const sequelize = require('sequelize')
const Path = require('path')
const packageJson = require('../../package.json')
const Logger = require('../Logger')
const SocketAuthority = require('../SocketAuthority')
const Database = require('../Database')
const fs = require('../libs/fsExtra')
const fileUtils = require('../utils/fileUtils')
const scanUtils = require('../utils/scandir')
const { LogLevel, ScanResult } = require('../utils/constants')
const libraryFilters = require('../utils/queries/libraryFilters')
const LibraryItemScanner = require('./LibraryItemScanner')
const LibraryScan = require('./LibraryScan')
const LibraryItemScanData = require('./LibraryItemScanData')

class LibraryScanner {
  constructor() {
    this.cancelLibraryScan = {}
    this.librariesScanning = []

    this.scanningFilesChanged = false
    /** @type {import('../Watcher').PendingFileUpdate[][]} */
    this.pendingFileUpdatesToScan = []
  }

  /**
   * @param {string} libraryId 
   * @returns {boolean}
   */
  isLibraryScanning(libraryId) {
    return this.librariesScanning.some(ls => ls.id === libraryId)
  }

  /**
   * 
   * @param {string} libraryId 
   */
  setCancelLibraryScan(libraryId) {
    const libraryScanning = this.librariesScanning.find(ls => ls.id === libraryId)
    if (!libraryScanning) return
    this.cancelLibraryScan[libraryId] = true
  }

  /**
   * 
   * @param {import('../objects/Library')} library 
   * @param {*} options 
   */
  async scan(library, options = {}) {
    if (this.isLibraryScanning(library.id)) {
      Logger.error(`[Scanner] Already scanning ${library.id}`)
      return
    }

    if (!library.folders.length) {
      Logger.warn(`[Scanner] Library has no folders to scan "${library.name}"`)
      return
    }

    const libraryScan = new LibraryScan()
    libraryScan.setData(library)
    libraryScan.verbose = true
    this.librariesScanning.push(libraryScan.getScanEmitData)

    SocketAuthority.emitter('scan_start', libraryScan.getScanEmitData)

    Logger.info(`[Scanner] Starting library scan ${libraryScan.id} for ${libraryScan.libraryName}`)

    const canceled = await this.scanLibrary(libraryScan)

    if (canceled) {
      Logger.info(`[Scanner] Library scan canceled for "${libraryScan.libraryName}"`)
      delete this.cancelLibraryScan[libraryScan.libraryId]
    }

    libraryScan.setComplete()

    Logger.info(`[Scanner] Library scan ${libraryScan.id} completed in ${libraryScan.elapsedTimestamp} | ${libraryScan.resultStats}`)
    this.librariesScanning = this.librariesScanning.filter(ls => ls.id !== library.id)

    if (canceled && !libraryScan.totalResults) {
      const emitData = libraryScan.getScanEmitData
      emitData.results = null
      SocketAuthority.emitter('scan_complete', emitData)
      return
    }

    SocketAuthority.emitter('scan_complete', libraryScan.getScanEmitData)

    if (libraryScan.totalResults) {
      libraryScan.saveLog()
    }
  }

  /**
   * 
   * @param {import('./LibraryScan')} libraryScan 
   * @returns {boolean} true if scan canceled
   */
  async scanLibrary(libraryScan) {
    // Make sure library filter data is set
    //   this is used to check for existing authors & series
    await libraryFilters.getFilterData(libraryScan.library.mediaType, libraryScan.libraryId)

    /** @type {LibraryItemScanData[]} */
    let libraryItemDataFound = []

    // Scan each library folder
    for (let i = 0; i < libraryScan.folders.length; i++) {
      const folder = libraryScan.folders[i]
      const itemDataFoundInFolder = await this.scanFolder(libraryScan.library, folder)
      libraryScan.addLog(LogLevel.INFO, `${itemDataFoundInFolder.length} item data found in folder "${folder.fullPath}"`)
      libraryItemDataFound = libraryItemDataFound.concat(itemDataFoundInFolder)
    }

    if (this.cancelLibraryScan[libraryScan.libraryId]) return true

    const existingLibraryItems = await Database.libraryItemModel.findAll({
      where: {
        libraryId: libraryScan.libraryId
      }
    })

