/**
 * @file Users.tsx
 * @description The Users page (`/users`, a sidebar item), server mode only and
 * only for an admin or analyst (docs/SERVER-MODE.md): every account with its
 * role, state, workspaces, sessions and the tokens/$ it used in the last 7 and
 * 30 days (`GET /api/users`), the audit log (`GET /api/users/audit`), and — for
 * an admin — add a user, and ONE Edit per row (`UserEditDialog`: profile,
 * role, active/disabled, password, owned workspaces, sign out everywhere, sent
 * as one change), and the Claude/Codex account pool every user's sessions run
 * on (`AccountPoolCard`). Every change asks for the admin's OWN password again (the
 * server refuses without it); an analyst only reads. A row shows the display
 * name and email under the username when set.
 * Laid out like the other list pages: icon header, a row of totals
 * (`StatCard`), the accounts in a `card` table, the audit log in a card.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useCallback, useEffect, useState, type KeyboardEvent, type ReactNode } from "react";
import { Navigate } from "react-router-dom";
import { useTranslation } from "react-i18next";
import {
  AlertCircle,
  DollarSign,
  Eye,
  FolderOpen,
  MessagesSquare,
  Pencil,
  RefreshCw,
  ScrollText,
  UserPlus,
  Users as UsersIcon,
} from "lucide-react";
import { api, type AuditEntry, type AuthUser, type ServerUserUsage } from "../lib/api";
import { fmt, fmtCost, formatDateTime } from "../lib/format";
import { toast } from "../lib/toast";
import { isSubmitEnter } from "../lib/keys";
import { useSpin } from "../hooks/useSpin";
import { useAuth } from "../components/AuthGate";
import { ConfirmModal } from "../components/ConfirmModal";
import { StatCard } from "../components/StatCard";
import { ROLE_BADGE, UserEditDialog } from "../components/users/UserEditDialog";
import { AccountPoolCard } from "../components/users/AccountPoolCard";
import { TableRowSkeleton } from "../components/Skeleton";

type Role = AuthUser["role"];
const ROLES: Role[] = ["admin", "analyst", "developer"];

export function Users() {
  const { t } = useTranslation("users");
  const auth = useAuth();
  const me = auth.state.mode === "server" ? auth.state.user : null;
  const isAdmin = me?.role === "admin";

  const [users, setUsers] = useState<ServerUserUsage[] | null>(null);
  const [audit, setAudit] = useState<AuditEntry[] | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [adding, setAdding] = useState(false);
  const [editing, setEditing] = useState<ServerUserUsage | null>(null);

  const load = useCallback(
    () =>
      Promise.all([
        api.users
          .list()
          .then((r) => {
            setUsers(r.users);
            setError(null);
          })
          .catch((e: Error) => setError(e.message)),
        api.users
          .audit()
          .then((r) => setAudit(r.entries))
          .catch(() => setAudit([])),
      ]),
    []
  );
  const [spinning, refresh] = useSpin(load);

  useEffect(() => {
    if (me && me.role !== "developer") void load();
  }, [me, load]);

  // Local mode, or a developer: there is no Users page for them.
  if (!me || me.role === "developer") return <Navigate to="/" replace />;

  const sum = (pick: (u: ServerUserUsage) => number) =>
    (users ?? []).reduce((n, u) => n + pick(u), 0);
  const active = (users ?? []).filter((u) => !u.disabled).length;
  const th = "px-5 py-3 text-[11px] font-semibold text-fg-muted uppercase tracking-wider";

