/*  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)

    /* 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.header match {

          case Exn.Res(deps) => deps.imports

          case _ => Nil

        }

      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 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_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

        val 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)

        }

      }

    }

  }

}