index.js

'use strict'

/**
 * Lightweight web framework for your serverless applications
 * @author Jeremy Daly <jeremy@jeremydaly.com>
 * @version 0.10.1
 * @license MIT
 */

const REQUEST = require('./lib/request') // Resquest object
const RESPONSE = require('./lib/response') // Response object
const UTILS = require('./lib/utils') // Require utils library
const LOGGER = require('./lib/logger') // Require logger library
const prettyPrint = require('./lib/prettyPrint') // Pretty print for debugging
const { ConfigurationError } = require('./lib/errors') // Require custom errors

// Create the API class
module.exports = class LambdaAPI {

  // Create the constructor function.
  constructor(props) {

    // Set the version and base paths
    this._version = props && props.version ? props.version : 'v1'
    this._base = props && props.base && typeof props.base === 'string' ? props.base.trim() : ''
    this._callbackName = props && props.callback ? props.callback.trim() : 'callback'
    this._mimeTypes = props && props.mimeTypes && typeof props.mimeTypes === 'object' ? props.mimeTypes : {}
    this._serializer = props && props.serializer && typeof props.serializer === 'function' ? props.serializer : JSON.stringify

    // Set sampling info
    this._sampleCounts = {}

    // Init request counter
    this._requestCount = 0

    // Track init date/time
    this._initTime = Date.now()

    // Logging levels
    this._logLevels = {
      trace: 10,
      debug: 20,
      info: 30,
      warn: 40,
      error: 50,
      fatal: 60
    }

    // Configure logger
    this._logger = LOGGER.config(props && props.logger,this._logLevels)

    // Prefix stack w/ base
    this._prefix = this.parseRoute(this._base)

    // Stores route mappings
    this._routes = {}

    // Init callback
    this._cb

    // Error middleware stack
    this._errors = []

    // Store app packages and namespaces
    this._app = {}

    // Executed after the callback
    this._finally = () => {}

    // Global error status (used for response parsing errors)
    this._errorStatus = 500

    // Methods
    this._methods = ['get','post','put','patch','delete','options','head','any']

    // Convenience methods for METHOD
    this._methods.forEach(m => {
      this[m] = (...a) => this.METHOD(m.toUpperCase(),...a)
    })

  } // end constructor

  // METHOD: Adds method, middleware, and handlers to routes
  METHOD(method,...args) {

    // Extract path if provided, otherwise default to global wildcard
    let path = typeof args[0] === 'string' ? args.shift() : '/*'

    // Extract the execution stack
    let stack = args.map((fn,i) => {
      if (typeof fn === 'function' && (fn.length === 3 || (i === args.length-1)))
        return fn
      throw new ConfigurationError('Route-based middleware must have 3 parameters')
    })

    if (stack.length === 0)
      throw new ConfigurationError(`No handler or middleware specified for ${method} method on ${path} route.`)

    // Ensure method is an array
    let methods = Array.isArray(method) ? method : method.split(',')

    // Parse the path
    let parsedPath = this.parseRoute(path)

    // Split the route and clean it up
    let route = this._prefix.concat(parsedPath)

    // For root path support
    if (route.length === 0) { route.push('') }

    // Keep track of path variables
    let pathVars = {}

    // Make a local copy of routes
    let routes = this._routes

    // Create a local stack for inheritance
    let _stack = {}

    // Loop through the paths
    for (let i=0; i<route.length; i++) {

      let end = i === route.length-1

      // If this is a variable
      if (/^:(.*)$/.test(route[i])) {
        // Assign it to the pathVars (trim off the : at the beginning)
        pathVars[i] = [route[i].substr(1)]
        // Set the route to __VAR__
        route[i] = '__VAR__'
      } // end if variable

      // Add methods to routess
      methods.forEach(_method => {
        if (typeof _method === 'string') {

          if (routes['ROUTES']) {

            // Wildcard routes
            if (routes['ROUTES']['*']) {

              // Inherit middleware
              if (routes['ROUTES']['*']['MIDDLEWARE']) {
                _stack[method] = routes['ROUTES']['*']['MIDDLEWARE'].stack
                //_stack[method] ?
                // _stack[method].concat(routes['ROUTES']['*']['MIDDLEWARE'].stack)
                // : routes['ROUTES']['*']['MIDDLEWARE'].stack
              }

              // Inherit methods and ANY
              if (routes['ROUTES']['*']['METHODS'] && routes['ROUTES']['*']['METHODS']) {
                ['ANY',method].forEach(m => {
                  if (routes['ROUTES']['*']['METHODS'][m]) {
                    _stack[method] = _stack[method] ?
                      _stack[method].concat(routes['ROUTES']['*']['METHODS'][m].stack)
                      : routes['ROUTES']['*']['METHODS'][m].stack
                  }
                }) // end for
              }
            }