    if (this.cancelLibraryScan[libraryScan.libraryId]) return true

    const libraryItemIdsMissing = []
    let oldLibraryItemsUpdated = []
    for (const existingLibraryItem of existingLibraryItems) {
      // First try to find matching library item with exact file path
      let libraryItemData = libraryItemDataFound.find(lid => lid.path === existingLibraryItem.path)
      if (!libraryItemData) {
        // Fallback to finding matching library item with matching inode value
        libraryItemData = libraryItemDataFound.find(lid => lid.ino === existingLibraryItem.ino)
        if (libraryItemData) {
          libraryScan.addLog(LogLevel.INFO, `Library item with path "${existingLibraryItem.path}" was not found, but library item inode "${existingLibraryItem.ino}" was found at path "${libraryItemData.path}"`)
        }
      }

      if (!libraryItemData) {
        // Podcast folder can have no episodes and still be valid
        if (libraryScan.libraryMediaType === 'podcast' && await fs.pathExists(existingLibraryItem.path)) {
          libraryScan.addLog(LogLevel.INFO, `Library item "${existingLibraryItem.relPath}" folder exists but has no episodes`)
        } else {
          libraryScan.addLog(LogLevel.WARN, `Library Item "${existingLibraryItem.path}" (inode: ${existingLibraryItem.ino}) is missing`)
          libraryScan.resultsMissing++
          if (!existingLibraryItem.isMissing) {
            libraryItemIdsMissing.push(existingLibraryItem.id)

            // TODO: Temporary while using old model to socket emit
            const oldLibraryItem = await Database.libraryItemModel.getOldById(existingLibraryItem.id)
            oldLibraryItem.isMissing = true
            oldLibraryItem.updatedAt = Date.now()
            oldLibraryItemsUpdated.push(oldLibraryItem)
          }
        }
      } else {
        libraryItemDataFound = libraryItemDataFound.filter(lidf => lidf !== libraryItemData)
        if (await libraryItemData.checkLibraryItemData(existingLibraryItem, libraryScan)) {
          libraryScan.resultsUpdated++
          if (libraryItemData.hasLibraryFileChanges || libraryItemData.hasPathChange) {
            const libraryItem = await LibraryItemScanner.rescanLibraryItem(existingLibraryItem, libraryItemData, libraryScan.library.settings, libraryScan)
            const oldLibraryItem = Database.libraryItemModel.getOldLibraryItem(libraryItem)
            oldLibraryItemsUpdated.push(oldLibraryItem)
          } else {
            // TODO: Temporary while using old model to socket emit
            const oldLibraryItem = await Database.libraryItemModel.getOldById(existingLibraryItem.id)
            oldLibraryItemsUpdated.push(oldLibraryItem)
          }
        }
      }

      // Emit item updates in chunks of 10 to client
      if (oldLibraryItemsUpdated.length === 10) {
        // TODO: Should only emit to clients where library item is accessible
        SocketAuthority.emitter('items_updated', oldLibraryItemsUpdated.map(li => li.toJSONExpanded()))
        oldLibraryItemsUpdated = []
      }

      if (this.cancelLibraryScan[libraryScan.libraryId]) return true
    }
    // Emit item updates to client
    if (oldLibraryItemsUpdated.length) {
      // TODO: Should only emit to clients where library item is accessible
      SocketAuthority.emitter('items_updated', oldLibraryItemsUpdated.map(li => li.toJSONExpanded()))
    }

    // Authors and series that were removed from books should be removed if they are now empty
    await LibraryItemScanner.checkAuthorsAndSeriesRemovedFromBooks(libraryScan.libraryId, libraryScan)

    // Update missing library items
    if (libraryItemIdsMissing.length) {
      libraryScan.addLog(LogLevel.INFO, `Updating ${libraryItemIdsMissing.length} library items missing`)
      await Database.libraryItemModel.update({
        isMissing: true,
        lastScan: Date.now(),
        lastScanVersion: packageJson.version
      }, {
        where: {
          id: libraryItemIdsMissing
        }
      })
    }

    if (this.cancelLibraryScan[libraryScan.libraryId]) return true

    // Add new library items
    if (libraryItemDataFound.length) {
      let newOldLibraryItems = []
      for (const libraryItemData of libraryItemDataFound) {
        const newLibraryItem = await LibraryItemScanner.scanNewLibraryItem(libraryItemData, libraryScan.library.settings, libraryScan)
        if (newLibraryItem) {
          const oldLibraryItem = Database.libraryItemModel.getOldLibraryItem(newLibraryItem)
          newOldLibraryItems.push(oldLibraryItem)

