--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/System/web_app.scala Sat Mar 30 01:08:25 2024 +0100
@@ -0,0 +1,496 @@
+/* Title: Pure/System/web_app.scala
+ Author: Fabian Huch, TU Muenchen
+
+Technical layer for web apps using server-side rendering with HTML forms.
+ */
+package isabelle
+
+
+import scala.annotation.tailrec
+import scala.collection.immutable.SortedMap
+
+
+object Web_App {
+ /* form html elements */
+
+ object More_HTML {
+ import HTML._
+
+ def css(s: String): Attribute = new Attribute("style", s)
+ def name(n: String): Attribute = new Attribute("name", n)
+ def value(v: String): Attribute = new Attribute("value", v)
+ def placeholder(p: String): Attribute = new Attribute("placeholder", p)
+
+ val fieldset = new Operator("fieldset")
+ val button = new Operator("button")
+
+ def legend(txt: String): XML.Elem = XML.Elem(Markup("legend", Nil), text(txt))
+ def input(typ: String): XML.Elem = XML.Elem(Markup("input", List("type" -> typ)), Nil)
+ def hidden(k: Params.Key, v: String): XML.Elem =
+ id(k.print)(name(k.print)(value(v)(input("hidden"))))
+
+ def textfield(i: Params.Key, p: String, v: String): XML.Elem =
+ id(i.print)(name(i.print)(value(v)(placeholder(p)(input("text")))))
+
+ def browse(i: Params.Key, accept: List[String]): XML.Elem =
+ id(i.print)(name(i.print)(input("file"))) + ("accept" -> accept.mkString(","))
+
+ def label(`for`: Params.Key, txt: String): XML.Elem =
+ XML.Elem(Markup("label", List("for" -> `for`.print)), text(txt))
+
+ def option(k: String, v: String): XML.Elem = value(k)(XML.elem("option", text(v)))
+
+ def optgroup(txt: String, opts: XML.Body): XML.Elem =
+ XML.Elem(Markup("optgroup", List("label" -> txt)), opts)
+
+ def select(i: Params.Key, opts: XML.Body): XML.Elem =
+ id(i.print)(name(i.print)(XML.elem("select", opts)))
+
+ def textarea(i: Params.Key, v: String): XML.Elem =
+ id(i.print)(name(i.print)(value(v)(XML.elem("textarea", text(v + "\n")))))
+
+ def radio(i: Params.Key, v: Params.Key, values: List[(Params.Key, String)]): XML.Elem = {
+ def to_option(k: Params.Key): XML.Elem = {
+ val elem = id(i.print + k)(name(i.print)(value(k.print)(input("radio"))))
+ if (v == k) elem + ("checked" -> "checked") else elem
+ }
+
+ span(values.map { case (k, v) => span(List(label(i + k, v), to_option(k))) })
+ }
+
+ def selection(i: Params.Key, selected: Option[String], opts: XML.Body): XML.Elem = {
+ def sel(elem: XML.Tree): XML.Tree = {
+ selected match {
+ case Some(value) =>
+ val Value = new Properties.String("value")
+ elem match {
+ case XML.Elem(Markup("optgroup", props), body) =>
+ XML.Elem(Markup("optgroup", props), body.map(sel))
+ case e@XML.Elem(Markup("option", Value(v)), _) if v == value =>
+ e + ("selected" -> "selected")
+ case e => e
+ }
+ case None => elem
+ }
+ }
+
+ def is_empty_group(elem: XML.Tree): Boolean = elem match {
+ case XML.Elem(Markup("optgroup", _), body) if body.isEmpty => true
+ case _ => false
+ }
+
+ val default = if (selected.isEmpty) List(option("", "") + ("hidden" -> "hidden")) else Nil
+ select(i, default ::: opts.filterNot(is_empty_group).map(sel))
+ }
+
+ def api_button(call: String, label: String): XML.Elem =
+ button(text(label)) + ("formaction" -> call) + ("type" -> "submit")
+
+ def submit_form(endpoint: String, body: XML.Body): XML.Elem = {
+ val default_button = css("display: none")(input("submit") + ("formaction" -> endpoint))
+ val attrs =
+ List("method" -> "post", "target" -> "iframe", "enctype" -> "multipart/form-data")
+ XML.Elem(Markup("form", attrs), default_button :: body)
+ }
+ }
+
+
+ /* form http handling */
+
+ object Multi_Part {
+ abstract class Data(name: String)
+ case class Param(name: String, value: String) extends Data(name)