            // Matching routes
            if (routes['ROUTES'][route[i]]) {

              // Inherit middleware
              if (end && routes['ROUTES'][route[i]]['MIDDLEWARE']) {
                _stack[method] = _stack[method] ?
                  _stack[method].concat(routes['ROUTES'][route[i]]['MIDDLEWARE'].stack)
                  : routes['ROUTES'][route[i]]['MIDDLEWARE'].stack
              }

              // Inherit ANY methods (DISABLED)
              // if (end && routes['ROUTES'][route[i]]['METHODS'] && routes['ROUTES'][route[i]]['METHODS']['ANY']) {
              //   _stack[method] = _stack[method] ?
              //     _stack[method].concat(routes['ROUTES'][route[i]]['METHODS']['ANY'].stack)
              //       : routes['ROUTES'][route[i]]['METHODS']['ANY'].stack
              // }
            }
          }

          // Add the route to the global _routes
          this.setRoute(
            this._routes,
            _method.trim().toUpperCase(),
            (end ? {
              vars: pathVars,
              stack,
              inherited: _stack[method] ? _stack[method] : [],
              route: '/'+parsedPath.join('/'),
              path: '/'+this._prefix.concat(parsedPath).join('/')
            } : null),
            route.slice(0,i+1)
          )

        }
      }) // end methods loop

      routes = routes['ROUTES'][route[i]]

    } // end for loop

  } // end main METHOD function

  // RUN: This runs the routes
  async run(event,context,cb) {

    // Set the event, context and callback
    this._event = event || {}
    this._context = this.context = typeof context === 'object' ? context : {}
    this._cb = cb ? cb : undefined

    // Initalize request and response objects
    let request = new REQUEST(this)
    let response = new RESPONSE(this,request)

    try {

      // Parse the request
      await request.parseRequest()

      // Loop through the execution stack
      for (const fn of request._stack) {
        // Only run if in processing state
        if (response._state !== 'processing') break

        await new Promise(async r => {
          try {
            let rtn = await fn(request,response,() => { r() })
            if (rtn) response.send(rtn)
            if (response._state === 'done') r() // if state is done, resolve promise
          } catch(e) {
            await this.catchErrors(e,response)
            r() // resolve the promise
          }
        })

      } // end for

    } catch(e) {
      await this.catchErrors(e,response)
    }

    

    // Added: await for finally //
    await this._finally(request, response)

    // Return the final response
    return response._response

  } // end run function



  // Catch all async/sync errors
  async catchErrors(e,response,code,detail) {

    // Error messages should never be base64 encoded
    response._isBase64 = false

    // Strip the headers (TODO: find a better way to handle this)
    response._headers = {}

    let message

    // Set the status code
    response.status(code ? code : this._errorStatus)

    let info = {
      detail,
      statusCode: response._statusCode,
      coldStart: response._request.coldStart,
      stack: this._logger.stack && e.stack || undefined
    }

    if (e instanceof Error) {
      message = e.message
      this.log.fatal(message,info)
    } else {
      message = e
      this.log.error(message,info)
    }

    // If first time through, process error middleware
    if (response._state === 'processing') {

      // Flag error state (this will avoid infinite error loops)
      response._state = 'error'

      // Execute error middleware
      for (const err of this._errors) {
        if (response._state === 'done') break
        // Promisify error middleware
        await new Promise(r => {
          let rtn = err(e,response._request,response,() => { r() })
          if (rtn) response.send(rtn)
        })
      } // end for
    }

    // Throw standard error unless callback has already been executed
    if (response._state !== 'done') response.json({'error':message})

  } // end catch



  // Custom callback
  async _callback(err,res,response) {

    // Set done status
    response._state = 'done'

    // Execute finally
    // await this._finally(response._request,response)

    // Output logs
    response._request._logs.forEach(log => {
      console.log(JSON.stringify(this._logger.detail ? // eslint-disable-line no-console
        this._logger.format(log,response._request,response) : log))
    })

    // Generate access log
    if ((this._logger.access || response._request._logs.length > 0) && this._logger.access !== 'never') {
      let access = Object.assign(
        this._logger.log('access',undefined,response._request,response._request.context),
        { statusCode: res.statusCode, coldStart: response._request.coldStart, count: response._request.requestCount }
      )
      console.log(JSON.stringify(this._logger.format(access,response._request,response))) // eslint-disable-line no-console
    }

