/*************************************************************************
 *
 * HTCd - Copyright (C) 1998-2006 Henrik Rydberg
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef FILEMAPH
#define FILEMAPH

#include <mt/mstring.h>
#include <mt/lock.h>
#include <mt/mlock.h>
#include <mt/mlock.h>
#include <netinet/in.h>

//////////////////////////////////////////////
//
// NOTE that filemap is MT unsafe:
// it needs to be called from dbmap
//
// The exception is when filelocking;
// that's MT safe per filemap, and hence
// should not be locked further
//

#define HEADLOCK(fm) headlock_t headlock(fm)

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

// network byteorder
class byte4 {
public:
  byte4() {} // must be uninitialized
  explicit byte4(int h): n(htonl(h)) {}
  void set(int h) { n=htonl(h); }
  void add(int h) { n=htonl(ntohl(n)+h); }
  int get() const { return ntohl(n); }
private:
  long n;
};

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

class filemap {
public:
  typedef char char32[32];
  static const int maxtabs=32;
  
  ////////////////////////////////////////////////////

  struct head_t {
    char32 ident;
    byte4 lock;
    byte4 minor;
    byte4 major;
    byte4 fatal;
    byte4 filesize;
    byte4 filetop;
    byte4 tables;
    byte4 index;
    char32 compname;
    char32 tabs[maxtabs];
    byte4 frame;

    head_t();
    head_t(const head_t* hd,int mem);

    void setcomp(int idx, const sref& cp);

    sref get(int col) const { return sref(tabs[col]); }
    void set(int col,const sref& s);
    void insert(int col,const sref& s);
    void remove(int col);
  };
  
  head_t* head() { return hd; }
  const head_t* head() const { return hd; }

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

  struct rec_t {
    byte4 mem;
    byte4 caps;
  };

  rec_t* at(int off) {
    for(chunk_t* p=mem;p;p=p->next) if(p->own(off)) return p->at(off); return 0;
  }
  const rec_t* at(int off) const {
    for(const chunk_t* p=mem;p;p=p->next) if(p->own(off)) return p->at(off);
    return 0;
  }

  int recs() const { return hd->frame.get(); }
  int size(int off) const {
    if(off<hd->filetop.get()) {
      for(const chunk_t* p=mem;p;p=p->next)
        if(p->own(off)) return p->at(off)->mem.get();
    }
    return 0;
  }

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

  void remap();

  rec_t* add(int n);
  void rem(rec_t* rec);
  
  ///////////////////////////////////////////////////////

  filemap(filemap* p);
  filemap(filemap* p,const mstring& path,int update=0,int prot=0600);
  ~filemap();

  filemap* next;

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

  void open(const mstring& path,int update=0,int prot=0600) throw(merror_t);
  void save(const mstring& path,int prot=0600) throw(merror_t);
  void check() throw(merror_t);
  void close();
  void sync();

  const mstring& Pathname() const { return pathname; }
  time_t Lastmod() const;

  int reference() const { return refs; }
  int writable() const { return wok; }

  void pushref() { refs++; }
  void popref() { refs--; }

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

  void lock();
  void unlock();

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

protected:
  struct chunk_t {
    chunk_t* next;
    long begin;
    long end;
    char* map;

    int size() const { return end-begin; }
    
    chunk_t(chunk_t* p,int fd,int wok,int off,int size);
    ~chunk_t();
    
    int own(int off) const { return off>=begin&&off<end; }
    void sync();

    rec_t* at(int off) { return (rec_t*)(map+(off-begin)); }
    const rec_t* at(int off) const { return (rec_t*)(map+(off-begin)); }

    int fill(int off);
  };
private:
  int fd,wok,refs;
  mstring pathname;
  head_t* hd;
  chunk_t* mem;
  mutex_t mutex;
  nodelock_t* nodelock;
private:
  filemap(const filemap&) {}
  void operator=(const filemap&) {}
};

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

struct headlock_t {
  filemap* fm;
  headlock_t(filemap* f) : fm(f) { fm->lock(); }
  ~headlock_t() { if(fm) fm->unlock(); }
};

#endif