import {
  type NewStoredProviderSource,
  type NewStoredSlot,
  type NewStoredTimeline,
  SignageStoreConflict,
  type SignageTimelineStore,
  type SlotChanges,
  type StoredProviderSource,
  type StoredSlot,
  type StoredTimeline,
  type StoredTimelineDetail,
  type StoredTimelineUsage,
  type TimelineChanges,
} from "../../src/server/store/types.js";

/**
 * The timeline half of the in-memory store.
 *
 * It enforces the same invariants the database does — contiguous positions, an exhaustive reorder,
 * a revision that increments once per semantic change — so a test cannot pass here and fail against
 * PostgreSQL. Where the production store uses a transaction, this uses the fact that JavaScript does
 * not interleave synchronous work; the property being proven is the same.
 */
export interface MemoryTimelineStore extends SignageTimelineStore {
  /** Test-only: pretend a channel group has this timeline active, pending, or scheduled. */
  setTimelineUsage(timelineId: string, usage: StoredTimelineUsage): void;
  readonly timelines: Map<string, StoredTimeline>;
  readonly slots: Map<string, StoredSlot>;
  readonly sources: Map<string, StoredProviderSource>;
}

export function createMemoryTimelineStore(
  options: { readonly now?: () => Date } = {},
): MemoryTimelineStore {
  const now = options.now ?? (() => new Date());
  const timelines = new Map<string, StoredTimeline>();
  const slots = new Map<string, StoredSlot>();
  const sources = new Map<string, StoredProviderSource>();
  const usage = new Map<string, StoredTimelineUsage>();

  function slotsOf(timelineId: string): StoredSlot[] {
    return [...slots.values()]
      .filter((slot) => slot.timelineId === timelineId)
      .sort((left, right) => left.position - right.position);
  }

  function bump(timelineId: string): void {
    const timeline = timelines.get(timelineId);
    if (timeline) {
      timelines.set(timelineId, {
        ...timeline,
        revision: timeline.revision + 1,
        updatedAt: now(),
      });
    }
  }

  function renumber(timelineId: string, orderedSlotIds: readonly string[]): void {
    for (const [index, slotId] of orderedSlotIds.entries()) {
      const slot = slots.get(slotId);
      if (slot) {
        slots.set(slotId, { ...slot, position: index });
      }
    }
    bump(timelineId);
  }

  return {
    addSlot(slot: NewStoredSlot, position?: number): Promise<void> {
      const existing = slotsOf(slot.timelineId).map((entry) => entry.id);
      const index =
        position === undefined ? existing.length : Math.max(0, Math.min(position, existing.length));
      slots.set(slot.id, { ...slot, position: -1 });
      renumber(slot.timelineId, [...existing.slice(0, index), slot.id, ...existing.slice(index)]);
      return Promise.resolve();
    },

    addSource(source: NewStoredProviderSource): Promise<void> {
      sources.set(source.id, { ...source, createdAt: now() });
      return Promise.resolve();
    },

    createTimeline(input: {
      readonly timeline: NewStoredTimeline;
      readonly sources: readonly NewStoredProviderSource[];
      readonly slots: readonly NewStoredSlot[];
    }): Promise<void> {
      const createdAt = now();
      timelines.set(input.timeline.id, {
        ...input.timeline,
        createdAt,
        revision: 1,
        updatedAt: createdAt,
      });
      for (const source of input.sources) {
        sources.set(source.id, { ...source, createdAt });
      }
      for (const [index, slot] of input.slots.entries()) {
        slots.set(slot.id, { ...slot, position: index });
      }
      return Promise.resolve();
    },

    deleteTimeline(timelineId: string): Promise<void> {
      timelines.delete(timelineId);
      for (const [id, slot] of slots) {
        if (slot.timelineId === timelineId) {
          slots.delete(id);
        }
      }
      for (const [id, source] of sources) {
        if (source.timelineId === timelineId) {
          sources.delete(id);
        }
      }
      return Promise.resolve();
    },

