﻿/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

#pragma once

namespace antlr4 {

  /**
   * Useful for rewriting out a buffered input token stream after doing some
   * augmentation or other manipulations on it.
   *
   * <p>
   * You can insert stuff, replace, and delete chunks. Note that the operations
   * are done lazily--only if you convert the buffer to a {@link String} with
   * {@link TokenStream#getText()}. This is very efficient because you are not
   * moving data around all the time. As the buffer of tokens is converted to
   * strings, the {@link #getText()} method(s) scan the input token stream and
   * check to see if there is an operation at the current index. If so, the
   * operation is done and then normal {@link String} rendering continues on the
   * buffer. This is like having multiple Turing machine instruction streams
   * (programs) operating on a single input tape. :)</p>
   *
   * <p>
   * This rewriter makes no modifications to the token stream. It does not ask the
   * stream to fill itself up nor does it advance the input cursor. The token
   * stream {@link TokenStream#index()} will return the same value before and
   * after any {@link #getText()} call.</p>
   *
   * <p>
   * The rewriter only works on tokens that you have in the buffer and ignores the
   * current input cursor. If you are buffering tokens on-demand, calling
   * {@link #getText()} halfway through the input will only do rewrites for those
   * tokens in the first half of the file.</p>
   *
   * <p>
   * Since the operations are done lazily at {@link #getText}-time, operations do
   * not screw up the token index values. That is, an insert operation at token
   * index {@code i} does not change the index values for tokens
   * {@code i}+1..n-1.</p>
   *
   * <p>
   * Because operations never actually alter the buffer, you may always get the
   * original token stream back without undoing anything. Since the instructions
   * are queued up, you can easily simulate transactions and roll back any changes
   * if there is an error just by removing instructions. For example,</p>
   *
   * <pre>
   * CharStream input = new ANTLRFileStream("input");
   * TLexer lex = new TLexer(input);
   * CommonTokenStream tokens = new CommonTokenStream(lex);
   * T parser = new T(tokens);
   * TokenStreamRewriter rewriter = new TokenStreamRewriter(tokens);
   * parser.startRule();
   * </pre>
   *
   * <p>
   * Then in the rules, you can execute (assuming rewriter is visible):</p>
   *
   * <pre>
   * Token t,u;
   * ...
   * rewriter.insertAfter(t, "text to put after t");}
   * rewriter.insertAfter(u, "text after u");}
   * System.out.println(rewriter.getText());
   * </pre>
   *
   * <p>
   * You can also have multiple "instruction streams" and get multiple rewrites
   * from a single pass over the input. Just name the instruction streams and use
   * that name again when printing the buffer. This could be useful for generating
   * a C file and also its header file--all from the same buffer:</p>
   *
   * <pre>
   * rewriter.insertAfter("pass1", t, "text to put after t");}
   * rewriter.insertAfter("pass2", u, "text after u");}
   * System.out.println(rewriter.getText("pass1"));
   * System.out.println(rewriter.getText("pass2"));
   * </pre>
   *
   * <p>
   * If you don't use named rewrite streams, a "default" stream is used as the
   * first example shows.</p>
   */
  class ANTLR4CPP_PUBLIC TokenStreamRewriter {
  public:
    static const std::string DEFAULT_PROGRAM_NAME;
    static const size_t PROGRAM_INIT_SIZE = 100;
    static const size_t MIN_TOKEN_INDEX = 0;

    TokenStreamRewriter(TokenStream *tokens);
    virtual ~TokenStreamRewriter();

    TokenStream *getTokenStream();

    virtual void rollback(size_t instructionIndex);

    /// Rollback the instruction stream for a program so that
    /// the indicated instruction (via instructionIndex) is no
    /// longer in the stream.  UNTESTED!
    virtual void rollback(const std::string &programName, size_t instructionIndex);

    virtual void deleteProgram();

    /// Reset the program so that no instructions exist.
    virtual void deleteProgram(const std::string &programName);
    virtual void insertAfter(Token *t, const std::string& text);
    virtual void insertAfter(size_t index, const std::string& text);
    virtual void insertAfter(const std::string &programName, Token *t, const std::string& text);
    virtual void insertAfter(const std::string &programName, size_t index, const std::string& text);

    virtual void insertBefore(Token *t, const std::string& text);
    virtual void insertBefore(size_t index, const std::string& text);
    virtual void insertBefore(const std::string &programName, Token *t, const std::string& text);
    virtual void insertBefore(const std::string &programName, size_t index, const std::string& text);

    virtual void replace(size_t index, const std::string& text);
    virtual void replace(size_t from, size_t to, const std::string& text);
    virtual void replace(Token *indexT, const std::string& text);
    virtual void replace(Token *from, Token *to, const std::string& text);
    virtual void replace(const std::string &programName, size_t from, size_t to, const std::string& text);
    virtual void replace(const std::string &programName, Token *from, Token *to, const std::string& text);

    virtual void Delete(size_t index);
    virtual void Delete(size_t from, size_t to);
    virtual void Delete(Token *indexT);
    virtual void Delete(Token *from, Token *to);
    virtual void Delete(const std::string &programName, size_t from, size_t to);
    virtual void Delete(const std::string &programName, Token *from, Token *to);

    virtual size_t getLastRewriteTokenIndex();

    /// Return the text from the original tokens altered per the
    /// instructions given to this rewriter.
    virtual std::string getText();

    /** Return the text from the original tokens altered per the
     *  instructions given to this rewriter in programName.
     */
    std::string getText(std::string programName);

