import {
  Box,
  Button,
  List,
  ListItem,
  ListSubheader,
  Tooltip,
  Typography,
  useTheme
} from '@mui/material'
import JSZip from 'jszip'
import { MuiFileInput } from 'mui-file-input'
import { Event, kinds, verifyEvent } from 'nostr-tools'
import { useEffect, useState } from 'react'
import { toast } from 'react-toastify'
import { LoadingSpinner } from '../../components/LoadingSpinner'
import { UserAvatar } from '../../components/UserAvatar'
import { MetadataController, NostrController } from '../../controllers'
import {
  CreateSignatureEventContent,
  Meta,
  ProfileMetadata,
  SignedEventContent
} from '../../types'
import {
  decryptArrayBuffer,
  extractMarksFromSignedMeta,
  extractZipUrlAndEncryptionKey,
  getHash,
  hexToNpub,
  now,
  npubToHex,
  parseJson,
  readContentOfZipEntry,
  shorten,
  signEventForMetaFile
} from '../../utils'
import styles from './style.module.scss'
import { Cancel, CheckCircle } from '@mui/icons-material'
import { useLocation } from 'react-router-dom'
import axios from 'axios'
import { PdfFile } from '../../types/drawing.ts'
import {
  addMarks,
  convertToPdfBlob,
  convertToPdfFile,
  groupMarksByPage
} from '../../utils/pdf.ts'
import { State } from '../../store/rootReducer.ts'
import { useSelector } from 'react-redux'
import { getLastSignersSig } from '../../utils/sign.ts'
import { saveAs } from 'file-saver'
import { Container } from '../../components/Container'

export const VerifyPage = () => {
  const theme = useTheme()
  const textColor = theme.palette.getContrastText(
    theme.palette.background.paper
  )

  const location = useLocation()
  /**
   * uploadedZip will be received from home page when a user uploads a sigit zip wrapper that contains meta.json
   * meta will be received in navigation from create & home page in online mode
   */
  const { uploadedZip, meta: metaInNavState } = location.state || {}

  const [isLoading, setIsLoading] = useState(false)
  const [loadingSpinnerDesc, setLoadingSpinnerDesc] = useState('')

  const [selectedFile, setSelectedFile] = useState<File | null>(null)
  const [meta, setMeta] = useState<Meta | null>(null)

  const [submittedBy, setSubmittedBy] = useState<string>()

  const [signers, setSigners] = useState<`npub1${string}`[]>([])
  const [viewers, setViewers] = useState<`npub1${string}`[]>([])
  const [creatorFileHashes, setCreatorFileHashes] = useState<{
    [key: string]: string
  }>({})
  const [currentFileHashes, setCurrentFileHashes] = useState<{
    [key: string]: string | null
  }>({})
  const [files, setFiles] = useState<{ [filename: string]: PdfFile }>({})

  const [metadata, setMetadata] = useState<{ [key: string]: ProfileMetadata }>(
    {}
  )
  const usersPubkey = useSelector((state: State) => state.auth.usersPubkey)
  const nostrController = NostrController.getInstance()

  useEffect(() => {
    if (uploadedZip) {
      setSelectedFile(uploadedZip)
    } else if (metaInNavState) {
      const processSigit = async () => {
        setIsLoading(true)
        setLoadingSpinnerDesc('Extracting zipUrl and encryption key from meta')

        const res = await extractZipUrlAndEncryptionKey(metaInNavState)
        if (!res) {
          setIsLoading(false)
          return
        }

        const {
          zipUrl,
          encryptionKey,
          createSignatureEvent,
          createSignatureContent
        } = res

        setLoadingSpinnerDesc('Fetching file from file server')
        axios
          .get(zipUrl, {
            responseType: 'arraybuffer'
          })
          .then(async (res) => {
            const fileName = zipUrl.split('/').pop()
            const file = new File([res.data], fileName!)

            const encryptedArrayBuffer = await file.arrayBuffer()
            const arrayBuffer = await decryptArrayBuffer(
              encryptedArrayBuffer,
              encryptionKey
            ).catch((err) => {
              console.log('err in decryption:>> ', err)
              toast.error(
                err.message || 'An error occurred in decrypting file.'
              )
              return null
            })

            if (arrayBuffer) {
              const zip = await JSZip.loadAsync(arrayBuffer).catch((err) => {
                console.log('err in loading zip file :>> ', err)
                toast.error(
                  err.message || 'An error occurred in loading zip file.'
                )
                return null
              })

              if (!zip) return

              const files: { [filename: string]: PdfFile } = {}
              const fileHashes: { [key: string]: string | null } = {}
              const fileNames = Object.values(zip.files).map(
                (entry) => entry.name
              )

