/*

  * Document as editable list of commands

  *

  * @author Makarius

  */

 package isabelle.proofdocument

 object Document

 {

   /* command start positions */

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

   {

     var offset = 0

     for (cmd <- commands.elements) yield {

       val start = offset

       offset += cmd.length

       (cmd, start)

     }

   }

   /* empty document */

   def empty(id: Isar_Document.Document_ID): Document =

   {

     val doc = new Document(id, Linear_Set(), Map())

     doc.assign_states(Nil)

     doc

   }

   // FIXME

   var phase0: List[Text_Edit] = null

   var phase1: Linear_Set[Command] = null

   var phase2: Linear_Set[Command] = null

   var phase3: List[Edit] = null

   var raw_source: String = null

   /** document edits **/

   type Edit = (Option[Command], Option[Command])

   def text_edits(session: Session, old_doc: Document, new_id: Isar_Document.Document_ID,

     edits: List[Text_Edit]): (List[Edit], Document) =

   {

     require(old_doc.assignment.is_finished)

     phase0 = edits

     /* unparsed dummy commands */

     def unparsed(source: String) =

       new Command(null, List(Outer_Lex.Token(Outer_Lex.Token_Kind.UNPARSED, source)))

     def is_unparsed(command: Command) = command.id == null

     assert(!old_doc.commands.exists(is_unparsed))

     /* phase 1: edit individual command source */

     var commands = old_doc.commands

     def edit_text(eds: List[Text_Edit]): Unit =

     {

       eds match {

         case e :: es =>

           command_starts(commands).find {   // FIXME relative search!

             case (cmd, cmd_start) => e.can_edit(cmd.length, cmd_start)

           } match {  // FIXME try to append after command

             case Some((cmd, cmd_start)) =>

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

               // FIXME Linear_Set.edit (?)

               commands = commands.insert_after(Some(cmd), unparsed(source))

               commands -= cmd

               edit_text(rest.toList ::: es)

             case None =>

               require(e.isInstanceOf[Text_Edit.Insert] && e.start == 0)

               commands = commands.insert_after(None, unparsed(e.text))

               edit_text(es)

           }

         case Nil =>

       }

     }

     edit_text(edits)

     phase1 = commands

     /* phase 2: command range edits */

     def edit_commands(): Unit =

     {

       // FIXME relative search!

       commands.elements.find(is_unparsed) match {

         case Some(first_unparsed) =>

           val prefix = commands.prev(first_unparsed)

           val body = commands.elements(first_unparsed).takeWhile(is_unparsed).toList

           val suffix = commands.next(body.last)

           val source =

             (prefix.toList ::: body ::: suffix.toList).flatMap(_.span.map(_.source)).mkString

           assert(source != "")

           raw_source = source

           val spans0 = Thy_Syntax.parse_spans(session.current_syntax.scan(source))

           val (before_edit, spans1) =

             if (!spans0.isEmpty && Some(spans0.first) == prefix.map(_.span))

               (prefix, spans0.tail)

             else (if (prefix.isDefined) commands.prev(prefix.get) else None, spans0)

           val (after_edit, spans2) =

             if (!spans1.isEmpty && Some(spans1.last) == suffix.map(_.span))

               (suffix, spans1.take(spans1.length - 1))

             else (if (suffix.isDefined) commands.next(suffix.get) else None, spans1)

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

           commands = commands.delete_between(before_edit, after_edit)

           commands = commands.append_after(before_edit, new_commands)

           edit_commands()

         case None =>

       }

     }

     edit_commands()

     phase2 = commands

     /* phase 3: resulting document edits */

     val removed_commands = old_doc.commands.elements.filter(!commands.contains(_)).toList

     val inserted_commands = commands.elements.filter(!old_doc.commands.contains(_)).toList

     // FIXME proper order

     val doc_edits =

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

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

     val former_states = old_doc.assignment.join -- removed_commands

     phase3 = doc_edits

     (doc_edits, new Document(new_id, commands, former_states))

   }

 }

 class Document(

     val id: Isar_Document.Document_ID,

     val commands: Linear_Set[Command],

     former_states: Map[Command, Command])

 {

   /* command ranges */

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

   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

   }

   /* command state assignment */

   val assignment = Future.promise[Map[Command, Command]]

   def await_assignment { assignment.join }

   @volatile private var tmp_states = former_states

   def assign_states(new_states: List[(Command, Command)])

   {

     assignment.fulfill(tmp_states ++ new_states)

     tmp_states = Map()

   }

   def current_state(cmd: Command): State =

   {

     require(assignment.is_finished)

     (assignment.join)(cmd).current_state

   }

 }