/*  Title:      Pure/PIDE/markup_tree.scala

     Module:     PIDE

     Author:     Fabian Immler, TU Munich

     Author:     Makarius

 Markup trees over nested / non-overlapping text ranges.

 */

 package isabelle

 import scala.collection.immutable.SortedMap

 import scala.collection.mutable

 import scala.annotation.tailrec

 object Markup_Tree

 {

   /* construct trees */

   val empty: Markup_Tree = new Markup_Tree(Branches.empty)

   def merge_disjoint(trees: List[Markup_Tree]): Markup_Tree =

     trees match {

       case Nil => empty

       case head :: tail =>

         new Markup_Tree(

           (head.branches /: tail) {

             case (branches, tree) =>

               (branches /: tree.branches) {

                 case (bs, (r, entry)) =>

                   require(!bs.isDefinedAt(r))

                   bs + (r -> entry)

               }

           })

     }

   /* tree building blocks */

   object Elements

   {

     val empty = new Elements(Set.empty)

   }

   final class Elements private(private val rep: Set[String])

   {

     def contains(name: String): Boolean = rep.contains(name)

     def + (name: String): Elements =

       if (contains(name)) this

       else new Elements(rep + name)

     def + (elem: XML.Elem): Elements = this + elem.markup.name

     def ++ (elems: Iterable[XML.Elem]): Elements = (this /: elems.iterator)(_ + _)

     def ++ (other: Elements): Elements =

       if (this eq other) this

       else if (rep.isEmpty) other

       else (this /: other.rep)(_ + _)

   }

   object Entry

   {

     def apply(markup: Text.Markup, subtree: Markup_Tree): Entry =

       Entry(markup.range, List(markup.info), Elements.empty + markup.info,

         subtree, subtree.make_elements)

     def apply(range: Text.Range, rev_markups: List[XML.Elem], subtree: Markup_Tree): Entry =

       Entry(range, rev_markups, Elements.empty ++ rev_markups,

         subtree, subtree.make_elements)

   }

   sealed case class Entry(

     range: Text.Range,

     rev_markup: List[XML.Elem],

     elements: Elements,

     subtree: Markup_Tree,

     subtree_elements: Elements)

   {

     def markup: List[XML.Elem] = rev_markup.reverse

     def + (markup: Text.Markup): Entry =

       copy(rev_markup = markup.info :: rev_markup, elements = elements + markup.info)

     def \ (markup: Text.Markup): Entry =

       copy(subtree = subtree + markup, subtree_elements = subtree_elements + markup.info)

   }

   object Branches

   {

     type T = SortedMap[Text.Range, Entry]

     val empty: T = SortedMap.empty(Text.Range.Ordering)

   }

   /* XML representation */

   @tailrec private def strip_elems(

       elems: List[XML.Elem], body: XML.Body): (List[XML.Elem], XML.Body) =

     body match {

       case List(XML.Wrapped_Elem(markup1, body1, body2)) =>

         strip_elems(XML.Elem(markup1, body1) :: elems, body2)

       case List(XML.Elem(markup1, body1)) =>

         strip_elems(XML.Elem(markup1, Nil) :: elems, body1)

       case _ => (elems, body)

     }

   private def make_trees(acc: (Int, List[Markup_Tree]), tree: XML.Tree): (Int, List[Markup_Tree]) =

     {

       val (offset, markup_trees) = acc

       strip_elems(Nil, List(tree)) match {

         case (Nil, body) =>

           (offset + XML.text_length(body), markup_trees)

         case (elems, body) =>

           val (end_offset, subtrees) = ((offset, Nil: List[Markup_Tree]) /: body)(make_trees)

           if (offset == end_offset) acc

           else {

             val range = Text.Range(offset, end_offset)

             val entry = Entry(range, elems, merge_disjoint(subtrees))

             (end_offset, new Markup_Tree(Branches.empty, entry) :: markup_trees)

           }

       }

     }

   def from_XML(body: XML.Body): Markup_Tree =

     merge_disjoint(((0, Nil: List[Markup_Tree]) /: body)(make_trees)._2)

 }

 final class Markup_Tree private(val branches: Markup_Tree.Branches.T)

 {

   import Markup_Tree._

   private def this(branches: Markup_Tree.Branches.T, entry: Markup_Tree.Entry) =

     this(branches + (entry.range -> entry))

   override def toString =

     branches.toList.map(_._2) match {

       case Nil => "Empty"

       case list => list.mkString("Tree(", ",", ")")

