'use strict'

const Promise = require('bluebird')
const path = require('path')
const fs = Promise.promisifyAll(require('fs-extra'))
const _ = require('lodash')
const crypto = require('crypto')
const qs = require('querystring')

/**
 * Entries Model
 */
module.exports = {

  _repoPath: 'repo',
  _cachePath: 'data/cache',

  /**
   * Initialize Entries model
   *
   * @return     {Object}  Entries model instance
   */
  init () {
    let self = this

    self._repoPath = path.resolve(ROOTPATH, appconfig.paths.repo)
    self._cachePath = path.resolve(ROOTPATH, appconfig.paths.data, 'cache')

    return self
  },

  /**
   * Check if a document already exists
   *
   * @param      {String}  entryPath  The entry path
   * @return     {Promise<Boolean>}  True if exists, false otherwise
   */
  exists (entryPath) {
    let self = this

    return self.fetchOriginal(entryPath, {
      parseMarkdown: false,
      parseMeta: false,
      parseTree: false,
      includeMarkdown: false,
      includeParentInfo: false,
      cache: false
    }).then(() => {
      return true
    }).catch((err) => { // eslint-disable-line handle-callback-err
      return false
    })
  },

  /**
   * Fetch a document from cache, otherwise the original
   *
   * @param      {String}           entryPath  The entry path
   * @return     {Promise<Object>}  Page Data
   */
  fetch (entryPath) {
    let self = this

    let cpath = self.getCachePath(entryPath)

    return fs.statAsync(cpath).then((st) => {
      return st.isFile()
    }).catch((err) => { // eslint-disable-line handle-callback-err
      return false
    }).then((isCache) => {
      if (isCache) {
        // Load from cache

        return fs.readFileAsync(cpath).then((contents) => {
          return JSON.parse(contents)
        }).catch((err) => { // eslint-disable-line handle-callback-err
          winston.error('Corrupted cache file. Deleting it...')
          fs.unlinkSync(cpath)
          return false
        })
      } else {
        // Load original

        return self.fetchOriginal(entryPath)
      }
    })
  },

  /**
   * Fetches the original document entry
   *
   * @param      {String}           entryPath  The entry path
   * @param      {Object}           options    The options
   * @return     {Promise<Object>}  Page data
   */
  fetchOriginal (entryPath, options) {
    let self = this

    let fpath = self.getFullPath(entryPath)
    let cpath = self.getCachePath(entryPath)

    options = _.defaults(options, {
      parseMarkdown: true,
      parseMeta: true,
      parseTree: true,
      includeMarkdown: false,
      includeParentInfo: true,
      cache: true
    })

    return fs.statAsync(fpath).then((st) => {
      if (st.isFile()) {
        return fs.readFileAsync(fpath, 'utf8').then((contents) => {
          // Parse contents

          let pageData = {
            markdown: (options.includeMarkdown) ? contents : '',
            html: (options.parseMarkdown) ? mark.parseContent(contents) : '',
            meta: (options.parseMeta) ? mark.parseMeta(contents) : {},
            tree: (options.parseTree) ? mark.parseTree(contents) : []
          }

          if (!pageData.meta.title) {
            pageData.meta.title = _.startCase(entryPath)
          }

          pageData.meta.path = entryPath

          // Get parent

          let parentPromise = (options.includeParentInfo) ? self.getParentInfo(entryPath).then((parentData) => {
            return (pageData.parent = parentData)
          }).catch((err) => { // eslint-disable-line handle-callback-err
            return (pageData.parent = false)
          }) : Promise.resolve(true)

          return parentPromise.then(() => {
            // Cache to disk

            if (options.cache) {
              let cacheData = JSON.stringify(_.pick(pageData, ['html', 'meta', 'tree', 'parent']), false, false, false)
              return fs.writeFileAsync(cpath, cacheData).catch((err) => {
                winston.error('Unable to write to cache! Performance may be affected.')
                winston.error(err)
                return true
              })
            } else {
              return true
            }
          }).return(pageData)
        })
      } else {
        return false
      }
    }).catch((err) => { // eslint-disable-line handle-callback-err
      throw new Promise.OperationalError('Entry ' + entryPath + ' does not exist!')
    })
  },

