//
// Copyright © 2023 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, {
  Account,
  AccountRole,
  AttachedDoc,
  Class,
  DOMAIN_MODEL,
  Doc,
  DocumentQuery,
  Domain,
  FindOptions,
  FindResult,
  LookupData,
  MeasureContext,
  ObjQueryType,
  Position,
  PullArray,
  Ref,
  SearchOptions,
  SearchQuery,
  SearchResult,
  Space,
  Tx,
  TxCUD,
  TxCreateDoc,
  TxProcessor,
  TxRemoveDoc,
  TxUpdateDoc,
  TxWorkspaceEvent,
  WorkspaceEvent,
  generateId,
  systemAccountEmail,
  toFindResult
} from '@hcengineering/core'
import platform, { PlatformError, Severity, Status } from '@hcengineering/platform'
import { Middleware, SessionContext, TxMiddlewareResult, type ServerStorage } from '@hcengineering/server-core'
import { BaseMiddleware } from './base'
import { getUser, isOwner, isSystem } from './utils'

type SpaceWithMembers = Pick<Space, '_id' | 'members' | 'private' | '_class'>

/**
 * @public
 */
export class SpaceSecurityMiddleware extends BaseMiddleware implements Middleware {
  private allowedSpaces: Record<Ref<Account>, Ref<Space>[]> = {}
  private readonly spacesMap = new Map<Ref<Space>, SpaceWithMembers>()
  private readonly privateSpaces = new Set<Ref<Space>>()
  private readonly _domainSpaces = new Map<string, Set<Ref<Space>> | Promise<Set<Ref<Space>>>>()
  private readonly publicSpaces = new Set<Ref<Space>>()
  private readonly systemSpaces = new Set<Ref<Space>>()

  private spaceMeasureCtx!: MeasureContext

  private spaceSecurityInit: Promise<void> | undefined

  private readonly mainSpaces = [
    core.space.Configuration,
    core.space.DerivedTx,
    core.space.Model,
    core.space.Space,
    core.space.Workspace,
    core.space.Tx
  ]

  private constructor (storage: ServerStorage, next?: Middleware) {
    super(storage, next)
  }

  static async create (
    ctx: MeasureContext,
    storage: ServerStorage,
    next?: Middleware
  ): Promise<SpaceSecurityMiddleware> {
    const res = new SpaceSecurityMiddleware(storage, next)
    res.spaceMeasureCtx = ctx.newChild('space chain', {})
    res.spaceSecurityInit = res.init(res.spaceMeasureCtx)
    return res
  }

  private resyncDomains (): void {
    this.spaceSecurityInit = this.init(this.spaceMeasureCtx)
  }

  private addMemberSpace (member: Ref<Account>, space: Ref<Space>): void {
    const arr = this.allowedSpaces[member] ?? []
    arr.push(space)
    this.allowedSpaces[member] = arr
  }

  private addSpace (space: SpaceWithMembers): void {
    this.spacesMap.set(space._id, space)
    if (space.private) {
      this.privateSpaces.add(space._id)
    } else {
      this.publicSpaces.add(space._id)
    }
    for (const member of space.members) {
      this.addMemberSpace(member, space._id)
    }
  }

  private async init (ctx: MeasureContext): Promise<void> {
    const spaces: SpaceWithMembers[] = await this.storage.findAll(
      ctx,
      core.class.Space,
      {},
      {
        projection: {
          private: 1,
          _class: 1,
          _id: 1,
          members: 1
        }
      }
    )
    this.spacesMap.clear()
    this.publicSpaces.clear()
    this.systemSpaces.clear()
    for (const space of spaces) {
      if (space._class === core.class.SystemSpace) {
        this.systemSpaces.add(space._id)
      } else {
        this.addSpace(space)
      }
    }
  }

  async waitInit (): Promise<void> {
    if (this.spaceSecurityInit !== undefined) {
      await this.spaceSecurityInit
      this.spaceSecurityInit = undefined
    }
  }

  private removeMemberSpace (member: Ref<Account>, space: Ref<Space>): void {
    const arr = this.allowedSpaces[member]
    if (arr !== undefined) {
      const index = arr.findIndex((p) => p === space)
      if (index !== -1) {
        arr.splice(index, 1)
        this.allowedSpaces[member] = arr
      }
    }
  }

