/*  Title:      Pure/PIDE/document.scala

     Author:     Makarius

 Document as collection of named nodes, each consisting of an editable

 list of commands.

 */

 package isabelle

 import scala.collection.mutable

 import scala.annotation.tailrec

 object Document

 {

   /* formal identifiers */

   type ID = Long

   type Version_ID = ID

   type Command_ID = ID

   type Exec_ID = ID

   val NO_ID: ID = 0

   def parse_id(s: String): ID = java.lang.Long.parseLong(s)

   def print_id(id: ID): String = id.toString

   /** named document nodes **/

   object Node

   {

     val empty: Node = new Node(Linear_Set())

     def command_starts(commands: Iterator[Command], offset: Int = 0): Iterator[(Command, Int)] =

     {

       var i = offset

       for (command <- commands) yield {

         val start = i

         i += command.length

         (command, start)

       }

     }

   }

   class Node(val commands: Linear_Set[Command])

   {

     /* command ranges */

     def command_starts: Iterator[(Command, Int)] =

       Node.command_starts(commands.iterator)

     def command_start(cmd: Command): Option[Int] =

       command_starts.find(_._1 == cmd).map(_._2)

     def command_range(i: Int): Iterator[(Command, Int)] =

       command_starts dropWhile { case (cmd, start) => start + cmd.length <= i }

     def command_range(i: Int, j: Int): Iterator[(Command, Int)] =

       command_range(i) takeWhile { case (_, start) => start < j }

     def command_at(i: Int): Option[(Command, Int)] =

     {

       val range = command_range(i)

       if (range.hasNext) Some(range.next) else None

     }

     def proper_command_at(i: Int): Option[Command] =

       command_at(i) match {

         case Some((command, _)) =>

           commands.reverse_iterator(command).find(cmd => !cmd.is_ignored)

         case None => None

       }

   }

   /* initial document */

   val init: Document = new Document(NO_ID, Map().withDefaultValue(Node.empty))

   /** changes of plain text, eventually resulting in document edits **/

   type Node_Text_Edit = (String, List[Text_Edit])  // FIXME None: remove

   type Edit[C] =

    (String,  // node name

     Option[List[(Option[C], Option[C])]])  // None: remove, Some: insert/remove commands

   abstract class Snapshot

   {

     val document: Document

     val node: Document.Node

     val is_outdated: Boolean

     def convert(offset: Int): Int

     def revert(offset: Int): Int

     def lookup_command(id: Command_ID): Option[Command]

     def state(command: Command): Command.State

   }

   object Change

   {

     val init = new Change(Future.value(Document.init), Nil, Future.value(Nil, Document.init))

   }

   class Change(

     val prev: Future[Document],

     val edits: List[Node_Text_Edit],

     val result: Future[(List[Edit[Command]], Document)])

   {

     val document: Future[Document] = result.map(_._2)

     def is_finished: Boolean = prev.is_finished && document.is_finished

   }

   /** editing **/

   def text_edits(session: Session, old_doc: Document, edits: List[Node_Text_Edit])

       : (List[Edit[Command]], Document) =

   {

     /* phase 1: edit individual command source */

     @tailrec def edit_text(eds: List[Text_Edit],

         commands: Linear_Set[Command]): Linear_Set[Command] =

     {

       eds match {

         case e :: es =>

           Node.command_starts(commands.iterator).find {

             case (cmd, cmd_start) =>

               e.can_edit(cmd.source, cmd_start) ||

                 e.is_insert && e.start == cmd_start + cmd.length

           } match {

             case Some((cmd, cmd_start)) if e.can_edit(cmd.source, cmd_start) =>

               val (rest, text) = e.edit(cmd.source, cmd_start)

               val new_commands = commands.insert_after(Some(cmd), Command.unparsed(text)) - cmd

               edit_text(rest.toList ::: es, new_commands)

             case Some((cmd, cmd_start)) =>

               edit_text(es, commands.insert_after(Some(cmd), Command.unparsed(e.text)))

             case None =>

               require(e.is_insert && e.start == 0)

               edit_text(es, commands.insert_after(None, Command.unparsed(e.text)))

           }

         case Nil => commands

       }

     }

     /* phase 2: recover command spans */

     @tailrec def parse_spans(commands: Linear_Set[Command]): Linear_Set[Command] =

     {

       commands.iterator.find(_.is_unparsed) match {

         case Some(first_unparsed) =>

           val first =

             commands.reverse_iterator(first_unparsed).find(_.is_command) getOrElse commands.head

           val last =

             commands.iterator(first_unparsed).find(_.is_command) getOrElse commands.last

           val range =

             commands.iterator(first).takeWhile(_ != last).toList ::: List(last)

           val sources = range.flatMap(_.span.map(_.source))

           val spans0 = Thy_Syntax.parse_spans(session.current_syntax.scan(sources.mkString))

           val (before_edit, spans1) =

             if (!spans0.isEmpty && first.is_command && first.span == spans0.head)

