/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Henri Sivonen <hsivonen@iki.fi>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef nsHtml5StreamParser_h__
#define nsHtml5StreamParser_h__

#include "nsAutoPtr.h"
#include "nsCOMPtr.h"
#include "nsIStreamListener.h"
#include "nsICharsetDetectionObserver.h"
#include "nsHtml5MetaScanner.h"
#include "nsIUnicodeDecoder.h"
#include "nsHtml5TreeOpExecutor.h"
#include "nsHtml5UTF16Buffer.h"
#include "nsIInputStream.h"
#include "nsICharsetAlias.h"
#include "mozilla/Mutex.h"
#include "nsHtml5AtomTable.h"
#include "nsHtml5Speculation.h"
#include "nsITimer.h"
#include "nsICharsetDetector.h"

class nsHtml5Parser;

#define NS_HTML5_STREAM_PARSER_READ_BUFFER_SIZE 1024
#define NS_HTML5_STREAM_PARSER_SNIFFING_BUFFER_SIZE 1024

enum eBomState {
  /**
   * BOM sniffing hasn't started.
   */
  BOM_SNIFFING_NOT_STARTED = 0,

  /**
   * BOM sniffing is ongoing, and the first byte of an UTF-16LE BOM has been
   * seen.
   */
  SEEN_UTF_16_LE_FIRST_BYTE = 1,

  /**
   * BOM sniffing is ongoing, and the first byte of an UTF-16BE BOM has been
   * seen.
   */
  SEEN_UTF_16_BE_FIRST_BYTE = 2,

  /**
   * BOM sniffing is ongoing, and the first byte of an UTF-8 BOM has been
   * seen.
   */
  SEEN_UTF_8_FIRST_BYTE = 3,

  /**
   * BOM sniffing is ongoing, and the first and second bytes of an UTF-8 BOM
   * have been seen.
   */
  SEEN_UTF_8_SECOND_BYTE = 4,

  /**
   * BOM sniffing was started but is now over for whatever reason.
   */
  BOM_SNIFFING_OVER = 5
};

enum eHtml5StreamState {
  STREAM_NOT_STARTED = 0,
  STREAM_BEING_READ = 1,
  STREAM_ENDED = 2
};

class nsHtml5StreamParser : public nsIStreamListener,
                            public nsICharsetDetectionObserver {

  friend class nsHtml5RequestStopper;
  friend class nsHtml5DataAvailable;
  friend class nsHtml5StreamParserContinuation;
  friend class nsHtml5TimerKungFu;

  public:
    NS_DECL_AND_IMPL_ZEROING_OPERATOR_NEW
    NS_DECL_CYCLE_COLLECTING_ISUPPORTS
    NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsHtml5StreamParser, nsIStreamListener)

    static void InitializeStatics();

    nsHtml5StreamParser(nsHtml5TreeOpExecutor* aExecutor,
                        nsHtml5Parser* aOwner);
                        
    virtual ~nsHtml5StreamParser();

    // nsIRequestObserver methods:
    NS_DECL_NSIREQUESTOBSERVER
    // nsIStreamListener methods:
    NS_DECL_NSISTREAMLISTENER
    
    // nsICharsetDetectionObserver
    /**
     * Chardet calls this to report the detection result
     */
    NS_IMETHOD Notify(const char* aCharset, nsDetectionConfident aConf);

    // EncodingDeclarationHandler
    // http://hg.mozilla.org/projects/htmlparser/file/tip/src/nu/validator/htmlparser/common/EncodingDeclarationHandler.java
    /**
     * Tree builder uses this to report a late <meta charset>
     */
    PRBool internalEncodingDeclaration(nsString* aEncoding);

    // Not from an external interface

    /**
     *  Call this method once you've created a parser, and want to instruct it
     *  about what charset to load
     *
     *  @param   aCharset the charset of a document
     *  @param   aCharsetSource the source of the charset
     */
    inline void SetDocumentCharset(const nsACString& aCharset, PRInt32 aSource) {
      NS_PRECONDITION(mStreamState == STREAM_NOT_STARTED,
                      "SetDocumentCharset called too late.");
      NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
      mCharset = aCharset;
      mCharsetSource = aSource;
    }
    
    inline void SetObserver(nsIRequestObserver* aObserver) {
      NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
      mObserver = aObserver;
    }

    nsresult GetChannel(nsIChannel** aChannel);

    /**
     * The owner parser must call this after script execution
     * when no scripts are executing and the document.written 
     * buffer has been exhausted.
     */
    void ContinueAfterScripts(nsHtml5Tokenizer* aTokenizer, 
                              nsHtml5TreeBuilder* aTreeBuilder,
                              PRBool aLastWasCR);

    /**
     * Continues the stream parser if the charset switch failed.
     */
    void ContinueAfterFailedCharsetSwitch();

    void Terminate() {
      mozilla::MutexAutoLock autoLock(mTerminatedMutex);
      mTerminated = PR_TRUE;
    }
    
    void DropTimer();

  private:

