import {
  type NewStoredSelection,
  type PlaybackChanges,
  type SelectionChanges,
  type SignagePlaybackStore,
  SignageStoreConflict,
  type StoredChannel,
  type StoredChannelGroup,
  type StoredChannelGroupDetail,
  type StoredPlaybackState,
  type StoredSelection,
} from "../../src/server/store/types.js";

/**
 * The playback half of the in-memory store.
 *
 * It enforces the guarantees the database enforces — one default channel that cannot be removed, a
 * sequence that is never handed out twice, variants replaced wholesale — so a decision proven here
 * holds against PostgreSQL too.
 */
export interface MemoryPlaybackStore extends SignagePlaybackStore {
  readonly groups: Map<string, StoredChannelGroup>;
  readonly channels: Map<string, StoredChannel>;
  readonly playback: Map<string, StoredPlaybackState>;
  readonly selections: Map<string, StoredSelection>;
}

export function createMemoryPlaybackStore(
  options: { readonly now?: () => Date } = {},
): MemoryPlaybackStore {
  const now = options.now ?? (() => new Date());
  const groups = new Map<string, StoredChannelGroup>();
  const channels = new Map<string, StoredChannel>();
  const playback = new Map<string, StoredPlaybackState>();
  const selections = new Map<string, StoredSelection>();

  function detail(groupId: string): StoredChannelGroupDetail | undefined {
    const group = groups.get(groupId);
    const state = playback.get(groupId);
    if (!group || !state) {
      return undefined;
    }
    return {
      channels: [...channels.values()]
        .filter((channel) => channel.groupId === groupId)
        .sort((left, right) =>
          left.isDefault === right.isDefault
            ? left.key.localeCompare(right.key)
            : left.isDefault
              ? -1
              : 1,
        ),
      group,
      playback: state,
    };
  }

  return {
    addChannel(channel: StoredChannel): Promise<void> {
      channels.set(channel.id, channel);
      const group = groups.get(channel.groupId);
      if (group) {
        groups.set(group.id, { ...group, revision: group.revision + 1 });
      }
      return Promise.resolve();
    },

    channels,

    createChannelGroup(input: {
      readonly groupId: string;
      readonly name: string;
      readonly channelId: string;
      readonly channelName: string;
    }): Promise<void> {
      groups.set(input.groupId, { id: input.groupId, name: input.name, revision: 1 });
      channels.set(input.channelId, {
        groupId: input.groupId,
        id: input.channelId,
        isDefault: true,
        key: "default",
        name: input.channelName,
      });
      playback.set(input.groupId, {
        activeTimelineId: null,
        blackout: false,
        currentSelectionId: null,
        currentSlotId: null,
        groupId: input.groupId,
        nextSequence: 1,
        paused: false,
        pausedRemainingMs: null,
        pendingRequestedAt: null,
        pendingTimelineId: null,
        revision: 1,
        scheduledActivationAt: null,
        scheduledTimelineId: null,
        slotDeadlineAt: null,
        slotStartedAt: null,
        staticAssetId: null,
        updatedAt: now(),
      });
      return Promise.resolve();
    },

    deleteChannelGroup(groupId: string): Promise<void> {
      groups.delete(groupId);
      playback.delete(groupId);
      for (const [id, channel] of channels) {
        if (channel.groupId === groupId) {
          channels.delete(id);
        }
      }
      for (const [id, selection] of selections) {
        if (selection.groupId === groupId) {
          selections.delete(id);
        }
      }
      return Promise.resolve();
    },

    findChannelGroup(groupId: string): Promise<StoredChannelGroupDetail | undefined> {
      return Promise.resolve(detail(groupId));
    },

    findLatestSelectionForScope(
      groupId: string,
      selectionScope: string,
    ): Promise<StoredSelection | undefined> {
      const matching = [...selections.values()]
        .filter(
          (selection) =>
            selection.groupId === groupId && selection.selectionScope === selectionScope,
        )
        .sort((left, right) => right.sequence - left.sequence);
      return Promise.resolve(matching[0]);
    },

