/*  Title:      Pure/General/symbol.scala

    Author:     Makarius

Detecting and recoding Isabelle symbols.

*/

package isabelle

import scala.io.Source

import scala.collection.mutable

import scala.util.matching.Regex

object Symbol

{

  type Symbol = String

  /* spaces */

  val spc = ' '

  val space = " "

  private val static_spaces = space * 4000

  def spaces(k: Int): String =

  {

    require(k >= 0)

    if (k < static_spaces.length) static_spaces.substring(0, k)

    else space * k

  }

  /* ASCII characters */

  def is_ascii_letter(c: Char): Boolean = 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'

  def is_ascii_digit(c: Char): Boolean = '0' <= c && c <= '9'

  def is_ascii_quasi(c: Char): Boolean = c == '_' || c == '\''

  def is_ascii_letdig(c: Char): Boolean =

    is_ascii_letter(c) || is_ascii_digit(c) || is_ascii_quasi(c)

  def is_ascii_identifier(s: String): Boolean =

    s.length > 0 && is_ascii_letter(s(0)) && s.substring(1).forall(is_ascii_letdig)

  /* Symbol regexps */

  private val plain = new Regex("""(?xs)

      [^\r\\\ud800-\udfff\ufffd] | [\ud800-\udbff][\udc00-\udfff] """)

  private val physical_newline = new Regex("""(?xs) \n | \r\n | \r """)

  private val symbol = new Regex("""(?xs)

      \\ < (?:

      \^? [A-Za-z][A-Za-z0-9_']* |

      \^raw: [\x20-\x7e\u0100-\uffff && [^.>]]* ) >""")

  private val malformed_symbol = new Regex("(?xs) (?!" + symbol + ")" +

    """ [\ud800-\udbff\ufffd] | \\<\^? """)

  val regex_total =

    new Regex(plain + "|" + physical_newline + "|" + symbol + "|" + malformed_symbol + "| .")

  /* basic matching */

  def is_plain(c: Char): Boolean = !(c == '\r' || c == '\\' || '\ud800' <= c && c <= '\udfff')

  def is_physical_newline(s: Symbol): Boolean =

    s == "\n" || s == "\r" || s == "\r\n"

  def is_malformed(s: Symbol): Boolean =

    !(s.length == 1 && is_plain(s(0))) && malformed_symbol.pattern.matcher(s).matches

  class Matcher(text: CharSequence)

  {

    private val matcher = regex_total.pattern.matcher(text)

    def apply(start: Int, end: Int): Int =

    {

      require(0 <= start && start < end && end <= text.length)

      if (is_plain(text.charAt(start))) 1

      else {

        matcher.region(start, end).lookingAt

        matcher.group.length

      }

    }

  }

  /* iterator */

  private val char_symbols: Array[Symbol] =

    (0 until 256).iterator.map(i => new String(Array(i.toChar))).toArray

  def iterator(text: CharSequence): Iterator[Symbol] =

    new Iterator[Symbol]

    {

      private val matcher = new Matcher(text)

      private var i = 0

      def hasNext = i < text.length

      def next =

      {

        val n = matcher(i, text.length)

        val s =

          if (n == 0) ""

          else if (n == 1) {

            val c = text.charAt(i)

            if (c < char_symbols.length) char_symbols(c)

            else text.subSequence(i, i + n).toString

          }

          else text.subSequence(i, i + n).toString

        i += n

        s

      }

    }

  /* decoding offsets */

  class Index(text: CharSequence)

  {

    case class Entry(chr: Int, sym: Int)

    val index: Array[Entry] =

    {

      val matcher = new Matcher(text)

      val buf = new mutable.ArrayBuffer[Entry]

      var chr = 0

      var sym = 0

      while (chr < text.length) {

        val n = matcher(chr, text.length)

        chr += n

        sym += 1

        if (n > 1) buf += Entry(chr, sym)

      }

      buf.toArray

    }

    def decode(sym1: Int): Int =

    {

      val sym = sym1 - 1

      val end = index.length

      def bisect(a: Int, b: Int): Int =

      {

        if (a < b) {

          val c = (a + b) / 2

          if (sym < index(c).sym) bisect(a, c)

          else if (c + 1 == end || sym < index(c + 1).sym) c

          else bisect(c + 1, b)

        }

        else -1

      }

      val i = bisect(0, end)

      if (i < 0) sym

      else index(i).chr + sym - index(i).sym

    }

    def decode(range: Text.Range): Text.Range = range.map(decode(_))

  }

  /* recoding text */

  private class Recoder(list: List[(String, String)])

  {

    private val (min, max) =

    {

      var min = '\uffff'

      var max = '\u0000'

      for ((x, _) <- list) {

        val c = x(0)

        if (c < min) min = c

        if (c > max) max = c

      }

      (min, max)

    }

    private val table =

    {

      var tab = Map[String, String]()

      for ((x, y) <- list) {

        tab.get(x) match {

          case None => tab += (x -> y)

          case Some(z) =>

            error("Duplicate mapping of \"" + x + "\" to \"" + y + "\" vs. \"" + z + "\"")

