const OpenLibrary = require('../providers/OpenLibrary')
const GoogleBooks = require('../providers/GoogleBooks')
const Audible = require('../providers/Audible')
const iTunes = require('../providers/iTunes')
const Audnexus = require('../providers/Audnexus')
const FantLab = require('../providers/FantLab')
const AudiobookCovers = require('../providers/AudiobookCovers')
const Logger = require('../Logger')
const { levenshteinDistance } = require('../utils/index')

class BookFinder {
  constructor() {
    this.openLibrary = new OpenLibrary()
    this.googleBooks = new GoogleBooks()
    this.audible = new Audible()
    this.iTunesApi = new iTunes()
    this.audnexus = new Audnexus()
    this.fantLab = new FantLab()
    this.audiobookCovers = new AudiobookCovers()

    this.providers = ['google', 'itunes', 'openlibrary', 'fantlab', 'audiobookcovers', 'audible', 'audible.ca', 'audible.uk', 'audible.au', 'audible.fr', 'audible.de', 'audible.jp', 'audible.it', 'audible.in', 'audible.es']

    this.verbose = false
  }

  async findByISBN(isbn) {
    var book = await this.openLibrary.isbnLookup(isbn)
    if (book.errorCode) {
      Logger.error('Book not found')
    }
    return book
  }

  stripSubtitle(title) {
    if (title.includes(':')) {
      return title.split(':')[0].trim()
    } else if (title.includes(' - ')) {
      return title.split(' - ')[0].trim()
    }
    return title
  }

  replaceAccentedChars(str) {
    try {
      return str.normalize('NFD').replace(/[\u0300-\u036f]/g, "")
    } catch (error) {
      Logger.error('[BookFinder] str normalize error', error)
      return str
    }
  }

  cleanTitleForCompares(title) {
    if (!title) return ''
    // Remove subtitle if there (i.e. "Cool Book: Coolest Ever" becomes "Cool Book")
    let stripped = this.stripSubtitle(title)

    // Remove text in paranthesis (i.e. "Ender's Game (Ender's Saga)" becomes "Ender's Game")
    let cleaned = stripped.replace(/ *\([^)]*\) */g, "")

    // Remove single quotes (i.e. "Ender's Game" becomes "Enders Game")
    cleaned = cleaned.replace(/'/g, '')
    return this.replaceAccentedChars(cleaned).toLowerCase()
  }

  cleanAuthorForCompares(author) {
    if (!author) return ''
    let cleanAuthor = this.replaceAccentedChars(author).toLowerCase()
    // separate initials
    cleanAuthor = cleanAuthor.replace(/([a-z])\.([a-z])/g, '$1. $2')
    // remove middle initials
    cleanAuthor = cleanAuthor.replace(/(?<=\w\w)(\s+[a-z]\.?)+(?=\s+\w\w)/g, '')
    return cleanAuthor
  }

  filterSearchResults(books, title, author, maxTitleDistance, maxAuthorDistance) {
    var searchTitle = this.cleanTitleForCompares(title)
    var searchAuthor = this.cleanAuthorForCompares(author)
    return books.map(b => {
      b.cleanedTitle = this.cleanTitleForCompares(b.title)
      b.titleDistance = levenshteinDistance(b.cleanedTitle, title)

      // Total length of search (title or both title & author)
      b.totalPossibleDistance = b.title.length

      if (author) {
        if (!b.author) {
          b.authorDistance = author.length
        } else {
          b.totalPossibleDistance += b.author.length
          b.cleanedAuthor = this.cleanAuthorForCompares(b.author)

          var cleanedAuthorDistance = levenshteinDistance(b.cleanedAuthor, searchAuthor)
          var authorDistance = levenshteinDistance(b.author || '', author)

          // Use best distance
          b.authorDistance = Math.min(cleanedAuthorDistance, authorDistance)

          // Check book author contains searchAuthor
          if (searchAuthor.length > 4 && b.cleanedAuthor.includes(searchAuthor)) b.includesAuthor = searchAuthor
          else if (author.length > 4 && b.author.includes(author)) b.includesAuthor = author
        }
      }
      b.totalDistance = b.titleDistance + (b.authorDistance || 0)