               (Some(first), spans0.tail)

             else (commands.prev(first), spans0)

           val (after_edit, spans2) =

             if (!spans1.isEmpty && last.is_command && last.span == spans1.last)

               (Some(last), spans1.take(spans1.length - 1))

             else (commands.next(last), spans1)

           val inserted = spans2.map(span => new Command(session.create_id(), span))

           val new_commands =

             commands.delete_between(before_edit, after_edit).append_after(before_edit, inserted)

           parse_spans(new_commands)

         case None => commands

       }

     }

     /* resulting document edits */

     {

       val doc_edits = new mutable.ListBuffer[Edit[Command]]

       var nodes = old_doc.nodes

       for ((name, text_edits) <- edits) {

         val commands0 = nodes(name).commands

         val commands1 = edit_text(text_edits, commands0)

         val commands2 = parse_spans(commands1)   // FIXME somewhat slow

         val removed_commands = commands0.iterator.filter(!commands2.contains(_)).toList

         val inserted_commands = commands2.iterator.filter(!commands0.contains(_)).toList

         val cmd_edits =

           removed_commands.reverse.map(cmd => (commands0.prev(cmd), None)) :::

           inserted_commands.map(cmd => (commands2.prev(cmd), Some(cmd)))

         doc_edits += (name -> Some(cmd_edits))

         nodes += (name -> new Node(commands2))

       }

       (doc_edits.toList, new Document(session.create_id(), nodes))

     }

   }

   /** global state -- accumulated prover results **/

   object State

   {

     class Fail(state: State) extends Exception

     val init = State().define_document(Document.init, Map()).assign(Document.init.id, Nil)

     class Assignment(former_assignment: Map[Command, Exec_ID])

     {

       @volatile private var tmp_assignment = former_assignment

       private val promise = Future.promise[Map[Command, Exec_ID]]

       def is_finished: Boolean = promise.is_finished

       def join: Map[Command, Exec_ID] = promise.join

       def assign(command_execs: List[(Command, Exec_ID)])

       {

         promise.fulfill(tmp_assignment ++ command_execs)

         tmp_assignment = Map()

       }

     }

   }

   case class State(

     val documents: Map[Version_ID, Document] = Map(),

     val commands: Map[Command_ID, Command.State] = Map(),

     val execs: Map[Exec_ID, (Command.State, Set[Document])] = Map(),

     val assignments: Map[Document, State.Assignment] = Map(),

     val disposed: Set[ID] = Set())  // FIXME unused!?

   {

     private def fail[A]: A = throw new State.Fail(this)

     def define_document(document: Document, former_assignment: Map[Command, Exec_ID]): State =

     {

       val id = document.id

       if (documents.isDefinedAt(id) || disposed(id)) fail

       copy(documents = documents + (id -> document),

         assignments = assignments + (document -> new State.Assignment(former_assignment)))

     }

     def define_command(command: Command): State =

     {

       val id = command.id

       if (commands.isDefinedAt(id) || disposed(id)) fail

       copy(commands = commands + (id -> command.empty_state))

     }

     def lookup_command(id: Command_ID): Option[Command] = commands.get(id).map(_.command)

     def the_document(id: Version_ID): Document = documents.getOrElse(id, fail)

     def the_command(id: Command_ID): Command.State = commands.getOrElse(id, fail)

     def the_exec_state(id: Exec_ID): Command.State = execs.getOrElse(id, fail)._1

     def the_assignment(document: Document): State.Assignment = assignments.getOrElse(document, fail)

     def accumulate(id: ID, message: XML.Tree): (Command.State, State) =

       execs.get(id) match {

         case Some((st, docs)) =>

           val new_st = st.accumulate(message)

           (new_st, copy(execs = execs + (id -> (new_st, docs))))

         case None =>

           commands.get(id) match {

             case Some(st) =>

               val new_st = st.accumulate(message)

               (new_st, copy(commands = commands + (id -> new_st)))

             case None => fail

           }

       }

     def assign(id: Version_ID, edits: List[(Command_ID, Exec_ID)]): State =

     {

       val doc = the_document(id)

       val docs = Set(doc)  // FIXME unused (!?)

       var new_execs = execs

       val assigned_execs =

         for ((cmd_id, exec_id) <- edits) yield {

           val st = the_command(cmd_id)

           if (new_execs.isDefinedAt(exec_id) || disposed(exec_id)) fail

           new_execs += (exec_id -> (st, docs))

           (st.command, exec_id)

         }

       the_assignment(doc).assign(assigned_execs)  // FIXME explicit value instead of promise (!?)

       copy(execs = new_execs)

     }

     def is_assigned(document: Document): Boolean =

       assignments.get(document) match {

         case Some(assgn) => assgn.is_finished

         case None => false

       }

     def command_state(document: Document, command: Command): Command.State =

     {

       val assgn = the_assignment(document)

       require(assgn.is_finished)

       the_exec_state(assgn.join.getOrElse(command, fail))

     }

   }

 }

 class Document(

     val id: Document.Version_ID,

     val nodes: Map[String, Document.Node])