  return (
    <div className="animate-fade-in space-y-6">
      <div className="flex flex-wrap items-start justify-between gap-3">
        <div className="flex items-center gap-3">
          <div className="w-9 h-9 rounded-xl bg-accent/15 flex items-center justify-center">
            <UsersIcon className="w-4.5 h-4.5 text-accent" />
          </div>
          <div>
            <h1 className="text-lg font-semibold text-fg-primary">{t("title")}</h1>
            <p className="text-xs text-fg-muted">{t("description")}</p>
          </div>
        </div>
        <div className="flex items-center gap-2">
          <button
            type="button"
            onClick={refresh}
            disabled={spinning}
            aria-busy={spinning}
            className="btn-ghost"
          >
            <RefreshCw className={`w-4 h-4 ${spinning ? "animate-spin" : ""}`} />{" "}
            {t("common:refresh")}
          </button>
          {isAdmin && (
            <button type="button" onClick={() => setAdding(true)} className="btn-primary">
              <UserPlus className="w-4 h-4" /> {t("add")}
            </button>
          )}
        </div>
      </div>

      <div className="grid grid-cols-2 lg:grid-cols-4 gap-4">
        <StatCard
          label={t("title")}
          value={users?.length ?? 0}
          icon={UsersIcon}
          trend={users ? t("activeCount", { n: active }) : undefined}
          loading={!users && !error}
        />
        <StatCard
          label={t("workspaces")}
          value={sum((u) => u.workspaces)}
          icon={FolderOpen}
          loading={!users && !error}
        />
        <StatCard
          label={t("sessions")}
          value={sum((u) => u.sessions)}
          icon={MessagesSquare}
          loading={!users && !error}
        />
        <StatCard
          label={t("cost30d")}
          value={fmtCost(sum((u) => u.last30d.cost))}
          icon={DollarSign}
          trend={users ? `${t("last7d")}: ${fmtCost(sum((u) => u.last7d.cost))}` : undefined}
          raw={t("tokens", { n: fmt(sum((u) => u.last30d.tokens)) })}
          loading={!users && !error}
        />
      </div>

      {error && (
        <div
          role="alert"
          className="card flex flex-wrap items-center gap-3 p-3 border-status-danger/40 text-sm text-status-danger"
        >
          <AlertCircle className="w-4 h-4 flex-shrink-0" />
          <span className="flex-1 min-w-0">{error}</span>
          <button type="button" onClick={refresh} className="btn-ghost text-xs">
            {t("common:retry")}
          </button>
        </div>
      )}
      {!isAdmin && (
        <p className="flex items-center gap-1.5 text-xs text-fg-muted">
          <Eye className="w-3.5 h-3.5" /> {t("readOnly")}
        </p>
      )}

      <div className="card overflow-x-auto">
        <table className="w-full min-w-[760px]" data-testid="users-table">
          <thead>
            <tr className="border-b border-border text-left">
              <th className={th}>{t("name")}</th>
              <th className={th}>{t("role")}</th>
              <th className={`${th} text-right`}>{t("workspaces")}</th>
              <th className={`${th} text-right`}>{t("sessions")}</th>
              <th className={`${th} text-right`}>{t("last7d")}</th>
              <th className={`${th} text-right`}>{t("last30d")}</th>
              {isAdmin && <th className={`${th} text-right`}>{t("actions")}</th>}
            </tr>
          </thead>
          <tbody className="divide-y divide-border">
            {!users &&
              !error &&
              Array.from({ length: 4 }).map((_, i) => (
                <TableRowSkeleton
                  key={i}
                  columns={isAdmin ? 7 : 6}
                  widths={["w-36", "w-20", "w-8", "w-8", "w-14", "w-14", "w-28"]}
                />
              ))}
            {users?.map((u) => {
              const self = u.id === me.id;
              return (
                <tr
                  key={u.id}
                  className={`hover:bg-surface-4/40 transition-colors ${u.disabled ? "opacity-60" : ""}`}
                >
                  <td className="px-5 py-3">
                    <div className="flex items-center gap-3 min-w-0">
                      <span
                        aria-hidden
                        className="w-8 h-8 flex-shrink-0 rounded-full bg-surface-4 flex items-center justify-center text-xs font-semibold uppercase text-fg-secondary"
                      >
                        {(u.displayName || u.username).slice(0, 2)}
                      </span>
                      <div className="min-w-0">
                        <div className="truncate text-sm font-medium text-fg-primary">
                          {u.displayName || u.username}
                          {u.displayName && (
                            <span className="ml-1.5 font-normal text-fg-muted">@{u.username}</span>
                          )}
                        </div>
                        {u.email && (
                          <div className="truncate text-[11px] text-fg-muted">{u.email}</div>
                        )}
                      </div>
                      {self && (
                        <span className="badge py-0.5 text-[11px] bg-accent/15 text-accent border-accent/20">
                          {t("you")}
                        </span>
                      )}
                      {u.disabled && (
                        <span className="badge py-0.5 text-[11px] bg-status-danger/10 text-status-danger border-status-danger/20">
                          {t("disabled")}
                        </span>
                      )}
                    </div>
                  </td>
                  <td className="px-5 py-3">
                    <span
                      className={`badge py-0.5 text-[11px] ${ROLE_BADGE[u.role]}`}
                      title={t(`roleHint.${u.role}`)}
                    >
                      {t(`roles.${u.role}`)}
                    </span>
                  </td>
                  <td className="px-5 py-3 text-right text-sm tabular-nums text-fg-secondary">
                    {u.workspaces}
                  </td>
                  <td className="px-5 py-3 text-right text-sm tabular-nums text-fg-secondary">
                    {u.sessions}
                  </td>
                  <UsageCell usage={u.last7d} />
                  <UsageCell usage={u.last30d} />
                  {isAdmin && (
                    <td className="px-5 py-2 text-right whitespace-nowrap">
                      <RowAction label={t("edit.button")} onClick={() => setEditing(u)}>
                        <Pencil className="h-4 w-4" />
                      </RowAction>
                    </td>
                  )}
                </tr>
              );
            })}
          </tbody>
        </table>
      </div>