  /**
   * Parse raw url path and make it safe
   *
   * @param      {String}  urlPath  The url path
   * @return     {String}  Safe entry path
   */
  parsePath (urlPath) {
    urlPath = qs.unescape(urlPath)
    let wlist = new RegExp('(?!([^a-z0-9]|' + appdata.regex.cjk.source + '|[/-]))', 'g')

    urlPath = _.toLower(urlPath).replace(wlist, '')

    if (urlPath === '/') {
      urlPath = 'home'
    }

    let urlParts = _.filter(_.split(urlPath, '/'), (p) => { return !_.isEmpty(p) })

    return _.join(urlParts, '/')
  },

  /**
   * Gets the parent information.
   *
   * @param      {String}                 entryPath  The entry path
   * @return     {Promise<Object|False>}  The parent information.
   */
  getParentInfo (entryPath) {
    let self = this

    if (_.includes(entryPath, '/')) {
      let parentParts = _.initial(_.split(entryPath, '/'))
      let parentPath = _.join(parentParts, '/')
      let parentFile = _.last(parentParts)
      let fpath = self.getFullPath(parentPath)

      return fs.statAsync(fpath).then((st) => {
        if (st.isFile()) {
          return fs.readFileAsync(fpath, 'utf8').then((contents) => {
            let pageMeta = mark.parseMeta(contents)

            return {
              path: parentPath,
              title: (pageMeta.title) ? pageMeta.title : _.startCase(parentFile),
              subtitle: (pageMeta.subtitle) ? pageMeta.subtitle : false
            }
          })
        } else {
          return Promise.reject(new Error('Parent entry is not a valid file.'))
        }
      })
    } else {
      return Promise.reject(new Error('Parent entry is root.'))
    }
  },

  /**
   * Gets the full original path of a document.
   *
   * @param      {String}  entryPath  The entry path
   * @return     {String}  The full path.
   */
  getFullPath (entryPath) {
    return path.join(this._repoPath, entryPath + '.md')
  },

  /**
   * Gets the full cache path of a document.
   *
   * @param      {String}    entryPath  The entry path
   * @return     {String}  The full cache path.
   */
  getCachePath (entryPath) {
    return path.join(this._cachePath, crypto.createHash('md5').update(entryPath).digest('hex') + '.json')
  },

  /**
   * Gets the entry path from full path.
   *
   * @param      {String}  fullPath  The full path
   * @return     {String}  The entry path
   */
  getEntryPathFromFullPath (fullPath) {
    let absRepoPath = path.resolve(ROOTPATH, this._repoPath)
    return _.chain(fullPath).replace(absRepoPath, '').replace('.md', '').replace(new RegExp('\\\\', 'g'), '/').value()
  },

  /**
   * Update an existing document
   *
   * @param      {String}            entryPath  The entry path
   * @param      {String}            contents   The markdown-formatted contents
   * @return     {Promise<Boolean>}  True on success, false on failure
   */
  update (entryPath, contents) {
    let self = this
    let fpath = self.getFullPath(entryPath)

    return fs.statAsync(fpath).then((st) => {
      if (st.isFile()) {
        return self.makePersistent(entryPath, contents).then(() => {
          return self.updateCache(entryPath).then(entry => {
            return search.add(entry)
          })
        })
      } else {
        return Promise.reject(new Error('Entry does not exist!'))
      }
    }).catch((err) => {
      winston.error(err)
      return Promise.reject(new Error('Failed to save document.'))
    })
  },

  /**
   * Update local cache
   *
   * @param      {String}   entryPath  The entry path
   * @return     {Promise}  Promise of the operation
   */
  updateCache (entryPath) {
    let self = this

    return self.fetchOriginal(entryPath, {
      parseMarkdown: true,
      parseMeta: true,
      parseTree: true,
      includeMarkdown: true,
      includeParentInfo: true,
      cache: true
    }).catch(err => {
      winston.error(err)
      return err
    }).then((pageData) => {
      return {
        entryPath,
        meta: pageData.meta,
        parent: pageData.parent || {},
        text: mark.removeMarkdown(pageData.markdown)
      }
    }).catch(err => {
      winston.error(err)
      return err
    }).then((content) => {
      let parentPath = _.chain(content.entryPath).split('/').initial().join('/').value()
      return db.Entry.findOneAndUpdate({
        _id: content.entryPath
      }, {
        _id: content.entryPath,
        title: content.meta.title || content.entryPath,
        subtitle: content.meta.subtitle || '',
        parentTitle: content.parent.title || '',
        parentPath: parentPath,
        isDirectory: false,
        isEntry: true
      }, {
        new: true,
        upsert: true
      })
    }).then(result => {
      return self.updateTreeInfo().then(() => {
        return result
      })
    }).catch(err => {
      winston.error(err)
      return err
    })
  },