          libraryScan.resultsAdded++
        }

        // Emit new items in chunks of 10 to client
        if (newOldLibraryItems.length === 10) {
          // TODO: Should only emit to clients where library item is accessible
          SocketAuthority.emitter('items_added', newOldLibraryItems.map(li => li.toJSONExpanded()))
          newOldLibraryItems = []
        }

        if (this.cancelLibraryScan[libraryScan.libraryId]) return true
      }
      // Emit new items to client
      if (newOldLibraryItems.length) {
        // TODO: Should only emit to clients where library item is accessible
        SocketAuthority.emitter('items_added', newOldLibraryItems.map(li => li.toJSONExpanded()))
      }
    }
  }

  /**
   * Get scan data for library folder
   * @param {import('../objects/Library')} library 
   * @param {import('../objects/Folder')} folder 
   * @returns {LibraryItemScanData[]}
   */
  async scanFolder(library, folder) {
    const folderPath = fileUtils.filePathToPOSIX(folder.fullPath)

    const pathExists = await fs.pathExists(folderPath)
    if (!pathExists) {
      Logger.error(`[scandir] Invalid folder path does not exist "${folderPath}"`)
      return []
    }

    const fileItems = await fileUtils.recurseFiles(folderPath)
    const libraryItemGrouping = scanUtils.groupFileItemsIntoLibraryItemDirs(library.mediaType, fileItems, library.settings.audiobooksOnly)

    if (!Object.keys(libraryItemGrouping).length) {
      Logger.error(`Root path has no media folders: ${folderPath}`)
      return []
    }

    const items = []
    for (const libraryItemPath in libraryItemGrouping) {
      let isFile = false // item is not in a folder
      let libraryItemData = null
      let fileObjs = []
      if (libraryItemPath === libraryItemGrouping[libraryItemPath]) {
        // Media file in root only get title
        libraryItemData = {
          mediaMetadata: {
            title: Path.basename(libraryItemPath, Path.extname(libraryItemPath))
          },
          path: Path.posix.join(folderPath, libraryItemPath),
          relPath: libraryItemPath
        }
        fileObjs = await scanUtils.buildLibraryFile(folderPath, [libraryItemPath])
        isFile = true
      } else {
        libraryItemData = scanUtils.getDataFromMediaDir(library.mediaType, folderPath, libraryItemPath)
        fileObjs = await scanUtils.buildLibraryFile(libraryItemData.path, libraryItemGrouping[libraryItemPath])
      }

      const libraryItemFolderStats = await fileUtils.getFileTimestampsWithIno(libraryItemData.path)

      if (!libraryItemFolderStats.ino) {
        Logger.warn(`[LibraryScanner] Library item folder "${libraryItemData.path}" has no inode value`)
        continue
      }

      items.push(new LibraryItemScanData({
        libraryFolderId: folder.id,
        libraryId: folder.libraryId,
        mediaType: library.mediaType,
        ino: libraryItemFolderStats.ino,
        mtimeMs: libraryItemFolderStats.mtimeMs || 0,
        ctimeMs: libraryItemFolderStats.ctimeMs || 0,
        birthtimeMs: libraryItemFolderStats.birthtimeMs || 0,
        path: libraryItemData.path,
        relPath: libraryItemData.relPath,
        isFile,
        mediaMetadata: libraryItemData.mediaMetadata || null,
        libraryFiles: fileObjs
      }))
    }
    return items
  }

  /**
   * Scan files changed from Watcher
   * @param {import('../Watcher').PendingFileUpdate[]} fileUpdates 
   */
  async scanFilesChanged(fileUpdates) {
    if (!fileUpdates?.length) return

    // If already scanning files from watcher then add these updates to queue
    if (this.scanningFilesChanged) {
      this.pendingFileUpdatesToScan.push(fileUpdates)
      Logger.debug(`[LibraryScanner] Already scanning files from watcher - file updates pushed to queue (size ${this.pendingFileUpdatesToScan.length})`)
      return
    }
    this.scanningFilesChanged = true

