#ifndef BLOCKARRAY_H
#define BLOCKARRAY_H

#include <unistd.h>

//#error Dont use in KDE 2.1

#define BlockSize (1 << 12)
#define ENTRIES   ((BlockSize - sizeof(size_t) ) / sizeof(unsigned char))

struct Block {
    Block() { size = 0; }
    unsigned char data[ENTRIES];
    size_t size;
};

// ///////////////////////////////////////////////////////

class BlockArray {
public:
    /**
    * Creates a history file for holding
    * maximal size blocks. If more blocks
    * are requested, then it drops earlier
    * added ones.
    */
    BlockArray();

    /// destructor
    ~BlockArray();

    /**
    * adds the Block at the end of history.
    * This may drop other blocks.
    *
    * The ownership on the block is transfered.
    * An unique index number is returned for accessing
    * it later (if not yet droped then)
    *
    * Note, that the block may be dropped completely
    * if history is turned off.
    */
    size_t append(Block *block);

    /**
    * gets the block at the index. Function may return
    * 0 if the block isn't available any more.
    *
    * The returned block is strictly readonly as only
    * maped in memory - and will be invalid on the next
    * operation on this class.
    */
    const Block *at(size_t index);

    /**
    * reorders blocks as needed. If newsize is null,
    * the history is emptied completely. The indices
    * returned on append won't change their semantic,
    * but they may not be valid after this call.
    */
    bool setHistorySize(size_t newsize);

    size_t newBlock();

    Block *lastBlock() const;

    /**
    * Convenient function to set the size in KBytes
    * instead of blocks
    */
    bool setSize(size_t newsize);

    size_t len() const { return length; }

    bool has(size_t index) const;

    size_t getCurrent() const { return current; }

private:
    void unmap();
    void increaseBuffer();
    void decreaseBuffer(size_t newsize);

    size_t size;
    // current always shows to the last inserted block
    size_t current;
    size_t index;

    Block *lastmap;
    size_t lastmap_index;
    Block *lastblock;

    int ion;
    size_t length;

};


#endif
