import { without } from 'lodash'
import { reactive } from 'vue'
import { UploadFile, UploadStatus } from '@/config'
import { httpService } from '@/services'
import { albumStore, overviewStore, songStore } from '@/stores'
import { eventBus, logger } from '@/utils'

interface UploadResult {
  song: Song
  album: Album
}

export const uploadService = {
  state: reactive({
    files: [] as UploadFile[]
  }),

  simultaneousUploads: 5,

  queue (file: UploadFile | UploadFile[]) {
    this.state.files = this.state.files.concat(file)
    this.proceed()
  },

  remove (file: UploadFile) {
    this.state.files = without(this.state.files, file)
    this.proceed()
  },

  proceed () {
    const remainingSlots = this.simultaneousUploads - this.getUploadingFiles().length

    if (remainingSlots <= 0) {
      return
    }

    for (let i = 0; i < remainingSlots; ++i) {
      const file = this.getUploadCandidate()
      file && this.upload(file)
    }
  },

  getUploadingFiles () {
    return this.state.files.filter(file => file.status === 'Uploading')
  },

  getUploadCandidate () {
    return this.state.files.find(file => file.status === 'Ready')
  },

  shouldWarnUponWindowUnload () {
    return this.state.files.length > 0
  },

  async upload (file: UploadFile) {
    if (file.status === 'Uploading') {
      return
    }

    const formData = new FormData()
    formData.append('file', file.file)
    file.progress = 0
    file.status = 'Uploading'

    try {
      const result = await httpService.post<UploadResult>('upload', formData, (progressEvent: ProgressEvent) => {
        file.progress = progressEvent.loaded * 100 / progressEvent.total
      })

      file.status = 'Uploaded'

      songStore.syncWithVault(result.song)
      albumStore.syncWithVault(result.album)
      overviewStore.refresh()

      this.proceed() // upload the next file

      window.setTimeout(() => this.remove(file), 1000)
    } catch (error: any) {
      logger.error(error)
      file.message = `Upload failed: ${error.response?.data?.message || 'Unknown error'}`
      file.status = 'Errored'
      this.proceed() // upload the next file
    } finally {
      this.checkUploadQueueStatus()
    }
  },

  retry (file: UploadFile) {
    // simply reset the status and wait for the next process
    this.resetFile(file)
    this.proceed()
  },

  retryAll () {
    this.state.files.forEach(this.resetFile)
    this.proceed()
  },

  resetFile: (file: UploadFile) => {
    file.status = 'Ready'
    file.progress = 0
  },

  clear () {
    this.state.files = []
  },

  removeFailed () {
    this.state.files = this.state.files.filter(file => file.status !== 'Errored')
  },

  checkUploadQueueStatus () {
    const uploadingFiles = this.state.files.filter(file => file.status === 'Uploading')

    if (uploadingFiles.length === 0) {
      eventBus.emit('UPLOAD_QUEUE_FINISHED')
    }
  },

  getFilesByStatus (status: UploadStatus) {
    return this.state.files.filter(file => file.status === status)
  }
}