/*  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 = Counter()

   /** document structure **/

   /* individual nodes */

   type Edit[A, B] = (Node.Name, 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[Node.Deps]

   object Node

   {

     sealed case class Deps(

       imports: List[Name],

       keywords: List[Outer_Syntax.Decl],

       uses: List[(String, Boolean)])

     object Name

     {

       val empty = Name("", "", "")

       def apply(path: Path): Name =

       {

         val node = path.implode

         val dir = path.dir.implode

         val theory = Thy_Header.thy_name(node) getOrElse error("Bad theory file name: " + path)

         Name(node, dir, theory)

       }

       object Ordering extends scala.math.Ordering[Name]

       {

         def compare(name1: Name, name2: Name): Int = name1.node compare name2.node

       }

     }

     sealed case class Name(node: String, dir: String, theory: String)

     {

       override def hashCode: Int = node.hashCode

       override def equals(that: Any): Boolean =

         that match {

           case other: Name => node == other.node

           case _ => false

         }

       override def toString: String = theory

     }

     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 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

     val empty: Node = new Node()

   }

   final class Node private(

     val header: Node_Header = Exn.Exn(ERROR("Bad theory header")),

     val perspective: Command.Perspective = Command.Perspective.empty,

     val blobs: Map[String, Blob] = Map.empty,

     val commands: Linear_Set[Command] = Linear_Set.empty)

   {

     def clear: Node = new Node(header = header)

     def update_header(new_header: Node_Header): Node =

       new Node(new_header, perspective, blobs, commands)

     def update_perspective(new_perspective: Command.Perspective): Node =

       new Node(header, new_perspective, blobs, commands)

     def update_blobs(new_blobs: Map[String, Blob]): Node =

       new Node(header, perspective, new_blobs, commands)

     def update_commands(new_commands: Linear_Set[Command]): Node =

       new Node(header, perspective, blobs, new_commands)

     def imports: List[Node.Name] =

       header match { case Exn.Res(deps) => deps.imports case _ => Nil }

     def keywords: List[Outer_Syntax.Decl] =

       header match { case Exn.Res(deps) => deps.keywords case _ => Nil }

     /* 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 += Node.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 / Node.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 command_start(cmd: Command): Option[Text.Offset] =

       Node.command_starts(commands.iterator).find(_._1 == cmd).map(_._2)

   }

   /* development graph */

   object Nodes

   {

     val empty: Nodes = new Nodes(Graph.empty(Node.Name.Ordering))

   }

   final class Nodes private(graph: Graph[Node.Name, Node])

   {

     def get_name(s: String): Option[Node.Name] =

       graph.keys.find(name => name.node == s)

     def apply(name: Node.Name): Node =

       graph.default_node(name, Node.empty).get_node(name)

     def + (entry: (Node.Name, Node)): Nodes =

     {

       val (name, node) = entry

       val imports = node.imports

       val graph1 =

         (graph.default_node(name, Node.empty) /: imports)((g, p) => g.default_node(p, Node.empty))

       val graph2 = (graph1 /: graph1.imm_preds(name))((g, dep) => g.del_edge(dep, name))

       val graph3 = (graph2 /: imports)((g, dep) => g.add_edge(dep, name))

       new Nodes(graph3.map_node(name, _ => node))

     }

     def entries: Iterator[(Node.Name, Node)] =

       graph.entries.map({ case (name, (node, _)) => (name, node) })

     def descendants(names: List[Node.Name]): List[Node.Name] = graph.all_succs(names)

     def topological_order: List[Node.Name] = graph.topological_order

   }

   /** versioning **/

   /* particular document versions */

   object Version

   {

     val init: Version = new Version()

     def make(syntax: Outer_Syntax, nodes: Nodes): Version =

       new Version(new_id(), syntax, nodes)

   }

   final class Version private(

     val id: Version_ID = no_id,

     val syntax: Outer_Syntax = Outer_Syntax.empty,

     val nodes: Nodes = Nodes.empty)

   {

     def is_init: Boolean = id == no_id

   }

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

   object Change

   {

     val init: Change = new Change()

     def make(previous: Future[Version], edits: List[Edit_Text], version: Future[Version]): Change =

       new Change(Some(previous), edits, version)

   }

   final class Change private(

     val previous: Option[Future[Version]] = Some(Future.value(Version.init)),

     val edits: List[Edit_Text] = Nil,

     val version: Future[Version] = Future.value(Version.init))

   {

     def is_finished: Boolean =

       (previous match { case None => true case Some(future) => future.is_finished }) &&

       version.is_finished

     def truncate: Change = new Change(None, Nil, version)

   }

   /* history navigation */

   object History

   {

     val init: History = new History()

   }

   final class History private(

     val undo_list: List[Change] = List(Change.init))  // non-empty list

   {

     def tip: Change = undo_list.head

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

     def prune(check: Change => Boolean, retain: Int): Option[(List[Change], History)] =

