//
// Copyright © 2020, 2021 Anticrm Platform Contributors.
// Copyright © 2021 Hardcore Engineering Inc.
//
// Licensed under the Eclipse Public License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License. You may
// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//
// See the License for the specific language governing permissions and
// limitations under the License.
//

import core, {
  Tx,
  Doc,
  TxCreateDoc,
  Ref,
  Account,
  TxCollectionCUD,
  AttachedDoc,
  DocumentQuery,
  matchQuery,
  TxFactory,
  Hierarchy,
  Class,
  Obj
} from '@hcengineering/core'

import { getResource } from '@hcengineering/platform'
import type { Trigger, TriggerFunc, TriggerControl } from './types'

import serverCore from './plugin'

/**
 * @public
 */
export class Triggers {
  private readonly triggers: [DocumentQuery<Tx> | undefined, TriggerFunc][] = []

  constructor (protected readonly hierarchy: Hierarchy) {}

  async tx (tx: Tx): Promise<void> {
    if (tx._class === core.class.TxCollectionCUD) {
      tx = (tx as TxCollectionCUD<Doc, AttachedDoc>).tx
    }
    if (tx._class === core.class.TxCreateDoc) {
      const createTx = tx as TxCreateDoc<Doc>
      if (createTx.objectClass === serverCore.class.Trigger) {
        const trigger = (createTx as TxCreateDoc<Trigger>).attributes.trigger
        const match = (createTx as TxCreateDoc<Trigger>).attributes.txMatch
        const func = await getResource(trigger)
        this.triggers.push([match, func])
      }
    }
  }

  async apply (account: Ref<Account>, tx: Tx, ctrl: Omit<TriggerControl, 'txFactory'>): Promise<Tx[]> {
    const control = { ...ctrl, txFactory: new TxFactory(account, true) }
    const derived = this.triggers
      .filter(([query]) => {
        if (query === undefined) {
          return true
        }
        this.addDerived(query, 'objectClass')
        this.addDerived(query, 'tx.objectClass')
        return matchQuery([tx], query, core.class.Tx, control.hierarchy).length > 0
      })
      .map(([, trigger]) => trigger(tx, control))
    const result = await Promise.all(derived)
    return result.flatMap((x) => x)
  }

  private addDerived (q: DocumentQuery<Tx>, key: string): void {
    if (q[key] === undefined) {
      return
    }
    if (typeof q[key] === 'string') {
      const descendants = this.hierarchy.getDescendants(q[key])
      q[key] = {
        $in: [...(q[key].$in ?? []), ...descendants]
      }
    } else {
      if (Array.isArray(q[key].$in)) {
        const oldIn = q[key].$in
        const newIn = new Set(oldIn)
        q[key].$in.forEach((element: Ref<Class<Obj>>) => {
          const descendants = this.hierarchy.getDescendants(element)
          descendants.forEach((d) => newIn.add(d))
        })
        q[key].$in = Array.from(newIn.values())
      }
      if (Array.isArray(q[key].$nin)) {
        const oldNin = q[key].$nin
        const newNin = new Set(oldNin)
        q[key].$nin.forEach((element: Ref<Class<Obj>>) => {
          const descendants = this.hierarchy.getDescendants(element)
          descendants.forEach((d) => newNin.add(d))
        })
        q[key].$nin = Array.from(newNin.values())
      }
      if (q[key].$ne !== undefined) {
        const descendants = this.hierarchy.getDescendants(q[key].$ne)
        delete q[key].$ne
        q[key].$nin = [...(q[key].$nin ?? []), ...descendants]
      }
    }
  }
}