//
// Copyright © 2020 Anticrm Platform Contributors.
//
// 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 type { Tx, Ref, Doc, Class, DocumentQuery, FindResult, FindOptions, TxCreateDoc, TxUpdateDoc } from '@anticrm/core'
import core, { TxProcessor, Hierarchy, DOMAIN_TX, SortingOrder } from '@anticrm/core'
import type { DbAdapter, TxAdapter } from '@anticrm/server-core'

import { MongoClient, Db, Filter, Document, Sort } from 'mongodb'

function translateQuery<T extends Doc> (clazz: Ref<Class<T>>, query: DocumentQuery<T>): Filter<Document> {
  // return Object.assign({}, query, { _class: clazz })
  return query as Filter<Document>
}

function translateDoc (doc: Doc): Document {
  return doc as Document
}

abstract class MongoAdapterBase extends TxProcessor {
  constructor (
    protected readonly db: Db,
    protected readonly hierarchy: Hierarchy
  ) {
    super()
  }

  async init (): Promise<void> {}

  private async lookup<T extends Doc> (clazz: Ref<Class<T>>, query: DocumentQuery<T>, options: FindOptions<T>): Promise<FindResult<T>> {
    const pipeline = []
    pipeline.push({ $match: translateQuery(clazz, query) })
    const lookups = options.lookup as any
    for (const key in lookups) {
      const clazz = lookups[key]
      const step = {
        from: this.hierarchy.getDomain(clazz),
        localField: key,
        foreignField: '_id',
        as: key + '_lookup'
      }
      pipeline.push({ $lookup: step })
    }
    const domain = this.hierarchy.getDomain(clazz)
    const cursor = this.db.collection(domain).aggregate(pipeline)
    const result = await cursor.toArray() as FindResult<T>
    for (const row of result) {
      const object = row as any
      object.$lookup = {}
      for (const key in lookups) {
        const arr = object[key + '_lookup']
        object.$lookup[key] = arr[0]
      }
    }
    return result
  }

  async findAll<T extends Doc> (
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<FindResult<T>> {
    // TODO: rework this
    if (options !== null && options !== undefined) {
      if (options.lookup !== undefined) { return await this.lookup(_class, query, options) }
    }
    const domain = this.hierarchy.getDomain(_class)
    let cursor = this.db.collection(domain).find<T>(translateQuery(_class, query))
    if (options !== null && options !== undefined) {
      if (options.sort !== undefined) {
        const sort: Sort = {}
        for (const key in options.sort) {
          const order = options.sort[key] === SortingOrder.Ascending ? 1 : -1
          sort[key] = order
        }
        cursor = cursor.sort(sort)
      }
    }
    return await cursor.toArray()
  }
}

class MongoAdapter extends MongoAdapterBase {
  protected override async txCreateDoc (tx: TxCreateDoc<Doc>): Promise<void> {
    const doc = TxProcessor.createDoc2Doc(tx)
    const domain = this.hierarchy.getDomain(doc._class)
    await this.db.collection(domain).insertOne(translateDoc(doc))
  }

  protected override async txUpdateDoc (tx: TxUpdateDoc<Doc>): Promise<void> {
    const domain = this.hierarchy.getDomain(tx.objectClass)
    const result = await this.db.collection(domain).updateOne({ _id: tx.objectId }, { $set: tx.operations })
    console.log('update result', result)
  }
}

class MongoTxAdapter extends MongoAdapterBase implements TxAdapter {
  override async tx (tx: Tx): Promise<void> {
    console.log('mongotx', tx)
    await this.db.collection(DOMAIN_TX).insertOne(translateDoc(tx))
  }

  async getModel (): Promise<Tx[]> {
    return await this.db.collection(DOMAIN_TX).find<Tx>({ objectSpace: core.space.Model }).sort({ _id: 1 }).toArray()
  }
}

/**
 * @public
 */
export async function createMongoAdapter (hierarchy: Hierarchy, url: string, dbName: string): Promise<DbAdapter> {
  const client = new MongoClient(url)
  await client.connect()
  const db = client.db(dbName)
  return new MongoAdapter(db, hierarchy)
}

/**
 * @public
 */
export async function createMongoTxAdapter (hierarchy: Hierarchy, url: string, dbName: string): Promise<TxAdapter> {
  const client = new MongoClient(url)
  await client.connect()
  const db = client.db(dbName)
  return new MongoTxAdapter(db, hierarchy)
}