import {
  defineModuleRuntime,
  type ModuleRuntimeContext,
  type ModuleRuntimeDefinition,
} from "@ekklesia/module-sdk";
import type { DisplayRealtimePayload } from "../shared/display-protocol.js";
import { SIGNAGE_SLIDE_RENDERER_INPUT_VERSION } from "../shared/renderer-input.js";
import {
  SIGNAGE_IMAGE_MAX_BYTES,
  SIGNAGE_IMAGE_MAX_PIXELS,
  SIGNAGE_UPLOAD_BATCH_MAX_FILES,
  SIGNAGE_UPLOAD_CONCURRENCY,
} from "./images/limits.js";
import { createPlaybackCapability } from "./playback/capability.js";
import {
  createPlaybackService,
  type PlaybackSnapshot,
  type SignagePlaybackService,
} from "./playback/service.js";
import type { SignageProviderHandle } from "./providers/contract.js";
import {
  createNativeImageProvider,
  type NativeImageProvider,
} from "./providers/native-provider.js";
import { createProviderRegistry, type SignageProviderRegistry } from "./providers/registry.js";
import { registerImageRoutes } from "./routes/images.js";
import { registerPlaybackRoutes } from "./routes/playback.js";
import { registerProviderRoutes } from "./routes/providers.js";
import { registerTimelineRoutes } from "./routes/timelines.js";
import { registerViewerRoutes } from "./routes/viewers.js";
import { readSignageSettings } from "./settings.js";
import { createSignageStore } from "./store/drizzle.js";
import { createDisplaysCapability } from "./viewers/capability.js";

/**
 * Signage's server runtime, as a factory rather than a module-level singleton.
 *
 * A factory because the runtime owns real state — the live provider registry, the built-in image
 * provider's registration handle, the playback service and its timers — and a test that exercised
 * registration twice against one shared instance would be testing leftovers. `index.ts` calls this
 * once; a test calls it per case.
 *
 * Registration stays declarative and I/O-free: nothing here connects to PostgreSQL, contacts object
 * storage, reads the environment, opens a socket, or applies a migration. Live services reach
 * Signage only through the contexts the platform hands `start`, `stop`, and route handlers.
 */
export interface SignageRuntimeOptions {
  readonly now?: () => Date;
}

export interface SignageModuleRuntime {
  readonly definition: ModuleRuntimeDefinition;
  /** The live registry, exposed for tests and for the routes that report provider health. */
  readonly registry: SignageProviderRegistry;
}

/** Realtime carries compact authoritative state and revisions, never content (ADR 0005). Large
 * state — a timeline, a history, a renderer payload — is fetched over authorized HTTP keyed by
 * revision, which closes the GET-then-subscribe race without a second transport. */
export const SIGNAGE_DISPLAY_CHANNEL = "display-state";
export const SIGNAGE_MANAGEMENT_CHANNEL = "management-state";

export function createSignageModuleRuntime(
  options: SignageRuntimeOptions = {},
): SignageModuleRuntime {
  const now = options.now ?? (() => new Date());
  let registry: SignageProviderRegistry | undefined;
  let nativeProvider: NativeImageProvider | undefined;
  let nativeHandle: SignageProviderHandle | undefined;
  let playback: SignagePlaybackService | undefined;
  let store: ReturnType<typeof createSignageStore> | undefined;
  /** The latest snapshot per group, so a publication never has to read the database from inside the
   * very lock that produced it. */
  const snapshots = new Map<string, PlaybackSnapshot>();

  function requireRegistry(): SignageProviderRegistry {
    if (!registry) {
      throw new Error("Signage's provider registry is only available after registration.");
    }
    return registry;
  }

  function requirePlayback(): SignagePlaybackService {
    if (!playback) {
      throw new Error("Signage's playback service is only available after start.");
    }
    return playback;
  }

  function requireStore(): ReturnType<typeof createSignageStore> {
    if (!store) {
      throw new Error("Signage's store is only available after start.");
    }
    return store;
  }

  function publish(context: ModuleRuntimeContext): void {
    const groups = [...snapshots.values()].sort((left, right) =>
      left.groupId.localeCompare(right.groupId),
    );
    try {
      // The shape the display reads (`src/shared/display-protocol.ts`): each group's whole snapshot
      // carries the revisions it compares.
      const display: DisplayRealtimePayload = { groups, serverNowMs: now().getTime() };
      context.realtime.publish(SIGNAGE_DISPLAY_CHANNEL, display);
      context.realtime.publish(SIGNAGE_MANAGEMENT_CHANNEL, {
        // Revisions only. The dashboard refetches what changed over authorized HTTP.
        groups: groups.map((snapshot) => ({
          groupId: snapshot.groupId,
          revision: snapshot.revision,
          selectionRevision: snapshot.selectionRevision,
          transport: snapshot.transport,
        })),
        providers: requireRegistry()
          .health()
          .map((provider) => ({
            consecutiveFailures: provider.consecutiveFailures,
            lastFailureCode: provider.lastFailureCode,
            providerId: provider.providerId,
          })),
        serverNowMs: now().getTime(),
      });
    } catch {
      // Realtime is best effort and never blocks or changes committed playback state.
    }
  }

  const definition = defineModuleRuntime({
    // Matches `database.abi` in the manifest: `context.services.database` is this module's Module
    // Database ABI v1 executor, which `createSignageStore` binds Signage's own Drizzle adapter to.
    database: { abi: 1 },
    id: "signage",
    version: "0.1.3",

    register({ capabilities, config, http, realtime }) {
      const settings = readSignageSettings(config);

      registry = createProviderRegistry({
        now,
        onInvalidate: (notice) => {
          // A notification, never a command: playback decides what to refresh and when, because it
          // is the only thing that knows what is on screen.
          void playback?.invalidate(notice).catch(() => undefined);
        },
        timeoutMs: settings.providerTimeoutMs,
      });

