#' @include server-input-handlers.R

appsByToken <- Map$new()
appsNeedingFlush <- Map$new()

# Provide a character representation of the WS that can be used
# as a key in a Map.
wsToKey <- function(WS) {
  as.character(WS$socket)
}

.globals$clients <- function(req) NULL


clearClients <- function() {
  .globals$clients <- function(req) NULL
}


registerClient <- function(client) {
  .globals$clients <- append(.globals$clients, client)
}


.globals$resourcePaths <- list()
.globals$resources <- list()

.globals$showcaseDefault <- 0

.globals$showcaseOverride <- FALSE

#' Resource Publishing
#'
#' Add, remove, or list directory of static resources to Shiny's web server,
#' with the given path prefix. Primarily intended for package authors to make
#' supporting JavaScript/CSS files available to their components.
#'
#' Shiny provides two ways of serving static files (i.e., resources):
#'
#' 1. Static files under the `www/` directory are automatically made available
#' under a request path that begins with `/`.
#' 2. `addResourcePath()` makes static files in a `directoryPath` available
#' under a request path that begins with `prefix`.
#'
#' The second approach is primarily intended for package authors to make
#' supporting JavaScript/CSS files available to their components.
#'
#' Tools for managing static resources published by Shiny's web server:
#'  * `addResourcePath()` adds a directory of static resources.
#'  * `resourcePaths()` lists the currently active resource mappings.
#'  * `removeResourcePath()` removes a directory of static resources.
#'
#' @param prefix The URL prefix (without slashes). Valid characters are a-z,
#'   A-Z, 0-9, hyphen, period, and underscore. For example, a value of 'foo'
#'   means that any request paths that begin with '/foo' will be mapped to the
#'   given directory.
#' @param directoryPath The directory that contains the static resources to be
#'   served.
#'
#' @rdname resourcePaths
#' @seealso [singleton()]
#'
#' @examples
#' addResourcePath('datasets', system.file('data', package='datasets'))
#' resourcePaths()
#' removeResourcePath('datasets')
#' resourcePaths()
#'
#' # make sure all resources are removed
#' lapply(names(resourcePaths()), removeResourcePath)
#' @export
addResourcePath <- function(prefix, directoryPath) {
  if (length(prefix) != 1) stop("prefix must be of length 1")
  if (!grepl('^[a-z0-9\\-_][a-z0-9\\-_.]*$', prefix, ignore.case = TRUE, perl = TRUE)) {
    stop("addResourcePath called with invalid prefix; please see documentation")
  }
  if (prefix %in% c('shared')) {
    stop("addResourcePath called with the reserved prefix '", prefix, "'; ",
         "please use a different prefix")
  }
  normalizedPath <- tryCatch(normalizePath(directoryPath, mustWork = TRUE),
    error = function(e) {
      stop("Couldn't normalize path in `addResourcePath`, with arguments: ",
        "`prefix` = '", prefix, "'; `directoryPath` = '" , directoryPath, "'")
    }
  )

  # Often times overwriting a resource path is "what you want",
  # but sometimes it can lead to difficult to diagnose issues
  # (e.g. an implict dependency might set a resource path that
  # conflicts with what you, the app author, are trying to register)
  # Note that previous versions of shiny used to warn about this case,
  # but it was eventually removed since it caused confusion (#567).
  # It seems a good comprimise is to throw a more information message.
  if (prefix %in% names(.globals$resourcePaths)) {
    existingPath <- .globals$resourcePaths[[prefix]]$path
    if (normalizedPath != existingPath) {
      message(
        "The resource path '", prefix, "' used to point to ",
        existingPath, ", but it now points to ", normalizedPath, ". ",
        "If your app doesn't work as expected, you may want to ",
        "choose a different prefix name."
      )
    }
  }

  # If a shiny app is currently running, dynamically register this path with
  # the corresponding httpuv server object.
  if (!is.null(getShinyOption("server")))
  {
    getShinyOption("server")$setStaticPath(.list = stats::setNames(normalizedPath, prefix))
  }

  # .globals$resourcePaths and .globals$resources persist across runs of applications.
  .globals$resourcePaths[[prefix]] <- staticPath(normalizedPath)
  # This is necessary because resourcePaths is only for serving assets out of C++;
  # to support subapps, we also need assets to be served out of R, because those
  # URLs are rewritten by R code (i.e. routeHandler) before they can be matched to
  # a resource path.
  .globals$resources[[prefix]] <- list(
    directoryPath = normalizedPath,
    func = staticHandler(normalizedPath)
  )
}

#' @rdname resourcePaths
#' @export
resourcePaths <- function() {
  urls <- names(.globals$resourcePaths)
  paths <- vapply(.globals$resourcePaths, function(x) x$path, character(1))
  stats::setNames(paths, urls)
}

hasResourcePath <- function(prefix) {
  prefix %in% names(resourcePaths())
}

#' @rdname resourcePaths
#' @export
removeResourcePath <- function(prefix) {
  if (length(prefix) > 1) stop("`prefix` must be of length 1.")
  if (!hasResourcePath(prefix)) {
    warning("Resource ", prefix, " not found.")
    return(invisible(FALSE))
  }
  .globals$resourcePaths[[prefix]] <- NULL
  .globals$resources[[prefix]] <- NULL
  invisible(TRUE)
}