      // Check book title contains the searchTitle
      if (searchTitle.length > 4 && b.cleanedTitle.includes(searchTitle)) b.includesTitle = searchTitle
      else if (title.length > 4 && b.title.includes(title)) b.includesTitle = title

      return b
    }).filter(b => {
      if (b.includesTitle) { // If search title was found in result title then skip over leven distance check
        if (this.verbose) Logger.debug(`Exact title was included in "${b.title}", Search: "${b.includesTitle}"`)
      } else if (b.titleDistance > maxTitleDistance) {
        if (this.verbose) Logger.debug(`Filtering out search result title distance = ${b.titleDistance}: "${b.cleanedTitle}"/"${searchTitle}"`)
        return false
      }

      if (author) {
        if (b.includesAuthor) { // If search author was found in result author then skip over leven distance check
          if (this.verbose) Logger.debug(`Exact author was included in "${b.author}", Search: "${b.includesAuthor}"`)
        } else if (b.authorDistance > maxAuthorDistance) {
          if (this.verbose) Logger.debug(`Filtering out search result "${b.author}", author distance = ${b.authorDistance}: "${b.author}"/"${author}"`)
          return false
        }
      }

      // If book total search length < 5 and was not exact match, then filter out
      if (b.totalPossibleDistance < 5 && b.totalDistance > 0) return false
      return true
    })
  }

  async getOpenLibResults(title, author, maxTitleDistance, maxAuthorDistance) {
    var books = await this.openLibrary.searchTitle(title)
    if (this.verbose) Logger.debug(`OpenLib Book Search Results: ${books.length || 0}`)
    if (books.errorCode) {
      Logger.error(`OpenLib Search Error ${books.errorCode}`)
      return []
    }
    var booksFiltered = this.filterSearchResults(books, title, author, maxTitleDistance, maxAuthorDistance)
    if (!booksFiltered.length && books.length) {
      if (this.verbose) Logger.debug(`Search has ${books.length} matches, but no close title matches`)
    }
    booksFiltered.sort((a, b) => {
      return a.totalDistance - b.totalDistance
    })

    return booksFiltered
  }

  async getGoogleBooksResults(title, author) {
    var books = await this.googleBooks.search(title, author)
    if (this.verbose) Logger.debug(`GoogleBooks Book Search Results: ${books.length || 0}`)
    if (books.errorCode) {
      Logger.error(`GoogleBooks Search Error ${books.errorCode}`)
      return []
    }
    // Google has good sort
    return books
  }

  async getFantLabResults(title, author) {
    var books = await this.fantLab.search(title, author)
    if (this.verbose) Logger.debug(`FantLab Book Search Results: ${books.length || 0}`)
    if (books.errorCode) {
      Logger.error(`FantLab Search Error ${books.errorCode}`)
      return []
    }

    return books
  }

  async getAudiobookCoversResults(search) {
    const covers = await this.audiobookCovers.search(search)
    if (this.verbose) Logger.debug(`AudiobookCovers Search Results: ${covers.length || 0}`)
    return covers || []
  }

  async getiTunesAudiobooksResults(title, author) {
    return this.iTunesApi.searchAudiobooks(title)
  }

  async getAudibleResults(title, author, asin, provider) {
    const region = provider.includes('.') ? provider.split('.').pop() : ''
    const books = await this.audible.search(title, author, asin, region)
    if (this.verbose) Logger.debug(`Audible Book Search Results: ${books.length || 0}`)
    if (!books) return []
    return books
  }

  static TitleCandidates = class {

    constructor(bookFinder, cleanAuthor) {
      this.bookFinder = bookFinder
      this.candidates = new Set()
      this.cleanAuthor = cleanAuthor
      this.priorities = {}
      this.positions = {}
    }

    add(title, position = 0) {
      // if title contains the author, remove it
      if (this.cleanAuthor) {
        const authorRe = new RegExp(`(^| | by |)${this.cleanAuthor}(?= |$)`, "g")
        title = this.bookFinder.cleanAuthorForCompares(title).replace(authorRe, '').trim()
      }

      const titleTransformers = [
        [/([,:;_]| by ).*/g, ''],                  // Remove subtitle
        [/(^| )\d+k(bps)?( |$)/, ' '],             // Remove bitrate
        [/ (2nd|3rd|\d+th)\s+ed(\.|ition)?/g, ''], // Remove edition
        [/(^| |\.)(m4b|m4a|mp3)( |$)/g, ''],       // Remove file-type
        [/ a novel.*$/g, ''],                      // Remove "a novel"
        [/^\d+ | \d+$/g, ''],                      // Remove preceding/trailing numbers
      ]

