import { designToken } from "@ekklesia/design-tokens";
import type { CSSProperties, ReactElement } from "react";
import type { DashboardDestination, DashboardRoute } from "../dashboard-routes.js";
import type { DashboardNavigation, DashboardNavigationEntry } from "../host-protocol.js";
import { DashboardLink } from "./DashboardLink.js";
import type { HostHistory } from "./host-history.js";
import { useNavTooltip } from "./NavTooltip.js";
import { ShellIcon, type ShellIconName } from "./shell-icons.js";

/**
 * How a navigation surface presents itself. `collapsed` is the desktop sidebar's icon-only mode;
 * `compact` is the phone drawer, which always shows labels and uses larger touch targets.
 */
export interface NavigationPresentation {
  readonly collapsed: boolean;
  readonly compact: boolean;
}

/** The control height for this presentation: the medium control on desktop, the large one in the
 * drawer, so a fingertip has room (WCAG 2.2 §2.5.8 asks for 24px; this is 40px and 48px). */
export function controlHeight(presentation: NavigationPresentation): string {
  return designToken(presentation.compact ? "control.height-lg" : "control.height-md");
}

/**
 * The identity slot at the top of the navigation (ADR 0058).
 *
 * A neutral placeholder — a plain mark and the product's name — until the installation's own
 * branding replaces it (DESIGN.md §2.1, §3.4). It is one component with no inputs on purpose: the
 * branding work owns the decision of what goes here and where it comes from, and replaces this
 * component's body rather than undoing a configuration model invented early. It is not a heading;
 * each page's own title is. Collapsed, only the mark shows.
 */
export function ShellBrand(props: { readonly collapsed: boolean }): ReactElement {
  return (
    <div className="ek-shell-brand" data-testid="shell-brand">
      <span aria-hidden="true" className="ek-shell-brand__mark" />
      <span className={props.collapsed ? "ek-shell-visually-hidden" : undefined}>Ekklesia</span>
    </div>
  );
}

function NavigationItem(props: {
  readonly destination: DashboardDestination;
  readonly label: string;
  readonly icon: ShellIconName;
  readonly current: boolean;
  readonly history: HostHistory;
  readonly presentation: NavigationPresentation;
  readonly onNavigate?: () => void;
  readonly testId: string;
}): ReactElement {
  const { tooltip, triggerProps } = useNavTooltip(props.label, props.presentation.collapsed);
  const style: CSSProperties = { minHeight: controlHeight(props.presentation) };
  return (
    <li>
      <DashboardLink
        className="ek-shell-nav-item"
        current={props.current}
        data-testid={props.testId}
        history={props.history}
        {...(props.onNavigate ? { onNavigate: props.onNavigate } : {})}
        style={style}
        to={props.destination}
        {...triggerProps}
      >
        <ShellIcon name={props.icon} />
        <span
          className={
            props.presentation.collapsed ? "ek-shell-visually-hidden" : "ek-shell-nav-item__label"
          }
          data-nav-label=""
        >
          {props.label}
        </span>
      </DashboardLink>
      {tooltip}
    </li>
  );
}

function ModuleItems(props: {
  readonly entries: readonly DashboardNavigationEntry[];
  readonly route: DashboardRoute;
  readonly history: HostHistory;
  readonly presentation: NavigationPresentation;
  readonly onNavigate?: () => void;
  readonly labelledBy?: string;
}): ReactElement {
  return (
    <ul
      aria-labelledby={props.labelledBy}
      className="ek-shell-nav__group"
      style={{ listStyle: "none", margin: 0, padding: 0 }}
    >
      {props.entries.map((entry) => {
        const moduleId = entry.descriptor.id;
        return (
          <NavigationItem
            current={props.route.kind === "module" && props.route.moduleId === moduleId}
            destination={{ kind: "module", moduleId }}
            history={props.history}
            // Every module gets the one generic icon until modules can declare their own
            // (ADR 0058); there is no table of known modules.
            icon="module"
            key={`${moduleId}@${entry.descriptor.version}`}
            label={entry.name}
            {...(props.onNavigate ? { onNavigate: props.onNavigate } : {})}
            presentation={props.presentation}
            testId={`select-${moduleId}`}
          />
        );
      })}
    </ul>
  );
}

export interface NavigationListProps {
  readonly id: string;
  readonly navigation: DashboardNavigation;
  readonly route: DashboardRoute;
  readonly history: HostHistory;
  readonly presentation: NavigationPresentation;
  /** Called once a destination is chosen, for the drawer to close. */
  readonly onNavigate?: () => void;
}

/**
 * The Dashboard's one navigation hierarchy, identical in the desktop sidebar and the phone drawer
 * (DESIGN.md §4.6): the Overview first, then the server's groups in the server's order, then any
 * ungrouped modules. The shell sorts and filters nothing — a disabled module is absent because the
 * server's navigation does not list it (ADR 0027, ADR 0028).
 *
 * Collapsed, group labels stay in the DOM for assistive technology and a divider stands in for them
 * visually.
 */
export function NavigationList(props: NavigationListProps): ReactElement {
  const { groups, ungrouped } = props.navigation;
  const { collapsed } = props.presentation;
  const onNavigate = props.onNavigate ? { onNavigate: props.onNavigate } : {};
  const empty = groups.length === 0 && ungrouped.length === 0;
  return (
    <nav aria-label="Dashboard" className="ek-shell-nav" id={props.id}>
      <ul className="ek-shell-nav__group" style={{ listStyle: "none", margin: 0, padding: 0 }}>
        <NavigationItem
          current={props.route.kind === "overview"}
          destination={{ kind: "overview" }}
          history={props.history}
          icon="overview"
          label="Overview"
          {...onNavigate}
          presentation={props.presentation}
          testId="select-overview"
        />
      </ul>
      {empty && !collapsed ? (
        <p data-testid="host-empty" style={{ color: designToken("text.secondary"), margin: 0 }}>
          No installed module provides a user interface.
        </p>
      ) : undefined}
      {groups.map((group) => {
        const labelId = `${props.id}-group-${group.id}`;
        return (
          <section data-testid={`group-${group.id}`} key={group.id}>
            {collapsed ? <div aria-hidden="true" className="ek-shell-nav__divider" /> : undefined}
            <h2
              className={collapsed ? "ek-shell-visually-hidden" : "ek-shell-nav__group-label"}
              id={labelId}
            >
              {group.label}
            </h2>
            <ModuleItems
              entries={group.modules}
              history={props.history}
              labelledBy={labelId}
              {...onNavigate}
              presentation={props.presentation}
              route={props.route}
            />
          </section>
        );
      })}
      {ungrouped.length > 0 ? (
        <section data-testid="group-ungrouped">
          {groups.length > 0 ? (
            <>
              {collapsed ? <div aria-hidden="true" className="ek-shell-nav__divider" /> : undefined}
              <h2
                className={collapsed ? "ek-shell-visually-hidden" : "ek-shell-nav__group-label"}
                id={`${props.id}-group-other`}
              >
                Other
              </h2>
            </>
          ) : undefined}
          <ModuleItems
            entries={ungrouped}
            history={props.history}
            {...(groups.length > 0 ? { labelledBy: `${props.id}-group-other` } : {})}
            {...onNavigate}
            presentation={props.presentation}
            route={props.route}
          />
        </section>
      ) : undefined}
    </nav>
  );
}