  /**
   * Update tree info for all directory and parent entries
   *
   * @returns {Promise<Boolean>} Promise of the operation
   */
  updateTreeInfo () {
    return db.Entry.distinct('parentPath', { parentPath: { $ne: '' } }).then(allPaths => {
      if (allPaths.length > 0) {
        return Promise.map(allPaths, pathItem => {
          let parentPath = _.chain(pathItem).split('/').initial().join('/').value()
          let guessedTitle = _.chain(pathItem).split('/').last().startCase().value()
          return db.Entry.update({ _id: pathItem }, {
            $set: { isDirectory: true },
            $setOnInsert: { isEntry: false, title: guessedTitle, parentPath }
          }, { upsert: true })
        })
      } else {
        return true
      }
    })
  },

  /**
   * Create a new document
   *
   * @param      {String}            entryPath  The entry path
   * @param      {String}            contents   The markdown-formatted contents
   * @return     {Promise<Boolean>}  True on success, false on failure
   */
  create (entryPath, contents) {
    let self = this

    return self.exists(entryPath).then((docExists) => {
      if (!docExists) {
        return self.makePersistent(entryPath, contents).then(() => {
          return self.updateCache(entryPath).then(entry => {
            return search.add(entry)
          })
        })
      } else {
        return Promise.reject(new Error('Entry already exists!'))
      }
    }).catch((err) => {
      winston.error(err)
      return Promise.reject(new Error('Something went wrong.'))
    })
  },

  /**
   * Makes a document persistent to disk and git repository
   *
   * @param      {String}            entryPath  The entry path
   * @param      {String}            contents   The markdown-formatted contents
   * @return     {Promise<Boolean>}  True on success, false on failure
   */
  makePersistent (entryPath, contents) {
    let self = this
    let fpath = self.getFullPath(entryPath)

    return fs.outputFileAsync(fpath, contents).then(() => {
      return git.commitDocument(entryPath)
    })
  },

  /**
   * Move a document
   *
   * @param      {String}   entryPath     The current entry path
   * @param      {String}   newEntryPath  The new entry path
   * @return     {Promise}  Promise of the operation
   */
  move (entryPath, newEntryPath) {
    let self = this

    if (_.isEmpty(entryPath) || entryPath === 'home') {
      return Promise.reject(new Error('Invalid path!'))
    }

    return git.moveDocument(entryPath, newEntryPath).then(() => {
      return git.commitDocument(newEntryPath).then(() => {
        // Delete old cache version

        let oldEntryCachePath = self.getCachePath(entryPath)
        fs.unlinkAsync(oldEntryCachePath).catch((err) => { return true }) // eslint-disable-line handle-callback-err

        // Delete old index entry

        search.delete(entryPath)

        // Create cache for new entry

        return self.updateCache(newEntryPath).then(entry => {
          return search.add(entry)
        })
      })
    })
  },

  /**
   * Generate a starter page content based on the entry path
   *
   * @param      {String}           entryPath  The entry path
   * @return     {Promise<String>}  Starter content
   */
  getStarter (entryPath) {
    let formattedTitle = _.startCase(_.last(_.split(entryPath, '/')))

    return fs.readFileAsync(path.join(ROOTPATH, 'client/content/create.md'), 'utf8').then((contents) => {
      return _.replace(contents, new RegExp('{TITLE}', 'g'), formattedTitle)
    })
  },

  /**
   * Get all entries from base path
   *
   * @param {String} basePath Path to list from
   * @return {Promise<Array>} List of entries
   */
  getFromTree (basePath) {
    return db.Entry.find({ parentPath: basePath }, 'title parentPath isDirectory isEntry').sort({ title: 'asc' })
  }
}