      // Main variant
      const cleanTitle = this.bookFinder.cleanTitleForCompares(title).trim()
      if (!cleanTitle) return
      this.candidates.add(cleanTitle)
      this.priorities[cleanTitle] = 0
      this.positions[cleanTitle] = position

      let candidate = cleanTitle

      for (const transformer of titleTransformers)
        candidate = candidate.replace(transformer[0], transformer[1]).trim()

      if (candidate != cleanTitle) {
        if (candidate) {
          this.candidates.add(candidate)
          this.priorities[candidate] = 0
          this.positions[candidate] = position
        }
        this.priorities[cleanTitle] = 1
      }
    }

    get size() {
      return this.candidates.size
    }

    getCandidates() {
      var candidates = [...this.candidates]
      candidates.sort((a, b) => {
        // Candidates that include the author are likely low quality
        const includesAuthorDiff = !b.includes(this.cleanAuthor) - !a.includes(this.cleanAuthor)
        if (includesAuthorDiff) return includesAuthorDiff
        // Candidates that include only digits are also likely low quality
        const onlyDigits = /^\d+$/
        const includesOnlyDigitsDiff = !onlyDigits.test(b) - !onlyDigits.test(a)
        if (includesOnlyDigitsDiff) return includesOnlyDigitsDiff
        // transformed candidates receive higher priority
        const priorityDiff = this.priorities[a] - this.priorities[b]
        if (priorityDiff) return priorityDiff
        // if same priorirty, prefer candidates that are closer to the beginning (e.g. titles before subtitles)
        const positionDiff = this.positions[a] - this.positions[b]
        if (positionDiff) return positionDiff
        // Start with longer candidaets, as they are likely more specific
        const lengthDiff = b.length - a.length
        if (lengthDiff) return lengthDiff
        return b.localeCompare(a)
      })
      Logger.debug(`[${this.constructor.name}] Found ${candidates.length} fuzzy title candidates`)
      Logger.debug(candidates)
      return candidates
    }

    delete(title) {
      return this.candidates.delete(title)
    }
  }

  static AuthorCandidates = class {
    constructor(bookFinder, cleanAuthor) {
      this.bookFinder = bookFinder
      this.candidates = new Set()
      this.cleanAuthor = cleanAuthor
      if (cleanAuthor) this.candidates.add(cleanAuthor)
    }

    validateAuthor(name, region = '', maxLevenshtein = 3) {
      return this.bookFinder.audnexus.authorASINsRequest(name, region).then((asins) => {
        for (const asin of asins) {
          let cleanName = this.bookFinder.cleanAuthorForCompares(asin.name)
          if (!cleanName) continue
          if (cleanName.includes(name)) return name
          if (name.includes(cleanName)) return cleanName
          if (levenshteinDistance(cleanName, name) <= maxLevenshtein) return cleanName
        }
        return ''
      })
    }

    add(author) {
      const authorTransformers = []

      // Main variant
      const cleanAuthor = this.bookFinder.cleanAuthorForCompares(author).trim()
      if (!cleanAuthor) return false
      this.candidates.add(cleanAuthor)

      let candidate = cleanAuthor

      for (const transformer of authorTransformers) {
        candidate = candidate.replace(transformer[0], transformer[1]).trim()
        if (candidate) {
          this.candidates.add(candidate)
        }
      }

      return true
    }

    get size() {
      return this.candidates.size
    }

    async getCandidates() {
      var filteredCandidates = []
      var promises = []
      for (const candidate of this.candidates) {
        promises.push(this.validateAuthor(candidate))
      }
      const results = [...new Set(await Promise.all(promises))]
      filteredCandidates = results.filter(author => author)
      // if no valid candidates were found, add back the original clean author
      if (!filteredCandidates.length && this.cleanAuthor) filteredCandidates.push(this.cleanAuthor)
      // always add an empty author candidate
      filteredCandidates.push('')
      Logger.debug(`[${this.constructor.name}] Found ${filteredCandidates.length} fuzzy author candidates`)
      Logger.debug(filteredCandidates)
      return filteredCandidates
    }

