/**
 * @file users.js
 * @description `/api/users` — server mode's per-user view for an admin or
 * analyst (members are refused by STAFF_ONLY_PREFIXES in server/lib/auth.js):
 * `GET /` lists every account with its workspaces, sessions and $ spent in the
 * last 7 and 30 days (from `token_usage_hourly`, sessions owned through their
 * workspace — server/lib/scope.js); `GET /audit` the newest audit entries
 * (server/lib/audit.js).
 *
 * The Users page's account changes — `POST /` (create), `PATCH /:id` (role,
 * disabled), `POST /:id/password` (reset) and `POST /:id/workspaces` (give a
 * workspace) — are an admin's only (`/users` is in ADMIN_WRITE_PREFIXES), each
 * needs the admin's own password again (`currentPassword`, `confirmPassword`),
 * an admin never demotes or disables themselves (ESELF), every change is
 * audited, and in local mode — no login to check — they all refuse.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const { Router } = require("express");
const { db, stmts } = require("../db");
const auth = require("../lib/auth");
const { listUsers } = auth;
const { sessionWhere } = require("../lib/scope");
const { listAudit, recordAccountChange } = require("../lib/audit");

const router = Router();

const USAGE_COLS = [
  "input_tokens",
  "output_tokens",
  "cache_read_tokens",
  "cache_write_tokens",
  "cache_write_1h_tokens",
  "web_search_requests",
  "web_fetch_requests",
  "code_execution_requests",
  "long_input_tokens",
  "long_output_tokens",
  "long_cache_read_tokens",
  "long_cache_write_tokens",
  "long_cache_write_1h_tokens",
];

/** $ and tokens a member's sessions spent since `sinceHour` (UTC `YYYY-MM-DDTHH`). */
function usageSince(userId, sinceHour, rules) {
  const { calculateCost } = require("./pricing");
  const w = sessionWhere({ user: { id: userId, role: "developer" } }, "s.id", "s.lane_id");
  const rows = db
    .prepare(
      `SELECT h.model, h.speed, h.inference_geo, h.service_tier,
              ${USAGE_COLS.map((c) => `SUM(h.${c}) AS ${c}`).join(", ")}
         FROM token_usage_hourly h JOIN sessions s ON s.id = h.session_id
        WHERE h.hour >= ? AND ${w.where}
        GROUP BY h.model, h.speed, h.inference_geo, h.service_tier`
    )
    .all(sinceHour, ...w.params);
  const tokens = rows.reduce(
    (n, r) => n + r.input_tokens + r.output_tokens + r.cache_read_tokens + r.cache_write_tokens,
    0
  );
  return { cost: rows.length ? calculateCost(rows, rules).total_cost : 0, tokens };
}

const hourAgo = (days) => new Date(Date.now() - days * 864e5).toISOString().slice(0, 13);

router.get("/", (_req, res) => {
  const rules = stmts.listPricing.all();
  const users = listUsers().map((u) => {
    const w = sessionWhere({ user: { id: u.id, role: "developer" } });
    return {
      ...u,
      workspaces: db.prepare("SELECT COUNT(*) AS n FROM lanes WHERE owner_id = ?").get(u.id).n,
      sessions: db.prepare(`SELECT COUNT(*) AS n FROM sessions WHERE ${w.where}`).get(...w.params)
        .n,
      last7d: usageSince(u.id, hourAgo(7), rules),
      last30d: usageSince(u.id, hourAgo(30), rules),
    };
  });
  res.json({ users });
});

router.get("/audit", (req, res) => {
  res.json({ entries: listAudit(req.query.limit) });
});

const STATUS = {
  EBADUSER: 400,
  EBADPASSWORD: 400,
  EBADROLE: 400,
  EBADFIELD: 400,
  EREAUTH: 403,
  ELOCALMODE: 403,
  ENOUSER: 404,
  ENOLANE: 404,
  EEXISTS: 409,
  ESELF: 409,
  ETOOMANY: 429,
};

/**
 * One account change: server mode only, the admin's password confirmed, the
 * change made, then audited. `fn(target)` returns the audit text.
 */
function accountChange(handler) {
  return async (req, res) => {
    try {
      if (!auth.isServerMode() || !req.user) {
        throw Object.assign(new Error("accounts are managed in server mode only"), {
          code: "ELOCALMODE",
        });
      }
      const body = req.body && typeof req.body === "object" ? req.body : {};
      await auth.confirmPassword(req.user, body.currentPassword);
      const out = await handler(req, body);
      recordAccountChange(req.user.id, out.user.id, req.method, out.action);
      res.status(out.status || 200).json({ user: out.user });
    } catch (err) {
      const status = STATUS[err.code];
      if (!status) return res.status(500).json({ error: { message: err.message } });
      res.status(status).json({ error: { code: err.code, message: err.message } });
    }
  };
}

/** The account `:id` names (404 ENOUSER otherwise). */
function target(req) {
  const u = db.prepare("SELECT * FROM users WHERE id = ?").get(Number(req.params.id));
  if (!u) throw Object.assign(new Error("no such user"), { code: "ENOUSER" });
  return u;
}

router.post(
  "/",
  accountChange(async (_req, body) => {
    const role = body.role === undefined ? "developer" : body.role;
    const user = await auth.createUser(body.username, body.password, role);
    return { status: 201, user, action: `create ${user.username} (${user.role})` };
  })
);

router.patch(
  "/:id",
  accountChange(async (req, body) => {
    const u = target(req);
    const self = u.id === req.user.id;
    const done = [];
    if (body.role !== undefined && body.role !== u.role) {
      if (self)
        throw Object.assign(new Error("you cannot change your own role"), { code: "ESELF" });
      auth.setRole(u.username, body.role);
      done.push(`role ${body.role}`);
    }
    if (body.disabled !== undefined) {
      if (typeof body.disabled !== "boolean") {
        throw Object.assign(new Error("disabled: true or false"), { code: "EBADFIELD" });
      }
      if (self && body.disabled) {
        throw Object.assign(new Error("you cannot disable yourself"), { code: "ESELF" });
      }
      auth.setDisabled(u.username, body.disabled);
      done.push(body.disabled ? "disable" : "enable");
    }
    return {
      user: auth.publicUser(target(req)),
      action: `${u.username}: ${done.join(", ") || "no change"}`,
    };
  })
);

router.post(
  "/:id/password",
  accountChange(async (req, body) => {
    const u = target(req);
    await auth.setPassword(u.username, body.password);
    return { user: auth.publicUser(u), action: `${u.username}: password reset` };
  })
);

router.post(
  "/:id/workspaces",
  accountChange(async (req, body) => {
    const u = target(req);
    auth.assignWorkspace(body.laneId, u.username);
    return { user: auth.publicUser(u), action: `${u.username}: workspace ${Number(body.laneId)}` };
  })
);

module.exports = router;