# This function handles any GET request with two or more path elements where the
# first path element matches a prefix that was previously added using
# addResourcePath().
#
# For example, if `addResourcePath("foo", "~/bar")` was called, then a GET
# request for /foo/one/two.html would rewrite the PATH_INFO as /one/two.html and
# send it to the resource path function for "foo". As of this writing, that
# function will always be a staticHandler, which serves up a file if it exists
# and NULL if it does not.
#
# Since Shiny 1.3.x, assets registered via addResourcePath should mostly be
# served out of httpuv's native static file serving features. However, in the
# specific case of subapps, the R code path must be used, because subapps insert
# a giant random ID into the beginning of the URL that must be stripped off by
# an R route handler (see addSubApp()).
resourcePathHandler <- function(req) {
  if (!identical(req$REQUEST_METHOD, 'GET'))
    return(NULL)

  # e.g. "/foo/one/two.html"
  path <- req$PATH_INFO

  match <- regexpr('^/([^/]+)/', path, perl=TRUE)
  if (match == -1)
    return(NULL)
  len <- attr(match, 'capture.length')
  # e.g. "foo"
  prefix <- substr(path, 2, 2 + len - 1)

  resInfo <- .globals$resources[[prefix]]
  if (is.null(resInfo))
    return(NULL)

  # e.g. "/one/two.html"
  suffix <- substr(path, 2 + len, nchar(path))

  # Create a new request that's a clone of the current request, but adjust
  # PATH_INFO and SCRIPT_NAME to reflect that we have already matched the first
  # path element (e.g. "/foo"). See routeHandler() for more info.
  subreq <- as.environment(as.list(req, all.names=TRUE))
  subreq$PATH_INFO <- suffix
  subreq$SCRIPT_NAME <- paste(subreq$SCRIPT_NAME, substr(path, 1, 2 + len), sep='')

  return(resInfo$func(subreq))
}

#' Define Server Functionality
#'
#' Defines the server-side logic of the Shiny application. This generally
#' involves creating functions that map user inputs to various kinds of output.
#' In older versions of Shiny, it was necessary to call `shinyServer()` in
#' the `server.R` file, but this is no longer required as of Shiny 0.10.
#' Now the `server.R` file may simply return the appropriate server
#' function (as the last expression in the code), without calling
#' `shinyServer()`.
#'
#' Call `shinyServer` from your application's `server.R`
#' file, passing in a "server function" that provides the server-side logic of
#' your application.
#'
#' The server function will be called when each client (web browser) first loads
#' the Shiny application's page. It must take an `input` and an
#' `output` parameter. Any return value will be ignored. It also takes an
#' optional `session` parameter, which is used when greater control is
#' needed.
#'
#' See the [tutorial](http://rstudio.github.com/shiny/tutorial/) for more
#' on how to write a server function.
#'
#' @param func The server function for this application. See the details section
#'   for more information.
#'
#' @examples
#' \dontrun{
#' # A very simple Shiny app that takes a message from the user
#' # and outputs an uppercase version of it.
#' shinyServer(function(input, output, session) {
#'   output$uppercase <- renderText({
#'     toupper(input$message)
#'   })
#' })
#'
#'
#' # It is also possible for a server.R file to simply return the function,
#' # without calling shinyServer().
#' # For example, the server.R file could contain just the following:
#' function(input, output, session) {
#'   output$uppercase <- renderText({
#'     toupper(input$message)
#'   })
#' }
#' }
#' @export
#' @keywords internal
shinyServer <- function(func) {
  .globals$server <- list(func)
  invisible(func)
}

decodeMessage <- function(data) {
  readInt <- function(pos) {
    packBits(rawToBits(data[pos:(pos+3)]), type='integer')
  }

  if (readInt(1) != 0x01020202L) {
    # Treat message as UTF-8
    charData <- rawToChar(data)
    Encoding(charData) <- 'UTF-8'
    return(safeFromJSON(charData, simplifyVector=FALSE))
  }

  i <- 5
  parts <- list()
  while (i <= length(data)) {
    length <- readInt(i)
    i <- i + 4
    if (length != 0)
      parts <- append(parts, list(data[i:(i+length-1)]))
    else
      parts <- append(parts, list(raw(0)))
    i <- i + length
  }

  mainMessage <- decodeMessage(parts[[1]])
  mainMessage$blobs <- parts[2:length(parts)]
  return(mainMessage)
}

createAppHandlers <- function(httpHandlers, serverFuncSource) {
  appvars <- new.env()
  appvars$server <- NULL

  sys.www.root <- system.file('www', package='shiny')

