/**
 * @file account-pins.js
 * @description Account pins: an admin's choice that one server-mode user's
 * new sessions of a tool run on one named pool account instead of the one the
 * balancer would pick (claude-pool.js / codex-pool.js `pick`). One pin per
 * user and tool (`account_pins`); the user is the workspace's OWNER
 * (`lanes.owner_id`), never whoever clicked Start. A pin is a preference the
 * pool still bounds: an account a pane may not use (expired, or a login the
 * pane's home cannot take) falls back to the balancer, and a login never
 * replaces another one a live pane in the same home runs on.
 *
 * Server mode only: in local mode there are no users and nothing is pinned.
 * Removing the account drops its pins (`dropAccount`); deleting the user drops
 * theirs (ON DELETE CASCADE, and `auth.deleteUser`).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const TOOLS = ["claude", "codex"];

const err = (code, message) => Object.assign(new Error(message), { code });
const db = () => require("../db").db;
const poolOf = (tool) => require(tool === "codex" ? "./codex-pool" : "./claude-pool");

function validTool(tool) {
  if (!TOOLS.includes(tool)) throw err("EBADTOOL", "tool: claude or codex");
  return tool;
}

/** The account name `ownerId`'s new `tool` sessions are pinned to, or null. */
function pinFor(ownerId, tool) {
  if (!require("./auth").isServerMode() || !Number.isInteger(ownerId)) return null;
  try {
    return (
      db()
        .prepare("SELECT account FROM account_pins WHERE user_id = ? AND tool = ?")
        .get(ownerId, tool)?.account ?? null
    );
  } catch {
    return null; // a spawn never fails over a pin
  }
}

/** Every pin of `tool`, with its user's name: `[{userId, username, account, pinnedAt}]`. */
function listPins(tool) {
  return db()
    .prepare(
      `SELECT p.user_id AS userId, u.username, p.account, p.pinned_at AS pinnedAt
         FROM account_pins p JOIN users u ON u.id = p.user_id
        WHERE p.tool = ? ORDER BY u.username`
    )
    .all(validTool(tool));
}

/**
 * Pin `userId`'s new `tool` sessions to `account`, or unpin them (`account`
 * null). Returns `{userId, username, account}`.
 */
function setPin(userId, tool, account) {
  validTool(tool);
  const user = Number.isInteger(userId)
    ? db().prepare("SELECT id, username FROM users WHERE id = ?").get(userId)
    : null;
  if (!user) throw err("ENOUSER", `no user ${userId}`);
  if (account == null || account === "") {
    db().prepare("DELETE FROM account_pins WHERE user_id = ? AND tool = ?").run(user.id, tool);
    return { userId: user.id, username: user.username, account: null };
  }
  const name = String(account);
  if (!poolOf(tool).hasAccount(name)) {
    throw err("ENOACCOUNT", `no ${tool} account ${name} in the pool`);
  }
  db()
    .prepare(
      `INSERT INTO account_pins (user_id, tool, account) VALUES (?, ?, ?)
       ON CONFLICT(user_id, tool) DO UPDATE SET account = excluded.account,
         pinned_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now')`
    )
    .run(user.id, tool, name);
  return { userId: user.id, username: user.username, account: name };
}

/** A removed account takes its pins with it. */
function dropAccount(tool, account) {
  try {
    db().prepare("DELETE FROM account_pins WHERE tool = ? AND account = ?").run(tool, account);
  } catch {
    /* no database (a bare CLI test): nothing pinned */
  }
}

module.exports = { TOOLS, pinFor, listPins, setPin, dropAccount };