/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * 
 *************************************************************/

// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_desktop.hxx"

#include "dp_misc.h"
#include "dp_persmap.h"
#include "rtl/strbuf.hxx"

using namespace ::rtl;

// the persistent map is used to manage a handful of key-value string pairs
// this implementation replaces a rather heavy-weight berkeleydb integration

// the file backing up a persistent map consists of line pairs with
// - a key string   (encoded with chars 0x00..0x0F being escaped)
// - a value string (encoded with chars 0x00..0x0F being escaped)

namespace dp_misc
{

static const char PmapMagic[4] = {'P','m','p','1'};

//______________________________________________________________________________
PersistentMap::PersistentMap( OUString const & url_, bool readOnly )
:	m_MapFile( expandUnoRcUrl(url_) )
,	m_bReadOnly( readOnly)
,	m_bIsOpen( false)
,	m_bToBeCreated( !readOnly)
,	m_bIsDirty( false)
{
	open();
}

//______________________________________________________________________________
PersistentMap::PersistentMap()
:	m_MapFile( OUString())
,	m_bReadOnly( false)
,	m_bIsOpen( false)
,	m_bToBeCreated( false)
,	m_bIsDirty( false)
{}

//______________________________________________________________________________
PersistentMap::~PersistentMap()
{
	if( m_bIsDirty)
		flush();
	if( m_bIsOpen)
		m_MapFile.close();
}

//______________________________________________________________________________

// replace 0x00..0x0F with "%0".."%F"
// replace "%" with "%%"
static OString encodeString( const OString& rStr)
{
	const sal_Char* pChar = rStr.getStr();
	const sal_Int32 nLen = rStr.getLength();
	sal_Int32 i = nLen;
	// short circuit for the simple non-encoded case
	while( --i >= 0)
	{
		const sal_Char c = *(pChar++);
		if( (0x00 <= c) && (c <= 0x0F))
			break;
		if( c == '%')
			break;
	}
	if( i < 0)
		return rStr;

	// escape chars 0x00..0x0F with "%0".."%F"
	OStringBuffer aEncStr( nLen + 32);
	aEncStr.append( pChar - (nLen-i), nLen - i);
	while( --i >= 0)
	{
		sal_Char c = *(pChar++);
		if( (0x00 <= c) && (c <= 0x0F))
		{
			aEncStr.append( '%');
			c += (c <= 0x09) ? '0' : 'A'-10;
		} else if( c == '%')
			aEncStr.append( '%');
		aEncStr.append( c);
	}

	return aEncStr.makeStringAndClear();
}

//______________________________________________________________________________

// replace "%0".."%F" with 0x00..0x0F
// replace "%%" with "%"
static OString decodeString( const sal_Char* pEncChars, int nLen)
{
	const char* pChar = pEncChars;
	sal_Int32 i = nLen;
	// short circuit for the simple non-encoded case
	while( --i >= 0)
		if( *(pChar++) == '%')
			break;
	if( i < 0)
		return OString( pEncChars, nLen);

	// replace escaped chars with their decoded counterparts
	OStringBuffer aDecStr( nLen);
	pChar = pEncChars;
	for( i = nLen; --i >= 0;)
	{
		sal_Char c = *(pChar++);
		// handle escaped character
		if( c == '%')
		{
			--i;
			OSL_ASSERT( i >= 0);
			c = *(pChar++);
			if( ('0' <= c) && (c <= '9'))
				c -= '0';
			else
			{
				OSL_ASSERT( ('A' <= c) && (c <= 'F'));
				c -= ('A'-10);
			}
		}
		aDecStr.append( c);
	}

	return aDecStr.makeStringAndClear();
}

//______________________________________________________________________________
bool PersistentMap::open()
{
	// open the existing file
	sal_uInt32 nOpenFlags = osl_File_OpenFlag_Read;
	if( !m_bReadOnly)
		nOpenFlags |= osl_File_OpenFlag_Write;

	const ::osl::File::RC rcOpen = m_MapFile.open( nOpenFlags);
	m_bIsOpen = (rcOpen == osl::File::E_None);

	// or create later if needed
	m_bToBeCreated &= (rcOpen == osl::File::E_NOENT) && !m_bIsOpen;
	if( !m_bIsOpen)
		return m_bToBeCreated;

	const bool readOK = readAll();
	return readOK;
}

//______________________________________________________________________________
bool PersistentMap::readAll()
{
	// prepare for re-reading the map-file
	m_MapFile.setPos( osl_Pos_Absolut, 0);
	m_entries.clear();