  # This value, if non-NULL, must be present on all HTTP and WebSocket
  # requests as the Shiny-Shared-Secret header or else access will be
  # denied (403 response for HTTP, and instant close for websocket).
  checkSharedSecret <- loadSharedSecret()

  appHandlers <- list(
    http = joinHandlers(c(
      sessionHandler,
      httpHandlers,
      sys.www.root,
      resourcePathHandler,
      reactLogHandler
    )),
    ws = function(ws) {
      if (!checkSharedSecret(ws$request$HTTP_SHINY_SHARED_SECRET)) {
        ws$close()
        return(TRUE)
      }

      if (!is.null(getOption("shiny.observer.error", NULL))) {
        warning(
          call. = FALSE,
          "options(shiny.observer.error) is no longer supported; please unset it!"
        )
        stopApp()
      }

      shinysession <- ShinySession$new(ws)
      appsByToken$set(shinysession$token, shinysession)
      shinysession$setShowcase(.globals$showcaseDefault)

      messageHandler <- function(binary, msg) {
        withReactiveDomain(shinysession, {
          # To ease transition from websockets-based code. Should remove once we're stable.
          if (is.character(msg))
            msg <- charToRaw(msg)

          traceOption <- getOption('shiny.trace', FALSE)
          if (isTRUE(traceOption) || traceOption == "recv") {
            if (binary)
              message("RECV ", '$$binary data$$')
            else
              message("RECV ", rawToChar(msg))
          }

          if (isEmptyMessage(msg))
            return()

          msg <- decodeMessage(msg)

          # Set up a restore context from .clientdata_url_search before
          # handling all the input values, because the restore context may be
          # used by an input handler (like the one for "shiny.file"). This
          # should only happen once, when the app starts.
          if (is.null(shinysession$restoreContext)) {
            bookmarkStore <- getShinyOption("bookmarkStore", default = "disable")
            if (bookmarkStore == "disable") {
              # If bookmarking is disabled, use empty context
              shinysession$restoreContext <- RestoreContext$new()
            } else {
              # If there's bookmarked state, save it on the session object
              shinysession$restoreContext <- RestoreContext$new(msg$data$.clientdata_url_search)
              shinysession$createBookmarkObservers()
            }
          }


          msg$data <- applyInputHandlers(msg$data)

          switch(
            msg$method,
            init = {

              serverFunc <- withReactiveDomain(NULL, serverFuncSource())
              if (!identicalFunctionBodies(serverFunc, appvars$server)) {
                appvars$server <- serverFunc
                if (!is.null(appvars$server))
                {
                  # Tag this function as the Shiny server function. A debugger may use this
                  # tag to give this function special treatment.
                  # It's very important that it's appvars$server itself and NOT a copy that
                  # is invoked, otherwise new breakpoints won't be picked up.
                  attr(appvars$server, "shinyServerFunction") <- TRUE
                  registerDebugHook("server", appvars, "Server Function")
                }
              }

              # Check for switching into/out of showcase mode
              if (.globals$showcaseOverride &&
                  exists(".clientdata_url_search", where = msg$data)) {
                mode <- showcaseModeOfQuerystring(msg$data$.clientdata_url_search)
                if (!is.null(mode))
                  shinysession$setShowcase(mode)
              }

              # In shinysession$createBookmarkObservers() above, observers may be
              # created, which puts the shiny session in busyCount > 0 state. That
              # prevents the manageInputs here from taking immediate effect, by
              # default. The manageInputs here needs to take effect though, because
              # otherwise the bookmark observers won't find the clientData they are
              # looking for. So use `now = TRUE` to force the changes to be
              # immediate.
              #
              # FIXME: break createBookmarkObservers into two separate steps, one
              # before and one after manageInputs, and put the observer creation
              # in the latter. Then add an assertion that busyCount == 0L when
              # this manageInputs is called.
              shinysession$manageInputs(msg$data, now = TRUE)

              # The client tells us what singletons were rendered into
              # the initial page
              if (!is.null(msg$data$.clientdata_singletons)) {
                shinysession$singletons <- strsplit(
                  msg$data$.clientdata_singletons, ',')[[1]]
              }

              local({
                args <- argsForServerFunc(serverFunc, shinysession)

                withReactiveDomain(shinysession, {
                  do.call(
                    # No corresponding ..stacktraceoff; the server func is pure
                    # user code
                    wrapFunctionLabel(appvars$server, "server",
                      ..stacktraceon = TRUE
                    ),
                    args
                  )
                })
              })
            },
            update = {
              shinysession$manageInputs(msg$data)
            },
            shinysession$dispatch(msg)
          )
          # The HTTP_GUID, if it exists, is for Shiny Server reporting purposes
          shinysession$startTiming(ws$request$HTTP_GUID)
          shinysession$requestFlush()

          # Make httpuv return control to Shiny quickly, instead of waiting
          # for the usual timeout
          httpuv::interrupt()
        })
      }
      ws$onMessage(function(binary, msg) {
        # If unhandled errors occur, make sure they get properly logged
        withLogErrors(messageHandler(binary, msg))
      })

      ws$onClose(function() {
        shinysession$wsClosed()
        appsByToken$remove(shinysession$token)
        appsNeedingFlush$remove(shinysession$token)
      })

      return(TRUE)
    }
  )
  return(appHandlers)
}

# Determine what arguments should be passed to this serverFunc. All server funcs
# must take input and output, but clientData (obsolete) and session are
# optional.
argsForServerFunc <- function(serverFunc, session) {
  args <- list(input = session$input, output = .createOutputWriter(session))

  paramNames <- names(formals(serverFunc))