      <AccountPoolCard isAdmin={isAdmin} />

      <section className="card">
        <div className="flex items-center gap-2 px-5 py-4 border-b border-border">
          <ScrollText className="w-4 h-4 text-fg-muted" />
          <div>
            <h2 className="text-sm font-semibold text-fg-primary">{t("auditTitle")}</h2>
            <p className="text-xs text-fg-muted">{t("auditDescription")}</p>
          </div>
        </div>
        {audit?.length === 0 && (
          <p className="px-5 py-8 text-center text-sm text-fg-muted">{t("auditEmpty")}</p>
        )}
        {audit && audit.length > 0 && (
          <ul
            className="divide-y divide-border text-xs max-h-[28rem] overflow-y-auto"
            data-testid="audit-list"
          >
            {audit.map((a) => (
              <li
                key={a.id}
                className="flex items-center gap-3 px-5 py-2 hover:bg-surface-4/40 transition-colors"
              >
                <span className="w-36 flex-shrink-0 tabular-nums text-fg-muted">
                  {formatDateTime(a.at)}
                </span>
                <span className="w-44 flex-shrink-0 truncate text-fg-secondary">
                  <span className="font-medium text-fg-primary">
                    {a.reader_display || a.reader}
                  </span>
                  <span className="mx-1.5 text-fg-muted">→</span>
                  {a.owner_display || a.owner}
                </span>
                <span className="badge py-0 px-1.5 text-[10px] font-mono bg-surface-4 text-fg-muted border-border">
                  {a.method}
                </span>
                <span className="min-w-0 truncate font-mono text-fg-muted" title={a.path}>
                  {a.path}
                </span>
              </li>
            ))}
          </ul>
        )}
      </section>

      {adding && (
        <AddUserDialog
          onClose={() => setAdding(false)}
          onDone={(message) => {
            toast.success(message);
            setAdding(false);
            void load();
          }}
        />
      )}
      {editing && (
        <UserEditDialog
          user={editing}
          self={editing.id === me.id}
          users={users ?? []}
          onClose={() => setEditing(null)}
          onDone={(message) => {
            toast.success(message);
            setEditing(null);
            void load();
          }}
        />
      )}
    </div>
  );
}