     {

       val n = undo_list.iterator.zipWithIndex.find(p => check(p._1)).get._2 + 1

       val (retained, dropped) = undo_list.splitAt(n max retain)

       retained.splitAt(retained.length - 1) match {

         case (prefix, List(last)) => Some(dropped, new History(prefix ::: List(last.truncate)))

         case _ => None

       }

     }

   }

   /** 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 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 cumulate_markup[A](range: Text.Range, info: A, elements: Option[Set[String]],

       result: PartialFunction[(A, Text.Markup), A]): Stream[Text.Info[A]]

     def select_markup[A](range: Text.Range, elements: Option[Set[String]],

       result: PartialFunction[Text.Markup, A]): Stream[Text.Info[A]]

   }

   type Assign =

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

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

   object State

   {

     class Fail(state: State) extends Exception

     object Assignment

     {

       val init: Assignment = new Assignment()

     }

     final class Assignment private(

       val command_execs: Map[Command_ID, Exec_ID] = Map.empty,

       val last_execs: Map[String, Option[Command_ID]] = Map.empty,

       val is_finished: Boolean = false)

     {

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

       def unfinished: Assignment = new Assignment(command_execs, last_execs, 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)

           }

         new Assignment(command_execs1, last_execs ++ add_last_execs, true)

       }

     }

     val init: State =

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

   }

   final case class State private(

     val versions: Map[Version_ID, Version] = Map.empty,

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

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

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

     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

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

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

     }

     def define_command(command: Command): State =

     {

       val id = command.id

       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[(Node, Command)] =

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

         case None => None

         case Some(st) =>

           val command = st.command

           val node = version.nodes(command.node_name)

           Some((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 + message

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

         case None =>

           commands.get(id) match {

             case Some(st) =>

               val new_st = st + message

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

             case None => fail

           }

       }

     def assign(id: Version_ID, arg: Assign = (Nil, Nil)): (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_finished: Change = history.undo_list.find(_.is_finished) getOrElse fail

     def recent_stable: Change = history.undo_list.find(is_stable) getOrElse fail

     def tip_stable: Boolean = is_stable(history.tip)

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

     def last_exec_offset(name: Node.Name): Text.Offset =

     {

       val version = tip_version

       the_assignment(version).last_execs.get(name.node) 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.make(previous, edits, version)

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

     }

     def prune_history(retain: Int = 0): (List[Version], State) =

     {

       history.prune(is_stable, retain) match {

         case Some((dropped, history1)) =>

           val dropped_versions = dropped.map(change => change.version.get_finished)

           val state1 = copy(history = history1)

           (dropped_versions, state1)

         case None => fail

       }

     }

     def removed_versions(removed: List[Version_ID]): State =

     {

       val versions1 = versions -- removed

       val assignments1 = assignments -- removed

       var commands1 = Map.empty[Command_ID, Command.State]

       var execs1 = Map.empty[Exec_ID, Command.State]

       for {

         (version_id, version) <- versions1.iterator

         command_execs = assignments1(version_id).command_execs

         (_, node) <- version.nodes.entries

         command <- node.commands.iterator

       } {

         val id = command.id

         if (!commands1.isDefinedAt(id) && commands.isDefinedAt(id))

           commands1 += (id -> commands(id))

         if (command_execs.isDefinedAt(id)) {

           val exec_id = command_execs(id)

           if (!execs1.isDefinedAt(exec_id) && execs.isDefinedAt(exec_id))

             execs1 += (exec_id -> execs(exec_id))

         }

       }

       copy(versions = versions1, commands = commands1, execs = execs1, assignments = assignments1)

     }

     def command_state(version: Version, command: Command): Command.State =

     {

       require(is_assigned(version))

       try {

         the_exec(the_assignment(version).check_finished.command_execs

           .getOrElse(command.id, fail))

       }

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

     }

     // persistent user-view

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

     {

       val stable = recent_stable

       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 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 cumulate_markup[A](range: Text.Range, info: A, elements: Option[Set[String]],

           result: PartialFunction[(A, Text.Markup), A]): Stream[Text.Info[A]] =

         {

           val former_range = revert(range)

           for {

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

             Text.Info(r0, a) <- state.command_state(version, command).markup.

               cumulate[A]((former_range - command_start).restrict(command.range), info, elements,

                 {

                   case (a, Text.Info(r0, b))

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

                     result((a, Text.Info(convert(r0 + command_start), b)))

                 })

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

         }

         def select_markup[A](range: Text.Range, elements: Option[Set[String]],

           result: PartialFunction[Text.Markup, A]): Stream[Text.Info[A]] =

         {

           val result1 =

             new PartialFunction[(Option[A], Text.Markup), Option[A]] {

               def isDefinedAt(arg: (Option[A], Text.Markup)): Boolean = result.isDefinedAt(arg._2)

               def apply(arg: (Option[A], Text.Markup)): Option[A] = Some(result(arg._2))

             }

           for (Text.Info(r, Some(x)) <- cumulate_markup(range, None, elements, result1))

             yield Text.Info(r, x)

         }

       }

     }

   }

 }