    findSelection(selectionId: string): Promise<StoredSelection | undefined> {
      return Promise.resolve(selections.get(selectionId));
    },

    groups,

    insertSelection(selection: NewStoredSelection): Promise<void> {
      selections.set(selection.id, { ...selection, resolvedAt: now(), revision: 1 });
      return Promise.resolve();
    },

    listChannelGroups(): Promise<readonly StoredChannelGroupDetail[]> {
      return Promise.resolve(
        [...groups.values()]
          .sort((left, right) => left.name.localeCompare(right.name))
          .map((group) => detail(group.id))
          .filter((value): value is StoredChannelGroupDetail => value !== undefined),
      );
    },

    listSelections(groupId: string, limit: number): Promise<readonly StoredSelection[]> {
      return Promise.resolve(
        [...selections.values()]
          .filter((selection) => selection.groupId === groupId)
          .sort((left, right) => right.sequence - left.sequence)
          .slice(0, limit),
      );
    },

    playback,

    pruneSelections(groupId: string, limit: number): Promise<void> {
      const ordered = [...selections.values()]
        .filter((selection) => selection.groupId === groupId)
        .sort((left, right) => right.sequence - left.sequence);
      for (const selection of ordered.slice(limit)) {
        selections.delete(selection.id);
      }
      return Promise.resolve();
    },

    removeChannel(channelId: string): Promise<void> {
      const channel = channels.get(channelId);
      if (!channel) {
        return Promise.resolve();
      }
      if (channel.isDefault) {
        return Promise.reject(new SignageStoreConflict("channel.default"));
      }
      channels.delete(channelId);
      const group = groups.get(channel.groupId);
      if (group) {
        groups.set(group.id, { ...group, revision: group.revision + 1 });
      }
      return Promise.resolve();
    },

    selections,

    takeSelectionSequence(groupId: string): Promise<number> {
      const state = playback.get(groupId);
      if (!state) {
        return Promise.reject(new SignageStoreConflict("playback.sequence"));
      }
      playback.set(groupId, { ...state, nextSequence: state.nextSequence + 1 });
      return Promise.resolve(state.nextSequence);
    },

    updatePlayback(
      groupId: string,
      changes: PlaybackChanges,
      updateOptions?: { readonly bumpRevision?: boolean },
    ): Promise<void> {
      const state = playback.get(groupId);
      if (!state) {
        return Promise.resolve();
      }
      const next: Record<string, unknown> = { ...state };
      for (const key of Object.keys(changes)) {
        next[key] = (changes as Record<string, unknown>)[key] ?? null;
      }
      playback.set(groupId, {
        ...(next as unknown as StoredPlaybackState),
        revision: updateOptions?.bumpRevision === false ? state.revision : state.revision + 1,
        updatedAt: now(),
      });
      return Promise.resolve();
    },

    updateSelection(selectionId: string, changes: SelectionChanges): Promise<void> {
      const selection = selections.get(selectionId);
      if (!selection) {
        return Promise.resolve();
      }
      selections.set(selectionId, {
        ...selection,
        ...(changes.availableUntil === undefined ? {} : { availableUntil: changes.availableUntil }),
        ...(changes.deadlineAt === undefined ? {} : { deadlineAt: changes.deadlineAt }),
        ...(changes.durationMs === undefined ? {} : { durationMs: changes.durationMs }),
        ...(changes.itemRevision === undefined ? {} : { itemRevision: changes.itemRevision }),
        ...(changes.presentation === undefined ? {} : { presentation: changes.presentation }),
        ...(changes.stale === undefined ? {} : { stale: changes.stale }),
        ...(changes.startedAt === undefined ? {} : { startedAt: changes.startedAt }),
        ...(changes.withdrawn === undefined ? {} : { withdrawn: changes.withdrawn }),
        ...(changes.variants === undefined ? {} : { variants: changes.variants }),
        revision: changes.bumpRevision === true ? selection.revision + 1 : selection.revision,
      });
      return Promise.resolve();
    },
  };
}