/*

 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.jshell;

import com.sun.tools.javac.code.Source;

import com.sun.tools.javac.parser.Scanner;

import com.sun.tools.javac.parser.ScannerFactory;

import com.sun.tools.javac.parser.Tokens.Token;

import com.sun.tools.javac.parser.Tokens.TokenKind;

import com.sun.tools.javac.util.Context;

import com.sun.tools.javac.util.JCDiagnostic;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

import com.sun.tools.javac.util.Log;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.util.ArrayDeque;

import java.util.Deque;

import java.util.EnumMap;

import java.util.Iterator;

import jdk.jshell.SourceCodeAnalysis.Completeness;

import com.sun.source.tree.Tree;

import static jdk.jshell.CompletenessAnalyzer.TK.*;

import jdk.jshell.TaskFactory.ParseTask;

import java.util.List;

import java.util.function.Function;

import java.util.function.Supplier;

/**

 * Low level scanner to determine completeness of input.

 * @author Robert Field

 */

class CompletenessAnalyzer {

    private final ScannerFactory scannerFactory;

    private final JShell proc;

    private static Completeness error() {

        return Completeness.UNKNOWN;  // For breakpointing

    }

    static class CaInfo {

        CaInfo(Completeness status, int unitEndPos) {

            this.status = status;

            this.unitEndPos = unitEndPos;

        }

        final int unitEndPos;

        final Completeness status;

    }

    CompletenessAnalyzer(JShell proc) {

        this.proc = proc;

        Context context = new Context();

        Log log = CaLog.createLog(context);

        context.put(Log.class, log);

        context.put(Source.class, Source.JDK1_9);

        scannerFactory = ScannerFactory.instance(context);

    }

    CaInfo scan(String s) {

        try {

            Parser parser = new Parser(

                    () -> new Matched(scannerFactory.newScanner(s, false)),

            Completeness stat = parser.parseUnit();

            int endPos = stat == Completeness.UNKNOWN

                    ? s.length()

                    : parser.endPos();

            return new CaInfo(stat, endPos);

        } catch (SyntaxException ex) {

            return new CaInfo(error(), s.length());

        }

    }

    @SuppressWarnings("serial")             // serialVersionUID intentionally omitted

    private static class SyntaxException extends RuntimeException {

    }

    private static void die() {

        throw new SyntaxException();

    }

    /**

     * Subclass of Log used by compiler API to die on error and ignore

     * other messages

     */

    private static class CaLog extends Log {

        private static CaLog createLog(Context context) {

            PrintWriter pw = new PrintWriter(new StringWriter());

            CaLog log = new CaLog(context, pw);

            context.put(logKey, log);

            return log;

        }

        private CaLog(Context context, PrintWriter pw) {

            super(context, pw);

        }

        @Override

        public void error(String key, Object... args) {

            die();

        }

        @Override

        public void error(DiagnosticPosition pos, String key, Object... args) {

            die();

        }

        @Override

        public void error(DiagnosticFlag flag, DiagnosticPosition pos, String key, Object... args) {

            die();

        }

        @Override

        public void error(int pos, String key, Object... args) {

            die();

        }

        @Override

        public void error(DiagnosticFlag flag, int pos, String key, Object... args) {

            die();

        }

        @Override

        public void report(JCDiagnostic diagnostic) {

            // Ignore

        }

    }

    // Location position kinds -- a token is ...

    private static final int XEXPR         = 0b1;                       // OK in expression (not first)

    private static final int XDECL         = 0b10;                      // OK in declaration (not first)

    private static final int XSTMT         = 0b100;                     // OK in statement framework (not first)

    private static final int XEXPR1o       = 0b1000;                    // OK first in expression

    private static final int XDECL1o       = 0b10000;                   // OK first in declaration

    private static final int XSTMT1o       = 0b100000;                  // OK first or only in statement framework

    private static final int XEXPR1        = XEXPR1o | XEXPR;           // OK in expression (anywhere)

    private static final int XDECL1        = XDECL1o | XDECL;           // OK in declaration (anywhere)

    private static final int XSTMT1        = XSTMT1o | XSTMT;           // OK in statement framework (anywhere)

    private static final int XANY1         = XEXPR1o | XDECL1o | XSTMT1o;  // Mask: first in statement, declaration, or expression

    private static final int XTERM         = 0b100000000;               // Can terminate (last before EOF)

    private static final int XSTART        = 0b1000000000;              // Boundary, must be XTERM before

    private static final int XERRO         = 0b10000000000;             // Is an error

    private static final int XBRACESNEEDED = 0b100000000000;            // Expect {ANY} LBRACE

