//
// Copyright © 2022 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 {
  AccountUuid,
  Doc,
  isActiveMode,
  isArchivingMode,
  isDeletingMode,
  MeasureContext,
  RateLimiter,
  TxCUD,
  WorkspaceInfoWithStatus,
  WorkspaceUuid,
  type PersonId
} from '@hcengineering/core'
import { toMessageEvent, normalizeEmail } from '@hcengineering/mail-common'
import { ConsumerHandle, PlatformQueue, QueueTopic, type StorageAdapter } from '@hcengineering/server-core'
import { getPlatformQueue } from '@hcengineering/kafka'
import { getAccountClient } from '@hcengineering/server-client'

import { decode64 } from './base64'
import config from './config'
import { type GmailClient } from './gmail'
import { getWorkspaceTokens } from './tokens'
import {
  SyncState,
  IntegrationVersion,
  type ProjectCredentials,
  type Token,
  type User,
  type WorkspaceStateInfo
} from './types'
import { serviceToken } from './utils'
import { WorkspaceClient } from './workspaceClient'
import { getIntegrationClient } from './integrations'

import { AuthProvider } from './gmail/auth'
import { AccountClient } from '@hcengineering/account-client'
import { CreateMessageEvent } from '@hcengineering/communication-sdk-types'

export class GmailController {
  private readonly workspaces: Map<string, WorkspaceClient> = new Map<string, WorkspaceClient>()

  private readonly credentials: ProjectCredentials
  private readonly clients: Map<PersonId, Map<WorkspaceUuid, GmailClient>> = new Map<
  PersonId,
  Map<WorkspaceUuid, GmailClient>
  >()

  private readonly personIdByEmail = new Map<string, PersonId>()

  private readonly initLimitter = new RateLimiter(config.InitLimit)
  private readonly authProvider
  private queue: PlatformQueue | undefined
  private txConsumer: ConsumerHandle | undefined

  protected static _instance: GmailController

  private constructor (
    private readonly ctx: MeasureContext,
    private readonly storageAdapter: StorageAdapter
  ) {
    this.credentials = JSON.parse(config.Credentials)
    this.authProvider = new AuthProvider(this.credentials)
    GmailController._instance = this
  }

  static create (ctx: MeasureContext, storageAdapter: StorageAdapter): GmailController {
    if (GmailController._instance !== undefined) {
      throw new Error('GmailController already exists')
    }
    return new GmailController(ctx, storageAdapter)
  }

  static getGmailController (): GmailController {
    if (GmailController._instance !== undefined) {
      return GmailController._instance
    }
    throw new Error('GmailController not exist')
  }

  async startAll (): Promise<void> {
    try {
      const token = serviceToken()
      const sysClient = getAccountClient(token)
      const integrations = await getIntegrationClient().getIntegrations()
      this.ctx.info('Start integrations', { count: integrations.length })

      const workspaceIds = new Set<WorkspaceUuid>(
        integrations
          .map((integration) => {
            if (integration.workspaceUuid == null) {
              this.ctx.info('No workspace found', { integration })
              return undefined
            }
            return integration.workspaceUuid
          })
          .filter((id): id is WorkspaceUuid => id != null)
      )
      const pendingWorkspaces = await this.startWorkspaces(workspaceIds, sysClient)
      this.ctx.info('Pending workspaces', { count: pendingWorkspaces.size })
      // Start async check for pending workspaces
      void this.checkPendingWorkspaces(pendingWorkspaces, sysClient)
    } catch (err: any) {
      this.ctx.error('Failed to start existing integrations', { error: err.message })
    } finally {
      await this.startQueue()
    }
  }

  async startQueue (): Promise<void> {
    try {
      if (config.Version === IntegrationVersion.V1) {
        // For old gmail there is already handler for NewMessage class
        return
      }
      if (this.queue !== undefined) {
        this.ctx.warn('Queue is already started')
        return
      }
      this.queue = getPlatformQueue('gmail-service', config.QueueRegion)
      if (this.queue === undefined) {
        this.ctx.error('Queue not found')
        return
      }
      this.txConsumer = this.queue.createConsumer<TxCUD<Doc>>(
        this.ctx,
        QueueTopic.Tx,
        this.queue.getClientId(),
        async (ctx, msg) => {
          const workspaceUuid = msg.workspace

          const messageEvent = toMessageEvent(msg.value)
          if (messageEvent !== undefined) {
            await this.handleNewMessage(workspaceUuid, messageEvent)
          }
        },
        {
          fromBegining: false // Set to true to process all historical messages
        }
      )
      this.ctx.info('Queue consumer started', { topic: QueueTopic.Tx })
    } catch (err: any) {
      this.ctx.error('Failed to start queue consumer', { topic: QueueTopic.Tx })
    }
  }

