import { createLogger } from '@sim/logger'
import { getErrorMessage, toError } from '@sim/utils/errors'
import { fetchWithRetry, VALIDATE_RETRY_OPTIONS } from '@/lib/knowledge/documents/utils'
import { googleDriveConnectorMeta } from '@/connectors/google-drive/meta'
import type { ConnectorConfig, ExternalDocument, ExternalDocumentList } from '@/connectors/types'
import {
  buildDriveParentsClause,
  CONNECTOR_MAX_FILE_BYTES,
  ConnectorFileTooLargeError,
  htmlToPlainText,
  joinTagArray,
  markSkipped,
  parseMultiValue,
  parseTagDate,
  readBodyWithLimit,
  sizeLimitSkipReason,
} from '@/connectors/utils'

const logger = createLogger('GoogleDriveConnector')

const GOOGLE_WORKSPACE_MIME_TYPES: Record<string, string> = {
  'application/vnd.google-apps.document': 'text/plain',
  'application/vnd.google-apps.spreadsheet': 'text/csv',
  'application/vnd.google-apps.presentation': 'text/plain',
}

const SUPPORTED_TEXT_MIME_TYPES = [
  'text/plain',
  'text/csv',
  'text/html',
  'text/markdown',
  'application/json',
  'application/xml',
]

// Google Drive's `files.export` API rejects exports over 10 MB (exportSizeLimitExceeded),
// so this is a hard external limit for Google Workspace docs — not the connector cap.
const MAX_EXPORT_SIZE = 10 * 1024 * 1024

function isGoogleWorkspaceFile(mimeType: string): boolean {
  return mimeType in GOOGLE_WORKSPACE_MIME_TYPES
}

function isSupportedTextFile(mimeType: string): boolean {
  return SUPPORTED_TEXT_MIME_TYPES.some((t) => mimeType.startsWith(t))
}

async function exportGoogleWorkspaceFile(
  accessToken: string,
  fileId: string,
  sourceMimeType: string
): Promise<string> {
  const exportMimeType = GOOGLE_WORKSPACE_MIME_TYPES[sourceMimeType]
  if (!exportMimeType) {
    throw new Error(`Unsupported Google Workspace MIME type: ${sourceMimeType}`)
  }

  const url = `https://www.googleapis.com/drive/v3/files/${fileId}/export?mimeType=${encodeURIComponent(exportMimeType)}`

  const response = await fetchWithRetry(url, {
    method: 'GET',
    headers: { Authorization: `Bearer ${accessToken}` },
  })

  if (!response.ok) {
    // Google rejects exports over its 10 MB limit with a 403 exportSizeLimitExceeded
    // before streaming any bytes — surface that as an oversize skip, not a hard error.
    if (response.status === 403) {
      const body = await response.text().catch(() => '')
      if (body.includes('exportSizeLimitExceeded')) {
        throw new ConnectorFileTooLargeError(MAX_EXPORT_SIZE)
      }
    }
    throw new Error(`Failed to export file ${fileId}: ${response.status}`)
  }

  const buffer = await readBodyWithLimit(response, MAX_EXPORT_SIZE)
  if (!buffer) {
    throw new ConnectorFileTooLargeError(MAX_EXPORT_SIZE)
  }
  return buffer.toString('utf8')
}

async function downloadTextFile(accessToken: string, fileId: string): Promise<string> {
  const url = `https://www.googleapis.com/drive/v3/files/${fileId}?alt=media`

  const response = await fetchWithRetry(url, {
    method: 'GET',
    headers: { Authorization: `Bearer ${accessToken}` },
  })

  if (!response.ok) {
    throw new Error(`Failed to download file ${fileId}: ${response.status}`)
  }

  // Stream with a hard byte cap so a file with missing/under-reported listing
  // size metadata is never fully buffered into memory. Oversized files raise
  // DriveFileTooLargeError so getDocument can surface them as skipped (failed) rows.
  const buffer = await readBodyWithLimit(response, CONNECTOR_MAX_FILE_BYTES)
  if (!buffer) {
    throw new ConnectorFileTooLargeError(CONNECTOR_MAX_FILE_BYTES)
  }
  return buffer.toString('utf8')
}

async function fetchFileContent(
  accessToken: string,
  fileId: string,
  mimeType: string
): Promise<string> {
  if (isGoogleWorkspaceFile(mimeType)) {
    return exportGoogleWorkspaceFile(accessToken, fileId, mimeType)
  }
  if (mimeType === 'text/html') {
    const html = await downloadTextFile(accessToken, fileId)
    return htmlToPlainText(html)
  }
  if (isSupportedTextFile(mimeType)) {
    return downloadTextFile(accessToken, fileId)
  }

