/**
 * Session/account-scoped Marketplace projections.
 *
 * The package index is deliberately device-scoped and contains immutable
 * release facts only.  Library rows and release admissions live here instead,
 * keyed by the opaque Main-owned account binding and its session epoch.
 */

export interface AccountBinding {
  readonly accountKey: string;
  readonly epoch: number;
}

export type MarketplaceChannel = 'stable' | 'beta';
export type MarketplaceResolveAction = 'keep' | 'install' | 'update' | 'unavailable';

export interface MarketplaceLibraryEntry {
  readonly pluginId: string;
  readonly title: string;
  readonly summary: string;
  readonly category: string;
  readonly acquisition: 'free' | 'system_included';
  readonly acquisitionMode: 'system_included' | 'user_acquired';
  readonly catalogStatus: 'active' | 'retired';
  readonly runtimeStatus: 'enabled' | 'suspended';
  readonly acquiredAt: string | null;
  readonly removedAt: string | null;
  readonly stableVersion: string | null;
  readonly betaVersion: string | null;
}

export interface MarketplaceLibrarySnapshot {
  readonly items: readonly MarketplaceLibraryEntry[];
  readonly total: number;
  readonly stale: boolean;
  readonly fetchedAt: number;
}

export interface MarketplaceResolveItem {
  readonly pluginId: string;
  readonly action: MarketplaceResolveAction;
  readonly releaseId?: string | null;
  readonly version?: string | null;
  readonly sha256?: string | null;
  readonly sizeBytes?: number | null;
  readonly releaseAdmissionId?: string | null;
  readonly expiresAt?: string | null;
  readonly channel?: MarketplaceChannel | null;
  readonly reason?: string | null;
}

export interface MarketplaceResolveSnapshot {
  readonly resolveRequestId: string;
  readonly resolveRequestDigest: string;
  readonly items: readonly MarketplaceResolveItem[];
  readonly catalogGeneration: number;
  readonly etag: string | null;
  readonly stale: boolean;
}

export interface AccountPluginCacheRecord {
  readonly binding: AccountBinding;
  readonly library: MarketplaceLibrarySnapshot | null;
  readonly resolves: ReadonlyMap<string, MarketplaceResolveSnapshot>;
}

function assertBinding(binding: AccountBinding): void {
  if (typeof binding.accountKey !== 'string' || binding.accountKey.length === 0
    || binding.accountKey.length > 512 || !Number.isSafeInteger(binding.epoch)
    || binding.epoch < 0) {
    throw new TypeError('Marketplace account binding is invalid');
  }
}

function bindingId(binding: AccountBinding): string {
  assertBinding(binding);
  return `${binding.accountKey}\u0000${binding.epoch}`;
}

function clone<T>(value: T): T {
  return structuredClone(value);
}

/**
 * In-memory account cache.  Keeping this cache in Main memory prevents
 * admissions and Library state from entering the shared package index or a
 * project file.  A session change invalidates every account snapshot.
 */
export class AccountPluginCache {
  private readonly records = new Map<string, {
    binding: AccountBinding;
    library: MarketplaceLibrarySnapshot | null;
    resolves: Map<string, MarketplaceResolveSnapshot>;
  }>();
  private readonly libraryIntents = new Map<string, number>();

  private nextLibraryIntent(key: string): number {
    const next = (this.libraryIntents.get(key) ?? 0) + 1;
    this.libraryIntents.set(key, next);
    return next;
  }

  private setLibrarySnapshot(key: string, binding: AccountBinding, snapshot: MarketplaceLibrarySnapshot): void {
    const record = this.records.get(key) ?? {
      binding: { accountKey: binding.accountKey, epoch: binding.epoch },
      library: null,
      resolves: new Map<string, MarketplaceResolveSnapshot>(),
    };
    record.library = clone(snapshot);
    this.records.set(key, record);
  }

  getLibrary(binding: AccountBinding): MarketplaceLibrarySnapshot | null {
    const record = this.records.get(bindingId(binding));
    return record?.library ? clone(record.library) : null;
  }

  setLibrary(binding: AccountBinding, snapshot: MarketplaceLibrarySnapshot): void {
    const key = bindingId(binding);
    this.nextLibraryIntent(key);
    this.setLibrarySnapshot(key, binding, snapshot);
  }