  # The clientData and session arguments are optional; check if
  # each exists

  if ("clientData" %in% paramNames)
    args$clientData <- session$clientData

  if ("session" %in% paramNames)
    args$session <- session

  args
}

getEffectiveBody <- function(func) {
  if (is.null(func))
    NULL
  else if (isS4(func) && class(func) == "functionWithTrace")
    body(func@original)
  else
    body(func)
}

identicalFunctionBodies <- function(a, b) {
  identical(getEffectiveBody(a), getEffectiveBody(b))
}

handlerManager <- HandlerManager$new()

addSubApp <- function(appObj, autoRemove = TRUE) {
  path <- createUniqueId(16, "/app")
  appHandlers <- createAppHandlers(appObj$httpHandler, appObj$serverFuncSource)

  # remove the leading / from the path so a relative path is returned
  # (needed for the case where the root URL for the Shiny app isn't /, such
  # as portmapped URLs)
  finalPath <- paste(
    substr(path, 2, nchar(path)),
    "/?w=", workerId(),
    "&__subapp__=1",
    sep="")
  handlerManager$addHandler(routeHandler(path, appHandlers$http), finalPath)
  handlerManager$addWSHandler(routeWSHandler(path, appHandlers$ws), finalPath)

  if (autoRemove) {
    # If a session is currently active, remove this subapp automatically when
    # the current session ends
    onReactiveDomainEnded(getDefaultReactiveDomain(), function() {
      removeSubApp(finalPath)
    })
  }

  return(finalPath)
}

removeSubApp <- function(path) {
  handlerManager$removeHandler(path)
  handlerManager$removeWSHandler(path)
}

startApp <- function(appObj, port, host, quiet) {
  appHandlers <- createAppHandlers(appObj$httpHandler, appObj$serverFuncSource)
  handlerManager$addHandler(appHandlers$http, "/", tail = TRUE)
  handlerManager$addWSHandler(appHandlers$ws, "/", tail = TRUE)

  httpuvApp <- handlerManager$createHttpuvApp()
  httpuvApp$staticPaths <- c(
    appObj$staticPaths,
    list(
      # Always handle /session URLs dynamically, even if / is a static path.
      "session" = excludeStaticPath(),
      "shared" = system.file(package = "shiny", "www", "shared")
    ),
    .globals$resourcePaths
  )

  # throw an informative warning if a subdirectory of the
  # app's www dir conflicts with another resource prefix
  wwwDir <- httpuvApp$staticPaths[["/"]]$path
  if (length(wwwDir)) {
    # although httpuv allows for resource prefixes like 'foo/bar',
    # we won't worry about conflicts in sub-sub directories since
    # addResourcePath() currently doesn't allow it
    wwwSubDirs <- list.dirs(wwwDir, recursive = FALSE, full.names = FALSE)
    resourceConflicts <- intersect(wwwSubDirs, names(httpuvApp$staticPaths))
    if (length(resourceConflicts)) {
      warning(
        "Found subdirectories of your app's www/ directory that ",
        "conflict with other resource URL prefixes.",
        "Consider renaming these directories: '",
        paste0("www/", resourceConflicts, collapse = "', '"), "'",
        call. = FALSE
      )
    }
  }

  # check for conflicts in each pairwise combinations of resource mappings
  checkResourceConflict <- function(paths) {
    if (length(paths) < 2) return(NULL)
    # ensure paths is a named character vector: c(resource_path = local_path)
    paths <- vapply(paths, function(x) if (inherits(x, "staticPath")) x$path else x, character(1))
    # get all possible pairwise combinations of paths
    pair_indices <- utils::combn(length(paths), 2, simplify = FALSE)
    lapply(pair_indices, function(x) {
      p1 <- paths[x[1]]
      p2 <- paths[x[2]]
      if (identical(names(p1), names(p2)) && (p1 != p2)) {
        warning(
          "Found multiple local file paths pointing the same resource prefix: ", names(p1), ". ",
          "If you run into resource-related issues (e.g. 404 requests), consider ",
          "using `addResourcePath()` and/or `removeResourcePath()` to manage resource mappings.",
          call. = FALSE
        )
      }
    })
  }
  checkResourceConflict(httpuvApp$staticPaths)

  httpuvApp$staticPathOptions <- httpuv::staticPathOptions(
    html_charset = "utf-8",
    headers = list("X-UA-Compatible" = "IE=edge,chrome=1"),
    validation =
      if (!is.null(getOption("shiny.sharedSecret"))) {
        sprintf('"Shiny-Shared-Secret" == "%s"', getOption("shiny.sharedSecret"))
      } else {
        character(0)
      }
  )

  if (is.numeric(port) || is.integer(port)) {
    if (!quiet) {
      hostString <- host
      if (httpuv::ipFamily(host) == 6L)
        hostString <- paste0("[", hostString, "]")
      message('\n', 'Listening on http://', hostString, ':', port)
    }
    return(startServer(host, port, httpuvApp))
  } else if (is.character(port)) {
    if (!quiet) {
      message('\n', 'Listening on domain socket ', port)
    }
    mask <- attr(port, 'mask')
    if (is.null(mask)) {
      stop("`port` is not a valid domain socket (missing `mask` attribute). ",
           "Note that if you're using the default `host` + `port` ",
           "configuration (and not domain sockets), then `port` must ",
           "be numeric, not a string.")
    }
    return(startPipeServer(port, mask, httpuvApp))
  }
}

# Run an application that was created by \code{\link{startApp}}. This
# function should normally be called in a \code{while(TRUE)} loop.
serviceApp <- function() {
  timerCallbacks$executeElapsed()

  flushReact()
  flushPendingSessions()