        }

      }

      tab

    }

    def recode(text: String): String =

    {

      val len = text.length

      val matcher = regex_total.pattern.matcher(text)

      val result = new StringBuilder(len)

      var i = 0

      while (i < len) {

        val c = text(i)

        if (min <= c && c <= max) {

          matcher.region(i, len).lookingAt

          val x = matcher.group

          result.append(table.get(x) getOrElse x)

          i = matcher.end

        }

        else { result.append(c); i += 1 }

      }

      result.toString

    }

  }

  /** symbol interpretation **/

  private lazy val symbols =

    new Interpretation(

      Isabelle_System.try_read(Path.split(Isabelle_System.getenv_strict("ISABELLE_SYMBOLS"))))

  private class Interpretation(symbols_spec: String)

  {

    /* read symbols */

    private val empty = new Regex("""(?xs) ^\s* (?: \#.* )? $ """)

    private val key = new Regex("""(?xs) (.+): """)

    private def read_decl(decl: String): (Symbol, Map[String, String]) =

    {

      def err() = error("Bad symbol declaration: " + decl)

      def read_props(props: List[String]): Map[String, String] =

      {

        props match {

          case Nil => Map()

          case _ :: Nil => err()

          case key(x) :: y :: rest => read_props(rest) + (x -> y)

          case _ => err()

        }

      }

      decl.split("\\s+").toList match {

        case sym :: props if sym.length > 1 && !is_malformed(sym) => (sym, read_props(props))

        case _ => err()

      }

    }

    private val symbols: List[(Symbol, Map[String, String])] =

      Map((

        for (decl <- split_lines(symbols_spec) if !empty.pattern.matcher(decl).matches)

          yield read_decl(decl)): _*) toList

    /* misc properties */

    val names: Map[Symbol, String] =

    {

      val name = new Regex("""\\<\^?([A-Za-z][A-Za-z0-9_']*)>""")

      Map((for ((sym @ name(a), _) <- symbols) yield (sym -> a)): _*)

    }

    val abbrevs: Map[Symbol, String] =

      Map((

        for ((sym, props) <- symbols if props.isDefinedAt("abbrev"))

          yield (sym -> props("abbrev"))): _*)

    /* recoding */

    private val (decoder, encoder) =

    {

      val mapping =

        for {

          (sym, props) <- symbols

          val code =

            try { Integer.decode(props("code")).intValue }

            catch {

              case _: NoSuchElementException => error("Missing code for symbol " + sym)

              case _: NumberFormatException => error("Bad code for symbol " + sym)

            }

          val ch = new String(Character.toChars(code))

        } yield {

          if (code < 128) error("Illegal ASCII code for symbol " + sym)

          else (sym, ch)

        }

      (new Recoder(mapping),

       new Recoder(mapping map { case (x, y) => (y, x) }))

    }

    def decode(text: String): String = decoder.recode(text)

    def encode(text: String): String = encoder.recode(text)

    private def recode_set(elems: String*): Set[String] =

    {

      val content = elems.toList

      Set((content ::: content.map(decode)): _*)

    }

    private def recode_map[A](elems: (String, A)*): Map[String, A] =

    {

      val content = elems.toList

      Map((content ::: content.map({ case (sym, a) => (decode(sym), a) })): _*)

    }

    /* user fonts */

    val fonts: Map[Symbol, String] =

      recode_map((

        for ((sym, props) <- symbols if props.isDefinedAt("font"))

          yield (sym -> props("font"))): _*)

    val font_names: List[String] = Set(fonts.toList.map(_._2): _*).toList

    val font_index: Map[String, Int] = Map((font_names zip (0 until font_names.length).toList): _*)

