1, 75], or null when it will not even say. */
function cargoVersion(cargo: string): [number, number] | null {
  try {
    const out = Bun.spawnSync([cargo, '--version'], { stdout: 'pipe', stderr: 'pipe' });
    const match = new TextDecoder().decode(out.stdout).match(/cargo (\d+)\.(\d+)/);
    return match ? [Number(match[1]), Number(match[2])] : null;
  } catch {
    return null;
  }
}

const meetsMsrv = ([major, minor]: [number, number]): boolean =>
  major > MSRV[0] || (major === MSRV[0] && minor >= MSRV[1]);

/**
 * Build iris into ~/.local/bin. Streams cargo's output straight to PM2's log, because a silent
 * multi-minute compile is indistinguishable from a hang.
 *
 * `--locked` builds against upstream's committed lockfile rather than re-resolving dependencies at
 * install time — the platform's frozen-lockfile rule, honoured one language over.
 */
let building: Bun.Subprocess | null = null;

async function build(cargo: string): Promise<boolean> {
  log(`building ${CRATE} — first start only, takes a few minutes`);
  const proc = Bun.spawn([cargo, 'install', CRATE, '--locked', '--root', join(home, '.local')], {
    stdout: 'inherit',
    stderr: 'inherit',
  });
  // Remembered so `shutdown` can kill it. A cargo build spawns rustc processes that keep going long after
  // this process exits — `pm2 restart` during a build would otherwise leave the old compile running and
  // start a second one on top of it, both writing the same target directory.
  building = proc;
  const code = await proc.exited;
  building = null;
  if (code !== 0) {
    log(`build failed (cargo exited ${code}) — read the output above; restart this process to retry`);
    return false;
  }
  return true;
}

/**
 * Is the binary named `iris` actually ours?
 *
 * Presence is not identity. `iris` is a common enough name for a program, and a half-written file from a
 * cargo install that was killed mid-copy is also present — both make `which` succeed and both make this
 * sidecar report ready and never rebuild. The platform learned this once already: `os-deps.ts` grew
 * `identify` for exactly it, with the note that "a namesake on PATH is not the dependency".
 *
 * Cheap, and only on start.
 */
function isOurIris(path: string): boolean {
  try {
    const out = Bun.spawnSync([path, '--version'], { stdout: 'pipe', stderr: 'pipe', timeout: 5_000 });
    const text = `${new TextDecoder().decode(out.stdout)}${new TextDecoder().decode(out.stderr)}`;
    return text.toLowerCase().includes('iris');
  } catch {
    // Will not execute at all — a truncated or wrong-architecture file. No more useful than a missing one.
    return false;
  }
}

/** True when the binary is usable. Says why not, with the fix, when it is not. */
async function ensureIris(): Promise<boolean> {
  const present = which('iris');
  if (present && isOurIris(present)) {
    log(`iris ready at ${present}`);
    return true;
  }
  if (present) {
    log(`${present} does not identify as iris — rebuilding over it`);
  }

  const cargo = which('cargo');
  if (!cargo) {
    log('cargo is not on PATH — the install should have provided it; install rust and restart this process');
    return false;
  }

  const version = cargoVersion(cargo);
  if (!version || !meetsMsrv(version)) {
    log(`${cargo} is ${version ? `cargo ${version.join('.')}` : 'unidentifiable'}, and ${CRATE} needs ${MSRV.join('.')}+`);
    log('your distribution\'s rust is too old. Install rustup as the user officer runs as:');
    log("  curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal");
    log('then restart this process: pm2 restart officer-iris');
    return false;
  }

  if (!(await build(cargo))) return false;

  const built = which('iris');
  if (!built) {
    log('cargo reported success but iris is not in ~/.local/bin — read the build output above');
    return false;
  }
  log(`iris built and ready at ${built}`);
  return true;
}

log(`started (pid ${process.pid})`);

// ── Signals FIRST ──
//
// `ensureIris()` below can take minutes, and until these are registered a SIGTERM is handled by Bun's
// default, which kills this process and leaves the cargo build running as an orphan. `pm2 restart` during
// a first start is not an unusual thing to do — it is what somebody does when they think it is stuck.
let beat: ReturnType<typeof setInterval> | null = null;

const shutdown = (signal: string): void => {
  log(`${signal} — exiting`);
  if (beat) clearInterval(beat);
  if (building) {
    log('killing the in-progress cargo build');
    building.kill();
  }
  process.exit(0);
};

process.on('SIGTERM', () => shutdown('SIGTERM'));
process.on('SIGINT', () => shutdown('SIGINT'));

// Guarded, in a file whose every other failure logs and continues. An unwritable `~/.local/bin` — wrong
// ownership after an install run as the wrong user is the way this happens — threw here at top level and
// crash-looped the sidecar under PM2, which reports "errored" and says nothing about a directory.
try {
  installWrapper();
} catch (err) {
  log(`could not install iris-browser: ${err instanceof Error ? err.message : err}`);
  log(`check that ${localBin} exists and is writable; captures will fail until it is`);
}

let ready = await ensureIris();

// The heartbeat re-probes rather than repeating a remembered answer: a binary deleted out from under us
// shows up here, and a rustup installed after a refusal turns the next restart into a build — which the
// log has already told the owner. Building inside the interval is deliberately avoided: a periodic
// compile that nobody asked for is not a heartbeat.
beat = setInterval(() => {
  const present = which('iris');
  if (present && !ready) {
    ready = true;
    log(`iris appeared at ${present}`);
  } else if (!present && ready) {
    ready = false;
    log('iris is GONE from PATH — restart this process to rebuild');
  } else {
    log(`alive — iris ${present ? 'ready' : 'missing'}`);
  }
}, 300_000);