+ case class File(name: String, file_name: String, content: Bytes) extends Data(name)
+
+ def parse(body: Bytes): List[Data] = {
+ /* Seq for text with embedded bytes */
+ case class Seq(text: String, bytes: Bytes) {
+ def split_one(sep: String): Option[(Seq, Seq)] = {
+ val text_i = text.indexOf(sep)
+ if (text_i >= 0 && sep.nonEmpty) {
+ val (before_text, at_text) = text.splitAt(text_i)
+ val after_text = at_text.substring(sep.length)
+
+ // text might be shorter than bytes because of misinterpreted characters
+ var found = false
+ var bytes_i = 0
+ while (!found && bytes_i < bytes.length) {
+ var sep_ok = true
+ var sep_i = 0
+ while (sep_ok && sep_i < sep.length) {
+ if (bytes.charAt(bytes_i + sep_i) == sep.charAt(sep_i)) {
+ sep_i += 1
+ } else {
+ bytes_i += 1
+ sep_ok = false
+ }
+ }
+ if (sep_ok) found = true
+ }
+
+ val before_bytes = bytes.subSequence(0, bytes_i)
+ val after_bytes = bytes.subSequence(bytes_i + sep.length, bytes.length)
+
+ Some(Seq(before_text, before_bytes), Seq(after_text, after_bytes))
+ } else None
+ }
+ }
+
+ val s = Seq(body.text, body)
+
+ def perhaps_unprefix(pfx: String, s: Seq): Seq =
+ Library.try_unprefix(pfx, s.text) match {
+ case Some(text) => Seq(text, s.bytes.subSequence(pfx.length, s.bytes.length))
+ case None => s
+ }
+
+ val Separator = """--(.*)""".r
+
+ s.split_one(HTTP.NEWLINE) match {
+ case Some(Seq(Separator(sep), _), rest) =>
+ val Param = """Content-Disposition: form-data; name="([^"]+)"""".r
+ val File = """Content-Disposition: form-data; name="([^"]+)"; filename="([^"]+)"""".r
+
+ def parts(body: Seq): Option[List[Data]] =
+ for {
+ (first_line, more) <- body.split_one(HTTP.NEWLINE)
+ more1 = perhaps_unprefix(HTTP.NEWLINE, more)
+ (value, rest) <- more1.split_one(HTTP.NEWLINE + "--" + sep)
+ rest1 = perhaps_unprefix(HTTP.NEWLINE, rest)
+ } yield first_line.text match {
+ case Param(name) =>
+ Multi_Part.Param(name, Line.normalize(value.text)) :: parts(rest1).getOrElse(Nil)
+ case File(name, file_name) =>
+ value.split_one(HTTP.NEWLINE + HTTP.NEWLINE) match {
+ case Some(_, content) =>
+ Multi_Part.File(name, file_name, content.bytes) :: parts(rest1).getOrElse(Nil)
+ case _ => parts(rest1).getOrElse(Nil)
+ }
+ case _ => Nil
+ }
+
+ parts(rest).getOrElse(Nil)
+ case _ => Nil
+ }
+ }
+ }
+
+
+ /* request parameters as structured data */
+
+ object Params {
+ def key(elems: (String | Int)*): Key =
+ Key(
+ elems.toList.map {
+ case s: String => Key.elem(s)
+ case i: Int => Key.elem(i)
+ })
+
+ object Key {
+ sealed trait Elem { def print: String }
+
+ class Nested_Elem private[Key](val rep: String) extends Elem {
+ override def equals(that: Any): Boolean =
+ that match {
+ case other: Nested_Elem => rep == other.rep
+ case _ => false
+ }
+ override def hashCode(): Int = rep.hashCode
+
+ def print: String = rep
+ override def toString: String = print
+ }
+
+ class List_Elem private[Key](val rep: Int) extends Elem {
+ override def equals(that: Any): Boolean =
+ that match {
+ case other: List_Elem => rep == other.rep
+ case _ => false
+ }
+ override def hashCode(): Int = rep.hashCode
+
+ def print: String = rep.toString
+ override def toString: String = print
+ }
+
+ def elem(s: String): Nested_Elem =
+ if (!s.forall(Symbol.is_ascii_letter)) error("Illegal element in: " + quote(s))
+ else new Nested_Elem(s)
+
+ def elem(i: Int): List_Elem =
+ if (i < 0) error("Illegal list element") else new List_Elem(i)
+
+ def empty: Key = Key(Nil)
+ def apply(s: String): Key = new Key(List(elem(s)))
+ def explode(s: String): Key =
+ new Key(
+ space_explode('_', s).map {
+ case Value.Int(i) => elem(i)
+ case s => elem(s)
+ })
+
+
+ /* ordering */
+
+ object Ordering extends scala.math.Ordering[Key] {
+ def compare(key1: Key, key2: Key): Int = key1.print.compareTo(key2.print)
