const stream = require('stream')
const Promise = require('bluebird')
const _ = require('lodash')

const matchquery = require('./match-query')

/* global WIKI */

module.exports = {
  async activate() {
    if (WIKI.config.db.type !== 'sqlite') {
      throw new WIKI.Error.SearchActivationFailed('Must use Sqlite3 database to activate this engine!')
    }
    const opts = await WIKI.models.knex.schema.raw('PRAGMA compile_options')
    if (!_.find(opts, { compile_options: 'ENABLE_FTS5' })) {
      throw new WIKI.Error.SearchActivationFailed('Sqlite3 must have FTS5 module!')
    }
  },
  async deactivate() {
    WIKI.logger.info(`(SEARCH/SQLITE3) Dropping index tables...`)
    await WIKI.models.knex.schema.dropTable('fts5_pages_vector')
    WIKI.logger.info(`(SEARCH/SQLITE3) Index tables have been dropped.`)
  },
  /**
   * INIT
   */
  async init() {
    WIKI.logger.info(`(SEARCH/SQLITE3) Initializing...`)

    // -> Create Search Index
    const indexExists = await WIKI.models.knex.schema.hasTable('fts5_pages_vector')
    if (!indexExists) {
      WIKI.logger.info(`(SEARCH/SQLITE3) Creating Pages Vector table...`)
      await WIKI.models.knex.raw('CREATE VIRTUAL TABLE fts5_pages_vector USING fts5(tokenize=unicode61, path, locale, title, description, content)')
    }
    WIKI.logger.info(`(SEARCH/SQLITE3) Initialization completed.`)
  },
  /**
   * QUERY
   *
   * @param {String} q Query
   * @param {Object} opts Additional options
   */
  async query(q, opts) {
    try {
      const qry = `
        SELECT rowid AS id, path, locale, title, description
        FROM "fts5_pages_vector"`
      const qryEnd = 'ORDER BY rank'
      let qryWhere = 'WHERE fts5_pages_vector MATCH ?'

      const o = matchquery.parse(q)
      if (o.negated) {
        qryWhere = 'WHERE rowid NOT IN (SELECT rowid FROM fts5_pages_vector WHERE fts5_pages_vector MATCH ?)'
      }

      const results = await WIKI.models.knex.raw(`
        ${qry}
        ${qryWhere}
        ${qryEnd}
       `, [o.str])
      return {
        results,
        suggestions: [],
        totalHits: results.length
      }
    } catch (err) {
      WIKI.logger.warn('Search Engine Error:')
      WIKI.logger.warn(err)
    }
  },
  /**
   * CREATE
   *
   * @param {Object} page Page to create
   */
  async created(page) {
    await WIKI.models.knex.raw(`
      INSERT INTO "fts5_pages_vector" (path, locale, title, description, content) VALUES (
        ?, ?, ?, ?, ?
      )
    `, [page.path, page.localeCode, page.title, page.description, page.safeContent])
  },
  /**
   * UPDATE
   *
   * @param {Object} page Page to update
   */
  async updated(page) {
    await WIKI.models.knex.raw(`
      UPDATE "fts5_pages_vector" SET
        title = ?,
        description = ?,
        content = ?
        WHERE path = ? AND locale = ?
    `, [page.title, page.description, page.safeContent, page.path, page.localeCode])
  },
  /**
   * DELETE
   *
   * @param {Object} page Page to delete
   */
  async deleted(page) {
    await WIKI.models.knex('fts5_pages_vector').where({
      locale: page.localeCode,
      path: page.path
    }).del().limit(1)
  },
  /**
   * RENAME
   *
   * @param {Object} page Page to rename
   */
  async renamed(page) {
    await WIKI.models.knex('fts5_pages_vector').where({
      locale: page.localeCode,
      path: page.path
    }).update({
      locale: page.destinationLocaleCode,
      path: page.destinationPath
    })
  },
  /**
   * REBUILD INDEX
   */
  async rebuild() {
    WIKI.logger.info(`(SEARCH/SQLITE3) Rebuilding Index...`)
    await WIKI.models.knex('fts5_pages_vector').truncate()

    await WIKI.models.knex.raw(`
      INSERT INTO "fts5_pages_vector" (path, locale, title, description, content)
      SELECT path, localeCode, title, description, content FROM pages`
    )
  }
}