#' List Deployed Applications
#'
#' List all applications currently deployed for a given account.
#' @inheritParams deployApp
#' @return
#' Returns a data frame with the following columns:
#' \tabular{ll}{
#' `id`         \tab Application unique id \cr
#' `name`       \tab Name of application \cr
#' `title`       \tab Application title \cr
#' `url`        \tab URL where application can be accessed \cr
#'
#' `status`     \tab Current status of application. Valid values are `pending`,
#'                   `deploying`, `running`, `terminating`, and `terminated` \cr
#' `size`       \tab Instance size (small, medium, large, etc.) (on
#'                   ShinyApps.io) \cr
#' `instances`  \tab Number of instances (on ShinyApps.io) \cr
#' `config_url` \tab URL where application can be configured \cr
#' }
#' @note To register an account you call the [setAccountInfo()] function.
#' @examples
#' \dontrun{
#'
#' # list all applications for the default account
#' applications()
#'
#' # list all applications for a specific account
#' applications("myaccount")
#'
#' # view the list of applications in the data viewer
#' View(applications())
#' }
#' @seealso [deployApp()], [terminateApp()]
#' @family Deployment functions
#' @export
applications <- function(account = NULL, server = NULL) {

  # resolve account and create connect client
  accountDetails <- accountInfo(account, server)
  serverDetails <- serverInfo(accountDetails$server)
  client <- clientForAccount(accountDetails)

  isConnect <- isConnectServer(accountDetails$server)

  # retrieve applications
  apps <- client$listApplications(accountDetails$accountId)

  # extract the subset of fields we're interested in
  keep <- if (isConnect) {
    c(
      "id",
      "name",
      "title",
      "url",
      "build_status",
      "created_time",
      "last_deployed_time",
      "guid"
    )
  } else {
    c(
      "id",
      "name",
      "url",
      "status",
      "created_time",
      "updated_time",
      "deployment"
    )
  }
  res <- lapply(apps, `[`, keep)

  res <- if (isConnect) {
    lapply(res, function(x) {
      # set size and instance to NA since Connect doesn't return this info
      x$size <- NA
      x$instances <- NA
      x$title <- x$title %||% NA_character_
      x
    })
  } else {
    lapply(res, function(x) {
      # promote the size and instance data to first-level fields
      x$size <- x$deployment$properties$application.instances.template
      if (is.null(x$size))
        x$size <- NA
      x$instances <- x$deployment$properties$application.instances.count
      if (is.null(x$instances))
        x$instances <- NA
      x$deployment <- NULL
      x$guid <- NA
      x$title <- NA_character_
      x
    })
  }

  # The config URL may be provided by the server at some point, but for now
  # infer it from the account type
  res <- lapply(res, function(row) {
    if (isConnect) {
      prefix <- sub("/__api__", "", serverDetails$url)
      row$config_url <- paste(prefix, "connect/#/apps", row$id, sep = "/")
    } else {
      row$config_url <- paste("https://www.shinyapps.io/admin/#/application", row$id, sep = "/")
    }
    row
  })

  # convert to data frame
  res <- lapply(res, as.data.frame, stringsAsFactors = FALSE)
  res <- do.call("rbind", res)

  # Ensure the Connect and ShinyApps.io data frames have same column names
  idx <- match("last_deployed_time", names(res))
  if (!is.na(idx)) names(res)[idx] <- "updated_time"

  idx <- match("build_status", names(res))
  if (!is.na(idx)) names(res)[idx] <- "status"

  return(res)
}

# Use the API to filter applications by name and error when it does not exist.
getAppByName <- function(client, accountInfo, name, error_call = caller_env()) {
  # NOTE: returns a list with 0 or 1 elements
  app <- client$listApplications(accountInfo$accountId, filters = list(name = name))
  if (length(app)) {
    return(app[[1]])
  }
  cli::cli_abort(
    c(
      "No application found",
      i = "Specify the application directory, name, and/or associated account."
    ),
    call = error_call,
    class = "rsconnect_app_not_found"
  )
}

# Use the API to list all applications then filter the results client-side.
resolveApplication <- function(accountDetails, appName) {
  client <- clientForAccount(accountDetails)
  apps <- client$listApplications(accountDetails$accountId)
  for (app in apps) {
    if (identical(app$name, appName))
      return(app)
  }

  stopWithApplicationNotFound(appName)
}

getApplication <- function(account, server, appId) {
  accountDetails <- accountInfo(account, server)
  client <- clientForAccount(accountDetails)

  withCallingHandlers(
    client$getApplication(appId, "unknown"),
    rsconnect_http_404 = function(err) {
      cli::cli_abort("Can't find app with id {.str {appId}}", parent = err)
    }
  )
}

stopWithApplicationNotFound <- function(appName) {
  stop(paste("No application named '", appName, "' is currently deployed.",
             sep = ""), call. = FALSE)
}

applicationTask <- function(taskDef, appName, accountDetails, quiet) {

  # resolve target account and application
  application <- resolveApplication(accountDetails, appName)

  # get status function and display initial status
  displayStatus <- displayStatus(quiet)
  displayStatus(paste(taskDef$beginStatus, "...\n", sep = ""))