    /**

     * An extension of the compiler's TokenKind which adds our combined/processed

     * kinds. Also associates each TK with a union of acceptable kinds of code

     * position it can occupy.  For example: IDENTIFER is XEXPR1|XDECL1|XTERM,

     * meaning it can occur in expressions or declarations (but not in the

     * framework of a statement and that can be the final (terminating) token

     * in a snippet.

     * <P>

     * There must be a TK defined for each compiler TokenKind, an exception

     * will

     * be thrown if a TokenKind is defined and a corresponding TK is not. Add a

     * new TK in the appropriate category. If it is like an existing category

     * (e.g. a new modifier or type this may be all that is needed.  If it

     * is bracketing or modifies the acceptable positions of other tokens,

     * please closely examine the needed changes to this scanner.

     */

    static enum TK {

        // Special

        EOF(TokenKind.EOF, 0),  //

        ERROR(TokenKind.ERROR, XERRO),  //

        IDENTIFIER(TokenKind.IDENTIFIER, XEXPR1|XDECL1|XTERM),  //

        UNDERSCORE(TokenKind.UNDERSCORE, XERRO),  //  _

        CLASS(TokenKind.CLASS, XEXPR|XDECL1|XBRACESNEEDED),  //  class decl (MAPPED: DOTCLASS)

        MONKEYS_AT(TokenKind.MONKEYS_AT, XEXPR|XDECL1),  //  @

        IMPORT(TokenKind.IMPORT, XDECL1|XSTART),  //  import -- consider declaration

        SEMI(TokenKind.SEMI, XSTMT1|XTERM|XSTART),  //  ;

        // Shouldn't see -- error

        PACKAGE(TokenKind.PACKAGE, XERRO),  //  package

        CONST(TokenKind.CONST, XERRO),  //  reserved keyword -- const

        GOTO(TokenKind.GOTO, XERRO),  //  reserved keyword -- goto

        CUSTOM(TokenKind.CUSTOM, XERRO),  // No uses

        // Declarations

        ENUM(TokenKind.ENUM, XDECL1|XBRACESNEEDED),  //  enum

        IMPLEMENTS(TokenKind.IMPLEMENTS, XDECL),  //  implements

        INTERFACE(TokenKind.INTERFACE, XDECL1|XBRACESNEEDED),  //  interface

        THROWS(TokenKind.THROWS, XDECL|XBRACESNEEDED),  //  throws

        // Primarive type names

        BOOLEAN(TokenKind.BOOLEAN, XEXPR1|XDECL1),  //  boolean

        BYTE(TokenKind.BYTE, XEXPR1|XDECL1),  //  byte

        CHAR(TokenKind.CHAR, XEXPR1|XDECL1),  //  char

        DOUBLE(TokenKind.DOUBLE, XEXPR1|XDECL1),  //  double

        FLOAT(TokenKind.FLOAT, XEXPR1|XDECL1),  //  float

        INT(TokenKind.INT, XEXPR1|XDECL1),  //  int

        LONG(TokenKind.LONG, XEXPR1|XDECL1),  //  long

        SHORT(TokenKind.SHORT, XEXPR1|XDECL1),  //  short

        VOID(TokenKind.VOID, XEXPR1|XDECL1),  //  void

        // Modifiers keywords

        ABSTRACT(TokenKind.ABSTRACT, XDECL1),  //  abstract

        FINAL(TokenKind.FINAL, XDECL1),  //  final

        NATIVE(TokenKind.NATIVE, XDECL1),  //  native

        STATIC(TokenKind.STATIC, XDECL1),  //  static

        STRICTFP(TokenKind.STRICTFP, XDECL1),  //  strictfp

        PRIVATE(TokenKind.PRIVATE, XDECL1),  //  private

        PROTECTED(TokenKind.PROTECTED, XDECL1),  //  protected

        PUBLIC(TokenKind.PUBLIC, XDECL1),  //  public

        TRANSIENT(TokenKind.TRANSIENT, XDECL1),  //  transient

        VOLATILE(TokenKind.VOLATILE, XDECL1),  //  volatile

        // Declarations and type parameters (thus expressions)

