/**
 * @file HTTP surface for a user's OWN git identity (`server/lib/git-identity.js`),
 * mounted at `/api/me/git`: the SSH keys a clone uses — a default ed25519
 * and/or rsa one plus named ones (`name`, deleted by `?id=`) for more
 * accounts (make, replace, delete — only the PUBLIC key is ever returned) and
 * the HTTPS logins (save, delete — `hasToken` only, never a password),
 * whether the account's own terminal git uses the keys (`core.sshCommand`),
 * the SSH logins per host or alias (`url.<…>.insteadOf` — AWS CodeCommit's
 * SSH key ID — each optionally tied to one key), and the commit author (`user.name` /
 * `user.email` of the account's global git config — a member's commits fail
 * without one; a new SSH key is labelled with that email, else
 * `<username>@smartgift.vn`). The account is the signed-in user's
 * own Linux account under S3, else the host's, which only an admin (or local
 * mode) may change (`EHOSTIDENTITY`). Nothing here takes a path from the
 * request, and every write passes the same-origin guard.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const os = require("node:os");
const express = require("express");

const identity = require("../lib/git-identity");
const { sameOriginGuard } = require("../lib/same-origin");

const router = express.Router();

const STATUS = {
  EBADHOST: 400,
  EBADCRED: 400,
  EEXISTS: 409,
  EMEMBERGONE: 409,
  EHOSTIDENTITY: 403,
  EBADAUTHOR: 400,
  ESTOREUNREADABLE: 409,
  EBADKEYTYPE: 400,
  EFOREIGNSSH: 409,
  EBADSSHUSER: 400,
  EBADKEYNAME: 400,
  ETOOMANYKEYS: 409,
  EBADALIAS: 400,
  ENOKEY: 400,
};

function fail(res, e) {
  res
    .status(STATUS[e.code] || 500)
    .json({ error: { code: e.code || "EINTERNAL", message: e.message } });
}

async function view(account, username) {
  const keys = identity.sshKeysInfo(account);
  const terminal = keys.length ? await identity.terminalSshState(account) : undefined;
  return {
    account: account.kind,
    writable: account.kind === "member" || account.writable !== false,
    // `ssh`: the first key, as before there could be two; `sshKeys`: all.
    ssh: keys[0] ? { ...keys[0], terminal } : null,
    sshKeys: keys,
    sshTerminal: terminal ?? null,
    sshUsers: await identity.listSshUsers(account),
    https: identity.listHttps(account),
    author: await identity.getAuthor(account),
    // What the author email form suggests while none is set.
    defaultEmail: identity.defaultEmail(username),
  };
}

/** The signed-in user's name, or the OS user's in local mode. */
const usernameOf = (req) => req.user?.username || os.userInfo().username;

/** The request's account; a write to the host's identity needs an admin. */
function accountOf(req, { write = false } = {}) {
  const account = identity.accountForRequest(req);
  if (write && account.kind === "host" && !account.writable) {
    throw Object.assign(new Error("the host's git identity is an admin's to change"), {
      code: "EHOSTIDENTITY",
    });
  }
  return account;
}

router.get("/", async (req, res) => {
  try {
    res.json(await view(accountOf(req), usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

router.post("/ssh-key", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    await identity.generateSshKey(account, {
      replace: req.body?.replace === true,
      type: req.body?.type === "rsa" ? "rsa" : "ed25519",
      // A named key sits beside the default one of its type.
      name: typeof req.body?.name === "string" ? req.body.name : null,
      // The key is labelled with the commit author's email, else the default one.
      comment: (await identity.getAuthor(account)).email || identity.defaultEmail(usernameOf(req)),
    });
    res.status(201).json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

router.delete("/ssh-key", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    const type = req.query.type === undefined ? undefined : String(req.query.type);
    const id = req.query.id === undefined ? undefined : String(req.query.id);
    if (!(await identity.removeSshKey(account, { type, id }))) {
      return res.status(404).json({ error: { code: "ENOTFOUND", message: "no SSH key" } });
    }
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

/**
 * Whether a plain `git` in the account's own terminal uses the AgentHub key
 * (`core.sshCommand` in its `~/.gitconfig`, issue #82). `{on: boolean}`.
 */
router.put("/ssh-terminal", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    if (!identity.sshKeyInfo(account) && req.body?.on === true) {
      return res.status(404).json({ error: { code: "ENOTFOUND", message: "no SSH key" } });
    }
    await identity.setTerminalSsh(account, req.body?.on === true);
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

/**
 * An SSH login (`{host, user, alias?, key?}`) — e.g. AWS CodeCommit's SSH key
 * ID, so a plain `ssh://git-codecommit…/` URL logs in; with `alias`, one more
 * account on that host (`ssh://<alias>/…`); with `key`, the only key it uses.
 * DELETE `/ssh-user/<host or alias>` drops it.
 */
router.put("/ssh-user", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    await identity.setSshUser(account, req.body || {});
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

router.delete("/ssh-user/:host", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    if (!(await identity.removeSshUser(account, req.params.host))) {
      return res.status(404).json({ error: { code: "ENOTFOUND", message: "no such SSH user" } });
    }
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

router.post("/https", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    const { host, username, password } = req.body || {};
    identity.saveHttps(account, { protocol: "https", host, username, password });
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

router.delete("/https/:host", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    if (!identity.removeHttps(account, "https", req.params.host)) {
      return res.status(404).json({ error: { code: "ENOTFOUND", message: "no such login" } });
    }
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

/** The account's commit author (`git config --global user.name/email`). */
router.put("/author", sameOriginGuard, async (req, res) => {
  try {
    const account = accountOf(req, { write: true });
    await identity.setAuthor(account, req.body || {});
    res.json(await view(account, usernameOf(req)));
  } catch (e) {
    fail(res, e);
  }
});

module.exports = router;