              // generate hashes for all entries in files folder of zipArchive
              // these hashes can be used to verify the originality of files
              for (const fileName of fileNames) {
                const arrayBuffer = await readContentOfZipEntry(
                  zip,
                  fileName,
                  'arraybuffer'
                )

                if (arrayBuffer) {
                  files[fileName] = await convertToPdfFile(
                    arrayBuffer,
                    fileName!
                  )
                  const hash = await getHash(arrayBuffer)

                  if (hash) {
                    fileHashes[fileName.replace(/^files\//, '')] = hash
                  }
                } else {
                  fileHashes[fileName.replace(/^files\//, '')] = null
                }
              }

              setCurrentFileHashes(fileHashes)
              setFiles(files)

              setSigners(createSignatureContent.signers)
              setViewers(createSignatureContent.viewers)
              setCreatorFileHashes(createSignatureContent.fileHashes)
              setSubmittedBy(createSignatureEvent.pubkey)

              setMeta(metaInNavState)
              setIsLoading(false)
            }
          })
          .catch((err) => {
            console.error(`error occurred in getting file from ${zipUrl}`, err)
            toast.error(
              err.message || `error occurred in getting file from ${zipUrl}`
            )
          })
          .finally(() => {
            setIsLoading(false)
          })
      }

      processSigit()
    }
  }, [uploadedZip, metaInNavState])

  useEffect(() => {
    if (submittedBy) {
      const metadataController = new MetadataController()

      const users = [submittedBy, ...signers, ...viewers]

      users.forEach((user) => {
        const pubkey = npubToHex(user)!

        if (!(pubkey in metadata)) {
          const handleMetadataEvent = (event: Event) => {
            const metadataContent =
              metadataController.extractProfileMetadataContent(event)
            if (metadataContent)
              setMetadata((prev) => ({
                ...prev,
                [pubkey]: metadataContent
              }))
          }

          metadataController.on(pubkey, (kind: number, event: Event) => {
            if (kind === kinds.Metadata) {
              handleMetadataEvent(event)
            }
          })

          metadataController
            .findMetadata(pubkey)
            .then((metadataEvent) => {
              if (metadataEvent) handleMetadataEvent(metadataEvent)
            })
            .catch((err) => {
              console.error(
                `error occurred in finding metadata for: ${user}`,
                err
              )
            })
        }
      })
    }
  }, [submittedBy, signers, viewers])

  const handleVerify = async () => {
    if (!selectedFile) return
    setIsLoading(true)

    const zip = await JSZip.loadAsync(selectedFile).catch((err) => {
      console.log('err in loading zip file :>> ', err)
      toast.error(err.message || 'An error occurred in loading zip file.')
      return null
    })

    if (!zip) return

    const fileHashes: { [key: string]: string | null } = {}
    const fileNames = Object.values(zip.files)
      .filter((entry) => entry.name.startsWith('files/') && !entry.dir)
      .map((entry) => entry.name)

    // generate hashes for all entries in files folder of zipArchive
    // these hashes can be used to verify the originality of files
    for (const fileName of fileNames) {
      const arrayBuffer = await readContentOfZipEntry(
        zip,
        fileName,
        'arraybuffer'
      )

      if (arrayBuffer) {
        const hash = await getHash(arrayBuffer)

        if (hash) {
          fileHashes[fileName.replace(/^files\//, '')] = hash
        }
      } else {
        fileHashes[fileName.replace(/^files\//, '')] = null
      }
    }

    console.log('fileHashes :>> ', fileHashes)
    setCurrentFileHashes(fileHashes)

    setLoadingSpinnerDesc('Parsing meta.json')

    const metaFileContent = await readContentOfZipEntry(
      zip,
      'meta.json',
      'string'
    )

    if (!metaFileContent) {
      setIsLoading(false)
      return
    }

    const parsedMetaJson = await parseJson<Meta>(metaFileContent).catch(
      (err) => {
        console.log('err in parsing the content of meta.json :>> ', err)
        toast.error(
          err.message || 'error occurred in parsing the content of meta.json'
        )
        setIsLoading(false)
        return null
      }
    )

    if (!parsedMetaJson) return

    const createSignatureEvent = await parseJson<Event>(
      parsedMetaJson.createSignature
    ).catch((err) => {
      console.log('err in parsing the createSignature event:>> ', err)
      toast.error(
        err.message || 'error occurred in parsing the create signature event'
      )
      setIsLoading(false)
      return null
    })

    if (!createSignatureEvent) return

    const isValidCreateSignature = verifyEvent(createSignatureEvent)

    if (!isValidCreateSignature) {
      toast.error('Create signature is invalid')
      setIsLoading(false)
      return
    }

    const createSignatureContent = await parseJson<CreateSignatureEventContent>(
      createSignatureEvent.content
    ).catch((err) => {
      console.log(
        `err in parsing the createSignature event's content :>> `,
        err
      )
      toast.error(
        err.message ||
          `error occurred in parsing the create signature event's content`
      )
      setIsLoading(false)
      return null
    })