        EXTENDS(TokenKind.EXTENDS, XEXPR|XDECL),  //  extends

        COMMA(TokenKind.COMMA, XEXPR|XDECL),  //  ,

        AMP(TokenKind.AMP, XEXPR|XDECL),  //  &

        GT(TokenKind.GT, XEXPR|XDECL),  //  >

        LT(TokenKind.LT, XEXPR|XDECL1),  //  <

        LTLT(TokenKind.LTLT, XEXPR|XDECL1),  //  <<

        GTGT(TokenKind.GTGT, XEXPR|XDECL),  //  >>

        GTGTGT(TokenKind.GTGTGT, XEXPR|XDECL),  //  >>>

        QUES(TokenKind.QUES, XEXPR|XDECL),  //  ?

        DOT(TokenKind.DOT, XEXPR|XDECL),  //  .

        STAR(TokenKind.STAR, XEXPR),  //  * (MAPPED: DOTSTAR)

        // Statement keywords

        ASSERT(TokenKind.ASSERT, XSTMT1|XSTART),  //  assert

        BREAK(TokenKind.BREAK, XSTMT1|XTERM|XSTART),  //  break

        CATCH(TokenKind.CATCH, XSTMT1|XSTART),  //  catch

        CONTINUE(TokenKind.CONTINUE, XSTMT1|XTERM|XSTART),  //  continue

        DO(TokenKind.DO, XSTMT1|XSTART),  //  do

        ELSE(TokenKind.ELSE, XSTMT1|XTERM|XSTART),  //  else

        FINALLY(TokenKind.FINALLY, XSTMT1|XSTART),  //  finally

        FOR(TokenKind.FOR, XSTMT1|XSTART),  //  for

        IF(TokenKind.IF, XSTMT1|XSTART),  //  if

        RETURN(TokenKind.RETURN, XSTMT1|XTERM|XSTART),  //  return

        SWITCH(TokenKind.SWITCH, XSTMT1|XSTART),  //  switch

        SYNCHRONIZED(TokenKind.SYNCHRONIZED, XSTMT1|XDECL),  //  synchronized

        THROW(TokenKind.THROW, XSTMT1|XSTART),  //  throw

        TRY(TokenKind.TRY, XSTMT1|XSTART),  //  try

        WHILE(TokenKind.WHILE, XSTMT1|XSTART),  //  while

        // Statement keywords that we shouldn't see -- inside braces

        CASE(TokenKind.CASE, XSTMT|XSTART),  //  case

        DEFAULT(TokenKind.DEFAULT, XSTMT|XSTART),  //  default method, default case -- neither we should see

        // Expressions (can terminate)

        INTLITERAL(TokenKind.INTLITERAL, XEXPR1|XTERM),  //

        LONGLITERAL(TokenKind.LONGLITERAL, XEXPR1|XTERM),  //

        FLOATLITERAL(TokenKind.FLOATLITERAL, XEXPR1|XTERM),  //

        DOUBLELITERAL(TokenKind.DOUBLELITERAL, XEXPR1|XTERM),  //

        CHARLITERAL(TokenKind.CHARLITERAL, XEXPR1|XTERM),  //

        STRINGLITERAL(TokenKind.STRINGLITERAL, XEXPR1|XTERM),  //

        TRUE(TokenKind.TRUE, XEXPR1|XTERM),  //  true

        FALSE(TokenKind.FALSE, XEXPR1|XTERM),  //  false

        NULL(TokenKind.NULL, XEXPR1|XTERM),  //  null

        THIS(TokenKind.THIS, XEXPR1|XTERM),  //  this  -- shouldn't see

        // Expressions maybe terminate  //TODO handle these case separately

        PLUSPLUS(TokenKind.PLUSPLUS, XEXPR1|XTERM),  //  ++

        SUBSUB(TokenKind.SUBSUB, XEXPR1|XTERM),  //  --

        // Expressions cannot terminate

        INSTANCEOF(TokenKind.INSTANCEOF, XEXPR),  //  instanceof

        NEW(TokenKind.NEW, XEXPR1),  //  new (MAPPED: COLCOLNEW)

