/*  Title:      Pure/PIDE/document.scala

     Author:     Makarius

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

 list of commands, associated with asynchronous execution process.

 */

 package isabelle

 import scala.collection.mutable

 object Document

 {

   /* formal identifiers */

   type ID = Long

   val ID = Properties.Value.Long

   type Version_ID = ID

   type Command_ID = ID

   type Exec_ID = ID

   val no_id: ID = 0

   val new_id = new Counter

   /** document structure **/

   /* named nodes -- development graph */

   type Edit[A, B] = (String, Node.Edit[A, B])

   type Edit_Text = Edit[Text.Edit, Text.Perspective]

   type Edit_Command = Edit[(Option[Command], Option[Command]), Command.Perspective]

   type Node_Header = Exn.Result[Thy_Header]

   object Node

   {

     sealed abstract class Edit[A, B]

     {

       def foreach(f: A => Unit)

       {

         this match {

           case Edits(es) => es.foreach(f)

           case _ =>

         }

       }

     }

     case class Clear[A, B]() extends Edit[A, B]

     case class Edits[A, B](edits: List[A]) extends Edit[A, B]

     case class Header[A, B](header: Node_Header) extends Edit[A, B]

     case class Perspective[A, B](perspective: B) extends Edit[A, B]

     def norm_header(f: String => String, g: String => String, header: Node_Header): Node_Header =

       header match {

         case Exn.Res(h) => Exn.capture { h.norm_deps(f, g) }

         case exn => exn

       }

     val empty: Node =

       Node(Exn.Exn(ERROR("Bad theory header")), Command.Perspective.empty, Map(), Linear_Set())

     def command_starts(commands: Iterator[Command], offset: Text.Offset = 0)

       : Iterator[(Command, Text.Offset)] =

     {

       var i = offset

       for (command <- commands) yield {

         val start = i

         i += command.length

         (command, start)

       }

     }

   }

   private val block_size = 1024

   sealed case class Node(

     val header: Node_Header,

     val perspective: Command.Perspective,

     val blobs: Map[String, Blob],

     val commands: Linear_Set[Command])

   {

     def clear: Node = Node.empty.copy(header = header)

     /* commands */

     private lazy val full_index: (Array[(Command, Text.Offset)], Text.Range) =

     {

       val blocks = new mutable.ListBuffer[(Command, Text.Offset)]

       var next_block = 0

       var last_stop = 0

       for ((command, start) <- Node.command_starts(commands.iterator)) {

         last_stop = start + command.length

         while (last_stop + 1 > next_block) {

           blocks += (command -> start)

           next_block += block_size

         }

       }

       (blocks.toArray, Text.Range(0, last_stop))

     }

     def full_range: Text.Range = full_index._2

     def command_range(i: Text.Offset = 0): Iterator[(Command, Text.Offset)] =

     {

       if (!commands.isEmpty && full_range.contains(i)) {

         val (cmd0, start0) = full_index._1(i / block_size)

         Node.command_starts(commands.iterator(cmd0), start0) dropWhile {

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

       }

       else Iterator.empty

     }

     def command_range(range: Text.Range): Iterator[(Command, Text.Offset)] =

       command_range(range.start) takeWhile { case (_, start) => start < range.stop }

     def command_at(i: Text.Offset): Option[(Command, Text.Offset)] =

     {

       val range = command_range(i)

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

     }

     def proper_command_at(i: Text.Offset): Option[Command] =

       command_at(i) match {

         case Some((command, _)) =>

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

         case None => None

       }

     def command_start(cmd: Command): Option[Text.Offset] =

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

     def command_starts: Iterator[(Command, Text.Offset)] =

       Node.command_starts(commands.iterator)

   }

   /** versioning **/

   /* particular document versions */

   object Version

   {

     val init: Version = Version(no_id, Map().withDefaultValue(Node.empty))

   }

   type Nodes = Map[String, Node]

   sealed case class Version(val id: Version_ID, val nodes: Nodes)

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

   object Change

   {

     val init: Change = Change(Future.value(Version.init), Nil, Future.value(Version.init))

   }

   sealed case class Change(

     val previous: Future[Version],

     val edits: List[Edit_Text],

     val version: Future[Version])

   {

     def is_finished: Boolean = previous.is_finished && version.is_finished

   }

   /* history navigation */

   object History

   {

     val init: History = new History(List(Change.init))

   }

   // FIXME pruning, purging of state

   class History(val undo_list: List[Change])

   {

     require(!undo_list.isEmpty)

     def tip: Change = undo_list.head

     def +(change: Change): History = new History(change :: undo_list)

   }

   /** global state -- document structure, execution process, editing history **/

   abstract class Snapshot

   {

     val state: State

     val version: Version

     val node: Node

     val is_outdated: Boolean

     def command_state(command: Command): Command.State

     def convert(i: Text.Offset): Text.Offset

     def convert(range: Text.Range): Text.Range

     def revert(i: Text.Offset): Text.Offset

     def revert(range: Text.Range): Text.Range

     def select_markup[A](range: Text.Range)(result: Markup_Tree.Select[A])

       : Stream[Text.Info[Option[A]]]

   }

   type Assign =

    (List[(Document.Command_ID, Option[Document.Exec_ID])],  // exec state assignment

     List[(String, Option[Document.Command_ID])])  // last exec

   val no_assign: Assign = (Nil, Nil)

   object State

   {

     class Fail(state: State) extends Exception

     val init: State =

       State().define_version(Version.init, Assignment.init).assign(Version.init.id, no_assign)._2

     object Assignment

     {

       val init: Assignment = Assignment(Map.empty, Map.empty, false)