    if (!createSignatureContent) return

    setSigners(createSignatureContent.signers)
    setViewers(createSignatureContent.viewers)
    setCreatorFileHashes(createSignatureContent.fileHashes)
    setSubmittedBy(createSignatureEvent.pubkey)

    setMeta(parsedMetaJson)
    setIsLoading(false)
  }

  const getPrevSignersSig = (npub: string) => {
    if (!meta) return null

    // if user is first signer then use creator's signature
    if (signers[0] === npub) {
      try {
        const createSignatureEvent: Event = JSON.parse(meta.createSignature)
        return createSignatureEvent.sig
      } catch (error) {
        return null
      }
    }

    // find the index of signer
    const currentSignerIndex = signers.findIndex((signer) => signer === npub)
    // return null if could not found user in signer's list
    if (currentSignerIndex === -1) return null
    // find prev signer
    const prevSigner = signers[currentSignerIndex - 1]

    // get the signature of prev signer
    try {
      const prevSignersEvent: Event = JSON.parse(meta.docSignatures[prevSigner])
      return prevSignersEvent.sig
    } catch (error) {
      return null
    }
  }

  const handleExport = async () => {
    if (Object.entries(files).length === 0 || !meta || !usersPubkey) return

    const usersNpub = hexToNpub(usersPubkey)
    if (
      !signers.includes(usersNpub) &&
      !viewers.includes(usersNpub) &&
      submittedBy !== usersNpub
    ) {
      return
    }

    setIsLoading(true)
    setLoadingSpinnerDesc('Signing nostr event')

    if (!meta) return

    const prevSig = getLastSignersSig(meta, signers)
    if (!prevSig) return

    const signedEvent = await signEventForMetaFile(
      JSON.stringify({ prevSig }),
      nostrController,
      setIsLoading
    )

    if (!signedEvent) return

    const exportSignature = JSON.stringify(signedEvent, null, 2)
    const updatedMeta = { ...meta, exportSignature }
    const stringifiedMeta = JSON.stringify(updatedMeta, null, 2)

    const zip = new JSZip()
    zip.file('meta.json', stringifiedMeta)

    const marks = extractMarksFromSignedMeta(updatedMeta)
    const marksByPage = groupMarksByPage(marks)

    for (const [fileName, pdf] of Object.entries(files)) {
      const pages = await addMarks(pdf.file, marksByPage)
      const blob = await convertToPdfBlob(pages)
      zip.file(`/files/${fileName}`, blob)
    }

    const arrayBuffer = await zip
      .generateAsync({
        type: 'arraybuffer',
        compression: 'DEFLATE',
        compressionOptions: {
          level: 6
        }
      })
      .catch((err) => {
        console.log('err in zip:>> ', err)
        setIsLoading(false)
        toast.error(err.message || 'Error occurred in generating zip file')
        return null
      })

    if (!arrayBuffer) return

    const blob = new Blob([arrayBuffer])
    saveAs(blob, `exported-${now()}.sigit.zip`)

    setIsLoading(false)
  }

  const displayUser = (pubkey: string, verifySignature = false) => {
    const profile = metadata[pubkey]

    let isValidSignature = false

    if (verifySignature) {
      const npub = hexToNpub(pubkey)
      const signedEventString = meta ? meta.docSignatures[npub] : null
      if (signedEventString) {
        try {
          const signedEvent = JSON.parse(signedEventString)
          const isVerifiedEvent = verifyEvent(signedEvent)

          if (isVerifiedEvent) {
            // get the actual signature of prev signer
            const prevSignersSig = getPrevSignersSig(npub)

            // get the signature of prev signer from the content of current signers signedEvent

            try {
              const obj: SignedEventContent = JSON.parse(signedEvent.content)
              if (
                obj.prevSig &&
                prevSignersSig &&
                obj.prevSig === prevSignersSig
              ) {
                isValidSignature = true
              }
            } catch (error) {
              isValidSignature = false
            }
          }
        } catch (error) {
          console.error(
            `An error occurred in parsing and verifying the signature event for ${pubkey}`,
            error
          )
        }
      }
    }

    return (
      <>
        <UserAvatar
          pubkey={pubkey}
          name={
            profile?.display_name || profile?.name || shorten(hexToNpub(pubkey))
          }
          image={profile?.picture}
        />

        {verifySignature && (
          <>
            {isValidSignature && (
              <Tooltip title="Valid signature">
                <CheckCircle sx={{ color: theme.palette.success.light }} />
              </Tooltip>
            )}