/** A period's cost, with its tokens underneath. */
function UsageCell({ usage }: { usage: { cost: number; tokens: number } }) {
  const { t } = useTranslation("users");
  return (
    <td className="px-5 py-3 text-right tabular-nums">
      <div className="text-sm text-fg-primary">{fmtCost(usage.cost)}</div>
      <div className="text-[11px] text-fg-muted">{t("tokens", { n: fmt(usage.tokens) })}</div>
    </td>
  );
}

function RowAction({
  label,
  disabled,
  onClick,
  children,
}: {
  label: string;
  disabled?: boolean;
  onClick: () => void;
  children: ReactNode;
}) {
  return (
    <button
      type="button"
      onClick={onClick}
      disabled={disabled}
      title={label}
      aria-label={label}
      className="btn-icon disabled:opacity-30"
    >
      {children}
    </button>
  );
}

/** A new account: username, password, role, then the admin's own password. */
function AddUserDialog({
  onClose,
  onDone,
}: {
  onClose: () => void;
  onDone: (message: string) => void;
}) {
  const { t } = useTranslation("users");
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [role, setRole] = useState<Role>("developer");
  const [current, setCurrent] = useState("");
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const ready = current.length > 0 && username.trim().length > 0 && password.length > 0;

  const submit = async () => {
    if (!ready || busy) return;
    setBusy(true);
    setError(null);
    try {
      const r = await api.users.create({ username: username.trim(), password, role }, current);
      onDone(t("done.created", { name: r.user.displayName || r.user.username }));
    } catch (e) {
      const err = e as Error & { code?: string };
      setError(
        err.code && t(`errors.${err.code}`, { defaultValue: "" })
          ? t(`errors.${err.code}`)
          : err.message
      );
    } finally {
      setBusy(false);
    }
  };

  // Enter in any field submits — never mid-IME (Vietnamese typing commits with Enter).
  const onKeyDown = (e: KeyboardEvent) => {
    if (isSubmitEnter(e)) {
      e.preventDefault();
      void submit();
    }
  };

  return (
    <ConfirmModal
      open
      title={t("dialog.add")}
      confirmLabel={t("add")}
      cancelLabel={t("common:cancel")}
      busy={busy}
      disabled={!ready}
      onConfirm={() => void submit()}
      onCancel={onClose}
    >
      <div className="mt-3 space-y-3" onKeyDown={onKeyDown}>
        <Field label={t("username")} hint={t("usernameHint")}>
          <input
            className="input w-full text-sm"
            value={username}
            onChange={(e) => setUsername(e.target.value)}
            autoComplete="off"
            aria-label={t("username")}
          />
        </Field>
        <Field label={t("password")} hint={t("passwordHint")}>
          <input
            type="password"
            className="input w-full text-sm"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            autoComplete="new-password"
            aria-label={t("password")}
          />
        </Field>
        <Field label={t("role")} hint={t(`roleHint.${role}`)}>
          <select
            className="input w-full text-sm"
            value={role}
            onChange={(e) => setRole(e.target.value as Role)}
            aria-label={t("role")}
          >
            {ROLES.map((r) => (
              <option key={r} value={r}>
                {t(`roles.${r}`)}
              </option>
            ))}
          </select>
        </Field>
        <Field label={t("yourPassword")} hint={t("yourPasswordHint")}>
          <input
            type="password"
            className="input w-full text-sm"
            value={current}
            onChange={(e) => setCurrent(e.target.value)}
            autoComplete="current-password"
            aria-label={t("yourPassword")}
          />
        </Field>
        {error && (
          <p role="alert" className="text-xs text-status-danger">
            {error}
          </p>
        )}
      </div>
    </ConfirmModal>
  );
}

function Field({ label, hint, children }: { label: string; hint?: string; children: ReactNode }) {
  return (
    <label className="block">
      <span className="text-xs font-medium text-fg-secondary">{label}</span>
      <div className="mt-1">{children}</div>
      {hint && <span className="mt-0.5 block text-[11px] text-fg-muted">{hint}</span>}
    </label>
  );
}