  /** Reserve the commit slot before an async Library read or mutation starts. */
  beginLibraryIntent(binding: AccountBinding): number {
    return this.nextLibraryIntent(bindingId(binding));
  }

  /** Commit only the latest read/mutation intent for this account binding. */
  commitLibrary(
    binding: AccountBinding,
    intent: number,
    snapshot: MarketplaceLibrarySnapshot,
  ): boolean {
    const key = bindingId(binding);
    if (this.libraryIntents.get(key) !== intent) return false;
    this.setLibrarySnapshot(key, binding, snapshot);
    return true;
  }

  markLibraryStale(binding: AccountBinding, intent?: number): MarketplaceLibrarySnapshot | null {
    const key = bindingId(binding);
    if (intent !== undefined && this.libraryIntents.get(key) !== intent) return null;
    const record = this.records.get(key);
    if (!record?.library) return null;
    record.library = { ...record.library, stale: true };
    return clone(record.library);
  }

  getResolve(binding: AccountBinding, logicalKey: string): MarketplaceResolveSnapshot | null {
    if (typeof logicalKey !== 'string' || logicalKey.length === 0) return null;
    const record = this.records.get(bindingId(binding));
    const snapshot = record?.resolves.get(logicalKey);
    return snapshot ? clone(snapshot) : null;
  }

  setResolve(
    binding: AccountBinding,
    logicalKey: string,
    snapshot: MarketplaceResolveSnapshot,
  ): void {
    if (typeof logicalKey !== 'string' || logicalKey.length === 0 || logicalKey.length > 512) {
      throw new TypeError('Marketplace resolve cache key is invalid');
    }
    const key = bindingId(binding);
    const record = this.records.get(key) ?? {
      binding: { accountKey: binding.accountKey, epoch: binding.epoch },
      library: null,
      resolves: new Map<string, MarketplaceResolveSnapshot>(),
    };
    record.resolves.set(logicalKey, clone(snapshot));
    this.records.set(key, record);
  }

  markResolveStale(binding: AccountBinding, logicalKey: string): MarketplaceResolveSnapshot | null {
    const key = bindingId(binding);
    const record = this.records.get(key);
    const snapshot = record?.resolves.get(logicalKey);
    if (!record || !snapshot) return null;
    const stale = { ...snapshot, stale: true };
    record.resolves.set(logicalKey, stale);
    return clone(stale);
  }

  getRecord(binding: AccountBinding): AccountPluginCacheRecord | null {
    const record = this.records.get(bindingId(binding));
    if (!record) return null;
    return {
      binding: { ...record.binding },
      library: record.library ? clone(record.library) : null,
      resolves: new Map([...record.resolves.entries()].map(([key, value]) => [key, clone(value)])),
    };
  }

  /** Release IDs retained by all live account snapshots. */
  referencedReleaseIds(): ReadonlySet<string> {
    const result = new Set<string>();
    for (const record of this.records.values()) {
      for (const snapshot of record.resolves.values()) {
        for (const item of snapshot.items) {
          if (item.releaseId) result.add(item.releaseId);
        }
      }
    }
    return result;
  }

  /**
   * Forget device-resolution snapshots for one plugin in one account binding.
   * The Library projection is intentionally retained so uninstalling a device
   * package never becomes an account Library mutation.
   */
  invalidatePlugin(binding: AccountBinding, pluginId: string): void {
    const record = this.records.get(bindingId(binding));
    if (!record) return;
    for (const [key, snapshot] of record.resolves.entries()) {
      const items = snapshot.items.filter((item) => item.pluginId !== pluginId);
      if (items.length === 0) record.resolves.delete(key);
      else if (items.length !== snapshot.items.length) record.resolves.set(key, { ...snapshot, items });
    }
  }

  clearAccount(binding: AccountBinding): void {
    assertBinding(binding);
    for (const [key, record] of this.records.entries()) {
      if (record.binding.accountKey === binding.accountKey) {
        this.records.delete(key);
        this.libraryIntents.delete(key);
      }
    }
  }

  invalidateAll(): void {
    this.records.clear();
    this.libraryIntents.clear();
  }

  clear(): void {
    this.invalidateAll();
  }

  get size(): number {
    return this.records.size;
  }
}

export const accountBindingKey = bindingId;