     }

     case class Assignment(

       val command_execs: Map[Command_ID, Exec_ID],

       val last_execs: Map[String, Option[Command_ID]],

       val is_finished: Boolean)

     {

       def check_finished: Assignment = { require(is_finished); this }

       def unfinished: Assignment = copy(is_finished = false)

       def assign(add_command_execs: List[(Command_ID, Option[Exec_ID])],

         add_last_execs: List[(String, Option[Command_ID])]): Assignment =

       {

         require(!is_finished)

         val command_execs1 =

           (command_execs /: add_command_execs) {

             case (res, (command_id, None)) => res - command_id

             case (res, (command_id, Some(exec_id))) => res + (command_id -> exec_id)

           }

         Assignment(command_execs1, last_execs ++ add_last_execs, true)

       }

     }

   }

   sealed case class State(

     val versions: Map[Version_ID, Version] = Map(),

     val commands: Map[Command_ID, Command.State] = Map(),  // static markup from define_command

     val execs: Map[Exec_ID, Command.State] = Map(),  // dynamic markup from execution

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

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

     val history: History = History.init)

   {

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

     def define_version(version: Version, assignment: State.Assignment): State =

     {

       val id = version.id

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

       copy(versions = versions + (id -> version),

         assignments = assignments + (id -> assignment.unfinished))

     }

     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 defined_command(id: Command_ID): Boolean = commands.isDefinedAt(id)

     def find_command(version: Version, id: ID): Option[(String, Node, Command)] =

       commands.get(id) orElse execs.get(id) match {

         case None => None

         case Some(st) =>

           val command = st.command

           version.nodes.find({ case (_, node) => node.commands(command) })

             .map({ case (name, node) => (name, node, command) })

       }

     def the_version(id: Version_ID): Version = versions.getOrElse(id, fail)

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

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

     def the_assignment(version: Version): State.Assignment =

       assignments.getOrElse(version.id, fail)

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

       execs.get(id) match {

         case Some(st) =>

           val new_st = st.accumulate(message)

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

         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, arg: Assign): (List[Command], State) =

     {

       val version = the_version(id)

       val (command_execs, last_execs) = arg

       val (changed_commands, new_execs) =

         ((Nil: List[Command], execs) /: command_execs) {

           case ((commands1, execs1), (cmd_id, exec)) =>

             val st = the_command(cmd_id)

             val commands2 = st.command :: commands1

             val execs2 =

               exec match {

                 case None => execs1

                 case Some(exec_id) => execs1 + (exec_id -> st)

               }

             (commands2, execs2)

         }

       val new_assignment = the_assignment(version).assign(command_execs, last_execs)

       val new_state = copy(assignments = assignments + (id -> new_assignment), execs = new_execs)

       (changed_commands, new_state)

     }

     def is_assigned(version: Version): Boolean =

       assignments.get(version.id) match {

         case Some(assgn) => assgn.is_finished

         case None => false

       }

     def is_stable(change: Change): Boolean =

       change.is_finished && is_assigned(change.version.get_finished)

     def recent_stable: Option[Change] = history.undo_list.find(is_stable)

     def tip_stable: Boolean = is_stable(history.tip)

     def tip_version: Version = history.tip.version.get_finished

     def last_exec_offset(name: String): Text.Offset =

     {

       val version = tip_version

       the_assignment(version).last_execs.get(name) match {

         case Some(Some(id)) =>

           val node = version.nodes(name)

           val cmd = the_command(id).command

           node.command_start(cmd) match {

             case None => 0

             case Some(start) => start + cmd.length

           }

         case _ => 0

       }

     }

     def continue_history(

         previous: Future[Version],

         edits: List[Edit_Text],

         version: Future[Version]): (Change, State) =

     {

       val change = Change(previous, edits, version)

       (change, copy(history = history + change))

     }

     // persistent user-view

     def snapshot(name: String, pending_edits: List[Text.Edit]): Snapshot =

     {

       val stable = recent_stable.get

       val latest = history.tip

       // FIXME proper treatment of removed nodes

       val edits =

         (pending_edits /: history.undo_list.takeWhile(_ != stable))((edits, change) =>

             (for ((a, Node.Edits(es)) <- change.edits if a == name) yield es).flatten ::: edits)

       lazy val reverse_edits = edits.reverse

       new Snapshot

       {

         val state = State.this

         val version = stable.version.get_finished

         val node = version.nodes(name)

         val is_outdated = !(pending_edits.isEmpty && latest == stable)

         def command_state(command: Command): Command.State =

           try {

             the_exec(the_assignment(version).check_finished.command_execs

               .getOrElse(command.id, fail))

           }

           catch { case _: State.Fail => command.empty_state }

         def convert(offset: Text.Offset) = (offset /: edits)((i, edit) => edit.convert(i))

         def revert(offset: Text.Offset) = (offset /: reverse_edits)((i, edit) => edit.revert(i))

         def convert(range: Text.Range) = (range /: edits)((r, edit) => edit.convert(r))

         def revert(range: Text.Range) = (range /: reverse_edits)((r, edit) => edit.revert(r))

         def select_markup[A](range: Text.Range)(result: Markup_Tree.Select[A])

           : Stream[Text.Info[Option[A]]] =

         {

           val former_range = revert(range)

           for {

             (command, command_start) <- node.command_range(former_range).toStream

             Text.Info(r0, x) <- command_state(command).markup.

               select((former_range - command_start).restrict(command.range)) {

                 case Text.Info(r0, info)

                 if result.isDefinedAt(Text.Info(convert(r0 + command_start), info)) =>

                   result(Text.Info(convert(r0 + command_start), info))

               }

           } yield Text.Info(convert(r0 + command_start), x)

         }

       }

     }

   }

 }