      // The extension seam every future content module reaches Signage through (ADR 0002).
      capabilities.provide("signage.content-providers", registry.capability);

      // The browser half of the same seam. Nothing registers against it server-side: a contribution
      // is declared in a *contributing* module's manifest and published by the platform, and this
      // declaration is what makes `capabilityRange` mean something. Resolving it tells a module
      // which version of Signage's renderer input contract this installation speaks.
      capabilities.provide(
        "signage.slide-renderer",
        Object.freeze({ inputVersion: SIGNAGE_SLIDE_RENDERER_INPUT_VERSION }),
      );

      // Sanitized playback state and commands for a future consumer such as an Ekklesia Companion.
      // Exactly what an operator has in the dashboard, over the same serialized service — and
      // deliberately no transport, topic, broker, or integration vocabulary of any kind.
      capabilities.provide(
        "signage.playback",
        createPlaybackCapability(requirePlayback, async () => {
          const groups = await requireStore().listChannelGroups();
          return groups.map((group) => group.group.id);
        }),
      );

      // Sanitized viewer and channel health, and assignment, for another module. Names, online
      // state, and what a screen last reported — never a credential, a pairing token, or a host
      // internal.
      capabilities.provide("signage.displays", createDisplaysCapability(requireStore, now));

      realtime.channel({ channel: SIGNAGE_DISPLAY_CHANNEL, permission: "signage.display.view" });
      realtime.channel({ channel: SIGNAGE_MANAGEMENT_CHANNEL, permission: "signage.view" });

      http.route({
        method: "GET",
        path: "/settings",
        permission: "signage.view",
        // A GET route accepts no request body at all.
        maxBodyBytes: 0,
        handler(_request, context) {
          const current = readSignageSettings(context.config);
          // Operator settings and Signage's own declared limits. Signage declares no `secret`
          // configuration key, and this route would still never serialize one: what an operator may
          // see of a module's configuration is the module's deliberate decision, value by value.
          //
          // The limits travel with the settings so the dashboard never hardcodes a number the
          // server enforces — a UI believing a stale limit would offer an upload the server refuses.
          return Response.json({
            crossfadeMs: current.crossfadeMs,
            moduleVersion: "0.1.3",
            nativeImageDurationMs: current.nativeImageDurationMs,
            nativePresentation: current.nativePresentation,
            rendererInputVersion: SIGNAGE_SLIDE_RENDERER_INPUT_VERSION,
            timezone: current.timezone,
            uploads: {
              batchMaxFiles: SIGNAGE_UPLOAD_BATCH_MAX_FILES,
              concurrency: SIGNAGE_UPLOAD_CONCURRENCY,
              maxBytes: SIGNAGE_IMAGE_MAX_BYTES,
              maxPixels: SIGNAGE_IMAGE_MAX_PIXELS,
            },
          });
        },
      });

      registerImageRoutes(http);
      registerProviderRoutes(http, requireRegistry);
      registerTimelineRoutes(http);
      registerPlaybackRoutes(http, requirePlayback);
      registerViewerRoutes(http, requirePlayback, requireRegistry);
    },

    async start(context: ModuleRuntimeContext) {
      const settings = readSignageSettings(context.config);
      store = createSignageStore(context.services.database);

      // Signage's own content provider registers through the identical capability an external
      // provider uses. There is one selection pipeline, not a native special case (ADR 0001).
      nativeProvider = createNativeImageProvider({
        defaultDurationMs: settings.nativeImageDurationMs,
        now,
        store,
      });
      nativeHandle = requireRegistry().capability.register(nativeProvider.registration);

      playback = createPlaybackService({
        now: () => now().getTime(),
        onSnapshot: (snapshot) => {
          snapshots.set(snapshot.groupId, snapshot);
          publish(context);
        },
        registry: requireRegistry(),
        settings,
        store,
      });

      // One default channel group with one default channel, and nothing else. `in-person` and
      // `online` are an administrator's decision, not an install-time one (ADR 0004).
      await playback.ensureDefaultGroup();
      await playback.start();

      // Every declared channel must receive an initial publication before `start` completes, so a
      // subscriber that connects immediately is given state rather than silence.
      publish(context);
    },

    stop() {
      // Idempotent, and safe after a `start` that failed partway: `stop` runs before rollback, and
      // may run again during reverse-order shutdown.
      playback?.stop();
      playback = undefined;
      store = undefined;
      snapshots.clear();
      nativeHandle?.unregister();
      nativeHandle = undefined;
      nativeProvider = undefined;
      registry?.clear();
    },
  });

  return {
    definition,
    get registry(): SignageProviderRegistry {
      return requireRegistry();
    },
  };
}