/*  Title:      Pure/Thy/completion.scala

    Author:     Makarius

Completion of symbols and keywords.

*/

package isabelle

import scala.util.matching.Regex

import scala.util.parsing.combinator.RegexParsers

private object Completion

{

  /** word completion **/

  val word_regex = "[a-zA-Z0-9_']+".r

  def is_word(s: CharSequence): Boolean = word_regex.pattern.matcher(s).matches

  object Parse extends RegexParsers

  {

    override val whiteSpace = "".r

    def reverse_symbol: Parser[String] = """>[A-Za-z0-9_']+\^?<\\""".r

    def reverse_symb: Parser[String] = """[A-Za-z0-9_']{2,}\^?<\\""".r

    def word: Parser[String] = "[a-zA-Z0-9_']{2,}".r

    def read(in: CharSequence): Option[String] =

    {

      val reverse_in = new Library.Reverse(in)

      parse((reverse_symbol | reverse_symb | word) ^^ (_.reverse), reverse_in) match {

        case Success(result, _) => Some(result)

        case _ => None

      }

    }

  }

}

class Completion

{

  /* representation */

  protected val words_lex = Scan.Lexicon()

  protected val words_map = Map[String, String]()

  protected val abbrevs_lex = Scan.Lexicon()

  protected val abbrevs_map = Map[String, (String, String)]()

  /* adding stuff */

  def + (keyword: String, replace: String): Completion =

  {

    val old = this

    new Completion {

      override val words_lex = old.words_lex + keyword

      override val words_map = old.words_map + (keyword -> replace)

      override val abbrevs_lex = old.abbrevs_lex

      override val abbrevs_map = old.abbrevs_map

    }

  }

  def + (keyword: String): Completion = this + (keyword, keyword)

  def add_symbols: Completion =

  {

    val words =

      (for ((x, _) <- Symbol.names) yield (x, x)).toList :::

      (for ((x, y) <- Symbol.names) yield (y, x)).toList :::

      (for ((x, y) <- Symbol.abbrevs if Completion.is_word(y)) yield (y, x)).toList

    val abbrs =

      (for ((x, y) <- Symbol.abbrevs if !Completion.is_word(y))

        yield (y.reverse.toString, (y, x))).toList

    val old = this

    new Completion {

      override val words_lex = old.words_lex ++ words.map(_._1)

      override val words_map = old.words_map ++ words

      override val abbrevs_lex = old.abbrevs_lex ++ abbrs.map(_._1)

      override val abbrevs_map = old.abbrevs_map ++ abbrs

    }

  }

  /* complete */

  def complete(line: CharSequence): Option[(String, List[String])] =

  {

    abbrevs_lex.parse(abbrevs_lex.keyword, new Library.Reverse(line)) match {

      case abbrevs_lex.Success(reverse_a, _) =>

        val (word, c) = abbrevs_map(reverse_a)

        Some(word, List(c))

      case _ =>

        Completion.Parse.read(line) match {

          case Some(word) =>

            words_lex.completions(word).map(words_map(_)) match {

              case Nil => None

              case cs => Some(word, cs.sortWith(_ < _))

            }

          case None => None

        }

    }

  }

}