    /* classification */

    val letters = recode_set(

      "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",

      "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",

      "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",

      "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",

      "\\<A>", "\\<B>", "\\<C>", "\\<D>", "\\<E>", "\\<F>", "\\<G>",

      "\\<H>", "\\<I>", "\\<J>", "\\<K>", "\\<L>", "\\<M>", "\\<N>",

      "\\<O>", "\\<P>", "\\<Q>", "\\<R>", "\\<S>", "\\<T>", "\\<U>",

      "\\<V>", "\\<W>", "\\<X>", "\\<Y>", "\\<Z>", "\\<a>", "\\<b>",

      "\\<c>", "\\<d>", "\\<e>", "\\<f>", "\\<g>", "\\<h>", "\\<i>",

      "\\<j>", "\\<k>", "\\<l>", "\\<m>", "\\<n>", "\\<o>", "\\<p>",

      "\\<q>", "\\<r>", "\\<s>", "\\<t>", "\\<u>", "\\<v>", "\\<w>",

      "\\<x>", "\\<y>", "\\<z>",

      "\\<AA>", "\\<BB>", "\\<CC>", "\\<DD>", "\\<EE>", "\\<FF>",

      "\\<GG>", "\\<HH>", "\\<II>", "\\<JJ>", "\\<KK>", "\\<LL>",

      "\\<MM>", "\\<NN>", "\\<OO>", "\\<PP>", "\\<QQ>", "\\<RR>",

      "\\<SS>", "\\<TT>", "\\<UU>", "\\<VV>", "\\<WW>", "\\<XX>",

      "\\<YY>", "\\<ZZ>", "\\<aa>", "\\<bb>", "\\<cc>", "\\<dd>",

      "\\<ee>", "\\<ff>", "\\<gg>", "\\<hh>", "\\<ii>", "\\<jj>",

      "\\<kk>", "\\<ll>", "\\<mm>", "\\<nn>", "\\<oo>", "\\<pp>",

      "\\<qq>", "\\<rr>", "\\<ss>", "\\<tt>", "\\<uu>", "\\<vv>",

      "\\<ww>", "\\<xx>", "\\<yy>", "\\<zz>",

      "\\<alpha>", "\\<beta>", "\\<gamma>", "\\<delta>", "\\<epsilon>",

      "\\<zeta>", "\\<eta>", "\\<theta>", "\\<iota>", "\\<kappa>",

      "\\<mu>", "\\<nu>", "\\<xi>", "\\<pi>", "\\<rho>", "\\<sigma>",

      "\\<tau>", "\\<upsilon>", "\\<phi>", "\\<chi>", "\\<psi>",

      "\\<omega>", "\\<Gamma>", "\\<Delta>", "\\<Theta>", "\\<Lambda>",

      "\\<Xi>", "\\<Pi>", "\\<Sigma>", "\\<Upsilon>", "\\<Phi>",

      "\\<Psi>", "\\<Omega>",

      "\\<^isub>", "\\<^isup>")

    val blanks =

      recode_set(space, "\t", "\n", "\u000B", "\f", "\r", "\\<spacespace>", "\\<^newline>")

    val sym_chars =

      Set("!", "#", "$", "%", "&", "*", "+", "-", "/", "<", "=", ">", "?", "@", "^", "_", "|", "~")

    /* control symbols */

    val ctrl_decoded: Set[Symbol] =

      Set((for ((sym, _) <- symbols if sym.startsWith("\\<^")) yield decode(sym)): _*)

    val subscript_decoded = Set(decode("\\<^sub>"), decode("\\<^isub>"))

    val superscript_decoded = Set(decode("\\<^sup>"), decode("\\<^isup>"))

    val bold_decoded = decode("\\<^bold>")

    val bsub_decoded = decode("\\<^bsub>")

    val esub_decoded = decode("\\<^esub>")

    val bsup_decoded = decode("\\<^bsup>")

    val esup_decoded = decode("\\<^esup>")

  }

  /* tables */

  def names: Map[Symbol, String] = symbols.names

  def abbrevs: Map[Symbol, String] = symbols.abbrevs

  def decode(text: String): String = symbols.decode(text)

  def encode(text: String): String = symbols.encode(text)

  def fonts: Map[Symbol, String] = symbols.fonts

  def font_names: List[String] = symbols.font_names

  def font_index: Map[String, Int] = symbols.font_index

  def lookup_font(sym: Symbol): Option[Int] = symbols.fonts.get(sym).map(font_index(_))

  /* classification */

  def is_letter(sym: Symbol): Boolean = symbols.letters.contains(sym)

  def is_digit(sym: Symbol): Boolean = sym.length == 1 && '0' <= sym(0) && sym(0) <= '9'

  def is_quasi(sym: Symbol): Boolean = sym == "_" || sym == "'"

  def is_letdig(sym: Symbol): Boolean = is_letter(sym) || is_digit(sym) || is_quasi(sym)

  def is_blank(sym: Symbol): Boolean = symbols.blanks.contains(sym)

  def is_symbolic_char(sym: Symbol): Boolean = symbols.sym_chars.contains(sym)

  def is_symbolic(sym: Symbol): Boolean =

    sym.startsWith("\\<") && sym.endsWith(">") && !sym.startsWith("\\<^")

  /* control symbols */

  def is_ctrl(sym: Symbol): Boolean =

    sym.startsWith("\\<^") || symbols.ctrl_decoded.contains(sym)

  def is_controllable(sym: Symbol): Boolean =

    !is_blank(sym) && !is_ctrl(sym) && !is_malformed(sym)

  def is_subscript_decoded(sym: Symbol): Boolean = symbols.subscript_decoded.contains(sym)

  def is_superscript_decoded(sym: Symbol): Boolean = symbols.superscript_decoded.contains(sym)

  def is_bold_decoded(sym: Symbol): Boolean = sym == symbols.bold_decoded

  def is_bsub_decoded(sym: Symbol): Boolean = sym == symbols.bsub_decoded

  def is_esub_decoded(sym: Symbol): Boolean = sym == symbols.esub_decoded

  def is_bsup_decoded(sym: Symbol): Boolean = sym == symbols.bsup_decoded

  def is_esup_decoded(sym: Symbol): Boolean = sym == symbols.esup_decoded

}