  private removeSpace (_id: Ref<Space>): void {
    const space = this.spacesMap.get(_id)
    if (space !== undefined) {
      for (const member of space.members) {
        this.removeMemberSpace(member, space._id)
      }
    }
    this.spacesMap.delete(_id)
    this.privateSpaces.delete(_id)
    this.publicSpaces.delete(_id)
  }

  private handleCreate (tx: TxCUD<Space>): void {
    const createTx = tx as TxCreateDoc<Space>
    if (!this.storage.hierarchy.isDerived(createTx.objectClass, core.class.Space)) return
    if (createTx.objectClass === core.class.SystemSpace) {
      this.systemSpaces.add(createTx.objectId)
    } else {
      const res = TxProcessor.createDoc2Doc<Space>(createTx)
      this.addSpace(res)
    }
  }

  private async pushMembersHandle (
    ctx: SessionContext,
    addedMembers: Ref<Account> | Position<Ref<Account>>,
    space: Ref<Space>
  ): Promise<void> {
    if (typeof addedMembers === 'object') {
      for (const member of addedMembers.$each) {
        this.addMemberSpace(member, space)
      }
      await this.brodcastEvent(ctx, addedMembers.$each, space)
    } else {
      this.addMemberSpace(addedMembers, space)
      await this.brodcastEvent(ctx, [addedMembers], space)
    }
  }

  private async pullMembersHandle (
    ctx: SessionContext,
    removedMembers: Partial<Ref<Account>> | PullArray<Ref<Account>>,
    space: Ref<Space>
  ): Promise<void> {
    if (typeof removedMembers === 'object') {
      const { $in } = removedMembers as PullArray<Ref<Account>>
      if ($in !== undefined) {
        for (const member of $in) {
          this.removeMemberSpace(member, space)
        }
        await this.brodcastEvent(ctx, $in, space)
      }
    } else {
      this.removeMemberSpace(removedMembers, space)
      await this.brodcastEvent(ctx, [removedMembers], space)
    }
  }

  private async syncMembers (ctx: SessionContext, members: Ref<Account>[], space: SpaceWithMembers): Promise<void> {
    const oldMembers = new Set(space.members)
    const newMembers = new Set(members)
    const changed: Ref<Account>[] = []
    for (const old of oldMembers) {
      if (!newMembers.has(old)) {
        this.removeMemberSpace(old, space._id)
        changed.push(old)
      }
    }
    for (const newMem of newMembers) {
      if (!oldMembers.has(newMem)) {
        this.addMemberSpace(newMem, space._id)
        changed.push(newMem)
      }
    }
    if (changed.length > 0) {
      await this.brodcastEvent(ctx, changed, space._id)
    }
  }

  private async brodcastEvent (ctx: SessionContext, users: Ref<Account>[], space?: Ref<Space>): Promise<void> {
    const targets = await this.getTargets(users)
    const tx: TxWorkspaceEvent = {
      _class: core.class.TxWorkspaceEvent,
      _id: generateId(),
      event: WorkspaceEvent.SecurityChange,
      modifiedBy: core.account.System,
      modifiedOn: Date.now(),
      objectSpace: space ?? core.space.DerivedTx,
      space: core.space.DerivedTx,
      params: null
    }
    ctx.derived.txes.push(tx)
    ctx.derived.targets.security = (it) => {
      // TODO: I'm not sure it is called
      if (it._id === tx._id) {
        return targets
      }
    }
  }

  private async broadcastNonMembers (ctx: SessionContext, space: SpaceWithMembers): Promise<void> {
    const users = await this.storage.modelDb.findAll(core.class.Account, { _id: { $nin: space?.members } })
    await this.brodcastEvent(
      ctx,
      users.map((p) => p._id),
      space._id
    )
  }

  private async handleUpdate (ctx: SessionContext, tx: TxCUD<Space>): Promise<void> {
    await this.waitInit()

    const updateDoc = tx as TxUpdateDoc<Space>
    if (!this.storage.hierarchy.isDerived(updateDoc.objectClass, core.class.Space)) return