    /// Return the text associated with the tokens in the interval from the
    /// original token stream but with the alterations given to this rewriter.
    /// The interval refers to the indexes in the original token stream.
    /// We do not alter the token stream in any way, so the indexes
    /// and intervals are still consistent. Includes any operations done
    /// to the first and last token in the interval. So, if you did an
    /// insertBefore on the first token, you would get that insertion.
    /// The same is true if you do an insertAfter the stop token.
    virtual std::string getText(const misc::Interval &interval);

    virtual std::string getText(const std::string &programName, const misc::Interval &interval);

  protected:
    class RewriteOperation {
    public:
      /// What index into rewrites List are we?
      size_t index;
      std::string text;

      /// Token buffer index.
      size_t instructionIndex;

      RewriteOperation(TokenStreamRewriter *outerInstance, size_t index);
      RewriteOperation(TokenStreamRewriter *outerInstance, size_t index, const std::string& text);
      virtual ~RewriteOperation();

      /// Execute the rewrite operation by possibly adding to the buffer.
      /// Return the index of the next token to operate on.

      virtual size_t execute(std::string *buf);
      virtual std::string toString();

    private:
      TokenStreamRewriter *const outerInstance;
      void InitializeInstanceFields();
    };

    class InsertBeforeOp : public RewriteOperation {
    private:
      TokenStreamRewriter *const outerInstance;

    public:
      InsertBeforeOp(TokenStreamRewriter *outerInstance, size_t index, const std::string& text);

      virtual size_t execute(std::string *buf) override;
    };

    class ReplaceOp : public RewriteOperation {
    private:
      TokenStreamRewriter *const outerInstance;

    public:
      size_t lastIndex;

      ReplaceOp(TokenStreamRewriter *outerInstance, size_t from, size_t to, const std::string& text);
      virtual size_t execute(std::string *buf) override;
      virtual std::string toString() override;

    private:
      void InitializeInstanceFields();
    };

    /// Our source stream
    TokenStream *const tokens;

    /// You may have multiple, named streams of rewrite operations.
    /// I'm calling these things "programs."
    /// Maps String (name) -> rewrite (List)
    std::map<std::string, std::vector<RewriteOperation*>> _programs;

    /// <summary>
    /// Map String (program name) -> Integer index </summary>
    std::map<std::string, size_t> _lastRewriteTokenIndexes;
    virtual size_t getLastRewriteTokenIndex(const std::string &programName);
    virtual void setLastRewriteTokenIndex(const std::string &programName, size_t i);
    virtual std::vector<RewriteOperation*>& getProgram(const std::string &name);

    /// <summary>
    /// We need to combine operations and report invalid operations (like
    ///  overlapping replaces that are not completed nested).  Inserts to
    ///  same index need to be combined etc...   Here are the cases:
    ///
    ///  I.i.u I.j.v                                leave alone, nonoverlapping
    ///  I.i.u I.i.v                                combine: Iivu
    ///
    ///  R.i-j.u R.x-y.v    | i-j in x-y            delete first R
    ///  R.i-j.u R.i-j.v                            delete first R
    ///  R.i-j.u R.x-y.v    | x-y in i-j            ERROR
    ///  R.i-j.u R.x-y.v    | boundaries overlap    ERROR
    ///
    ///  Delete special case of replace (text==null):
    ///  D.i-j.u D.x-y.v    | boundaries overlap    combine to max(min)..max(right)
    ///
    ///  I.i.u R.x-y.v | i in (x+1)-y           delete I (since insert before
    ///                                         we're not deleting i)
    ///  I.i.u R.x-y.v | i not in (x+1)-y       leave alone, nonoverlapping
    ///  R.x-y.v I.i.u | i in x-y               ERROR
    ///  R.x-y.v I.x.u                          R.x-y.uv (combine, delete I)
    ///  R.x-y.v I.i.u | i not in x-y           leave alone, nonoverlapping
    ///
    ///  I.i.u = insert u before op @ index i
    ///  R.x-y.u = replace x-y indexed tokens with u
    ///
    ///  First we need to examine replaces.  For any replace op:
    ///
    ///         1. wipe out any insertions before op within that range.
    ///     2. Drop any replace op before that is contained completely within
    ///         that range.
    ///     3. Throw exception upon boundary overlap with any previous replace.
    ///
    ///  Then we can deal with inserts:
    ///
    ///         1. for any inserts to same index, combine even if not adjacent.
    ///         2. for any prior replace with same left boundary, combine this
    ///         insert with replace and delete this replace.
    ///         3. throw exception if index in same range as previous replace
    ///
    ///  Don't actually delete; make op null in list. Easier to walk list.
    ///  Later we can throw as we add to index -> op map.
    ///
    ///  Note that I.2 R.2-2 will wipe out I.2 even though, technically, the
    ///  inserted stuff would be before the replace range.  But, if you
    ///  add tokens in front of a method body '{' and then delete the method
    ///  body, I think the stuff before the '{' you added should disappear too.
    ///
    ///  Return a map from token index to operation.
    /// </summary>
    virtual std::unordered_map<size_t, RewriteOperation*> reduceToSingleOperationPerIndex(std::vector<RewriteOperation*> &rewrites);

    virtual std::string catOpText(std::string *a, std::string *b);

    /// Get all operations before an index of a particular kind.
    template <typename T>
    std::vector<T *> getKindOfOps(std::vector<RewriteOperation *> rewrites, size_t before) {
      std::vector<T *> ops;
      for (size_t i = 0; i < before && i < rewrites.size(); i++) {
        T *op = dynamic_cast<T *>(rewrites[i]);
        if (op == nullptr) { // ignore deleted or non matching entries
          continue;
        }
        ops.push_back(op);
      }
      return ops;
    }

  private:
    std::vector<RewriteOperation *>& initializeProgram(const std::string &name);

  };

} // namespace antlr4