+ }
+ }
+
+ case class Key(rep: List[Key.Elem]) {
+ def +(elem: Key.Elem): Key = Key(rep :+ elem)
+ def +(i: Int): Key = this + Key.elem(i)
+ def +(s: String): Key = this + Key.elem(s)
+ def +(key: Key) = Key(rep ++ key.rep)
+
+ def num: Option[Int] =
+ rep match {
+ case (e: Key.List_Elem) :: _ => Some(e.rep)
+ case _ => None
+ }
+
+ def get(key: Key): Option[Key] =
+ if (rep.startsWith(key.rep)) Some(Key(rep.drop(key.rep.length))) else None
+
+ def print = rep.map(_.print).mkString("_")
+ override def toString: String = print
+ }
+
+ def indexed[A, B](key: Key, xs: List[A], f: (Key, A) => B): List[B] =
+ for ((x, i) <- xs.zipWithIndex) yield f(key + i, x)
+
+
+ object Data {
+ def from_multipart(parts: List[Multi_Part.Data]): Data = {
+ val files = parts.collect { case f: Multi_Part.File => f }
+ val params =
+ parts.collect { case Multi_Part.Param(name, value) => Key.explode(name) -> value }
+ val file_params = files.map(file => Key.explode(file.name) -> file.file_name)
+ val file_files = files.map(file => Key.explode(file.name) -> file.content)
+
+ new Data(
+ SortedMap.from(params ++ file_params)(Key.Ordering),
+ SortedMap.from(file_files)(Key.Ordering))
+ }
+ }
+
+ class Data private(params: SortedMap[Key, String], files: SortedMap[Key, Bytes]) {
+ override def toString: String = "Data(" + params.toString() + "," + files.toString() + ")"
+
+ def get(key: Key): Option[String] = params.get(key)
+ def apply(key: Key): String = get(key).getOrElse("")
+ def list(key: Key): List[Key] =
+ (for {
+ key1 <- params.keys.toList
+ key2 <- key1.get(key)
+ i <- key2.num
+ } yield key + i).distinct
+
+ def file(key: Key): Option[Bytes] = files.get(key)
+ }
+ }
+
+
+ /* API with backend base path, and application url (e.g. for frontend links). */
+
+ case class Paths(
+ frontend: Url,
+ api_base: Path,
+ serve_frontend: Boolean = false,
+ landing: Path = Path.current
+ ) {
+ def api_path(path: Path, external: Boolean = true): Path =
+ (if (serve_frontend) Path.explode("backend") else Path.current) +
+ (if (external) api_base else Path.current) + path
+
+ def route(path: Path, params: Properties.T = Nil): String = {
+ def param(p: Properties.Entry): String = Url.encode(p._1) + "=" + Url.encode(p._2)
+ val route =
+ if (params.isEmpty) path.implode else path.implode + "?" + params.map(param).mkString("&")
+ "/" + route
+ }
+
+ def api_route(path: Path, params: Properties.T = Nil, external: Boolean = true): String =
+ route(api_path(path, external = external), params)
+
+ def frontend_url(path: Path, params: Properties.T = Nil): Url =
+ frontend.resolve(route(path, params))
+ }
+
+ abstract class Server[A](
+ paths: Paths,
+ port: Int = 0,
+ verbose: Boolean = false,
+ progress: Progress = new Progress(),
+ ) {
+ def render(model: A): XML.Body
+ val error_model: A
+ val endpoints: List[Endpoint]
+ val head: XML.Body
+
+ def output_document(content: XML.Body, post_height: Boolean = true): String = {
+ val attrs =
+ if (post_height) List("onLoad" -> "parent.postMessage(document.body.scrollHeight, '*')")
+ else Nil
+
+ cat_lines(
+ List(
+ HTML.header,
+ HTML.output(XML.elem("head", HTML.head_meta :: head), hidden = true, structural = true),
+ HTML.output(XML.Elem(Markup("body", attrs), content), hidden = true, structural = true),
+ HTML.footer))
+ }
+
+ class UI(path: Path) extends HTTP.Service(path.implode, "GET") {
+ def apply(request: HTTP.Request): Option[HTTP.Response] = {
+ progress.echo_if(verbose, "GET ui")
+
+ val on_load = """
+(function() {
+ window.addEventListener('message', (event) => {
+ if (Number.isInteger(event.data)) {
+ this.style.height=event.data + 32 + 'px'
+ }
+ })
+}).call(this)"""
+
+ val set_src = """