            {!isValidSignature && (
              <Tooltip title="Invalid signature">
                <Cancel sx={{ color: theme.palette.error.main }} />
              </Tooltip>
            )}
          </>
        )}
      </>
    )
  }

  const displayExportedBy = () => {
    if (!meta || !meta.exportSignature) return null

    const exportSignatureString = meta.exportSignature

    try {
      const exportSignatureEvent = JSON.parse(exportSignatureString) as Event

      if (verifyEvent(exportSignatureEvent)) {
        return displayUser(exportSignatureEvent.pubkey)
      } else {
        toast.error(`Invalid export signature!`)
        return (
          <Typography component="label" sx={{ color: 'red' }}>
            Invalid export signature
          </Typography>
        )
      }
    } catch (error) {
      console.error(`An error occurred wile parsing exportSignature`, error)
      return null
    }
  }

  return (
    <>
      {isLoading && <LoadingSpinner desc={loadingSpinnerDesc} />}
      <Container className={styles.container}>
        {!meta && (
          <>
            <Typography component="label" variant="h6">
              Select exported zip file
            </Typography>

            <MuiFileInput
              placeholder="Select file"
              value={selectedFile}
              onChange={(value) => setSelectedFile(value)}
              InputProps={{
                inputProps: {
                  accept: '.sigit.zip'
                }
              }}
            />

            {selectedFile && (
              <Box sx={{ mt: 2, display: 'flex', justifyContent: 'center' }}>
                <Button onClick={handleVerify} variant="contained">
                  Verify
                </Button>
              </Box>
            )}
          </>
        )}

        {meta && (
          <>
            <List
              sx={{
                bgcolor: 'background.paper',
                marginTop: 2
              }}
              subheader={
                <ListSubheader className={styles.subHeader}>
                  Meta Info
                </ListSubheader>
              }
            >
              {submittedBy && (
                <ListItem
                  sx={{
                    marginTop: 1,
                    gap: '15px'
                  }}
                >
                  <Typography variant="h6" sx={{ color: textColor }}>
                    Submitted By
                  </Typography>
                  {displayUser(submittedBy)}
                </ListItem>
              )}

              <ListItem
                sx={{
                  marginTop: 1,
                  gap: '15px'
                }}
              >
                <Typography variant="h6" sx={{ color: textColor }}>
                  Exported By
                </Typography>
                {displayExportedBy()}
                <Box sx={{ mt: 1, display: 'flex', justifyContent: 'center' }}>
                  <Button onClick={handleExport} variant="contained">
                    Export Sigit
                  </Button>
                </Box>
              </ListItem>

              {signers.length > 0 && (
                <ListItem
                  sx={{
                    marginTop: 1,
                    flexDirection: 'column',
                    alignItems: 'flex-start'
                  }}
                >
                  <Typography variant="h6" sx={{ color: textColor }}>
                    Signers
                  </Typography>
                  <ul className={styles.usersList}>
                    {signers.map((signer) => (
                      <li
                        key={signer}
                        style={{
                          color: textColor,
                          display: 'flex',
                          alignItems: 'center',
                          gap: '15px'
                        }}
                      >
                        {displayUser(npubToHex(signer)!, true)}
                      </li>
                    ))}
                  </ul>
                </ListItem>
              )}

              {viewers.length > 0 && (
                <ListItem
                  sx={{
                    marginTop: 1,
                    flexDirection: 'column',
                    alignItems: 'flex-start'
                  }}
                >
                  <Typography variant="h6" sx={{ color: textColor }}>
                    Viewers
                  </Typography>
                  <ul className={styles.usersList}>
                    {viewers.map((viewer) => (
                      <li key={viewer} style={{ color: textColor }}>
                        {displayUser(npubToHex(viewer)!)}
                      </li>
                    ))}
                  </ul>
                </ListItem>
              )}

              <ListItem
                sx={{
                  marginTop: 1,
                  flexDirection: 'column',
                  alignItems: 'flex-start'
                }}
              >
                <Typography variant="h6" sx={{ color: textColor }}>
                  Files
                </Typography>
                <Box className={styles.filesWrapper}>
                  {Object.entries(currentFileHashes).map(
                    ([filename, hash], index) => {
                      const isValidHash = creatorFileHashes[filename] === hash

                      return (
                        <Box key={`file-${index}`} className={styles.file}>
                          <Typography
                            component="label"
                            sx={{
                              color: textColor,
                              flexGrow: 1
                            }}
                          >
                            {filename}
                          </Typography>
                          {isValidHash && (
                            <Tooltip title="File integrity check passed" arrow>
                              <CheckCircle
                                sx={{ color: theme.palette.success.light }}
                              />
                            </Tooltip>
                          )}
                          {!isValidHash && (
                            <Tooltip title="File integrity check failed" arrow>
                              <Cancel
                                sx={{ color: theme.palette.error.main }}
                              />
                            </Tooltip>
                          )}
                        </Box>
                      )
                    }
                  )}
                </Box>
              </ListItem>
            </List>
          </>
        )}
      </Container>
    </>
  )
}