    delete(author) {
      return this.candidates.delete(author)
    }
  }


  /**
   * Search for books including fuzzy searches
   * 
   * @param {string} provider 
   * @param {string} title 
   * @param {string} author 
   * @param {string} isbn 
   * @param {string} asin 
   * @param {{titleDistance:number, authorDistance:number, maxFuzzySearches:number}} options 
   * @returns {Promise<Object[]>}
   */
  async search(provider, title, author, isbn, asin, options = {}) {
    let books = []
    const maxTitleDistance = !isNaN(options.titleDistance) ? Number(options.titleDistance) : 4
    const maxAuthorDistance = !isNaN(options.authorDistance) ? Number(options.authorDistance) : 4
    const maxFuzzySearches = !isNaN(options.maxFuzzySearches) ? Number(options.maxFuzzySearches) : 5
    let numFuzzySearches = 0

    if (!title)
      return books

    books = await this.runSearch(title, author, provider, asin, maxTitleDistance, maxAuthorDistance)

    if (!books.length && maxFuzzySearches > 0) {
      // normalize title and author
      title = title.trim().toLowerCase()
      author = author.trim().toLowerCase()

      const cleanAuthor = this.cleanAuthorForCompares(author)

      // Now run up to maxFuzzySearches fuzzy searches
      let authorCandidates = new BookFinder.AuthorCandidates(this, cleanAuthor)

      // remove underscores and parentheses with their contents, and replace with a separator
      const cleanTitle = title.replace(/\[.*?\]|\(.*?\)|{.*?}|_/g, " - ")
      // Split title into hypen-separated parts
      const titleParts = cleanTitle.split(/ - | -|- /)
      for (const titlePart of titleParts)
        authorCandidates.add(titlePart)
      authorCandidates = await authorCandidates.getCandidates()
      for (const authorCandidate of authorCandidates) {
        let titleCandidates = new BookFinder.TitleCandidates(this, authorCandidate)
        for (const [position, titlePart] of titleParts.entries())
          titleCandidates.add(titlePart, position)
        titleCandidates = titleCandidates.getCandidates()
        for (const titleCandidate of titleCandidates) {
          if (titleCandidate == title && authorCandidate == author) continue // We already tried this
          if (++numFuzzySearches > maxFuzzySearches) return books
          books = await this.runSearch(titleCandidate, authorCandidate, provider, asin, maxTitleDistance, maxAuthorDistance)
          if (books.length) return books
        }
      }
    }

    return books
  }

  /**
   * Search for books
   * 
   * @param {string} title 
   * @param {string} author 
   * @param {string} provider 
   * @param {string} asin only used for audible providers
   * @param {number} maxTitleDistance only used for openlibrary provider
   * @param {number} maxAuthorDistance only used for openlibrary provider
   * @returns {Promise<Object[]>}
   */
  async runSearch(title, author, provider, asin, maxTitleDistance, maxAuthorDistance) {
    Logger.debug(`Book Search: title: "${title}", author: "${author || ''}", provider: ${provider}`)

    let books = []

    if (provider === 'google') {
      books = await this.getGoogleBooksResults(title, author)
    } else if (provider.startsWith('audible')) {
      books = await this.getAudibleResults(title, author, asin, provider)
    } else if (provider === 'itunes') {
      books = await this.getiTunesAudiobooksResults(title, author)
    } else if (provider === 'openlibrary') {
      books = await this.getOpenLibResults(title, author, maxTitleDistance, maxAuthorDistance)
    } else if (provider === 'fantlab') {
      books = await this.getFantLabResults(title, author)
    } else if (provider === 'audiobookcovers') {
      books = await this.getAudiobookCoversResults(title)
    }
    else {
      books = await this.getGoogleBooksResults(title, author)
    }
    return books
  }

  async findCovers(provider, title, author, options = {}) {
    let searchResults = []

    if (provider === 'all') {
      for (const providerString of this.providers) {
        const providerResults = await this.search(providerString, title, author, options)
        Logger.debug(`[BookFinder] Found ${providerResults.length} covers from ${providerString}`)
        searchResults.push(...providerResults)
      }
    } else {
      searchResults = await this.search(provider, title, author, options)
    }
    Logger.debug(`[BookFinder] FindCovers search results: ${searchResults.length}`)

    const covers = []
    searchResults.forEach((result) => {
      if (result.covers && result.covers.length) {
        covers.push(...result.covers)
      }
      if (result.cover) {
        covers.push(result.cover)
      }
    })
    return [...(new Set(covers))]
  }

  findChapters(asin, region) {
    return this.audnexus.getChaptersByASIN(asin, region)
  }
}
module.exports = new BookFinder()