Youch.js

'use strict'

/*
 * youch
 *
 * (c) Harminder Virk <virk@adonisjs.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

const fs = require('fs')
const path = require('path')
const cookie = require('cookie')
const Mustache = require('mustache')
const { fileURLToPath } = require('url')
const StackTracey = require('stacktracey')
const VIEW_PATH = './error.compiled.mustache'

const viewTemplate = fs.readFileSync(path.join(__dirname, VIEW_PATH), 'utf-8')

class Youch {
  constructor (error, request, options = {}) {
    this.options = options
    this.options.postLines = options.postLines || 5
    this.options.preLines = options.preLines || 5

    this._filterHeaders = ['cookie', 'connection']
    this.error = error
    this.request = request
    this.links = []
    this.showAllFrames = false
  }

  /**
   * Returns the source code for a given file. It unable to
   * read file it resolves the promise with a null.
   *
   * @param  {Object} frame
   * @return {Promise}
   */
  _getFrameSource (frame) {
    let path = frame
      .file
      .replace(/dist\/webpack:\//g, '') // unix
      .replace(/dist\\webpack:\\/g, '') // windows

    /**
       * We ignore the error when "fileURLToPath" is unable to parse
       * the path, since returning the frame source is an optional
       * thing
       */
    try {
      path = path.startsWith('file:') ? fileURLToPath(path) : path
    } catch {
    }

    return new Promise((resolve) => {
      fs.readFile(path, 'utf-8', (error, contents) => {
        if (error) {
          resolve(null)
          return
        }

        const lines = contents.split(/\r?\n/)
        const lineNumber = frame.line

        resolve({
          pre: lines.slice(
            Math.max(0, lineNumber - (this.options.preLines + 1)),
            lineNumber - 1
          ),
          line: lines[lineNumber - 1],
          post: lines.slice(lineNumber, lineNumber + this.options.postLines)
        })
      })
    })
  }

  /**
   * Parses the error stack and returns serialized
   * frames out of it.
   *
   * @return {Object}
   */
  _parseError () {
    return new Promise((resolve, reject) => {
      const stack = new StackTracey(this.error)
      Promise.all(
        stack.items.map(async (frame) => {
          if (this._isNode(frame)) {
            return Promise.resolve(frame)
          }
          return this._getFrameSource(frame).then((context) => {
            frame.context = context
            return frame
          })
        })
      )
        .then(resolve)
        .catch(reject)
    })
  }

  /**
   * Returns the context with code for a given
   * frame.
   *
   * @param  {Object}
   * @return {Object}
   */
  _getContext (frame) {
    if (!frame.context) {
      return {}
    }

    return {
      start: frame.line - (frame.context.pre || []).length,
      pre: frame.context.pre.join('\n'),
      line: frame.context.line,
      post: frame.context.post.join('\n')
    }
  }

  /**
   * Returns classes to be used inside HTML when
   * displaying the frames list.
   *
   * @param  {Object}
   * @param  {Number}
   *
   * @return {String}
   */
  _getDisplayClasses (frame, index) {
    const classes = []
    if (index === 0) {
      classes.push('active')
    }

    if (!frame.isApp) {
      classes.push('native-frame')
    }

    return classes.join(' ')
  }

  /**
   * Compiles the view using HTML
   *
   * @param  {String}
   * @param  {Object}
   *
   * @return {String}
   */
  _compileView (view, data) {
    return Mustache.render(view, data)
  }

  /**
   * Serializes frame to a usable error object.
   *
   * @param  {Object}
   *
   * @return {Object}
   */
  _serializeFrame (frame) {
    return {
      file: frame.fileRelative,
      filePath: frame.file.startsWith('file:')
        ? fileURLToPath(frame.file).replaceAll('\\', '/')
        : frame.file,
      line: frame.line,
      callee: frame.callee,
      calleeShort: frame.calleeShort,
      column: frame.column,
      context: this._getContext(frame),
      isModule: frame.thirdParty,
      isNative: frame.native,
      isApp: this._isApp(frame)
    }
  }

