import {
  type Class,
  type Client,
  type Doc,
  type DocumentQuery,
  type FindOptions,
  type FindResult,
  type Hierarchy,
  type ModelDb,
  type Ref,
  type Tx,
  type TxResult,
  type WithLookup,
  toFindResult,
  type SearchQuery,
  type SearchOptions,
  type SearchResult,
  type MeasureClient,
  type MeasureDoneOperation
} from '@hcengineering/core'
import { type Resource } from '@hcengineering/platform'

/**
 * @public
 */
export interface PresentationMiddleware {
  next?: PresentationMiddleware

  tx: (tx: Tx) => Promise<TxResult>

  notifyTx: (tx: Tx) => Promise<void>

  findAll: <T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ) => Promise<FindResult<T>>

  findOne: <T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ) => Promise<WithLookup<T> | undefined>

  subscribe: <T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options: FindOptions<T> | undefined,
    refresh: () => void
  ) => Promise<{
    unsubscribe: () => void
    query?: DocumentQuery<T>
    options?: FindOptions<T>
  }>

  close: () => Promise<void>
}

/**
 * @public
 */
export type PresentationMiddlewareCreator = (client: Client, next?: PresentationMiddleware) => PresentationMiddleware

/**
 * @public
 */
export interface PresentationPipeline extends MeasureClient, Exclude<PresentationMiddleware, 'next'> {
  close: () => Promise<void>
}

/**
 * @public
 */
export class PresentationPipelineImpl implements PresentationPipeline {
  private head: PresentationMiddleware | undefined

  private constructor (readonly client: MeasureClient) {}

  getHierarchy (): Hierarchy {
    return this.client.getHierarchy()
  }

  getModel (): ModelDb {
    return this.client.getModel()
  }

  async notifyTx (tx: Tx): Promise<void> {
    await this.head?.notifyTx(tx)
  }

  async measure (operationName: string): Promise<MeasureDoneOperation> {
    return await this.client.measure(operationName)
  }

  static create (client: MeasureClient, constructors: PresentationMiddlewareCreator[]): PresentationPipeline {
    const pipeline = new PresentationPipelineImpl(client)
    pipeline.head = pipeline.buildChain(constructors)
    return pipeline
  }

  private buildChain (constructors: PresentationMiddlewareCreator[]): PresentationMiddleware | undefined {
    let current: PresentationMiddleware | undefined
    for (let index = constructors.length - 1; index >= 0; index--) {
      const element = constructors[index]
      current = element(this.client, current)
    }
    return current
  }

  async findAll<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<FindResult<T>> {
    return this.head !== undefined
      ? await this.head.findAll(_class, query, options)
      : await this.client.findAll(_class, query, options)
  }

  async searchFulltext (query: SearchQuery, options: SearchOptions): Promise<SearchResult> {
    return await this.client.searchFulltext(query, options)
  }

  async findOne<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<WithLookup<T> | undefined> {
    return this.head !== undefined
      ? await this.head.findOne(_class, query, options)
      : await this.client.findOne(_class, query, options)
  }

  async subscribe<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options: FindOptions<T> | undefined,
    refresh: () => void
  ): Promise<{
      unsubscribe: () => void
      query?: DocumentQuery<T>
      options?: FindOptions<T>
    }> {
    return this.head !== undefined
      ? await this.head.subscribe(_class, query, options, refresh)
      : { unsubscribe: () => {} }
  }

  async tx (tx: Tx): Promise<TxResult> {
    if (this.head === undefined) {
      return await this.client.tx(tx)
    } else {
      return await this.head.tx(tx)
    }
  }

  async close (): Promise<void> {
    await this.head?.close()
  }
}

/**
 * @public
 */
export abstract class BasePresentationMiddleware {
  constructor (
    protected readonly client: Client,
    readonly next?: PresentationMiddleware
  ) {}

  async provideNotifyTx (tx: Tx): Promise<void> {
    await this.next?.notifyTx(tx)
  }

  async provideClose (): Promise<void> {
    await this.next?.close()
  }

  async findAll<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<FindResult<T>> {
    return await this.provideFindAll(_class, query, options)
  }

  async findOne<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<WithLookup<T> | undefined> {
    return await this.provideFindOne(_class, query, options)
  }

  async subscribe<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options: FindOptions<T> | undefined,
    refresh: () => void
  ): Promise<{
      unsubscribe: () => void
      query?: DocumentQuery<T>
      options?: FindOptions<T>
    }> {
    return await this.provideSubscribe(_class, query, options, refresh)
  }

  protected async provideTx (tx: Tx): Promise<TxResult> {
    if (this.next !== undefined) {
      return await this.next.tx(tx)
    }
    return await this.client.tx(tx)
  }

  protected async provideFindAll<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<FindResult<T>> {
    if (this.next !== undefined) {
      return await this.next.findAll(_class, query, options)
    }
    return await this.client.findAll(_class, query, options)
  }

  protected async provideFindOne<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<WithLookup<T> | undefined> {
    if (this.next !== undefined) {
      return await this.next.findOne(_class, query, options)
    }
    return await this.client.findOne(_class, query, options)
  }

  protected async provideSubscribe<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options: FindOptions<T> | undefined,
    refresh: () => void
  ): Promise<{
      unsubscribe: () => void
      query?: DocumentQuery<T>
      options?: FindOptions<T>
    }> {
    if (this.next !== undefined) {
      return await this.next.subscribe(_class, query, options, refresh)
    }
    return { unsubscribe: () => {} }
  }
}

/**
 * @public
 */
export interface PresentationMiddlewareFactory extends Doc {
  createPresentationMiddleware: Resource<PresentationMiddlewareCreator>
}

/**
 * @public
 */
export class OptimizeQueryMiddleware extends BasePresentationMiddleware implements PresentationMiddleware {
  private constructor (client: Client, next?: PresentationMiddleware) {
    super(client, next)
  }

  static create (client: Client, next?: PresentationMiddleware): OptimizeQueryMiddleware {
    return new OptimizeQueryMiddleware(client, next)
  }

  async notifyTx (tx: Tx): Promise<void> {
    await this.provideNotifyTx(tx)
  }

  async close (): Promise<void> {
    await this.provideClose()
  }

  async tx (tx: Tx): Promise<TxResult> {
    return await this.provideTx(tx)
  }

  async subscribe<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options: FindOptions<T> | undefined,
    refresh: () => void
  ): Promise<{
      unsubscribe: () => void
      query?: DocumentQuery<T>
      options?: FindOptions<T>
    }> {
    return await this.provideSubscribe(_class, query, options, refresh)
  }

  async findAll<T extends Doc>(
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T> | undefined
  ): Promise<FindResult<T>> {
    if (_class == null || typeof query !== 'object' || ('_class' in query && query._class == null)) {
      console.error('_class must be specified in query', query)
      return toFindResult([], 0)
    }
    return await this.provideFindAll(_class, query, options)
  }
}