    // files grouped by folder
    const folderGroups = this.getFileUpdatesGrouped(fileUpdates)

    for (const folderId in folderGroups) {
      const libraryId = folderGroups[folderId].libraryId
      // const library = await Database.libraryModel.getOldById(libraryId)
      const library = await Database.libraryModel.findByPk(libraryId, {
        include: {
          model: Database.libraryFolderModel,
          where: {
            id: folderId
          }
        }
      })
      if (!library) {
        Logger.error(`[LibraryScanner] Library "${libraryId}" not found in files changed ${libraryId}`)
        continue
      }
      const folder = library.libraryFolders[0]

      const relFilePaths = folderGroups[folderId].fileUpdates.map(fileUpdate => fileUpdate.relPath)
      const fileUpdateGroup = scanUtils.groupFilesIntoLibraryItemPaths(library.mediaType, relFilePaths)

      if (!Object.keys(fileUpdateGroup).length) {
        Logger.info(`[LibraryScanner] No important changes to scan for in folder "${folderId}"`)
        continue
      }
      const folderScanResults = await this.scanFolderUpdates(library, folder, fileUpdateGroup)
      Logger.debug(`[LibraryScanner] Folder scan results`, folderScanResults)

      // If something was updated then reset numIssues filter data for library
      if (Object.values(folderScanResults).some(scanResult => scanResult !== ScanResult.NOTHING && scanResult !== ScanResult.UPTODATE)) {
        await Database.resetLibraryIssuesFilterData(libraryId)
      }
    }

    this.scanningFilesChanged = false

    if (this.pendingFileUpdatesToScan.length) {
      Logger.debug(`[LibraryScanner] File updates finished scanning with more updates in queue (${this.pendingFileUpdatesToScan.length})`)
      this.scanFilesChanged(this.pendingFileUpdatesToScan.shift())
    }
  }

  /**
   * Group array of PendingFileUpdate from Watcher by folder
   * @param {import('../Watcher').PendingFileUpdate[]} fileUpdates 
   * @returns {Record<string,{libraryId:string, folderId:string, fileUpdates:import('../Watcher').PendingFileUpdate[]}>}
   */
  getFileUpdatesGrouped(fileUpdates) {
    const folderGroups = {}
    fileUpdates.forEach((file) => {
      if (folderGroups[file.folderId]) {
        folderGroups[file.folderId].fileUpdates.push(file)
      } else {
        folderGroups[file.folderId] = {
          libraryId: file.libraryId,
          folderId: file.folderId,
          fileUpdates: [file]
        }
      }
    })
    return folderGroups
  }

  /**
   * Scan grouped paths for library folder coming from Watcher
   * @param {import('../models/Library')} library 
   * @param {import('../models/LibraryFolder')} folder 
   * @param {Record<string, string[]>} fileUpdateGroup 
   * @returns {Promise<Record<string,number>>}
   */
  async scanFolderUpdates(library, folder, fileUpdateGroup) {
    // Make sure library filter data is set
    //   this is used to check for existing authors & series
    await libraryFilters.getFilterData(library.mediaType, library.id)
    Logger.debug(`[Scanner] Scanning file update groups in folder "${folder.id}" of library "${library.name}"`)
    Logger.debug(`[Scanner] scanFolderUpdates fileUpdateGroup`, fileUpdateGroup)

    // First pass - Remove files in parent dirs of items and remap the fileupdate group
    //    Test Case: Moving audio files from library item folder to author folder should trigger a re-scan of the item
    const updateGroup = { ...fileUpdateGroup }
    for (const itemDir in updateGroup) {
      if (itemDir == fileUpdateGroup[itemDir]) continue // Media in root path

      const itemDirNestedFiles = fileUpdateGroup[itemDir].filter(b => b.includes('/'))
      if (!itemDirNestedFiles.length) continue

      const firstNest = itemDirNestedFiles[0].split('/').shift()
      const altDir = `${itemDir}/${firstNest}`

      const fullPath = Path.posix.join(fileUtils.filePathToPOSIX(folder.path), itemDir)
      const childLibraryItem = await Database.libraryItemModel.findOne({
        attributes: ['id', 'path'],
        where: {
          path: {
            [sequelize.Op.not]: fullPath
          },
          path: {
            [sequelize.Op.startsWith]: fullPath
          }
        }
      })
      if (!childLibraryItem) {
        continue
      }

      const altFullPath = Path.posix.join(fileUtils.filePathToPOSIX(folder.path), altDir)
      const altChildLibraryItem = await Database.libraryItemModel.findOne({
        attributes: ['id', 'path'],
        where: {
          path: {
            [sequelize.Op.not]: altFullPath
          },
          path: {
            [sequelize.Op.startsWith]: altFullPath
          }
        }
      })
      if (altChildLibraryItem) {
        continue
      }

      delete fileUpdateGroup[itemDir]
      fileUpdateGroup[altDir] = itemDirNestedFiles.map((f) => f.split('/').slice(1).join('/'))
      Logger.warn(`[LibraryScanner] Some files were modified in a parent directory of a library item "${childLibraryItem.path}" - ignoring`)
    }

