import type {
  DashboardDestination,
  DiscoverView,
  SettingsPageSection,
  SettingsSection,
} from "../dashboard-routes.js";
import type { DashboardSettings, DashboardSettingsModule } from "../host-protocol.js";
import type { ShellIconName } from "./shell-icons.js";

/**
 * How each platform Settings section is named and described to a person (ADR 0061). One table, so
 * the navigation, the Settings landing page, and each section's own page say the same thing. Plain
 * words — never "Core", "platform module", or another implementation term (DESIGN.md §2.3).
 */
export const SETTINGS_SECTION_COPY: Readonly<
  Record<
    SettingsSection,
    { readonly label: string; readonly description: string; readonly icon: ShellIconName }
  >
> = Object.freeze({
  branding: {
    description: "Your church's name, logo, and colours.",
    icon: "settingsBranding",
    label: "Branding",
  },
  displays: {
    description: "Screens paired with this installation.",
    icon: "settingsDisplays",
    label: "Displays",
  },
  general: {
    description: "How this installation works for everyone.",
    icon: "settingsGeneral",
    label: "General",
  },
  discover: {
    description: "Find, install, and manage the modules your church uses.",
    icon: "settingsDiscover",
    label: "Discover",
  },
  system: {
    description: "Version, health, and diagnostics for this installation.",
    icon: "settingsSystem",
    label: "System",
  },
});

/**
 * Discover's views (ADR 0061). "Discover" is where module lifecycle lives in the navigation; inside
 * it the pages speak of modules — "Discover modules", "Installed modules", "Module updates" —
 * because Modules is the product's word for them.
 */
export const DISCOVER_VIEW_COPY: Readonly<
  Record<
    DiscoverView,
    {
      readonly label: string;
      readonly title: string;
      readonly description: string;
      readonly notYet: string;
      readonly icon: ShellIconName;
    }
  >
> = Object.freeze({
  browse: {
    description:
      "Modules add capabilities to your church's Dashboard. Install and manage the modules your church uses.",
    icon: "discoverBrowse",
    label: "Browse",
    notYet: "Finding and installing modules will happen here.",
    title: "Discover modules",
  },
  installed: {
    description: "The modules installed for your church.",
    icon: "discoverInstalled",
    label: "Installed",
    notYet:
      "Seeing your installed modules, turning them on or off, inspecting them, and removing them will happen here.",
    title: "Installed modules",
  },
  updates: {
    description: "Updates for your modules and for this installation.",
    icon: "discoverUpdates",
    label: "Updates",
    notYet: "Checking for and applying module and platform updates will happen here.",
    title: "Module updates",
  },
});

/** Where a platform section's navigation item leads: its page, or — for Discover — Browse. */
export function settingsSectionDestination(section: SettingsSection): DashboardDestination {
  return section === "discover"
    ? { kind: "discover", view: "browse" }
    : { kind: "settings-section", section };
}

/** The module settings a person can open from navigation: running modules only. A disabled
 * module's settings are not offered, though its address still says it is unavailable. */
export function navigableModuleSettings(
  settings: DashboardSettings | "unavailable",
): readonly DashboardSettingsModule[] {
  return settings === "unavailable" ? [] : settings.modules.filter((module) => module.available);
}

/** Whether Settings has anything to offer this person. With nothing, the Settings link is not
 * shown at all, so nobody is shown administration they cannot carry out (DESIGN.md §9.2). */
export function hasVisibleSettings(settings: DashboardSettings | "unavailable"): boolean {
  return (
    settings !== "unavailable" &&
    (settings.sections.length > 0 || navigableModuleSettings(settings).length > 0)
  );
}

export function isSettingsRoute(kind: string): boolean {
  return (
    kind === "settings" ||
    kind === "settings-section" ||
    kind === "discover" ||
    kind === "module-settings"
  );
}

/** What a Settings address shows this person. */
export type SettingsPage =
  | { readonly kind: "home"; readonly settings: DashboardSettings }
  | { readonly kind: "section"; readonly section: SettingsPageSection }
  | { readonly kind: "discover"; readonly view: DiscoverView }
  | { readonly kind: "module"; readonly module: DashboardSettingsModule }
  | { readonly kind: "unavailable"; readonly reason: "no-access" | "module-disabled" }
  | { readonly kind: "load-failed" }
  | { readonly kind: "not-found" };

/**
 * Decides what a Settings address shows (ADR 0061), from what the server said this person may see:
 *
 * - a section or module they may see shows its page;
 * - a disabled module's settings say it is turned off — never a silent redirect;
 * - a section they may not see, or a module they know of but may not configure (or that has no
 *   settings), says the settings aren't available, without saying which;
 * - a name that is no module they know of is not found.
 */
export function resolveSettingsPage(
  route:
    | { readonly kind: "settings" }
    | { readonly kind: "settings-section"; readonly section: SettingsPageSection }
    | { readonly kind: "discover"; readonly view: DiscoverView }
    | { readonly kind: "module-settings"; readonly moduleId: string },
  settings: DashboardSettings | "unavailable",
  knownModuleIds: ReadonlySet<string>,
): SettingsPage {
  if (settings === "unavailable") {
    return { kind: "load-failed" };
  }
  if (route.kind === "settings") {
    return { kind: "home", settings };
  }
  if (route.kind === "discover") {
    return settings.sections.includes("discover")
      ? { kind: "discover", view: route.view }
      : { kind: "unavailable", reason: "no-access" };
  }
  if (route.kind === "settings-section") {
    return settings.sections.includes(route.section)
      ? { kind: "section", section: route.section }
      : { kind: "unavailable", reason: "no-access" };
  }
  const module = settings.modules.find((candidate) => candidate.id === route.moduleId);
  if (module) {
    return module.available
      ? { kind: "module", module }
      : { kind: "unavailable", reason: "module-disabled" };
  }
  return knownModuleIds.has(route.moduleId)
    ? { kind: "unavailable", reason: "no-access" }
    : { kind: "not-found" };
}

/** The browser tab's name for a Settings page. */
export function settingsPageTitle(page: SettingsPage): string {
  switch (page.kind) {
    case "home":
      return "Settings";
    case "section":
      return `${SETTINGS_SECTION_COPY[page.section].label} settings`;
    case "discover":
      return DISCOVER_VIEW_COPY[page.view].title;
    case "module":
      return `${page.module.name} settings`;
    case "unavailable":
      return page.reason === "module-disabled"
        ? "This module is turned off"
        : "These settings aren't available";
    case "load-failed":
      return "Settings could not be loaded";
    case "not-found":
      return "Page not found";
  }
}