    const space = this.spacesMap.get(updateDoc.objectId)
    if (space !== undefined) {
      if (updateDoc.operations.private !== undefined) {
        if (updateDoc.operations.private) {
          this.privateSpaces.add(updateDoc.objectId)
          this.publicSpaces.delete(updateDoc.objectId)
          await this.broadcastNonMembers(ctx, space)
        } else if (!updateDoc.operations.private) {
          this.privateSpaces.delete(updateDoc.objectId)
          this.publicSpaces.add(updateDoc.objectId)
          await this.broadcastNonMembers(ctx, space)
        }
      }

      if (updateDoc.operations.members !== undefined) {
        await this.syncMembers(ctx, updateDoc.operations.members, space)
      }
      if (updateDoc.operations.$push?.members !== undefined) {
        await this.pushMembersHandle(ctx, updateDoc.operations.$push.members, space._id)
      }

      if (updateDoc.operations.$pull?.members !== undefined) {
        await this.pullMembersHandle(ctx, updateDoc.operations.$pull.members, space._id)
      }
      const updatedSpace = TxProcessor.updateDoc2Doc(space as any, updateDoc)
      this.spacesMap.set(updateDoc.objectId, updatedSpace)
    }
  }

  private handleRemove (tx: TxCUD<Space>): void {
    const removeTx = tx as TxRemoveDoc<Space>
    if (!this.storage.hierarchy.isDerived(removeTx.objectClass, core.class.Space)) return
    if (removeTx._class !== core.class.TxCreateDoc) return
    this.removeSpace(tx.objectId)
  }

  private async handleTx (ctx: SessionContext, tx: TxCUD<Space>): Promise<void> {
    await this.waitInit()
    if (tx._class === core.class.TxCreateDoc) {
      this.handleCreate(tx)
    } else if (tx._class === core.class.TxUpdateDoc) {
      await this.handleUpdate(ctx, tx)
    } else if (tx._class === core.class.TxRemoveDoc) {
      this.handleRemove(tx)
    }
  }

  async getTargets (accounts: Ref<Account>[]): Promise<string[]> {
    const users = await this.storage.modelDb.findAll(core.class.Account, { _id: { $in: accounts } })
    const res = users.map((p) => p.email)
    res.push(systemAccountEmail)
    return res
  }

  private async processTxSpaceDomain (tx: TxCUD<Doc>): Promise<void> {
    const actualTx = TxProcessor.extractTx(tx)
    if (actualTx._class === core.class.TxCreateDoc) {
      const ctx = actualTx as TxCreateDoc<Doc>
      const doc = TxProcessor.createDoc2Doc(ctx)
      const domain = this.storage.hierarchy.getDomain(ctx.objectClass)
      const key = this.getKey(domain)
      const space = (doc as any)[key]
      if (space === undefined) return
      ;(await this.getDomainSpaces(domain)).add(space)
    } else if (actualTx._class === core.class.TxUpdateDoc) {
      const updTx = actualTx as TxUpdateDoc<Doc>
      const domain = this.storage.hierarchy.getDomain(updTx.objectClass)
      const key = this.getKey(domain)
      const space = (updTx.operations as any)[key]
      if (space !== undefined) {
        ;(await this.getDomainSpaces(domain)).add(space)
      }
    }
  }

  private async processTx (ctx: SessionContext, tx: Tx): Promise<void> {
    const h = this.storage.hierarchy
    if (TxProcessor.isExtendsCUD(tx._class)) {
      const cudTx = tx as TxCUD<Doc>
      const isSpace = h.isDerived(cudTx.objectClass, core.class.Space)
      if (isSpace) {
        const account = await getUser(this.storage, ctx)
        if (account.role === AccountRole.Guest) {
          throw new PlatformError(new Status(Severity.ERROR, platform.status.Forbidden, {}))
        }
        await this.handleTx(ctx, cudTx as TxCUD<Space>)
      }
      await this.processTxSpaceDomain(tx as TxCUD<Doc>)
      if (h.isDerived(cudTx.objectClass, core.class.Account) && cudTx._class === core.class.TxUpdateDoc) {
        const cud = cudTx as TxUpdateDoc<Account>
        if (cud.operations.role !== undefined) {
          await this.brodcastEvent(ctx, [cud.objectId])
        }
      }
    } else if (tx._class === core.class.TxWorkspaceEvent) {
      const event = tx as TxWorkspaceEvent
      if (event.event === WorkspaceEvent.BulkUpdate) {
        this.resyncDomains()
      }
    }
  }

