import { mkdir, readdir, stat } from 'node:fs/promises';
import { join } from 'node:path';
import { getOwnerHomeDir } from '@@/data-path';
import { readSettings } from './settings';

/**
 * The website checkout that lives under the root location.
 *
 * ── The URL is SSH and it is hardcoded ──
 *
 * `fofos/website` is private, so https would ask for a username and there is nobody at a terminal to
 * answer. The SSH remote is already authenticated by the owner's key — the same one every other clone
 * on this machine uses.
 *
 * Hardcoded because this plugin exists to administer exactly one website. A field for it would be a
 * setting nobody would ever change and one more thing that can be pointed somewhere wrong.
 *
 * ── Nothing here may hang ──
 *
 * These run inside an HTTP request, so every one of them is spawned with credential prompting off and
 * ssh in batch mode. Without that, a key that has lost access does not fail — it BLOCKS, forever,
 * waiting for a password at a terminal that does not exist, and the panel shows a spinner that never
 * stops. `GIT_TERMINAL_PROMPT=0` and `BatchMode=yes` are what turn that into an error message.
 */

const DIR_NAME = 'website';
const REMOTE = 'git@gitea.officer.dev:fofos/website.git';

/** Long enough for a cold clone on a slow link, short enough that a wedged git is not forever. */
const TIMEOUT_MS = 5 * 60 * 1000;

export type WebsiteStatus = {
  /** Absolute, always — `<root>/website`. */
  path: string;
  /** The directory is there. Says nothing about whether it is a checkout. */
  present: boolean;
  /** It is there and it has a `.git`. False with `present` true means something else is in the way. */
  isRepo: boolean;
  branch: string | null;
  /** `1a2b3c4 the subject line`, for somebody deciding whether to press Update. */
  head: string | null;
  /** Its `origin`. Shown because a checkout pointing somewhere else is worth seeing, not guessing at. */
  remote: string | null;
  /** Uncommitted changes. Update refuses while this is true rather than failing halfway through a pull. */
  dirty: boolean;
  /** What this plugin would clone from. */
  cloneUrl: string;
};

export type RunResult = { ok: boolean; output: string };

const run = async (argv: string[], cwd: string, email: string): Promise<RunResult> => {
  const proc = Bun.spawn(argv, {
    cwd,
    env: {
      ...process.env,
      HOME: getOwnerHomeDir(email),
      // See the note at the top: these two are the difference between a failure and a hang.
      GIT_TERMINAL_PROMPT: '0',
      GIT_SSH_COMMAND: 'ssh -o BatchMode=yes -o StrictHostKeyChecking=accept-new -o ConnectTimeout=15',
    },
    stdout: 'pipe',
    stderr: 'pipe',
  });

  const timer = setTimeout(() => proc.kill(), TIMEOUT_MS);
  const [out, err] = await Promise.all([new Response(proc.stdout).text(), new Response(proc.stderr).text()]);
  const code = await proc.exited;
  clearTimeout(timer);

  // git says almost everything useful on stderr, including progress, so both streams are kept.
  return { ok: code === 0, output: `${out}${err}`.trim() };
};

/** Empty string rather than null on failure — every caller here treats "could not tell" as "unknown". */
const gitLine = async (args: string[], cwd: string, email: string): Promise<string | null> => {
  const result = await run(['git', ...args], cwd, email);
  const line = result.output.split('\n')[0]?.trim() ?? '';
  return result.ok && line ? line : null;
};

const exists = async (path: string): Promise<boolean> => {
  try {
    await stat(path);
    return true;
  } catch {
    return false;
  }
};

export const websitePath = async (email: string): Promise<string> => {
  const settings = await readSettings(email);
  return join(settings.rootPath, DIR_NAME);
};

export async function readWebsiteStatus(email: string): Promise<WebsiteStatus> {
  const path = await websitePath(email);
  const base: WebsiteStatus = {
    path,
    present: false,
    isRepo: false,
    branch: null,
    head: null,
    remote: null,
    dirty: false,
    cloneUrl: REMOTE,
  };

  if (!(await exists(path))) return base;
  if (!(await exists(join(path, '.git')))) return { ...base, present: true };

  return {
    ...base,
    present: true,
    isRepo: true,
    branch: await gitLine(['rev-parse', '--abbrev-ref', 'HEAD'], path, email),
    head: await gitLine(['log', '-1', '--format=%h %s'], path, email),
    remote: await gitLine(['remote', 'get-url', 'origin'], path, email),
    // `--untracked-files=no`: a build artefact or an .env nobody committed is not a reason to refuse a
    // fast-forward, and treating it as one makes Update permanently unavailable on a working checkout.
    dirty: (await run(['git', 'status', '--porcelain', '--untracked-files=no'], path, email)).output.length > 0,
  };
}

/**
 * Clone it.
 *
 * Refuses onto anything already there rather than merging into it. `git clone` itself refuses a
 * non-empty directory, but it does so with a message about paths that reads as a bug in this plugin;
 * said here it reads as the fact it is.
 */
export async function cloneWebsite(email: string): Promise<RunResult> {
  const path = await websitePath(email);

  if (await exists(path)) {
    const entries = await readdir(path).catch(() => [] as string[]);
    if (entries.length > 0) return { ok: false, output: `${path} already exists and is not empty.` };
  }

  const settings = await readSettings(email);
  // The root itself may never have been made — it is a default until somebody saves it, and saving it
  // does not create anything. `recursive`, so a root several levels deep works the first time.
  await mkdir(settings.rootPath, { recursive: true });

  // Full history, not `--depth 1`. This is a working checkout somebody will pull into and read the log
  // of, and a shallow clone turns both into a support question later.
  return run(['git', 'clone', '--progress', REMOTE, path], settings.rootPath, email);
}

/**
 * Update it — fast-forward only.
 *
 * Never a merge. A merge commit made by a button, in a checkout nobody is watching, is a thing
 * somebody discovers days later; refusing is always recoverable and always legible.
 */
export async function updateWebsite(email: string): Promise<RunResult> {
  const status = await readWebsiteStatus(email);
  if (!status.isRepo) return { ok: false, output: `${status.path} is not a git checkout.` };
  if (status.dirty) return { ok: false, output: 'There are uncommitted changes. Sort those out first.' };

  return run(['git', 'pull', '--ff-only', '--progress'], status.path, email);
}