#ifndef __FILEHEAP_HPP
#define __FILEHEAP_HPP

typedef unsigned long BlockID;

class FileHeap {
public:
        enum createMode {
                create_fail,
                create_create,
        };
        enum existMode {
                exist_open,
                exist_fail,
                exist_trunc
        };
        FileHeap(const char *filename, createMode cm, existMode em);
        ~FileHeap();

        operator int() const { return fd>=0; }

        BlockID alloc(unsigned long bytes, BlockID around=0);
        void free(BlockID bid);


        int readBlock(BlockID id, void *dst, unsigned bytes);
        int writeBlock(BlockID id, const void *src, unsigned bytes);


        enum blockType {
                heapEmpty   =  1,
                heapOK      =  2,
                freeBlock   =  3,
                usedBlock   =  4,
                heapEnd     =  5,
                corruptHeap = -1,
                badBlock    = -2
        };
        blockType checkBlock(BlockID id, unsigned long *bytes);
        blockType checkHeap();
        struct heapInfo {
                BlockID bid;
                unsigned long size;
                int in_use;
        };
        blockType heapWalk(heapInfo *hi);
        
        int setSpecialBlock(BlockID id);
        BlockID getSpecialBlock();
private:
        int fd;
};

#endif