#ifdef DEBUG
    PRBool IsParserThread() {
      PRBool ret;
      mThread->IsOnCurrentThread(&ret);
      return ret;
    }
#endif

    /**
     * Marks the stream parser as interrupted. If you ever add calls to this
     * method, be sure to review Uninterrupt usage very, very carefully to
     * avoid having a previous in-flight runnable cancel your Interrupt()
     * call on the other thread too soon.
     */
    void Interrupt() {
      mozilla::MutexAutoLock autoLock(mTerminatedMutex);
      mInterrupted = PR_TRUE;
    }

    void Uninterrupt() {
      NS_ASSERTION(IsParserThread(), "Wrong thread!");
      mTokenizerMutex.AssertCurrentThreadOwns();
      // Not acquiring mTerminatedMutex because mTokenizerMutex is already
      // held at this point and is already stronger.
      mInterrupted = PR_FALSE;      
    }

    /**
     * Flushes the tree ops from the tree builder and disarms the flush
     * timer.
     */
    void FlushTreeOpsAndDisarmTimer();

    void ParseAvailableData();
    
    void DoStopRequest();
    
    void DoDataAvailable(PRUint8* aBuffer, PRUint32 aLength);

    PRBool IsTerminatedOrInterrupted() {
      mozilla::MutexAutoLock autoLock(mTerminatedMutex);
      return mTerminated || mInterrupted;
    }

    PRBool IsTerminated() {
      mozilla::MutexAutoLock autoLock(mTerminatedMutex);
      return mTerminated;
    }

    /**
     * True when there is a Unicode decoder already
     */
    inline PRBool HasDecoder() {
      return !!mUnicodeDecoder;
    }

    /**
     * Push bytes from network when there is no Unicode decoder yet
     */
    nsresult SniffStreamBytes(const PRUint8* aFromSegment,
                              PRUint32 aCount,
                              PRUint32* aWriteCount);

    /**
     * Push bytes from network when there is a Unicode decoder already
     */
    nsresult WriteStreamBytes(const PRUint8* aFromSegment,
                              PRUint32 aCount,
                              PRUint32* aWriteCount);

    /**
     * Check whether every other byte in the sniffing buffer is zero.
     */
    void SniffBOMlessUTF16BasicLatin(const PRUint8* aFromSegment,
                                     PRUint32 aCountToSniffingLimit);

    /**
     * <meta charset> scan failed. Try chardet if applicable. After this, the
     * the parser will have some encoding even if a last resolt fallback.
     *
     * @param aFromSegment The current network buffer or null if the sniffing
     *                     buffer is being flushed due to network stream ending.
     * @param aCount       The number of bytes in aFromSegment (ignored if
     *                     aFromSegment is null)
     * @param aWriteCount  Return value for how many bytes got read from the
     *                     buffer.
     * @param aCountToSniffingLimit The number of unfilled slots in
     *                              mSniffingBuffer
     */
    nsresult FinalizeSniffing(const PRUint8* aFromSegment,
                              PRUint32 aCount,
                              PRUint32* aWriteCount,
                              PRUint32 aCountToSniffingLimit);

    /**
     * Set up the Unicode decoder and write the sniffing buffer into it
     * followed by the current network buffer.
     *
     * @param aFromSegment The current network buffer or null if the sniffing
     *                     buffer is being flushed due to network stream ending.
     * @param aCount       The number of bytes in aFromSegment (ignored if
     *                     aFromSegment is null)
     * @param aWriteCount  Return value for how many bytes got read from the
     *                     buffer.
     */
    nsresult SetupDecodingAndWriteSniffingBufferAndCurrentSegment(const PRUint8* aFromSegment,
                                                                  PRUint32 aCount,
                                                                  PRUint32* aWriteCount);

    /**
     * Write the sniffing buffer into the Unicode decoder followed by the
     * current network buffer.
     *
     * @param aFromSegment The current network buffer or null if the sniffing
     *                     buffer is being flushed due to network stream ending.
     * @param aCount       The number of bytes in aFromSegment (ignored if
     *                     aFromSegment is null)
     * @param aWriteCount  Return value for how many bytes got read from the
     *                     buffer.
     */
    nsresult WriteSniffingBufferAndCurrentSegment(const PRUint8* aFromSegment,
                                                  PRUint32 aCount,
                                                  PRUint32* aWriteCount);

    /**
     * Initialize the Unicode decoder, mark the BOM as the source and
     * drop the sniffer.
     *
     * @param aCharsetName The charset name to report to the outside (UTF-16
     *                     or UTF-8)
     * @param aDecoderCharsetName The actual name for the decoder's charset
     *                            (UTF-16BE, UTF-16LE or UTF-8; the BOM has
     *                            been swallowed)
     */
    nsresult SetupDecodingFromBom(const char* aCharsetName,
                                  const char* aDecoderCharsetName);

    /**
     * Callback for mFlushTimer.
     */
    static void TimerCallback(nsITimer* aTimer, void* aClosure);