    // Reset global error code
    this._errorStatus = 500

    // Execute the primary callback
    typeof this._cb === 'function' && this._cb(err,res)

  } // end _callback



  // Middleware handler
  use(...args) {

    // Extract routes
    let routes = typeof args[0] === 'string' ? Array.of(args.shift()) : (Array.isArray(args[0]) ? args.shift() : ['/*'])

    // Init middleware stack
    let middleware = []

    // Add func args as middleware
    for (let arg in args) {
      if (typeof args[arg] === 'function') {
        if (args[arg].length === 3) {
          middleware.push(args[arg])
        } else if (args[arg].length === 4) {
          this._errors.push(args[arg])
        } else {
          throw new ConfigurationError('Middleware must have 3 or 4 parameters')
        }
      }
    }

    // Add middleware to path
    if (middleware.length > 0) {
      routes.forEach(route => {
        this.METHOD('__MW__',route,...middleware)
      })
    }

  } // end use


  // Finally handler
  finally(fn) {
    this._finally = fn
  }



  //-------------------------------------------------------------------------//
  // UTILITY FUNCTIONS
  //-------------------------------------------------------------------------//

  parseRoute(path) {
    return path.trim().replace(/^\/(.*?)(\/)*$/,'$1').split('/').filter(x => x.trim() !== '')
  }

  // Recursive function to create/merge routes object
  setRoute(obj, method, value, path) {
    if (path.length > 1) {
      let p = path.shift()
      if (p === '*') { throw new ConfigurationError('Wildcards can only be at the end of a route definition') }
      this.setRoute(obj['ROUTES'][p], method, value, path)
    } else {
      // Create routes and add path if they don't exist
      if (!obj['ROUTES']) obj['ROUTES'] = {}
      if (!obj['ROUTES'][path[0]]) obj['ROUTES'][path[0]] = {}

      // If a value exists in this iteration
      if (value !== null) {

        // If mounting middleware
        if (method === '__MW__') {
          // Merge stacks if middleware exists
          if (obj['ROUTES'][path[0]]['MIDDLEWARE']) {
            value.stack = obj['ROUTES'][path[0]]['MIDDLEWARE'].stack.concat(value.stack)
            value.vars = UTILS.mergeObjects(obj['ROUTES'][path[0]]['MIDDLEWARE'].vars,value.vars)
          }

          // Add/Update the middleware
          obj['ROUTES'][path[0]]['MIDDLEWARE'] = value

        // Else if mounting a regular route
        } else {

          // Create the methods section if it doesn't exist
          if (!obj['ROUTES'][path[0]]['METHODS']) obj['ROUTES'][path[0]]['METHODS'] = {}

          // Merge stacks if method exists
          if (obj['ROUTES'][path[0]]['METHODS'][method]) {
            value.stack = obj['ROUTES'][path[0]]['METHODS'][method].stack.concat(value.stack)
            value.vars = UTILS.mergeObjects(obj['ROUTES'][path[0]]['METHODS'][method].vars,value.vars)
          }

          // Add/Update the method
          obj['ROUTES'][path[0]]['METHODS'] = Object.assign(
            {},obj['ROUTES'][path[0]]['METHODS'],{ [method]: value }
          )

        }
      }

    }
  } // end setRoute

  // Load app packages
  app(packages) {

    // Check for supplied packages
    if (typeof packages === 'object') {
      // Loop through and set package namespaces
      for (let namespace in packages) {
        try {
          this._app[namespace] = packages[namespace]
        } catch(e) {
          console.error(e.message) // eslint-disable-line no-console
        }
      }
    } else if (arguments.length === 2 && typeof packages === 'string') {
      this._app[packages] = arguments[1]
    }// end if

    // Return a reference
    return this._app
  }


  // Register routes with options
  register(fn,opts) {

    let options = typeof opts === 'object' ? opts : {}

    // Extract Prefix
    let prefix = options.prefix && options.prefix.toString().trim() !== '' ?
      this.parseRoute(options.prefix) : []

    // Concat to existing prefix
    this._prefix = this._prefix.concat(prefix)

    // Execute the routing function
    fn(this,options)

    // Remove the last prefix
    this._prefix = this._prefix.slice(0,-(prefix.length))

  } // end register


  // prettyPrint debugger
  routes(format) {
    // Parse the routes
    let routes = UTILS.extractRoutes(this._routes)

    if (format) {
      console.log(prettyPrint(routes)) // eslint-disable-line no-console
    } else {
      return routes
    }
  }

} // end API class

// Export the API class as a new instance
// module.exports = opts => new API(opts)