B+ TREE HEADER FILE
-------------------

#ifndef _BTFILE_H
#define _BTFILE_H

/*
 * This is the main definition of class BTreeFile, which derives from 
 * abstract base class IndexFile.
 *
 * class BTreeFileScan is defined in btreefilescan.h; this class provides
 * a search/iterate interface to a BTreeFile.
 */


#define BT_TRACE
  /* When #defined, BT_TRACE causes a structured trace to be written to the
     ostream pointed to by the class variable BTreeFile::Trace.  This output is
     used to drive a visualization tool that shows the inner workings of the
     b-tree during its operations.  You must set BTreeFile::Trace to the
     ostream of your choice before creating your BTreeFile. */
 
#include "btindex_page.h"
#include "btleaf_page.h"
#include "index.h"
#include "btreefilescan.h"
#include "bt.h"


#define NAIVE_DELETE 0
#define FULL_DELETE  1

class BTreeFile: public IndexFile {

  friend class BTreeFileScan;
  friend class BTreeTest;

  private:

  /*
   * Structure of a B+ tree index header page.  There is quite a bit 
   * of wasted space here... 
   */

  public:

    enum ErrorTypes { 

      // our interface for the erroneous error protocol.

      _OK = 0,                // 0 is always OK
      CANT_FIND_HEADER,       // tried to open index but db said no header
      CANT_PIN_HEADER,        // buffer manager failed to pin header page
      CANT_ALLOC_HEADER,      // failed to allocate block for header page
      CANT_ADD_FILE_ENTRY,    // couldn't register new index file w/ db
      CANT_UNPIN_HEADER,      // can't unpin header page
      CANT_PIN_PAGE,          // can't pin some index/leaf page
      CANT_UNPIN_PAGE,        // can't unpin some index/leaf page
      INVALID_SCAN,           // attempt to use bad Scan object 
      DELETE_CURRENT_FAILED,  // failed to delete current rid in scan
      CANT_DELETE_FILE_ENTRY, // db failed to delete file entry
      CANT_FREE_PAGE,         // buffer manager failed to free a page
      CANT_DELETE_SUBTREE,    // _destroyFile failed on a subtree
      KEY_TOO_LONG,           // the key given in BTreeFile::insert is too long
      INSERT_FAILED,          // BTreeFile::insert not successful
      COULD_NOT_CREATE_ROOT,  // BtreeFile::insert could not create new root
      DELETE_DATAENTRY_FAILED,// could not delete a data entry 
      DATA_ENTRY_NOT_FOUND,   // could not find data entry to delete
      CANT_GET_PAGE_NO,       // get_page_no on BTIndexPage failed
      CANT_ALLOCATE_NEW_PAGE, // bm::newPage failed
      CANT_SPLIT_LEAF_PAGE,   // could not split leaf page
      CANT_SPLIT_INDEX_PAGE,  // could not split index page
  
      NR_ERRORS               // and this is the number of them
    }; 
  
    static const char *Errors[NR_ERRORS];

    // an index with given filename should already exist; this opens it.
    BTreeFile(Status& status, const char *filename);
  
    // if index exists, open it; else create it.
    BTreeFile(Status& status, const char *filename, const AttrType keytype,
              const int keysize, int delete_fashion = FULL_DELETE);
    
    // closes index
   ~BTreeFile();
    
    // destroy entire index file
    Status destroyFile();
    
    // insert recid with the key key
    Status insert(const void *key, const RID rid);
    
    // delete leaf entry recid given its key
    // (`rid' is IN the data entry; it is not the id of the data entry)
    Status Delete(const void *key, const RID rid);
    
    // create a scan with given keys
    // Cases:
    //      (1) lo_key = NULL, hi_key = NULL
    //              scan the whole index
    //      (2) lo_key = NULL, hi_key!= NULL
    //              range scan from min to the hi_key
    //      (3) lo_key!= NULL, hi_key = NULL
    //              range scan from the lo_key to max
    //      (4) lo_key!= NULL, hi_key!= NULL, lo_key = hi_key
    //              exact match ( might not unique)
    //      (5) lo_key!= NULL, hi_key!= NULL, lo_key < hi_key
    //              range scan from lo_key to hi_key
    IndexFileScan *new_scan(const void *lo_key = NULL,
                            const void *hi_key = NULL);

    int keysize();
    

    void PrintHeader();            // print the header info
    void PrintRoot();              // print the root page
    void PrintLeafPages();         // print all the leaf pages
    void PrintPage(PageId id);     // print page with id

#if defined(BT_TRACE)
    static class ostream *Trace;   // Set this to your stream to get a trace.
#endif

  private:

};

#endif // _BTFILE_H