    /**
     * Parser thread entry point for (maybe) flushing the ops and posting
     * a flush runnable back on the main thread.
     */
    void TimerFlush();

    nsCOMPtr<nsIRequest>          mRequest;
    nsCOMPtr<nsIRequestObserver>  mObserver;

    /**
     * The Unicode decoder
     */
    nsCOMPtr<nsIUnicodeDecoder>   mUnicodeDecoder;

    /**
     * The buffer for sniffing the character encoding
     */
    nsAutoArrayPtr<PRUint8>       mSniffingBuffer;

    /**
     * The number of meaningful bytes in mSniffingBuffer
     */
    PRUint32                      mSniffingLength;

    /**
     * BOM sniffing state
     */
    eBomState                     mBomState;

    /**
     * <meta> prescan implementation
     */
    nsAutoPtr<nsHtml5MetaScanner> mMetaScanner;

    // encoding-related stuff
    /**
     * The source (confidence) of the character encoding in use
     */
    PRInt32                       mCharsetSource;

    /**
     * The character encoding in use
     */
    nsCString                     mCharset;

    /**
     * Whether reparse is forbidden
     */
    PRBool                        mReparseForbidden;

    // Portable parser objects
    /**
     * The first buffer in the pending UTF-16 buffer queue
     */
    nsRefPtr<nsHtml5UTF16Buffer>  mFirstBuffer;

    /**
     * The last buffer in the pending UTF-16 buffer queue
     */
    nsHtml5UTF16Buffer*           mLastBuffer; // weak ref; always points to
                      // a buffer of the size NS_HTML5_STREAM_PARSER_READ_BUFFER_SIZE

    /**
     * The tree operation executor
     */
    nsHtml5TreeOpExecutor*        mExecutor;

    /**
     * The HTML5 tree builder
     */
    nsAutoPtr<nsHtml5TreeBuilder> mTreeBuilder;

    /**
     * The HTML5 tokenizer
     */
    nsAutoPtr<nsHtml5Tokenizer>   mTokenizer;

    /**
     * Makes sure the main thread can't mess the tokenizer state while it's
     * tokenizing. This mutex also protects the current speculation.
     */
    mozilla::Mutex                mTokenizerMutex;

    /**
     * The scoped atom table
     */
    nsHtml5AtomTable              mAtomTable;

    /**
     * The owner parser.
     */
    nsRefPtr<nsHtml5Parser>       mOwner;

    /**
     * Whether the last character tokenized was a carriage return (for CRLF)
     */
    PRBool                        mLastWasCR;

    /**
     * For tracking stream life cycle
     */
    eHtml5StreamState             mStreamState;
    
    /**
     * Whether we are speculating.
     */
    PRBool                        mSpeculating;

    /**
     * Whether the tokenizer has reached EOF. (Reset when stream rewinded.)
     */
    PRBool                        mAtEOF;

    /**
     * The speculations. The mutex protects the nsTArray itself.
     * To access the queue of current speculation, mTokenizerMutex must be 
     * obtained.
     * The current speculation is the last element
     */
    nsTArray<nsAutoPtr<nsHtml5Speculation> >  mSpeculations;
    mozilla::Mutex                            mSpeculationMutex;

    /**
     * True to terminate early; protected by mTerminatedMutex
     */
    PRBool                        mTerminated;
    PRBool                        mInterrupted;
    mozilla::Mutex                mTerminatedMutex;
    
    /**
     * The thread this stream parser runs on.
     */
    nsCOMPtr<nsIThread>           mThread;
    
    nsCOMPtr<nsIRunnable>         mExecutorFlusher;
    
    nsCOMPtr<nsIRunnable>         mLoadFlusher;

    /**
     * The chardet instance if chardet is enabled.
     */
    nsCOMPtr<nsICharsetDetector>  mChardet;

    /**
     * If false, don't push data to chardet.
     */
    PRBool                        mFeedChardet;

    /**
     * Timer for flushing tree ops once in a while when not speculating.
     */
    nsCOMPtr<nsITimer>            mFlushTimer;

    /**
     * Keeps track whether mFlushTimer has been armed. Unfortunately,
     * nsITimer doesn't enable querying this from the timer itself.
     */
    PRBool                        mFlushTimerArmed;

    /**
     * False initially and true after the timer has fired at least once.
     */
    PRBool                        mFlushTimerEverFired;

    /**
     * The pref html5.flushtimer.initialdelay: Time in milliseconds between
     * the time a network buffer is seen and the timer firing when the
     * timer hasn't fired previously in this parse.
     */
    static PRInt32                sTimerInitialDelay;

    /**
     * The pref html5.flushtimer.subsequentdelay: Time in milliseconds between
     * the time a network buffer is seen and the timer firing when the
     * timer has already fired previously in this parse.
     */
    static PRInt32                sTimerSubsequentDelay;
};

#endif // nsHtml5StreamParser_h__
