#ifndef LineBuffer_h__
#define LineBuffer_h__

#include "common_header.h"

namespace FileMerger
{
	struct StringView
	{
		int size;
		char* str;

		StringView( char* s, int sz  ) : str( s ), size( sz )
		{
			DEBUG_ASSERT( s );
			DEBUG_ASSERT( sz > 0 );
		}
	};

	class LineBuffer : public std::vector< StringView >
	{
	public:

		typedef vector< string > StringList;

		static float rangeRandom( float min, float max )
		{
			return ((float)rand()/(float)RAND_MAX)*(max-min) + min;
		}

		LineBuffer() :
		mTotalSize( 0 )
		{
			mLineBuf.reserve( 1024*1024 );
		}

		~LineBuffer()
		{

		}

		void addFile( const string& path )
		{
			FILE* file = fopen( path.c_str(), "r" );

			if( !file )
			{
				cout << "Error: cannot find file \"" << path << "\"" << endl;
				return;
			}

			//create a new file buffer
			fseek( file, 0, SEEK_END);

			mLoadedFiles.push_back( "" );
			mLoadedFiles.back().resize( ftell( file ) );

			fseek( file, 0, SEEK_SET );

			//load the file into the buffer
			char* buf = (char*)mLoadedFiles.back().c_str();
			char* endPtr = buf + mLoadedFiles.back().size();
			fread( buf, 1, mLoadedFiles.back().size(), file );

			fclose( file );

			char lastChar = 0;
			size_t lineSize = 0;
			while( buf < endPtr )
			{
				//find next line start
				for( ; buf < endPtr && *buf == ' ' && *buf == '\n'; ++buf );
				char* start = buf;

				//find next line end
				for( ; buf < endPtr && *buf != '\n'; ++buf );
				char* end = buf++;

				if( start == end )
					continue;

				//save the slice
				*end = 0;

				size_t size = end - start;
				push_back( StringView( start, size ) );
				mTotalSize += size;
			}
		}

		///shuffles n loaded lines selected at random
		void shuffle()
		{
			for( int i = 0; i < size(); ++i )
			{
				int first = randomIndex();
				int second = randomIndex();

				if( first == second )
					continue;

				auto temp = at(first);
				at(first) = at( second );
				at( second ) = temp;
			}
		}

		inline int randomIndex()
		{
			return rangeRandom( 0, (int)size()-1 );
		}

		inline size_t getTotalSize() const
		{
			return mTotalSize;
		}

	protected:

		size_t mTotalSize;
		string mLineBuf;
		StringList mLoadedFiles;

	private:
	};
}

#endif // LineBuffer_h__