  # If this R session is interactive, then call service() with a short timeout
  # to keep the session responsive to user input
  maxTimeout <- ifelse(interactive(), 100, 1000)

  timeout <- max(1, min(maxTimeout, timerCallbacks$timeToNextEvent(), later::next_op_secs()))
  service(timeout)

  flushReact()
  flushPendingSessions()
}

.shinyServerMinVersion <- '0.3.4'

# Global flag that's TRUE whenever we're inside of the scope of a call to runApp
.globals$running <- FALSE

#' Check whether a Shiny application is running
#'
#' This function tests whether a Shiny application is currently running.
#'
#' @return `TRUE` if a Shiny application is currently running. Otherwise,
#'   `FALSE`.
#' @export
isRunning <- function() {
  .globals$running
}

#' Run Shiny Application
#'
#' Runs a Shiny application. This function normally does not return; interrupt R
#' to stop the application (usually by pressing Ctrl+C or Esc).
#'
#' The host parameter was introduced in Shiny 0.9.0. Its default value of
#' `"127.0.0.1"` means that, contrary to previous versions of Shiny, only
#' the current machine can access locally hosted Shiny apps. To allow other
#' clients to connect, use the value `"0.0.0.0"` instead (which was the
#' value that was hard-coded into Shiny in 0.8.0 and earlier).
#'
#' @param appDir The application to run. Should be one of the following:
#'   \itemize{
#'   \item A directory containing `server.R`, plus, either `ui.R` or
#'    a `www` directory that contains the file `index.html`.
#'   \item A directory containing `app.R`.
#'   \item An `.R` file containing a Shiny application, ending with an
#'    expression that produces a Shiny app object.
#'   \item A list with `ui` and `server` components.
#'   \item A Shiny app object created by [shinyApp()].
#'   }
#' @param port The TCP port that the application should listen on. If the
#'   `port` is not specified, and the `shiny.port` option is set (with
#'   `options(shiny.port = XX)`), then that port will be used. Otherwise,
#'   use a random port.
#' @param launch.browser If true, the system's default web browser will be
#'   launched automatically after the app is started. Defaults to true in
#'   interactive sessions only. This value of this parameter can also be a
#'   function to call with the application's URL.
#' @param host The IPv4 address that the application should listen on. Defaults
#'   to the `shiny.host` option, if set, or `"127.0.0.1"` if not. See
#'   Details.
#' @param workerId Can generally be ignored. Exists to help some editions of
#'   Shiny Server Pro route requests to the correct process.
#' @param quiet Should Shiny status messages be shown? Defaults to FALSE.
#' @param display.mode The mode in which to display the application. If set to
#'   the value `"showcase"`, shows application code and metadata from a
#'   `DESCRIPTION` file in the application directory alongside the
#'   application. If set to `"normal"`, displays the application normally.
#'   Defaults to `"auto"`, which displays the application in the mode given
#'   in its `DESCRIPTION` file, if any.
#' @param test.mode Should the application be launched in test mode? This is
#'   only used for recording or running automated tests. Defaults to the
#'   `shiny.testmode` option, or FALSE if the option is not set.
#'
#' @examples
#' \dontrun{
#' # Start app in the current working directory
#' runApp()
#'
#' # Start app in a subdirectory called myapp
#' runApp("myapp")
#' }
#'
#' ## Only run this example in interactive R sessions
#' if (interactive()) {
#'   options(device.ask.default = FALSE)
#'
#'   # Apps can be run without a server.r and ui.r file
#'   runApp(list(
#'     ui = bootstrapPage(
#'       numericInput('n', 'Number of obs', 100),
#'       plotOutput('plot')
#'     ),
#'     server = function(input, output) {
#'       output$plot <- renderPlot({ hist(runif(input$n)) })
#'     }
#'   ))
#'
#'
#'   # Running a Shiny app object
#'   app <- shinyApp(
#'     ui = bootstrapPage(
#'       numericInput('n', 'Number of obs', 100),
#'       plotOutput('plot')
#'     ),
#'     server = function(input, output) {
#'       output$plot <- renderPlot({ hist(runif(input$n)) })
#'     }
#'   )
#'   runApp(app)
#' }
#' @export
runApp <- function(appDir=getwd(),
                   port=getOption('shiny.port'),
                   launch.browser=getOption('shiny.launch.browser',
                                            interactive()),
                   host=getOption('shiny.host', '127.0.0.1'),
                   workerId="", quiet=FALSE,
                   display.mode=c("auto", "normal", "showcase"),
                   test.mode=getOption('shiny.testmode', FALSE)) {
  on.exit({
    handlerManager$clear()
  }, add = TRUE)

  if (.globals$running) {
    stop("Can't call `runApp()` from within `runApp()`. If your ",
         "application code contains `runApp()`, please remove it.")
  }
  .globals$running <- TRUE
  on.exit({
    .globals$running <- FALSE
  }, add = TRUE)

  # Enable per-app Shiny options, for shinyOptions() and getShinyOption().
  oldOptionSet <- .globals$options
  on.exit({
    .globals$options <- oldOptionSet
  },add = TRUE)

  # A unique identifier associated with this run of this application. It is
  # shared across sessions.
  shinyOptions(appToken = createUniqueId(8))