  # perform the action
  client <- clientForAccount(accountDetails)
  task <- taskDef$action(client, application)
  client$waitForTask(task$task_id, quiet)
  displayStatus(paste(taskDef$endStatus, "\n", sep = ""))

  invisible(NULL)
}

# streams application logs from ShinyApps
streamApplicationLogs <- function(authInfo, applicationId, entries, skip) {
  # build the URL
  url <- paste0(serverInfo("shinyapps.io")$url, "/applications/", applicationId,
                "/logs?", "count=", entries, "&tail=1")
  parsed <- parseHttpUrl(url)

  # create the curl handle and perform the minimum necessary to create an
  # authenticated request. we ignore the rsconnect.http option here because only
  # curl supports the kind of streaming connection that we need.
  handle <- createCurlHandle("GET")
  curl::handle_setheaders(handle,
    .list = signatureHeaders(authInfo, "GET", parsed$path, NULL)
  )

  # begin the stream
  curl::curl_fetch_stream(url = url,
    fun = function(data) {
      if (skip > 0)
        skip <<- skip - 1
      else
        cat(rawToChar(data))
    }, handle = handle)
}

#' Show Application Logs
#'
#' Show the logs for a deployed ShinyApps application.
#'
#' @param appPath The path to the directory or file that was deployed.
#' @param appFile The path to the R source file that contains the application
#'   (for single file applications).
#' @param appName The name of the application to show logs for. May be omitted
#'   if only one application deployment was made from `appPath`.
#' @param account The account under which the application was deployed. May be
#'   omitted if only one account is registered on the system.
#' @param server Server name. Required only if you use the same account name on
#'   multiple servers.
#' @param entries The number of log entries to show. Defaults to 50 entries.
#' @param streaming Whether to stream the logs. If `TRUE`, then the
#'   function does not return; instead, log entries are written to the console
#'   as they are made, until R is interrupted. Defaults to `FALSE`.
#'
#' @note This function only uses the \code{libcurl} transport, and works only for
#'   ShinyApps servers.
#'
#' @export
showLogs <- function(appPath = getwd(), appFile = NULL, appName = NULL,
                     account = NULL, server = NULL, entries = 50, streaming = FALSE) {

  # determine the log target and target account info
  deployment <- findDeployment(
    appPath = appPath,
    appName = appName,
    server = server,
    account = account
  )
  accountDetails <- accountInfo(deployment$account, deployment$server)
  client <- clientForAccount(accountDetails)
  application <- getAppByName(client, accountDetails, deployment$name)

  if (streaming) {
    # streaming; poll for the entries directly
    skip <- 0
    repeat {
      tryCatch({
         streamApplicationLogs(accountDetails, application$id, entries, skip)
         # after the first fetch, we've seen all recent entries, so show
         # only new entries. unfortunately /logs/ doesn't support getting 0
         # entries, so get one and don't log it.
         entries <- 1
         skip <- 1
       },
       error = function(e) {
         # if the server times out, ignore the error; otherwise, let it
         # bubble through
         if (!identical(e$message,
                  "transfer closed with outstanding read data remaining")) {
           stop(e)
         }
       })
    }
  } else {
    # if not streaming, poll for the entries directly
    logs <- client$getLogs(application$id, entries)
    cat(logs)
  }
}

#' Update deployment records
#'
#' Update the deployment records for applications published to Posit Connect.
#' This updates application title and URL, and deletes records for deployments
#' where the application has been deleted on the server.
#'
#' @param appPath The path to the directory or file that was deployed.
#' @export
syncAppMetadata <- function(appPath = ".") {
  check_directory(appPath)

  deploys <- deployments(appPath)
  for (i in seq_len(nrow(deploys))) {
    curDeploy <- deploys[i, ]

    # don't sync if published to RPubs
    if (isRPubs(curDeploy$server)) {
      next
    }

    account <- accountInfo(curDeploy$account, curDeploy$server)
    client <- clientForAccount(account)

    application <- tryCatch(
      client$getApplication(curDeploy$appId),
      rsconnect_http_404 = function(c) {
        # if the app has been deleted, delete the deployment record
        file.remove(curDeploy$deploymentFile)
        cli::cli_inform("Deleting deployment record for deleted app {curDeploy$appId}.")
        NULL
      }
    )
    if (is.null(application)) {
      next
    }

    # update the record and save out a new config file
    path <- curDeploy$deploymentFile
    curDeploy$deploymentFile <- NULL # added on read

    # remove old fields
    curDeploy$when <- NULL
    curDeploy$lastSyncTime <- NULL

    curDeploy$title <- application$title
    curDeploy$url <- application$url

    writeDeploymentRecord(curDeploy, path)
  }
}