     }

   private def overlapping(range: Text.Range): Branches.T =

   {

     val start = Text.Range(range.start)

     val stop = Text.Range(range.stop)

     val bs = branches.range(start, stop)

     branches.get(stop) match {

       case Some(end) if range overlaps end.range => bs + (end.range -> end)

       case _ => bs

     }

   }

   def make_elements: Elements =

     (Elements.empty /: branches)(

       { case (elements, (_, entry)) => elements ++ entry.subtree_elements ++ entry.elements })

   def + (new_markup: Text.Markup): Markup_Tree =

   {

     val new_range = new_markup.range

     branches.get(new_range) match {

       case None => new Markup_Tree(branches, Entry(new_markup, empty))

       case Some(entry) =>

         if (entry.range == new_range)

           new Markup_Tree(branches, entry + new_markup)

         else if (entry.range.contains(new_range))

           new Markup_Tree(branches, entry \ new_markup)

         else if (new_range.contains(branches.head._1) && new_range.contains(branches.last._1))

           new Markup_Tree(Branches.empty, Entry(new_markup, this))

         else {

           val body = overlapping(new_range)

           if (body.forall(e => new_range.contains(e._1)))

             new Markup_Tree(branches -- body.keys, Entry(new_markup, new Markup_Tree(body)))

           else {

             java.lang.System.err.println("Ignored overlapping markup information: " + new_markup +

               body.filter(e => !new_range.contains(e._1)).mkString("\n"))

             this

           }

         }

     }

   }

   def ++ (other: Markup_Tree): Markup_Tree =

     (this /: other.branches)({ case (tree, (range, entry)) =>

       ((tree ++ entry.subtree) /: entry.markup)({ case (t, elem) => t + Text.Info(range, elem) }) })

   def to_XML(root_range: Text.Range, text: CharSequence, filter: XML.Elem => Boolean): XML.Body =

   {

     def make_text(start: Text.Offset, stop: Text.Offset): XML.Body =

       if (start == stop) Nil

       else List(XML.Text(text.subSequence(start, stop).toString))

     def make_elems(rev_markups: List[XML.Elem], body: XML.Body): XML.Body =

       (body /: rev_markups) {

         case (b, elem) =>

           if (!filter(elem)) b

           else if (elem.body.isEmpty) List(XML.Elem(elem.markup, b))

           else List(XML.Wrapped_Elem(elem.markup, elem.body, b))

       }

     def make_body(elem_range: Text.Range, elem_markup: List[XML.Elem], entries: Branches.T)

       : XML.Body =

     {

       val body = new mutable.ListBuffer[XML.Tree]

       var last = elem_range.start

       for ((range, entry) <- entries) {

         val subrange = range.restrict(elem_range)

         body ++= make_text(last, subrange.start)

         body ++= make_body(subrange, entry.rev_markup, entry.subtree.overlapping(subrange))

         last = subrange.stop

       }

       body ++= make_text(last, elem_range.stop)

       make_elems(elem_markup, body.toList)

     }

    make_body(root_range, Nil, overlapping(root_range))

   }

   def to_XML(text: CharSequence): XML.Body =

     to_XML(Text.Range(0, text.length), text, (_: XML.Elem) => true)

   def cumulate[A](root_range: Text.Range, root_info: A, result_elements: Option[Set[String]],

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

   {

     val notable: Elements => Boolean =

       result_elements match {

         case Some(res) => (elements: Elements) => res.exists(elements.contains)

         case None => (elements: Elements) => true

       }

     def results(x: A, entry: Entry): Option[A] =

     {

       val (y, changed) =

         // FIXME proper cumulation order (including status markup) (!?)

         ((x, false) /: entry.rev_markup)((res, info) =>

           {

             val (y, changed) = res

             val arg = (y, Text.Info(entry.range, info))

             if (result.isDefinedAt(arg)) (result(arg), true)

             else res

           })

       if (changed) Some(y) else None

     }

     def stream(

       last: Text.Offset,

       stack: List[(Text.Info[A], Stream[(Text.Range, Entry)])]): Stream[Text.Info[A]] =

     {

       stack match {

         case (parent, (range, entry) #:: more) :: rest =>

           val subrange = range.restrict(root_range)

           val subtree =

             if (notable(entry.subtree_elements))

               entry.subtree.overlapping(subrange).toStream

             else Stream.empty

           val start = subrange.start

           (if (notable(entry.elements)) results(parent.info, entry) else None) match {

             case Some(res) =>

               val next = Text.Info(subrange, res)

               val nexts = stream(start, (next, subtree) :: (parent, more) :: rest)

               if (last < start) parent.restrict(Text.Range(last, start)) #:: nexts

               else nexts

             case None => stream(last, (parent, subtree #::: more) :: rest)

           }

         case (parent, Stream.Empty) :: rest =>

           val stop = parent.range.stop

           val nexts = stream(stop, rest)

           if (last < stop) parent.restrict(Text.Range(last, stop)) #:: nexts

           else nexts

         case Nil =>

           val stop = root_range.stop

           if (last < stop) Stream(Text.Info(Text.Range(last, stop), root_info))

           else Stream.empty

       }

     }

     stream(root_range.start,

       List((Text.Info(root_range, root_info), overlapping(root_range).toStream)))

   }

 }