    findTimeline(timelineId: string): Promise<StoredTimelineDetail | undefined> {
      const timeline = timelines.get(timelineId);
      if (!timeline) {
        return Promise.resolve(undefined);
      }
      return Promise.resolve({
        slots: slotsOf(timelineId),
        sources: [...sources.values()]
          .filter((source) => source.timelineId === timelineId)
          .sort((left, right) => left.createdAt.getTime() - right.createdAt.getTime()),
        timeline,
      });
    },

    listTimelines(): Promise<readonly StoredTimeline[]> {
      return Promise.resolve(
        [...timelines.values()].sort((left, right) => left.name.localeCompare(right.name)),
      );
    },

    removeSlot(slotId: string): Promise<void> {
      const slot = slots.get(slotId);
      if (!slot) {
        return Promise.resolve();
      }
      slots.delete(slotId);
      renumber(
        slot.timelineId,
        slotsOf(slot.timelineId).map((entry) => entry.id),
      );
      return Promise.resolve();
    },

    removeSource(sourceId: string): Promise<void> {
      const source = sources.get(sourceId);
      if (!source) {
        return Promise.resolve();
      }
      sources.delete(sourceId);
      for (const [id, slot] of slots) {
        if (slot.sourceId === sourceId) {
          slots.delete(id);
        }
      }
      renumber(
        source.timelineId,
        slotsOf(source.timelineId).map((entry) => entry.id),
      );
      return Promise.resolve();
    },

    reorderSlots(timelineId: string, orderedSlotIds: readonly string[]): Promise<void> {
      const current = slotsOf(timelineId).map((slot) => slot.id);
      const given = new Set(orderedSlotIds);
      if (given.size !== orderedSlotIds.length || given.size !== current.length) {
        return Promise.reject(new SignageStoreConflict("timeline.slotOrder"));
      }
      for (const slotId of current) {
        if (!given.has(slotId)) {
          return Promise.reject(new SignageStoreConflict("timeline.slotOrder"));
        }
      }
      renumber(timelineId, orderedSlotIds);
      return Promise.resolve();
    },

    setTimelineUsage(timelineId: string, value: StoredTimelineUsage): void {
      usage.set(timelineId, value);
    },

    slots,

    sources,

    timelineUsage(timelineId: string): Promise<StoredTimelineUsage> {
      return Promise.resolve(
        usage.get(timelineId) ?? { activeGroups: 0, pendingGroups: 0, scheduledGroups: 0 },
      );
    },

    timelines,

    updateSlot(slotId: string, changes: SlotChanges): Promise<void> {
      const slot = slots.get(slotId);
      if (!slot) {
        return Promise.resolve();
      }
      slots.set(slotId, {
        ...slot,
        ...(changes.enabled === undefined ? {} : { enabled: changes.enabled }),
        ...(changes.durationOverrideMs === undefined
          ? {}
          : { durationOverrideMs: changes.durationOverrideMs }),
        ...(changes.eligibleFrom === undefined ? {} : { eligibleFrom: changes.eligibleFrom }),
        ...(changes.eligibleUntil === undefined ? {} : { eligibleUntil: changes.eligibleUntil }),
        ...(changes.itemId === undefined ? {} : { itemId: changes.itemId }),
        presentation: { ...slot.presentation, ...(changes.presentation ?? {}) },
      });
      bump(slot.timelineId);
      return Promise.resolve();
    },

    updateTimeline(timelineId: string, changes: TimelineChanges): Promise<void> {
      const timeline = timelines.get(timelineId);
      if (!timeline) {
        return Promise.resolve();
      }
      timelines.set(timelineId, {
        ...timeline,
        ...(changes.name === undefined ? {} : { name: changes.name }),
        ...(changes.description === undefined ? {} : { description: changes.description }),
        ...(changes.eligibleFrom === undefined ? {} : { eligibleFrom: changes.eligibleFrom }),
        ...(changes.eligibleUntil === undefined ? {} : { eligibleUntil: changes.eligibleUntil }),
        revision: timeline.revision + 1,
        updatedAt: now(),
      });
      return Promise.resolve();
    },
  };
}