  # Make warnings print immediately
  # Set pool.scheduler to support pool package
  ops <- options(
    # Raise warn level to 1, but don't lower it
    warn = max(1, getOption("warn", default = 1)),
    pool.scheduler = scheduleTask
  )
  on.exit(options(ops), add = TRUE)

  # Set up default cache for app.
  if (is.null(getShinyOption("cache"))) {
    shinyOptions(cache = MemoryCache$new())
  }

  appParts <- as.shiny.appobj(appDir)

  # The lines below set some of the app's running options, which
  # can be:
  #   - left unspeficied (in which case the arguments' default
  #     values from `runApp` kick in);
  #   - passed through `shinyApp`
  #   - passed through `runApp` (this function)
  #   - passed through both `shinyApp` and `runApp` (the latter
  #     takes precedence)
  #
  # Matrix of possibilities:
  # | IN shinyApp | IN runApp | result       | check                                                                                                                                  |
  # |-------------|-----------|--------------|----------------------------------------------------------------------------------------------------------------------------------------|
  # | no          | no        | use defaults | exhaust all possibilities: if it's missing (runApp does not specify); THEN if it's not in shinyApp appParts$options; THEN use defaults |
  # | yes         | no        | use shinyApp | if it's missing (runApp does not specify); THEN if it's in shinyApp appParts$options; THEN use shinyApp                                |
  # | no          | yes       | use runApp   | if it's not missing (runApp specifies), use those                                                                                      |
  # | yes         | yes       | use runApp   | if it's not missing (runApp specifies), use those                                                                                      |
  #
  # I tried to make this as compact and intuitive as possible,
  # given that there are four distinct possibilities to check
  appOps <- appParts$options
  findVal <- function(arg, default) {
    if (arg %in% names(appOps)) appOps[[arg]] else default
  }

  if (missing(port))
    port <- findVal("port", port)
  if (missing(launch.browser))
    launch.browser <- findVal("launch.browser", launch.browser)
  if (missing(host))
    host <- findVal("host", host)
  if (missing(quiet))
    quiet <- findVal("quiet", quiet)
  if (missing(display.mode))
    display.mode <- findVal("display.mode", display.mode)
  if (missing(test.mode))
    test.mode <- findVal("test.mode", test.mode)

  if (is.null(host) || is.na(host)) host <- '0.0.0.0'

  workerId(workerId)

  if (inShinyServer()) {
    # If SHINY_PORT is set, we're running under Shiny Server. Check the version
    # to make sure it is compatible. Older versions of Shiny Server don't set
    # SHINY_SERVER_VERSION, those will return "" which is considered less than
    # any valid version.
    ver <- Sys.getenv('SHINY_SERVER_VERSION')
    if (utils::compareVersion(ver, .shinyServerMinVersion) < 0) {
      warning('Shiny Server v', .shinyServerMinVersion,
              ' or later is required; please upgrade!')
    }
  }

  # Showcase mode is disabled by default; it must be explicitly enabled in
  # either the DESCRIPTION file for directory-based apps, or via
  # the display.mode parameter. The latter takes precedence.
  setShowcaseDefault(0)

  .globals$testMode <- test.mode
  if (test.mode) {
    message("Running application in test mode.")
  }

  # If appDir specifies a path, and display mode is specified in the
  # DESCRIPTION file at that path, apply it here.
  if (is.character(appDir)) {
    # if appDir specifies a .R file (single-file Shiny app), look for the
    # DESCRIPTION in the parent directory
    desc <- file.path.ci(
      if (tolower(tools::file_ext(appDir)) == "r")
        dirname(appDir)
      else
        appDir, "DESCRIPTION")
    if (file.exists(desc)) {
      con <- file(desc, encoding = checkEncoding(desc))
      on.exit(close(con), add = TRUE)
      settings <- read.dcf(con)
      if ("DisplayMode" %in% colnames(settings)) {
        mode <- settings[1, "DisplayMode"]
        if (mode == "Showcase") {
          setShowcaseDefault(1)
          if ("IncludeWWW" %in% colnames(settings)) {
            .globals$IncludeWWW <- as.logical(settings[1, "IncludeWWW"])
            if (is.na(.globals$IncludeWWW)) {
              stop("In your Description file, `IncludeWWW` ",
                   "must be set to `True` (default) or `False`")
            }
          } else {
            .globals$IncludeWWW <- TRUE
          }
        }
      }
    }
  }

  ## default is to show the .js, .css and .html files in the www directory
  ## (if not in showcase mode, this variable will simply be ignored)
  if (is.null(.globals$IncludeWWW) || is.na(.globals$IncludeWWW)) {
    .globals$IncludeWWW <- TRUE
  }

  # If display mode is specified as an argument, apply it (overriding the
  # value specified in DESCRIPTION, if any).
  display.mode <- match.arg(display.mode)
  if (display.mode == "normal") {
    setShowcaseDefault(0)
  }
  else if (display.mode == "showcase") {
    setShowcaseDefault(1)
  }

  require(shiny)

  # determine port if we need to
  if (is.null(port)) {

    # Try up to 20 random ports. If we don't succeed just plow ahead
    # with the final value we tried, and let the "real" startServer
    # somewhere down the line fail and throw the error to the user.
    #
    # If we (think we) succeed, save the value as .globals$lastPort,
    # and try that first next time the user wants a random port.