  /**
   * Returns whether frame belongs to nodejs
   * or not.
   *
   * @return {Boolean} [description]
   */
  _isNode (frame) {
    if (frame.native) {
      return true
    }

    const filename = frame.file || ''
    if (filename.startsWith('node:')) {
      return true
    }
    return false

    // return !path.isAbsolute(filename) && filename[0] !== '.'
  }

  /**
   * Returns whether code belongs to the app
   * or not.
   *
   * @return {Boolean} [description]
   */
  _isApp (frame) {
    return !this._isNode(frame) && !this._isNodeModule(frame)
  }

  /**
   * Returns whether frame belongs to a node_module or
   * not
   *
   * @method _isNodeModule
   *
   * @param  {Object}      frame
   *
   * @return {Boolean}
   *
   * @private
   */
  _isNodeModule (frame) {
    return (frame.file || '').indexOf('node_modules/') > -1
  }

  /**
   * Serializes stack to Mustache friendly object to
   * be used within the view. Optionally can pass
   * a callback to customize the frames output.
   *
   * @param  {Object}
   * @param  {Function} [callback]
   *
   * @return {Object}
   */
  _serializeData (stack, callback) {
    callback = callback || this._serializeFrame.bind(this)
    return {
      message: this.error.message,
      help: this.error.help,
      cause: this.error.cause,
      name: this.error.name,
      status: this.error.status,
      frames:
        stack instanceof Array === true
          ? stack.filter((frame) => frame.file).map(callback)
          : []
    }
  }

  /**
   * Returns a serialized object with important
   * information.
   *
   * @return {Object}
   */
  _serializeRequest () {
    const headers = []
    const cookies = []

    if (this.request.headers) {
      Object.keys(this.request.headers).forEach((key) => {
        if (this._filterHeaders.indexOf(key) > -1) {
          return
        }
        headers.push({
          key: key.toUpperCase(),
          value: this.request.headers[key]
        })
      })

      if (this.request.headers.cookie) {
        const parsedCookies = cookie.parse(this.request.headers.cookie || '')
        Object.keys(parsedCookies).forEach((key) => {
          cookies.push({ key, value: parsedCookies[key] })
        })
      }
    }

    return {
      url: this.request.url,
      httpVersion: this.request.httpVersion,
      method: this.request.method,
      connection: this.request.headers ? this.request.headers.connection : null,
      headers,
      cookies
    }
  }

  /**
   * Stores the link `callback` which
   * will be processed when rendering
   * the HTML view.
   *
   * @param {Function} callback
   *
   * @returns {Object}
   */
  addLink (callback) {
    if (typeof callback === 'function') {
      this.links.push(callback)
      return this
    }

    throw new Error('Pass a callback function to "addLink"')
  }

  /**
   * Toggle the state of showing all frames by default
   */
  toggleShowAllFrames () {
    this.showAllFrames = !this.showAllFrames
    return this
  }

  /**
   * Returns error stack as JSON.
   *
   * @return {Promise}
   */
  toJSON () {
    return new Promise((resolve, reject) => {
      this._parseError()
        .then((stack) => {
          resolve({
            error: this._serializeData(stack)
          })
        })
        .catch(reject)
    })
  }

  /**
   * Returns HTML representation of the error stack
   * by parsing the stack into frames and getting
   * important info out of it.
   *
   * @return {Promise}
   */
  toHTML (templateState) {
    return new Promise((resolve, reject) => {
      this._parseError()
        .then((stack) => {
          const data = this._serializeData(stack, (frame, index) => {
            const serializedFrame = this._serializeFrame(frame)
            serializedFrame.classes = this._getDisplayClasses(
              serializedFrame,
              index
            )
            return serializedFrame
          })

          if (templateState) {
            Object.assign(data, templateState)
          }

          if (this.request) {
            data.request = this._serializeRequest()
          }

          data.links = this.links.map((renderLink) => renderLink(data))
          data.loadFA = !!data.links.find((link) => link.includes('fa-'))
          data.showAllFrames = this.showAllFrames

          return resolve(this._compileView(viewTemplate, data))
        })
        .catch(reject)
    })
  }
}

module.exports = Youch