  async tx (ctx: SessionContext, tx: Tx): Promise<TxMiddlewareResult> {
    await this.waitInit()
    const account = await getUser(this.storage, ctx)
    if (account.role === AccountRole.DocGuest) {
      throw new PlatformError(new Status(Severity.ERROR, platform.status.Forbidden, {}))
    }
    await this.processTx(ctx, tx)
    const res = await this.provideTx(ctx, tx)
    for (const txd of ctx.derived.txes) {
      await this.processTx(ctx, txd)
    }
    return res
  }

  override async handleBroadcast (
    txes: Tx[],
    targets?: string | string[] | undefined,
    exclude?: string[] | undefined
  ): Promise<void> {
    for (const tx of txes) {
      if (TxProcessor.isExtendsCUD(tx._class)) {
        // TODO: Do we need security check here?
        const cudTx = tx as TxCUD<Doc>
        await this.processTxSpaceDomain(cudTx)
      } else if (tx._class === core.class.TxWorkspaceEvent) {
        const event = tx as TxWorkspaceEvent
        if (event.event === WorkspaceEvent.BulkUpdate) {
          this.resyncDomains()
        }
      }
    }
    await this.next?.handleBroadcast(txes, targets, exclude)
  }

  private getAllAllowedSpaces (account: Account, isData: boolean): Ref<Space>[] {
    const userSpaces = this.allowedSpaces[account._id] ?? []
    const res = [...userSpaces, account._id as string as Ref<Space>, ...this.systemSpaces, ...this.mainSpaces]
    return isData ? res : [...res, ...this.publicSpaces]
  }

  async getDomainSpaces (domain: Domain): Promise<Set<Ref<Space>>> {
    let domainSpaces = this._domainSpaces.get(domain)
    if (domainSpaces === undefined) {
      const p = this.storage.groupBy<Ref<Space>>(this.spaceMeasureCtx, domain, this.getKey(domain))
      this._domainSpaces.set(domain, p)
      domainSpaces = await p
      this._domainSpaces.set(domain, domainSpaces)
    }
    return domainSpaces instanceof Promise ? await domainSpaces : domainSpaces
  }

  private async filterByDomain (
    domain: Domain,
    spaces: Ref<Space>[]
  ): Promise<{ result: Ref<Space>[], allDomainSpaces: boolean, domainSpaces: Set<Ref<Space>> }> {
    const domainSpaces = await this.getDomainSpaces(domain)
    const result = spaces.filter((p) => domainSpaces.has(p))
    return {
      result: spaces.filter((p) => domainSpaces.has(p)),
      allDomainSpaces: result.length === domainSpaces.size,
      domainSpaces
    }
  }

  private async mergeQuery<T extends Doc>(
    account: Account,
    query: ObjQueryType<T['space']>,
    domain: Domain,
    isSpace: boolean
  ): Promise<ObjQueryType<T['space']> | undefined> {
    const spaces = await this.filterByDomain(domain, this.getAllAllowedSpaces(account, !isSpace))
    if (query == null) {
      if (spaces.allDomainSpaces) {
        return undefined
      }
      return { $in: spaces.result }
    }
    if (typeof query === 'string') {
      if (!spaces.result.includes(query)) {
        return { $in: [] }
      }
    } else if (query.$in != null) {
      query.$in = query.$in.filter((p) => spaces.result.includes(p))
      if (query.$in.length === spaces.domainSpaces.size) {
        // all domain spaces
        delete query.$in
      }
    } else {
      if (spaces.allDomainSpaces) {
        delete query.$in
      } else {
        query.$in = spaces.result
      }
    }
    if (Object.keys(query).length === 0) {
      return undefined
    }
    return query
  }

  private getKey (domain: string): string {
    return domain === 'tx' ? 'objectSpace' : domain === 'space' ? '_id' : 'space'
  }

  override async findAll<T extends Doc>(
    ctx: SessionContext,
    _class: Ref<Class<T>>,
    query: DocumentQuery<T>,
    options?: FindOptions<T>
  ): Promise<FindResult<T>> {
    await this.waitInit()