    // Second pass: Check for new/updated/removed items
    const itemGroupingResults = {}
    for (const itemDir in fileUpdateGroup) {
      const fullPath = Path.posix.join(fileUtils.filePathToPOSIX(folder.path), itemDir)
      const dirIno = await fileUtils.getIno(fullPath)

      const itemDirParts = itemDir.split('/').slice(0, -1)
      const potentialChildDirs = []
      for (let i = 0; i < itemDirParts.length; i++) {
        potentialChildDirs.push(Path.posix.join(fileUtils.filePathToPOSIX(folder.path), itemDir.split('/').slice(0, -1 - i).join('/')))
      }

      // Check if book dir group is already an item
      let existingLibraryItem = await Database.libraryItemModel.findOneOld({
        path: potentialChildDirs
      })

      if (!existingLibraryItem) {
        existingLibraryItem = await Database.libraryItemModel.findOneOld({
          ino: dirIno
        })
        if (existingLibraryItem) {
          Logger.debug(`[LibraryScanner] scanFolderUpdates: Library item found by inode value=${dirIno}. "${existingLibraryItem.relPath} => ${itemDir}"`)
          // Update library item paths for scan
          existingLibraryItem.path = fullPath
          existingLibraryItem.relPath = itemDir
        }
      }
      if (existingLibraryItem) {
        // Is the item exactly - check if was deleted
        if (existingLibraryItem.path === fullPath) {
          const exists = await fs.pathExists(fullPath)
          if (!exists) {
            Logger.info(`[LibraryScanner] Scanning file update group and library item was deleted "${existingLibraryItem.media.metadata.title}" - marking as missing`)
            existingLibraryItem.setMissing()
            await Database.updateLibraryItem(existingLibraryItem)
            SocketAuthority.emitter('item_updated', existingLibraryItem.toJSONExpanded())

            itemGroupingResults[itemDir] = ScanResult.REMOVED
            continue
          }
        }

        // Scan library item for updates
        Logger.debug(`[LibraryScanner] Folder update for relative path "${itemDir}" is in library item "${existingLibraryItem.media.metadata.title}" - scan for updates`)
        // itemGroupingResults[itemDir] = await this.scanLibraryItem(library, folder, existingLibraryItem)
        itemGroupingResults[itemDir] = await LibraryItemScanner.scanLibraryItem(existingLibraryItem.id)
        continue
      } else if (library.settings.audiobooksOnly && !fileUpdateGroup[itemDir].some?.(scanUtils.checkFilepathIsAudioFile)) {
        Logger.debug(`[LibraryScanner] Folder update for relative path "${itemDir}" has no audio files`)
        continue
      }

      // Check if a library item is a subdirectory of this dir
      const childItem = await Database.libraryItemModel.findOne({
        attributes: ['id', 'path'],
        where: {
          path: {
            [sequelize.Op.startsWith]: fullPath + '/'
          }
        }
      })
      if (childItem) {
        Logger.warn(`[LibraryScanner] Files were modified in a parent directory of a library item "${childItem.path}" - ignoring`)
        itemGroupingResults[itemDir] = ScanResult.NOTHING
        continue
      }

      Logger.debug(`[LibraryScanner] Folder update group must be a new item "${itemDir}" in library "${library.name}"`)
      const isSingleMediaItem = itemDir === fileUpdateGroup[itemDir]
      const newLibraryItem = await LibraryItemScanner.scanPotentialNewLibraryItem(fullPath, library, folder, isSingleMediaItem)
      if (newLibraryItem) {
        const oldNewLibraryItem = Database.libraryItemModel.getOldLibraryItem(newLibraryItem)
        SocketAuthority.emitter('item_added', oldNewLibraryItem.toJSONExpanded())
      }
      itemGroupingResults[itemDir] = newLibraryItem ? ScanResult.ADDED : ScanResult.NOTHING
    }

    return itemGroupingResults
  }
}
module.exports = new LibraryScanner()