  throw new Error(`Unsupported MIME type for content extraction: ${mimeType}`)
}

interface DriveFile {
  id: string
  name: string
  mimeType: string
  modifiedTime?: string
  createdTime?: string
  webViewLink?: string
  parents?: string[]
  owners?: { displayName?: string; emailAddress?: string }[]
  size?: string
  starred?: boolean
  trashed?: boolean
}

function buildQuery(sourceConfig: Record<string, unknown>): string {
  const parts: string[] = ['trashed = false']

  const parentsClause = buildDriveParentsClause(parseMultiValue(sourceConfig.folderId))
  if (parentsClause) parts.push(parentsClause)

  const fileType = (sourceConfig.fileType as string) || 'all'
  switch (fileType) {
    case 'documents':
      parts.push("mimeType = 'application/vnd.google-apps.document'")
      break
    case 'spreadsheets':
      parts.push("mimeType = 'application/vnd.google-apps.spreadsheet'")
      break
    case 'presentations':
      parts.push("mimeType = 'application/vnd.google-apps.presentation'")
      break
    case 'text':
      parts.push(`(${SUPPORTED_TEXT_MIME_TYPES.map((t) => `mimeType = '${t}'`).join(' or ')})`)
      break
    default: {
      // Include Google Workspace files + plain text files, exclude folders
      const allMimeTypes = [
        ...Object.keys(GOOGLE_WORKSPACE_MIME_TYPES),
        ...SUPPORTED_TEXT_MIME_TYPES,
      ]
      parts.push(`(${allMimeTypes.map((t) => `mimeType = '${t}'`).join(' or ')})`)
      break
    }
  }

  return parts.join(' and ')
}

function fileToStub(file: DriveFile): ExternalDocument {
  return {
    externalId: file.id,
    title: file.name || 'Untitled',
    content: '',
    contentDeferred: true,
    mimeType: 'text/plain',
    sourceUrl: file.webViewLink || `https://drive.google.com/file/d/${file.id}/view`,
    contentHash: `gdrive:${file.id}:${file.modifiedTime ?? ''}`,
    metadata: {
      originalMimeType: file.mimeType,
      modifiedTime: file.modifiedTime,
      createdTime: file.createdTime,
      owners: file.owners?.map((o) => o.displayName || o.emailAddress).filter(Boolean),
      starred: file.starred,
      fileSize: file.size ? Number(file.size) : undefined,
    },
  }
}

export const googleDriveConnector: ConnectorConfig = {
  ...googleDriveConnectorMeta,

  listDocuments: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>,
    cursor?: string,
    syncContext?: Record<string, unknown>
  ): Promise<ExternalDocumentList> => {
    const query = buildQuery(sourceConfig)
    const pageSize = 100

    const maxFiles = sourceConfig.maxFiles ? Number(sourceConfig.maxFiles) : 0
    const previouslyFetched = (syncContext?.totalDocsFetched as number) ?? 0

    if (maxFiles > 0 && previouslyFetched >= maxFiles) {
      return { documents: [], hasMore: false }
    }

    const remaining = maxFiles > 0 ? maxFiles - previouslyFetched : 0
    const effectivePageSize = maxFiles > 0 ? Math.min(pageSize, remaining) : pageSize

    const queryParams = new URLSearchParams({
      q: query,
      pageSize: String(effectivePageSize),
      orderBy: 'modifiedTime desc',
      fields:
        'nextPageToken,files(id,name,mimeType,modifiedTime,createdTime,webViewLink,parents,owners,size,starred)',
      supportsAllDrives: 'true',
      includeItemsFromAllDrives: 'true',
    })

    if (cursor) {
      queryParams.set('pageToken', cursor)
    }

    const url = `https://www.googleapis.com/drive/v3/files?${queryParams.toString()}`

    logger.info('Listing Google Drive files', { query, cursor: cursor ?? 'initial' })

    const response = await fetchWithRetry(url, {
      method: 'GET',
      headers: {
        Authorization: `Bearer ${accessToken}`,
        Accept: 'application/json',
      },
    })

    if (!response.ok) {
      const errorText = await response.text()
      logger.error('Failed to list Google Drive files', {
        status: response.status,
        error: errorText,
      })
      throw new Error(`Failed to list Google Drive files: ${response.status}`)
    }

    const data = await response.json()
    const files = (data.files || []) as DriveFile[]