        SUPER(TokenKind.SUPER, XEXPR1|XDECL),  //  super -- shouldn't see as rec. But in type parameters

        ARROW(TokenKind.ARROW, XEXPR),  //  ->

        COLCOL(TokenKind.COLCOL, XEXPR),  //  ::

        LPAREN(TokenKind.LPAREN, XEXPR),  //  (

        RPAREN(TokenKind.RPAREN, XEXPR),  //  )

        LBRACE(TokenKind.LBRACE, XEXPR),  //  {

        RBRACE(TokenKind.RBRACE, XEXPR),  //  }

        LBRACKET(TokenKind.LBRACKET, XEXPR),  //  [

        RBRACKET(TokenKind.RBRACKET, XEXPR),  //  ]

        ELLIPSIS(TokenKind.ELLIPSIS, XEXPR),  //  ...

        EQ(TokenKind.EQ, XEXPR),  //  =

        BANG(TokenKind.BANG, XEXPR1),  //  !

        TILDE(TokenKind.TILDE, XEXPR1),  //  ~

        COLON(TokenKind.COLON, XEXPR|XTERM),  //  :

        EQEQ(TokenKind.EQEQ, XEXPR),  //  ==

        LTEQ(TokenKind.LTEQ, XEXPR),  //  <=

        GTEQ(TokenKind.GTEQ, XEXPR),  //  >=

        BANGEQ(TokenKind.BANGEQ, XEXPR),  //  !=

        AMPAMP(TokenKind.AMPAMP, XEXPR),  //  &&

        BARBAR(TokenKind.BARBAR, XEXPR),  //  ||

        PLUS(TokenKind.PLUS, XEXPR1),  //  +

        SUB(TokenKind.SUB, XEXPR1),  //  -

        SLASH(TokenKind.SLASH, XEXPR),  //  /

        BAR(TokenKind.BAR, XEXPR),  //  |

        CARET(TokenKind.CARET, XEXPR),  //  ^

        PERCENT(TokenKind.PERCENT, XEXPR),  //  %

        PLUSEQ(TokenKind.PLUSEQ, XEXPR),  //  +=

        SUBEQ(TokenKind.SUBEQ, XEXPR),  //  -=

        STAREQ(TokenKind.STAREQ, XEXPR),  //  *=

        SLASHEQ(TokenKind.SLASHEQ, XEXPR),  //  /=

        AMPEQ(TokenKind.AMPEQ, XEXPR),  //  &=

        BAREQ(TokenKind.BAREQ, XEXPR),  //  |=

        CARETEQ(TokenKind.CARETEQ, XEXPR),  //  ^=

        PERCENTEQ(TokenKind.PERCENTEQ, XEXPR),  //  %=

        LTLTEQ(TokenKind.LTLTEQ, XEXPR),  //  <<=

        GTGTEQ(TokenKind.GTGTEQ, XEXPR),  //  >>=

        GTGTGTEQ(TokenKind.GTGTGTEQ, XEXPR),  //  >>>=

        // combined/processed kinds

        UNMATCHED(XERRO),

        PARENS(XEXPR1|XDECL|XSTMT|XTERM),

        BRACKETS(XEXPR|XDECL|XTERM),

        BRACES(XSTMT1|XEXPR|XTERM),

        DOTSTAR(XDECL|XTERM),  // import foo.*

        COLCOLNEW(XEXPR|XTERM),  //  :: new

        DOTCLASS(XEXPR|XTERM),  //  class decl and .class

        ;

        static final EnumMap<TokenKind,TK> tokenKindToTKMap = new EnumMap<>(TokenKind.class);

        final TokenKind tokenKind;

        final int belongs;

        Function<TK,TK> mapping;

        TK(int b) {

            this(null, b);

        }

        TK(TokenKind tokenKind, int b) {

            this.tokenKind = tokenKind;

            this.belongs = b;

            this.mapping = null;

        }

        private static TK tokenKindToTK(TK prev, TokenKind kind) {

            TK tk = tokenKindToTKMap.get(kind);

            if (tk == null) {

                System.err.printf("No corresponding %s for %s: %s\n",

                        TK.class.getCanonicalName(),

                        TokenKind.class.getCanonicalName(),

                        kind);

                throw new InternalError("No corresponding TK for TokenKind: " + kind);