  async handleNewMessage (workspaceUuid: WorkspaceUuid, message: CreateMessageEvent): Promise<void> {
    const client = this.workspaces.get(workspaceUuid)
    if (client === undefined) {
      return
    }
    await client.handleNewMessage(message)
  }

  async checkPendingWorkspaces (workspaceIds: Set<WorkspaceUuid>, sysClient: AccountClient): Promise<void> {
    try {
      let unprocessedWorkspaces = new Set(workspaceIds)
      while (unprocessedWorkspaces.size > 0) {
        unprocessedWorkspaces = await this.startWorkspaces(unprocessedWorkspaces, sysClient)
        if (unprocessedWorkspaces.size > 0) {
          this.ctx.info('Waiting for pending workspaces', { count: unprocessedWorkspaces.size })
          await new Promise<void>((resolve) => {
            setTimeout(
              () => {
                resolve()
              },
              5 * 60 * 1000
            ) // Wait 5 minutes
          })
        }
      }
    } catch (err: any) {
      this.ctx.error('Failed to check pending workspaces', { error: err.message, workspaceIds })
    }
  }

  async startWorkspaces (workspaceIds: Set<WorkspaceUuid>, sysClient: AccountClient): Promise<Set<WorkspaceUuid>> {
    const unprocessedWorkspaces = new Set(workspaceIds)
    const limiter = new RateLimiter(config.InitLimit)
    this.ctx.info('Workspaces with integrations', { count: unprocessedWorkspaces.size })

    const workspaceWithInfo = await sysClient.getWorkspacesInfo(Array.from(unprocessedWorkspaces))

    const allTokens = await getWorkspaceTokens(sysClient)
    let inactiveWorkspaceCount = 0
    let archivedWorkspaceCount = 0

    for (const info of workspaceWithInfo) {
      const workspace = info.uuid
      try {
        const { needSync, needRecheck, archived, inactive } = this.checkWorkspace(info)
        if (archived === true) {
          archivedWorkspaceCount++
        } else if (inactive === true) {
          inactiveWorkspaceCount++
        }
        if (!needSync) {
          if (!needRecheck) unprocessedWorkspaces.delete(workspace)
          continue
        }

        // So we will not start it one more time.
        unprocessedWorkspaces.delete(workspace)

        const tokens = allTokens.get(workspace) ?? []
        await limiter.add(async () => {
          this.ctx.info('Use stored tokens', { count: tokens.length })
          const startPromise = this.startWorkspace(workspace, tokens)
          const timeoutPromise = new Promise<void>((resolve) => {
            setTimeout(() => {
              // Not connected, recheck again.
              unprocessedWorkspaces.add(workspace)
              resolve()
            }, 60000)
          })
          await Promise.race([startPromise, timeoutPromise])
        })
      } catch (err: any) {
        this.ctx.error('Failed to create workspace client', { workspaceUuid: workspace, error: err.message })
      }
    }
    if (inactiveWorkspaceCount > 0 || archivedWorkspaceCount > 0) {
      this.ctx.info('Skip archived and inactive workspaces', {
        inactive: inactiveWorkspaceCount,
        archived: archivedWorkspaceCount
      })
    }

    await limiter.waitProcessing()
    return unprocessedWorkspaces
  }

  checkWorkspace (info: WorkspaceInfoWithStatus): WorkspaceStateInfo {
    if (isArchivingMode(info.mode) || isDeletingMode(info.mode)) {
      return { needSync: false, needRecheck: false, archived: true }
    }
    if (!isActiveMode(info.mode)) {
      return { needSync: false, needRecheck: true, inactive: true }
    }
    const lastVisit = (Date.now() - (info.lastVisit ?? 0)) / (3600 * 24 * 1000) // In days

    if (lastVisit > config.WorkspaceInactivityInterval) {
      return { needSync: false, needRecheck: true, inactive: true }
    }
    return { needSync: true, needRecheck: false }
  }