    for (i in 1:20) {
      if (!is.null(.globals$lastPort)) {
        port <- .globals$lastPort
        .globals$lastPort <- NULL
      }
      else {
        # Try up to 20 random ports
        while (TRUE) {
          port <- p_randomInt(3000, 8000)
          # Reject ports in this range that are considered unsafe by Chrome
          # http://superuser.com/questions/188058/which-ports-are-considered-unsafe-on-chrome
          # https://github.com/rstudio/shiny/issues/1784
          if (!port %in% c(3659, 4045, 6000, 6665:6669, 6697)) {
            break
          }
        }
      }

      # Test port to see if we can use it
      tmp <- try(startServer(host, port, list()), silent=TRUE)
      if (!inherits(tmp, 'try-error')) {
        stopServer(tmp)
        .globals$lastPort <- port
        break
      }
    }
  }

  # Invoke user-defined onStop callbacks, before the application's internal
  # onStop callbacks.
  on.exit({
    .globals$onStopCallbacks$invoke()
    .globals$onStopCallbacks <- Callbacks$new()
  }, add = TRUE)

  # Extract appOptions (which is a list) and store them as shinyOptions, for
  # this app. (This is the only place we have to store settings that are
  # accessible both the UI and server portion of the app.)
  unconsumeAppOptions(appParts$appOptions)

  # Set up the onStop before we call onStart, so that it gets called even if an
  # error happens in onStart.
  if (!is.null(appParts$onStop))
    on.exit(appParts$onStop(), add = TRUE)
  if (!is.null(appParts$onStart))
    appParts$onStart()

  server <- startApp(appParts, port, host, quiet)

  # Make the httpuv server object accessible. Needed for calling
  # addResourcePath while app is running.
  shinyOptions(server = server)

  on.exit({
    stopServer(server)
  }, add = TRUE)

  if (!is.character(port)) {
    browseHost <- host
    if (identical(host, "0.0.0.0")) {
      # http://0.0.0.0/ doesn't work on QtWebKit (i.e. RStudio viewer)
      browseHost <- "127.0.0.1"
    } else if (identical(host, "::")) {
      browseHost <- "::1"
    }

    if (httpuv::ipFamily(browseHost) == 6L) {
      browseHost <- paste0("[", browseHost, "]")
    }

    appUrl <- paste("http://", browseHost, ":", port, sep="")
    if (is.function(launch.browser))
      launch.browser(appUrl)
    else if (launch.browser)
      utils::browseURL(appUrl)
  } else {
    appUrl <- NULL
  }

  # call application hooks
  callAppHook("onAppStart", appUrl)
  on.exit({
    callAppHook("onAppStop", appUrl)
  }, add = TRUE)

  .globals$reterror <- NULL
  .globals$retval <- NULL
  .globals$stopped <- FALSE
  # Top-level ..stacktraceoff..; matches with ..stacktraceon in observe(),
  # reactive(), Callbacks$invoke(), and others
  ..stacktraceoff..(
    captureStackTraces({
      while (!.globals$stopped) {
        ..stacktracefloor..(serviceApp())
        Sys.sleep(0.001)
      }
    })
  )

  if (isTRUE(.globals$reterror)) {
    stop(.globals$retval)
  }
  else if (.globals$retval$visible)
    .globals$retval$value
  else
    invisible(.globals$retval$value)
}

#' Stop the currently running Shiny app
#'
#' Stops the currently running Shiny app, returning control to the caller of
#' [runApp()].
#'
#' @param returnValue The value that should be returned from
#'   [runApp()].
#' @export
stopApp <- function(returnValue = invisible()) {
  # reterror will indicate whether retval is an error (i.e. it should be passed
  # to stop() when the serviceApp loop stops) or a regular value (in which case
  # it should simply be returned with the appropriate visibility).
  .globals$reterror <- FALSE
  ..stacktraceoff..(
    tryCatch(
      {
        captureStackTraces(
          .globals$retval <- withVisible(..stacktraceon..(force(returnValue)))
        )
      },
      error = function(e) {
        .globals$retval <- e
        .globals$reterror <- TRUE
      }
    )
  )

  .globals$stopped <- TRUE
  httpuv::interrupt()
}

#' Run Shiny Example Applications
#'
#' Launch Shiny example applications, and optionally, your system's web browser.
#'
#' @param example The name of the example to run, or `NA` (the default) to
#'   list the available examples.
#' @param port The TCP port that the application should listen on. Defaults to
#'   choosing a random port.
#' @param launch.browser If true, the system's default web browser will be
#'   launched automatically after the app is started. Defaults to true in
#'   interactive sessions only.
#' @param host The IPv4 address that the application should listen on. Defaults
#'   to the `shiny.host` option, if set, or `"127.0.0.1"` if not.
#' @param display.mode The mode in which to display the example. Defaults to
#'   `showcase`, but may be set to `normal` to see the example without
#'   code or commentary.
#'
#' @examples
#' ## Only run this example in interactive R sessions
#' if (interactive()) {
#'   # List all available examples
#'   runExample()
#'
#'   # Run one of the examples
#'   runExample("01_hello")
#'
#'   # Print the directory containing the code for all examples
#'   system.file("examples", package="shiny")
#' }
#' @export
runExample <- function(example=NA,
                       port=NULL,
                       launch.browser=getOption('shiny.launch.browser',
                                                interactive()),
                       host=getOption('shiny.host', '127.0.0.1'),
                       display.mode=c("auto", "normal", "showcase")) {
  examplesDir <- system.file('examples', package='shiny')
  dir <- resolve(examplesDir, example)
  if (is.null(dir)) {
    if (is.na(example)) {
      errFun <- message
      errMsg <- ''
    }
    else {
      errFun <- stop
      errMsg <- paste('Example', example, 'does not exist. ')
    }

    errFun(errMsg,
           'Valid examples are "',
           paste(list.files(examplesDir), collapse='", "'),
           '"')
  }
  else {
    runApp(dir, port = port, host = host, launch.browser = launch.browser,
           display.mode = display.mode)
  }
}

