const Sequelize = require('sequelize')
const Database = require('../../Database')
const PlaybackSession = require('../../models/PlaybackSession')
const fsExtra = require('../../libs/fsExtra')

module.exports = {
  /**
   * 
   * @param {number} year YYYY
   * @returns {Promise<PlaybackSession[]>}
   */
  async getListeningSessionsForYear(year) {
    const sessions = await Database.playbackSessionModel.findAll({
      where: {
        createdAt: {
          [Sequelize.Op.gte]: `${year}-01-01`,
          [Sequelize.Op.lt]: `${year + 1}-01-01`
        }
      }
    })
    return sessions
  },

  /**
   * 
   * @param {number} year YYYY
   * @returns {Promise<number>}
   */
  async getNumAuthorsAddedForYear(year) {
    const count = await Database.authorModel.count({
      where: {
        createdAt: {
          [Sequelize.Op.gte]: `${year}-01-01`,
          [Sequelize.Op.lt]: `${year + 1}-01-01`
        }
      }
    })
    return count
  },

  /**
   * 
   * @param {number} year YYYY
   * @returns {Promise<import('../../models/Book')[]>}
   */
  async getBooksAddedForYear(year) {
    const books = await Database.bookModel.findAll({
      attributes: ['id', 'title', 'coverPath', 'duration', 'createdAt'],
      where: {
        createdAt: {
          [Sequelize.Op.gte]: `${year}-01-01`,
          [Sequelize.Op.lt]: `${year + 1}-01-01`
        }
      },
      include: {
        model: Database.libraryItemModel,
        attributes: ['id', 'mediaId', 'mediaType', 'size'],
        required: true
      },
      order: Database.sequelize.random()
    })
    return books
  },

  /**
   * 
   * @param {number} year YYYY
   */
  async getStatsForYear(year) {
    const booksAdded = await this.getBooksAddedForYear(year)

    let totalBooksAddedSize = 0
    let totalBooksAddedDuration = 0
    const booksWithCovers = []

    for (const book of booksAdded) {
      // Grab first 25 that have a cover
      if (book.coverPath && !booksWithCovers.includes(book.libraryItem.id) && booksWithCovers.length < 25 && await fsExtra.pathExists(book.coverPath)) {
        booksWithCovers.push(book.libraryItem.id)
      }
      if (book.duration && !isNaN(book.duration)) {
        totalBooksAddedDuration += book.duration
      }
      if (book.libraryItem.size && !isNaN(book.libraryItem.size)) {
        totalBooksAddedSize += book.libraryItem.size
      }
    }

    const numAuthorsAdded = await this.getNumAuthorsAddedForYear(year)

    const listeningSessions = await this.getListeningSessionsForYear(year)
    let totalListeningTime = 0
    for (const listeningSession of listeningSessions) {
      totalListeningTime += (listeningSession.timeListening || 0)
    }

    // Stats for total books, size and duration for everything added this year or earlier
    const [totalStatResultsRow] = await Database.sequelize.query(`SELECT SUM(li.size) AS totalSize, SUM(b.duration) AS totalDuration, COUNT(*) AS totalItems FROM libraryItems li, books b WHERE b.id = li.mediaId AND li.mediaType = 'book' AND li.createdAt < ":nextYear-01-01";`, {
      replacements: {
        nextYear: year + 1
      }
    })
    const totalStatResults = totalStatResultsRow[0]

    return {
      numListeningSessions: listeningSessions.length,
      numBooksAdded: booksAdded.length,
      numAuthorsAdded,
      totalBooksAddedSize,
      totalBooksAddedDuration: Math.round(totalBooksAddedDuration),
      booksAddedWithCovers: booksWithCovers,
      totalBooksSize: totalStatResults?.totalSize || 0,
      totalBooksDuration: totalStatResults?.totalDuration || 0,
      totalListeningTime,
      numBooks: totalStatResults?.totalItems || 0
    }
  }
}