  async startWorkspace (workspace: WorkspaceUuid, tokens: Token[]): Promise<void> {
    const workspaceClient = await this.getWorkspaceClient(workspace)
    const clients: GmailClient[] = []
    for (const token of tokens) {
      let timeout: NodeJS.Timeout | undefined
      try {
        timeout = setTimeout(() => {
          this.ctx.info('init client hang', { workspaceUuid: token.workspace, userId: token.userId })
        }, 60000)
        const client = await workspaceClient.createGmailClient(token)
        clearTimeout(timeout)
        clients.push(client)
      } catch (err: any) {
        if (timeout !== undefined) {
          clearTimeout(timeout)
        }
        this.ctx.error("Couldn't create client", {
          workspaceUuid: workspace,
          userId: token.userId,
          message: err.message
        })
      }
    }
    this.ctx.info('Start clients sync', { workspaceUuid: workspace, count: clients.length })
    for (const client of clients) {
      void this.initLimitter.add(async () => {
        await client.startSync()
      })
    }
    void workspaceClient.checkUsers().then(async () => {
      await workspaceClient.getNewMessages()
    })
  }

  push (message: string): void {
    const data = JSON.parse(decode64(message))
    const email = data.emailAddress
    const socialId = this.personIdByEmail.get(normalizeEmail(email))
    if (socialId === undefined) {
      this.ctx.warn('No socialId found for email', { email })
      return
    }

    const clients = this.clients.get(socialId)
    if (clients === undefined) {
      this.ctx.info('No clients found', { email, socialId })
      return
    }
    this.ctx.info('Processing push', { clients: clients.size, email })
    for (const client of clients.values()) {
      void client.sync({ noNotify: false })
    }
  }

  addClient (socialId: PersonId, workspace: WorkspaceUuid, email: string, client: GmailClient): void {
    let userClients = this.clients.get(socialId)
    if (userClients === undefined) {
      userClients = new Map<WorkspaceUuid, GmailClient>()
      this.clients.set(socialId, userClients)
    }
    this.personIdByEmail.set(normalizeEmail(email), socialId)

    const existingClient = userClients.get(workspace)
    if (existingClient != null) {
      void existingClient.close().catch((err) => {
        this.ctx.error('Error closing existing client', {
          socialId,
          workspace,
          error: err.message
        })
      })
    }

    userClients.set(workspace, client)
  }

  getAuthProvider (): AuthProvider {
    return this.authProvider
  }

  async signout (workspace: WorkspaceUuid, account: AccountUuid): Promise<void> {
    const workspaceClient = await this.getWorkspaceClient(workspace)
    const clients = await workspaceClient.signoutByAccountId(account)
    if (clients === 0) {
      this.workspaces.delete(workspace)
    }
  }

  async close (): Promise<void> {
    for (const workspace of this.workspaces.values()) {
      await workspace.close()
    }
    this.workspaces.clear()
    if (this.txConsumer !== undefined) {
      await this.txConsumer.close()
    }
    if (this.queue !== undefined) {
      await this.queue.shutdown()
    }
  }

  async createClient (user: User | Token, authCode?: string): Promise<GmailClient> {
    const workspace = await this.getWorkspaceClient(user.workspace)
    const newClient = await workspace.createGmailClient(user, authCode)
    return newClient
  }

  private async getWorkspaceClient (workspace: WorkspaceUuid): Promise<WorkspaceClient> {
    let res = this.workspaces.get(workspace)
    if (res === undefined) {
      try {
        this.ctx.info('create workspace worker', { workspaceUuid: workspace })
        res = await WorkspaceClient.create(this.ctx, this.credentials, this.storageAdapter, workspace)
        this.workspaces.set(workspace, res)
        this.ctx.info('created workspace worker', { workspaceUuid: workspace })
      } catch (err) {
        this.ctx.error("Couldn't create workspace worker", { workspaceUuid: workspace, reason: err })
        throw err
      }
    }
    return res
  }

  async getState (workspace: WorkspaceUuid, socialId: PersonId): Promise<SyncState | undefined> {
    const workspaceClient = this.workspaces.get(workspace)
    if (workspaceClient === undefined) {
      return undefined
    }
    const mailClient = workspaceClient.getGmailClient(socialId)
    if (mailClient === undefined) {
      return undefined
    }
    return await mailClient.getStateSummary()
  }

  async startSyncForClient (workspace: WorkspaceUuid, socialId: PersonId): Promise<void> {
    const workspaceClient = this.workspaces.get(workspace)
    if (workspaceClient === undefined) {
      this.ctx.info('Workspace client not found for startSync', { workspace, socialId })
      return
    }
    const mailClient = workspaceClient.getGmailClient(socialId)
    if (mailClient === undefined) {
      this.ctx.info('Gmail client not found for startSync', { workspace, socialId })
      return
    }
    this.ctx.info('Starting sync for specific client', { workspace, socialId })
    await mailClient.refreshIntegration()
    void mailClient.startSync()
  }
}