import { useMemo, useState } from "react";
import { useTranslation } from "react-i18next";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import {
  ApiError,
  can,
  createRole,
  deleteRole,
  fetchRoles,
  updateRole,
  type ManagedRole,
  type Permission,
  type SessionUser,
} from "./api.js";
import { Modal } from "./ui/Modal.js";

// Role management (admin). Compose a role from the permission grid (a checkbox
// matrix of resource × action) and name it; users are then assigned a role. The
// built-in `admin` role is shown read-only/locked (it always has every permission
// and can't be edited or deleted). The server enforces the same. See
// @parking/shared PERMISSIONS.

/** Group "resource:action" permissions by resource for the grid rows. */
function groupByResource(perms: Permission[]): Record<string, Permission[]> {
  const out: Record<string, Permission[]> = {};
  for (const p of perms) {
    const resource = p.split(":")[0]!;
    (out[resource] ??= []).push(p);
  }
  return out;
}

export function RolesManager({ user }: { user: SessionUser | null }) {
  const { t } = useTranslation();
  const qc = useQueryClient();
  const rolesQ = useQuery({ queryKey: ["roles"], queryFn: fetchRoles });

  const canCreate = can(user, "role:create");
  const canUpdate = can(user, "role:update");
  const canDelete = can(user, "role:delete");

  const catalog = rolesQ.data?.catalog ?? [];
  const roles = rolesQ.data?.roles ?? [];
  const grouped = useMemo(() => groupByResource(catalog), [catalog]);

  const [error, setError] = useState<string | null>(null);
  const [editing, setEditing] = useState<ManagedRole | "new" | null>(null);

  const invalidate = () => {
    void qc.invalidateQueries({ queryKey: ["roles"] });
    void qc.invalidateQueries({ queryKey: ["users"] });
  };
  const onError = (e: unknown) => setError(e instanceof ApiError ? e.message : (e as Error).message);

  return (
    <div className="">
      <div className="mb-3 flex items-center justify-between">
        <h1 className="text-sm font-bold uppercase tracking-widest text-term-amber">{t("roles.title")}</h1>
        {canCreate && (
          <button type="button" className="btn btn-go btn-sm" onClick={() => { setEditing("new"); setError(null); }}>
            {t("roles.add")}
          </button>
        )}
      </div>

      {error && <div className="mb-2 rounded-term border border-term-red px-3 py-2 text-[0.75rem] text-term-red">{error}</div>}

      <Modal
        open={editing != null}
        onClose={() => setEditing(null)}
        title={editing && editing !== "new" ? t("roles.editTitle") : t("roles.new")}
        width="max-w-2xl"
      >
        {editing && (
          <RoleEditor
            role={editing === "new" ? null : editing}
            grouped={grouped}
            onCancel={() => setEditing(null)}
            onSubmit={async (v) => {
              try {
                if (editing === "new") await createRole(v);
                else await updateRole(editing.id, v);
                setEditing(null);
                invalidate();
              } catch (e) { onError(e); }
            }}
          />
        )}
      </Modal>

      <div className="flex flex-col gap-2">
        {roles.map((r) => (
          <div key={r.id} className="rounded-term border border-term-border bg-term-panel p-3">
            <div className="flex items-center justify-between">
              <div className="flex items-center gap-2">
                <span className="text-[0.8125rem] font-semibold text-term-text">{r.name}</span>
                {r.builtin && (
                  <span className="rounded-term border border-term-amber/50 px-1.5 py-0.5 text-[0.625rem] uppercase tracking-wider text-term-amber">
                    {t("roles.builtin")}
                  </span>
                )}
                <span className="text-[0.6875rem] text-term-muted">
                  {t("roles.permCount", { count: r.permissions.length })} · {t("roles.userCount", { count: r.userCount })}
                </span>
              </div>
              <div className="flex gap-2">
                {canUpdate && !r.builtin && (
                  <button type="button" className="btn btn-ghost btn-sm" onClick={() => { setEditing(r); setError(null); }}>{t("roles.edit")}</button>
                )}
                {canDelete && !r.builtin && (
                  <button type="button" className="btn btn-danger btn-sm"
                    onClick={() => { if (confirm(t("roles.confirmDelete", { name: r.name }))) deleteRoleSafe(r.id, invalidate, onError); }}>{t("roles.delete")}</button>
                )}
              </div>
            </div>
          </div>
        ))}
      </div>
    </div>
  );
}

async function deleteRoleSafe(id: string, ok: () => void, onError: (e: unknown) => void) {
  try { await deleteRole(id); ok(); } catch (e) { onError(e); }
}

function RoleEditor({
  role, grouped, onCancel, onSubmit,
}: {
  role: ManagedRole | null;
  grouped: Record<string, Permission[]>;
  onCancel: () => void;
  onSubmit: (v: { name: string; permissions: Permission[] }) => void;
}) {
  const { t } = useTranslation();
  const [name, setName] = useState(role?.name ?? "");
  const [perms, setPerms] = useState<Set<Permission>>(new Set(role?.permissions ?? []));
  const toggle = (p: Permission) =>
    setPerms((prev) => {
      const next = new Set(prev);
      next.has(p) ? next.delete(p) : next.add(p);
      return next;
    });

  const valid = name.trim().length > 0;

  return (
    <div>
      <div className="field mb-3 w-64">
        <span className="label">{t("roles.name")}</span>
        <input className="input" value={name} onChange={(e) => setName(e.target.value)} />
      </div>

      <div className="label">{t("roles.permissions")}</div>
      <div className="mt-1 grid grid-cols-1 gap-1">
        {Object.entries(grouped).map(([resource, list]) => (
          <div key={resource} className="flex flex-wrap items-center gap-x-4 gap-y-1 border-t border-term-border py-1.5">
            <span className="w-28 shrink-0 text-[0.75rem] font-semibold text-term-text">{resource}</span>
            {list.map((p) => {
              const action = p.split(":")[1]!;
              return (
                <label key={p} className="flex items-center gap-1 text-[0.75rem] text-term-text">
                  <input type="checkbox" className="accent-term-amber" checked={perms.has(p)} onChange={() => toggle(p)} />
                  {action}
                </label>
              );
            })}
          </div>
        ))}
      </div>

      <div className="mt-3 flex justify-end gap-2">
        <button type="button" className="btn btn-sm" onClick={onCancel}>{t("common.cancel")}</button>
        <button type="button" className="btn btn-primary btn-sm" disabled={!valid} onClick={() => onSubmit({ name: name.trim(), permissions: [...perms] })}>{t("common.save")}</button>
      </div>
    </div>
  );
}