    /**
     * Drive sets `incompleteSearch` when it could not search every corpus (it
     * arises with the `allDrives` scope enabled by `includeItemsFromAllDrives`).
     * A partial listing drops still-existing files, so reconciliation must be
     * suppressed to avoid hard-deleting valid documents.
     */
    const incompleteSearch = data.incompleteSearch === true

    const documents = files
      .filter((f) => isGoogleWorkspaceFile(f.mimeType) || isSupportedTextFile(f.mimeType))
      .map(fileToStub)

    const totalFetched = previouslyFetched + documents.length
    if (syncContext) syncContext.totalDocsFetched = totalFetched
    const hitLimit = maxFiles > 0 && totalFetched >= maxFiles
    if (syncContext && (hitLimit || incompleteSearch)) syncContext.listingCapped = true

    const nextPageToken = data.nextPageToken as string | undefined

    return {
      documents,
      nextCursor: hitLimit ? undefined : nextPageToken,
      hasMore: hitLimit ? false : Boolean(nextPageToken),
    }
  },

  getDocument: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>,
    externalId: string
  ): Promise<ExternalDocument | null> => {
    const fields =
      'id,name,mimeType,modifiedTime,createdTime,webViewLink,parents,owners,size,starred,trashed'
    const url = `https://www.googleapis.com/drive/v3/files/${externalId}?fields=${encodeURIComponent(fields)}&supportsAllDrives=true`

    const response = await fetchWithRetry(url, {
      method: 'GET',
      headers: {
        Authorization: `Bearer ${accessToken}`,
        Accept: 'application/json',
      },
    })

    if (!response.ok) {
      if (response.status === 404) return null
      throw new Error(`Failed to get Google Drive file: ${response.status}`)
    }

    const file = (await response.json()) as DriveFile

    if (file.trashed) return null

    try {
      const content = await fetchFileContent(accessToken, file.id, file.mimeType)
      if (!content.trim()) return null

      const stub = fileToStub(file)
      return { ...stub, content, contentDeferred: false }
    } catch (error) {
      if (error instanceof ConnectorFileTooLargeError) {
        logger.info('Skipping oversized Google Drive file', { fileId: file.id, name: file.name })
        return markSkipped(fileToStub(file), sizeLimitSkipReason(error.limitBytes))
      }
      logger.warn(`Failed to fetch content for file: ${file.name} (${file.id})`, {
        error: toError(error).message,
      })
      return null
    }
  },

  validateConfig: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>
  ): Promise<{ valid: boolean; error?: string }> => {
    const folderIds = parseMultiValue(sourceConfig.folderId)
    const maxFiles = sourceConfig.maxFiles as string | undefined

    if (maxFiles && (Number.isNaN(Number(maxFiles)) || Number(maxFiles) <= 0)) {
      return { valid: false, error: 'Max files must be a positive number' }
    }

    // Verify access to Drive API
    try {
      if (folderIds.length > 0) {
        // Verify each folder exists, is accessible, and is actually a folder
        for (const folderId of folderIds) {
          const url = `https://www.googleapis.com/drive/v3/files/${encodeURIComponent(folderId)}?fields=id,name,mimeType&supportsAllDrives=true`
          const response = await fetchWithRetry(
            url,
            {
              method: 'GET',
              headers: {
                Authorization: `Bearer ${accessToken}`,
                Accept: 'application/json',
              },
            },
            VALIDATE_RETRY_OPTIONS
          )

          if (!response.ok) {
            if (response.status === 404) {
              return {
                valid: false,
                error: `Folder "${folderId}" not found. Check the folder ID and permissions.`,
              }
            }
            return {
              valid: false,
              error: `Failed to access folder "${folderId}": ${response.status}`,
            }
          }

          const folder = await response.json()
          if (folder.mimeType !== 'application/vnd.google-apps.folder') {
            return { valid: false, error: `"${folderId}" is not a folder` }
          }
        }
      } else {
        // Verify basic Drive access by listing one file
        const url = 'https://www.googleapis.com/drive/v3/files?pageSize=1&fields=files(id)'
        const response = await fetchWithRetry(
          url,
          {
            method: 'GET',
            headers: {
              Authorization: `Bearer ${accessToken}`,
              Accept: 'application/json',
            },
          },
          VALIDATE_RETRY_OPTIONS
        )

        if (!response.ok) {
          return { valid: false, error: `Failed to access Google Drive: ${response.status}` }
        }
      }

      return { valid: true }
    } catch (error) {
      const message = getErrorMessage(error, 'Failed to validate configuration')
      return { valid: false, error: message }
    }
  },

  mapTags: (metadata: Record<string, unknown>): Record<string, unknown> => {
    const result: Record<string, unknown> = {}

    const owners = joinTagArray(metadata.owners)
    if (owners) result.owners = owners

    if (typeof metadata.originalMimeType === 'string') {
      const mimeType = metadata.originalMimeType
      if (mimeType.includes('document')) result.fileType = 'Google Doc'
      else if (mimeType.includes('spreadsheet')) result.fileType = 'Google Sheet'
      else if (mimeType.includes('presentation')) result.fileType = 'Google Slides'
      else if (mimeType.startsWith('text/')) result.fileType = 'Text File'
      else result.fileType = mimeType
    }

    const lastModified = parseTagDate(metadata.modifiedTime)
    if (lastModified) result.lastModified = lastModified

    if (typeof metadata.starred === 'boolean') {
      result.starred = metadata.starred
    }

    return result
  },
}