#' Run a gadget
#'
#' Similar to `runApp`, but handles `input$cancel` automatically, and
#' if running in RStudio, defaults to viewing the app in the Viewer pane.
#'
#' @param app Either a Shiny app object as created by
#'   [`shinyApp()`][shiny] et al, or, a UI object.
#' @param server Ignored if `app` is a Shiny app object; otherwise, passed
#'   along to `shinyApp` (i.e. `shinyApp(ui = app, server = server)`).
#' @param port See [`runApp()`][shiny].
#' @param viewer Specify where the gadget should be displayed--viewer pane,
#'   dialog window, or external browser--by passing in a call to one of the
#'   [viewer()] functions.
#' @param stopOnCancel If `TRUE` (the default), then an `observeEvent`
#'   is automatically created that handles `input$cancel` by calling
#'   `stopApp()` with an error. Pass `FALSE` if you want to handle
#'   `input$cancel` yourself.
#' @return The value returned by the gadget.
#'
#' @examples
#' \dontrun{
#' library(shiny)
#'
#' ui <- fillPage(...)
#'
#' server <- function(input, output, session) {
#'   ...
#' }
#'
#' # Either pass ui/server as separate arguments...
#' runGadget(ui, server)
#'
#' # ...or as a single app object
#' runGadget(shinyApp(ui, server))
#' }
#' @export
runGadget <- function(app, server = NULL, port = getOption("shiny.port"),
  viewer = paneViewer(), stopOnCancel = TRUE) {

  if (!is.shiny.appobj(app)) {
    app <- shinyApp(app, server)
  }

  if (isTRUE(stopOnCancel)) {
    app <- decorateServerFunc(app, function(input, output, session) {
      observeEvent(input$cancel, {
        stopApp(stop("User cancel", call. = FALSE))
      })
    })
  }

  if (is.null(viewer)) {
    viewer <- utils::browseURL
  }

  shiny::runApp(app, port = port, launch.browser = viewer)
}

# Add custom functionality to a Shiny app object's server func
decorateServerFunc <- function(appobj, serverFunc) {
  origServerFuncSource <- appobj$serverFuncSource
  appobj$serverFuncSource <- function() {
    origServerFunc <- origServerFuncSource()
    function(input, output, session) {
      serverFunc(input, output, session)

      # The clientData and session arguments are optional; check if
      # each exists
      args <- argsForServerFunc(origServerFunc, session)
      do.call(origServerFunc, args)
    }
  }
  appobj
}

#' Viewer options
#'
#' Use these functions to control where the gadget is displayed in RStudio (or
#' other R environments that emulate RStudio's viewer pane/dialog APIs). If
#' viewer APIs are not available in the current R environment, then the gadget
#' will be displayed in the system's default web browser (see
#' [utils::browseURL()]).
#'
#' @return A function that takes a single `url` parameter, suitable for
#'   passing as the `viewer` argument of [runGadget()].
#'
#' @rdname viewer
#' @name viewer
NULL

#' @param minHeight The minimum height (in pixels) desired to show the gadget in
#'   the viewer pane. If a positive number, resize the pane if necessary to show
#'   at least that many pixels. If `NULL`, use the existing viewer pane
#'   size. If `"maximize"`, use the maximum available vertical space.
#' @rdname viewer
#' @export
paneViewer <- function(minHeight = NULL) {
  viewer <- getOption("viewer")
  if (is.null(viewer)) {
    utils::browseURL
  } else {
    function(url) {
      viewer(url, minHeight)
    }
  }
}

#' @param dialogName The window title to display for the dialog.
#' @param width,height The desired dialog width/height, in pixels.
#' @rdname viewer
#' @export
dialogViewer <- function(dialogName, width = 600, height = 600) {
  viewer <- getOption("shinygadgets.showdialog")
  if (is.null(viewer)) {
    utils::browseURL
  } else {
    function(url) {
      viewer(dialogName, url, width = width, height = height)
    }
  }
}

#' @param browser See [utils::browseURL()].
#' @rdname viewer
#' @export
browserViewer <- function(browser = getOption("browser")) {
  function(url) {
    utils::browseURL(url, browser = browser)
  }
}

# Returns TRUE if we're running in Shiny Server or other hosting environment,
# otherwise returns FALSE.
inShinyServer <- function() {
  nzchar(Sys.getenv('SHINY_PORT'))
}

# This check was moved out of the main function body because of an issue with
# the RStudio debugger. (#1474)
isEmptyMessage <- function(msg) {
  identical(charToRaw("\003\xe9"), msg)
}