            }

            return tk.mapping != null

                    ? tk.mapping.apply(prev)

                    : tk;

        }

        boolean isOkToTerminate() {

            return (belongs & XTERM) != 0;

        }

        boolean isExpression() {

            return (belongs & XEXPR) != 0;

        }

        boolean isDeclaration() {

            return (belongs & XDECL) != 0;

        }

        boolean isError() {

            return (belongs & XERRO) != 0;

        }

        boolean isStart() {

            return (belongs & XSTART) != 0;

        }

        boolean isBracesNeeded() {

            return (belongs & XBRACESNEEDED) != 0;

        }

        /**

         * After construction, check that all compiler TokenKind values have

         * corresponding TK values.

         */

        static {

            for (TK tk : TK.values()) {

                if (tk.tokenKind != null) {

                    tokenKindToTKMap.put(tk.tokenKind, tk);

                }

            }

            for (TokenKind kind : TokenKind.values()) {

                tokenKindToTK(null, kind); // assure they can be retrieved without error

            }

            // Mappings of disambiguated contexts

            STAR.mapping  = prev -> prev == DOT ? DOTSTAR : STAR;

            NEW.mapping   = prev -> prev == COLCOL ? COLCOLNEW : NEW;

            CLASS.mapping = prev -> prev == DOT ? DOTCLASS : CLASS;

        }

    }

    /**

     * A completeness scanner token.

     */

    private static class CT {

        /** The token kind */

        public final TK kind;

        /** The end position of this token */

        public final int endPos;

        /** The error message **/

        public final String message;

        private CT(TK tk, Token tok, String msg) {

            this.kind = tk;

            this.endPos = tok.endPos;

            this.message = msg;

            //throw new InternalError(msg); /* for debugging */

        }

        private CT(TK tk, Token tok) {

            this.kind = tk;

            this.endPos = tok.endPos;

            this.message = null;

        }

        private CT(TK tk, int endPos) {

            this.kind = tk;

            this.endPos = endPos;

            this.message = null;

        }

    }

    /**

     * Look for matching tokens (like parens) and other special cases, like "new"

     */

    private static class Matched implements Iterator<CT> {

        private final Scanner scanner;

        private Token current;

        private CT prevCT;

        private CT currentCT;

        private final Deque<Token> stack = new ArrayDeque<>();

        Matched(Scanner scanner) {

            this.scanner = scanner;

            advance();

            prevCT = currentCT = new CT(SEMI, 0); // So is valid for testing

        }

        @Override

        public boolean hasNext() {

            return currentCT.kind != EOF;

        }

        private Token advance() {

            Token prev = current;

            scanner.nextToken();

            current = scanner.token();

            return prev;

        }

        @Override

        public CT next() {

            prevCT = currentCT;

            currentCT = nextCT();

            return currentCT;

        }

        private CT match(TK tk, TokenKind open) {

            Token tok = advance();

            db("match desired-tk=%s, open=%s, seen-tok=%s", tk, open, tok.kind);

            if (stack.isEmpty()) {

                return new CT(ERROR, tok, "Encountered '" + tok + "' with no opening '" + open + "'");

            }

            Token p = stack.pop();

            if (p.kind != open) {

                return new CT(ERROR, tok, "No match for '" + p + "' instead encountered '" + tok + "'");

            }

            return new CT(tk, tok);

        }

        private void db(String format, Object ... args) {

//            System.err.printf(format, args);

//            System.err.printf(" -- stack(");

//            if (stack.isEmpty()) {

//

//            } else {

//                for (Token tok : stack) {

//                    System.err.printf("%s ", tok.kind);

//                }

//            }

//            System.err.printf(") current=%s / currentCT=%s\n", current.kind, currentCT.kind);

        }

        /**

         * @return the next scanner token

         */

        private CT nextCT() {

            // TODO Annotations?

            TK prevTK = currentCT.kind;

            while (true) {

                db("nextCT");

                CT ct;

                switch (current.kind) {

                    case EOF:

                        db("eof");

                        if (stack.isEmpty()) {

                            ct = new CT(EOF, current);

                        } else {

                            TokenKind unmatched = stack.pop().kind;

                            stack.clear(); // So we will get EOF next time

                            ct = new CT(UNMATCHED, current, "Unmatched " + unmatched);