    const domain = this.storage.hierarchy.getDomain(_class)
    const newQuery = { ...query }
    const account = await getUser(this.storage, ctx)
    const isSpace = this.storage.hierarchy.isDerived(_class, core.class.Space)
    const field = this.getKey(domain)

    let clientFilterSpaces: Set<Ref<Space>> | undefined

    if (!isSystem(account) && account.role !== AccountRole.DocGuest && domain !== DOMAIN_MODEL) {
      if (!isOwner(account, ctx) || !isSpace) {
        if (query[field] !== undefined) {
          const res = await this.mergeQuery(account, query[field], domain, isSpace)
          if (res === undefined) {
            // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
            delete (newQuery as any)[field]
          } else {
            ;(newQuery as any)[field] = res
            if (typeof res === 'object') {
              if (Array.isArray(res.$in) && res.$in.length === 1 && Object.keys(res).length === 1) {
                ;(newQuery as any)[field] = res.$in[0]
              }
            }
          }
        } else {
          const spaces = await this.filterByDomain(domain, this.getAllAllowedSpaces(account, !isSpace))
          if (spaces.allDomainSpaces) {
            // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
            delete (newQuery as any)[field]
          } else if (spaces.result.length === 1) {
            ;(newQuery as any)[field] = spaces.result[0]
          } else {
            // Check if spaces > 85% of all domain spaces, in this case return all and filter on client.
            if (spaces.result.length / spaces.domainSpaces.size > 0.85 && options?.limit === undefined) {
              clientFilterSpaces = new Set(spaces.result)
              delete newQuery.space
            } else {
              ;(newQuery as any)[field] = { $in: spaces.result }
            }
          }
        }
      }
    }

    let findResult = await this.provideFindAll(ctx, _class, newQuery, options)
    if (clientFilterSpaces !== undefined) {
      findResult = toFindResult(
        findResult.filter((it) => (clientFilterSpaces as Set<Ref<Space>>).has(it.space)),
        findResult.total,
        findResult.lookupMap
      )
    }
    if (!isOwner(account, ctx) && account.role !== AccountRole.DocGuest) {
      if (options?.lookup !== undefined) {
        for (const object of findResult) {
          if (object.$lookup !== undefined) {
            await this.filterLookup(ctx, object.$lookup)
          }
        }
      }
    }
    return findResult
  }

  override async searchFulltext (
    ctx: SessionContext,
    query: SearchQuery,
    options: SearchOptions
  ): Promise<SearchResult> {
    await this.waitInit()
    const newQuery = { ...query }
    const account = await getUser(this.storage, ctx)
    if (!isSystem(account)) {
      const allSpaces = this.getAllAllowedSpaces(account, true)
      if (query.classes !== undefined) {
        const res = new Set<Ref<Space>>()
        const passedDomains = new Set<string>()
        for (const _class of query.classes) {
          const domain = this.storage.hierarchy.getDomain(_class)
          if (passedDomains.has(domain)) {
            continue
          }
          passedDomains.add(domain)
          const spaces = await this.filterByDomain(domain, allSpaces)
          for (const space of spaces.result) {
            res.add(space)
          }
        }
        newQuery.spaces = [...res]
      } else {
        newQuery.spaces = allSpaces
      }
    }
    const result = await this.provideSearchFulltext(ctx, newQuery, options)
    return result
  }

  async isUnavailable (ctx: SessionContext, space: Ref<Space>): Promise<boolean> {
    const account = await getUser(this.storage, ctx)
    if (isSystem(account)) return false
    return !this.getAllAllowedSpaces(account, true).includes(space)
  }

  async filterLookup<T extends Doc>(ctx: SessionContext, lookup: LookupData<T>): Promise<void> {
    for (const key in lookup) {
      const val = lookup[key]
      if (Array.isArray(val)) {
        const arr: AttachedDoc[] = []
        for (const value of val) {
          if (!(await this.isUnavailable(ctx, value.space))) {
            arr.push(value)
          }
        }
        lookup[key] = arr as any
      } else if (val !== undefined) {
        if (await this.isUnavailable(ctx, val.space)) {
          lookup[key] = undefined
        }
      }
    }
  }
}