+const base = '""" + paths.frontend.toString.replace("/", "\\/") + """'
+document.getElementById('iframe').src = base + '""" + paths.api_route(path).replace("/", "\\/") + """' + window.location.search"""
+
+ Some(HTTP.Response.html(output_document(
+ List(
+ XML.Elem(
+ Markup(
+ "iframe",
+ List(
+ "id" -> "iframe",
+ "name" -> "iframe",
+ "style" -> "border-style: none; width: 100%",
+ "onload" -> on_load)),
+ HTML.text("content")),
+ HTML.script(set_src)),
+ post_height = false)))
+ }
+ }
+
+ sealed abstract class Endpoint(path: Path, method: String = "GET")
+ extends HTTP.Service(paths.api_path(path, external = false).implode, method) {
+
+ def reply(request: HTTP.Request): HTTP.Response
+
+ final def apply(request: HTTP.Request): Option[HTTP.Response] =
+ Exn.capture(reply(request)) match {
+ case Exn.Res(res) => Some(res)
+ case Exn.Exn(exn) =>
+ val id = UUID.random_string()
+ progress.echo_error_message("Internal error <" + id + ">: " + exn)
+ error("Internal server error. ID: " + id)
+ }
+ }
+
+ private def query_params(request: HTTP.Request): Properties.T = {
+ def decode(s: String): Option[Properties.Entry] =
+ s match {
+ case Properties.Eq(k, v) => Some(Url.decode(k) -> Url.decode(v))
+ case _ => None
+ }
+
+ Library.try_unprefix(request.query, request.uri_name).toList.flatMap(params =>
+ space_explode('&', params).flatMap(decode))
+ }
+
+
+ /* endpoint types */
+
+ class Get(val path: Path, description: String, get: Properties.T => Option[A])
+ extends Endpoint(path) {
+
+ def reply(request: HTTP.Request): HTTP.Response = {
+ progress.echo_if(verbose, "GET " + description)
+
+ val params = query_params(request)
+ progress.echo_if(verbose, "params: " + params.toString())
+
+ val model =
+ get(params) match {
+ case Some(model) => model
+ case None =>
+ progress.echo_if(verbose, "Parsing failed")
+ error_model
+ }
+ HTTP.Response.html(output_document(render(model)))
+ }
+ }
+
+ class Get_File(path: Path, description: String, download: Properties.T => Option[Path])
+ extends Endpoint(path) {
+
+ def reply(request: HTTP.Request): HTTP.Response = {
+ progress.echo_if(verbose, "DOWNLOAD " + description)
+
+ val params = query_params(request)
+ progress.echo_if(verbose, "params: " + params.toString())
+
+ download(params) match {
+ case Some(path) => HTTP.Response.content(HTTP.Content.read(path))
+ case None =>
+ progress.echo_if(verbose, "Fetching file path failed")
+ HTTP.Response.html(output_document(render(error_model)))
+ }
+ }
+ }
+
+ class Post(path: Path, description: String, post: Params.Data => Option[A])
+ extends Endpoint(path, method = "POST") {
+
+ def reply(request: HTTP.Request): HTTP.Response = {
+ progress.echo_if(verbose, "POST " + description)
+
+ val parts = Multi_Part.parse(request.input)
+ val params = Params.Data.from_multipart(parts)
+ progress.echo_if(verbose, "params: " + params.toString)
+
+ val model =
+ post(params) match {
+ case Some(model) => model
+ case None =>
+ progress.echo_if(verbose, "Parsing failed")
+ error_model
+ }
+ HTTP.Response.html(output_document(render(model)))
+ }
+ }
+
+
+ /* server */
+
+ private def ui_endpoints =
+ if (paths.serve_frontend) endpoints.collect { case page: Get => new UI(page.path) } else Nil
+
+ private lazy val server =
+ HTTP.server(port = port, name = "", services = endpoints ::: ui_endpoints)
+
+ def run(): Unit = {
+ start()
+
+ @tailrec
+ def loop(): Unit = {
+ Thread.sleep(Long.MaxValue)
+ loop()
+ }
+
+ Isabelle_Thread.interrupt_handler(_ => server.stop()) { loop() }
+ }
+
+ def start(): Unit = {
+ server.start()
+ progress.echo("Server started on " + paths.frontend_url(paths.landing))
+ }
+
+ def stop(): Unit = {
+ server.stop()
+ progress.echo("Server stopped")
+ }
+ }
+}
\ No newline at end of file