	// read header and check magic
	char aHeaderBytes[ sizeof(PmapMagic)];
	sal_uInt64 nBytesRead = 0;
	m_MapFile.read( aHeaderBytes, sizeof(aHeaderBytes), nBytesRead);
	OSL_ASSERT( nBytesRead == sizeof(aHeaderBytes));
	if( nBytesRead != sizeof(aHeaderBytes))
		return false;
	// check header magic
	for( int i = 0; i < (int)sizeof(PmapMagic); ++i)
		if( aHeaderBytes[i] != PmapMagic[i])
			return false;

	// read key value pairs and add them to the map
	ByteSequence aKeyLine;
	ByteSequence aValLine;
	for(;;)
	{
		// read key-value line pair
		// an empty key name indicates the end of the line pairs
		if( m_MapFile.readLine( aKeyLine) != osl::File::E_None)
			return false;
		if( !aKeyLine.getLength())
			break;
		if( m_MapFile.readLine( aValLine) != osl::File::E_None)
			return false;
		// decode key and value strings
		const OString aKeyName = decodeString( (sal_Char*)aKeyLine.getConstArray(), aKeyLine.getLength());
		const OString aValName = decodeString( (sal_Char*)aValLine.getConstArray(), aValLine.getLength());
		// insert key-value pair into map
		put( aKeyName, aValName);
		// check end-of-file status
		sal_Bool bIsEOF = true;
		if( m_MapFile.isEndOfFile( &bIsEOF) != osl::File::E_None)
			return false;
		if( bIsEOF)
			break;
	}

	m_bIsDirty = false;
	return true;
}

//______________________________________________________________________________
void PersistentMap::flush( void)
{
	if( !m_bIsDirty)
		return;
	OSL_ASSERT( !m_bReadOnly);
	if( m_bToBeCreated && !m_entries.empty())
	{
		const sal_uInt32 nOpenFlags = osl_File_OpenFlag_Read | osl_File_OpenFlag_Write | osl_File_OpenFlag_Create;
		const ::osl::File::RC rcOpen = m_MapFile.open( nOpenFlags);
		m_bIsOpen = (rcOpen == osl::File::E_None);
		m_bToBeCreated = !m_bIsOpen;
	}
	if( !m_bIsOpen)
		return;

	// write header magic
	m_MapFile.setPos( osl_Pos_Absolut, 0);
	sal_uInt64 nBytesWritten = 0;
	m_MapFile.write( PmapMagic, sizeof(PmapMagic), nBytesWritten);

	// write key value pairs
	t_string2string_map::const_iterator it = m_entries.begin();
	for(; it != m_entries.end(); ++it) {
		// write line for key
		const OString aKeyString = encodeString( (*it).first);
		const sal_Int32 nKeyLen = aKeyString.getLength();
		m_MapFile.write( aKeyString.getStr(), nKeyLen, nBytesWritten);
		OSL_ASSERT( nKeyLen == (sal_Int32)nBytesWritten);
		m_MapFile.write( "\n", 1, nBytesWritten);
		// write line for value
		const OString& rValString = encodeString( (*it).second);
		const sal_Int32 nValLen = rValString.getLength();
		m_MapFile.write( rValString.getStr(), nValLen, nBytesWritten);
		OSL_ASSERT( nValLen == (sal_Int32)nBytesWritten);
		m_MapFile.write( "\n", 1, nBytesWritten);
	}

	// write a file delimiter (an empty key-string)
	m_MapFile.write( "\n", 1, nBytesWritten);
	// truncate file here
	sal_uInt64 nNewFileSize;
	if( m_MapFile.getPos( nNewFileSize) == osl::File::E_None)
		m_MapFile.setSize( nNewFileSize);
	// flush to disk
	m_MapFile.sync();
	// the in-memory map now matches to the file on disk
	m_bIsDirty = false;
}

//______________________________________________________________________________
bool PersistentMap::has( OString const & key ) const
{
    return get( NULL, key );
}

//______________________________________________________________________________
bool PersistentMap::get( OString * value, OString const & key ) const
{
	t_string2string_map::const_iterator it = m_entries.find( key);
	if( it == m_entries.end())
		return false;
	if( value)
		*value = it->second;
	return true;
}

//______________________________________________________________________________
void PersistentMap::put( OString const & key, OString const & value )
{
	if( m_bReadOnly)
		return;
	typedef std::pair<t_string2string_map::iterator,bool> InsertRC;
	InsertRC r = m_entries.insert( t_string2string_map::value_type(key,value));
	m_bIsDirty = r.second;
}

//______________________________________________________________________________
bool PersistentMap::erase( OString const & key, bool flush_immediately )
{
	if( m_bReadOnly)
		return false;
	size_t nCount = m_entries.erase( key);
	if( !nCount)
		return false;
	m_bIsDirty = true;
	if( flush_immediately)
		flush();
	return true;
}

//______________________________________________________________________________
t_string2string_map PersistentMap::getEntries() const
{
	// TODO: return by const reference instead?
	return m_entries;
}

}