//
// Part of the ht://Dig package   <http://www.htdig.org/>
// Copyright (c) 1999-2004 The ht://Dig Group
// For copyright details, see the file COPYING in your distribution
// or the GNU Library General Public License (LGPL) version 2 or later
// <http://www.gnu.org/copyleft/lgpl.html>
//
#ifdef HAVE_CONFIG_H
#include "htconfig.h"
#endif /* HAVE_CONFIG_H */

#include <stdio.h>

#ifndef _MSC_VER /* _WIN32 */
#include <unistd.h>
#endif

#include <stdlib.h>
#include <sys/stat.h>

#include "WordKey.h"
#include "WordDB.h"
#include "WordDBCache.h"
#include "WordMeta.h"
#include "ber.h"

int WordDBCaches::Add(char* key, int key_size, char* data, int data_size)
{
  int ret;
  if((ret = cache.Allocate(key_size + data_size)) == ENOMEM) {
    if((ret = CacheFlush()) != 0) return ret;
    if((ret = cache.Allocate(key_size + data_size))) return ret;
  }

  return cache.Add(key, key_size, data, data_size);
}

int WordDBCaches::AddFile(String& filename)
{
  char tmp[32];
  unsigned int serial;
  words->Meta()->Serial(WORD_META_SERIAL_FILE, serial);
  if(serial == WORD_META_SERIAL_INVALID)
    return NOTOK;
  filename = words->Filename();
  sprintf(tmp, "C%08d", serial - 1);
  filename << tmp;

  String dummy;
  if(files->Put(0, filename, dummy, 0) != 0)
    return NOTOK;

  size = (cache.GetMax() / 1024) * serial;

  return OK;
}

int WordDBCaches::CacheFlush()
{
  if(cache.Empty()) return OK;

  if(cache.Sort() != OK) return NOTOK;
  String filename;
  int locking = 0;
  if(!lock) {
    words->Meta()->Lock("cache", lock);
    locking = 1;
  }
  if(AddFile(filename) != OK) return NOTOK;
  if(CacheWrite(filename) != OK) return NOTOK;

  unsigned int serial;
  words->Meta()->GetSerial(WORD_META_SERIAL_FILE, serial);
  if(serial >= (unsigned int)file_max || Full())
    if(Merge() != OK) return NOTOK;
  if(locking) words->Meta()->Unlock("cache", lock);

  return OK;
}

static int merge_cmp_size(WordDBCaches* , WordDBCacheFile* a, WordDBCacheFile* b)
{
  return b->size - a->size;
}

int WordDBCaches::Merge()
{
  if(CacheFlush() != OK) return NOTOK;

  int locking = 0;
  if(!lock) {
    words->Meta()->Lock("cache", lock);
    locking = 1;
  }
  unsigned int serial;
  words->Meta()->GetSerial(WORD_META_SERIAL_FILE, serial);
  if(serial <= 1) return OK;
  
  //
  // heap lists all the files in decreasing size order (biggest first)
  //
  WordDBCacheFile* heap = new WordDBCacheFile[serial];
  {
    String filename;
    String dummy;
    WordDBCursor* cursor = files->Cursor();
    struct stat stat_buf;
    int i;
    int ret;
    for(i = 0; (ret = cursor->Get(filename, dummy, DB_NEXT)) == 0; i++) {
      WordDBCacheFile& file = heap[i];
      file.filename = filename;
      if(stat((char*)file.filename, &stat_buf) == 0) {
	file.size = stat_buf.st_size;
      } else {
	const String message = String("WordDBCaches::Merge: cannot stat ") + file.filename;
	perror((const char*)message);
	return NOTOK;
      }
      cursor->Del();
    }
    delete cursor;
    myqsort((void*)heap, serial, sizeof(WordDBCacheFile), (myqsort_cmp)merge_cmp_size, (void*)this);
  }

  String tmpname = words->Filename() + String("C.tmp");

  while(serial > 1) {
    WordDBCacheFile* a = &heap[serial - 1];
    WordDBCacheFile* b = &heap[serial - 2];

    if(Merge(a->filename, b->filename, tmpname) != OK) return NOTOK;

    //
    // Remove file a
    //
    if(unlink((char*)a->filename) != 0) {
      const String message = String("WordDBCaches::Merge: unlink ") + a->filename;
      perror((const char*)message);
      return NOTOK;
    }

    //
    // Remove file b
    //
    if(unlink((char*)b->filename) != 0) {
      const String message = String("WordDBCaches::Merge: unlink ") + b->filename;
      perror((const char*)message);
      return NOTOK;
    }

    //
    // Rename tmp file into file b
    //
    if(rename((char*)tmpname, (char*)b->filename) != 0) {
      const String message = String("WordDBCaches::Merge: rename ") + tmpname + String(" ") + b->filename;
      perror((const char*)message);
      return NOTOK;
    }

    //
    // Update b file size. The size need not be accurate number as long
    // as it reflects the relative size of each file.
    //
    b->size += a->size;
    
    serial--;
    //
    // update heap
    //
    myqsort((void*)heap, serial, sizeof(WordDBCacheFile), (myqsort_cmp)merge_cmp_size, (void*)this);
  }

  {
    String newname(words->Filename());
    newname << "C00000000";

    if(rename((char*)heap[0].filename, (char*)newname) != 0) {
      const String message = String("WordDBCaches::Merge: rename ") + heap[0].filename + String(" ") + newname;
      perror((const char*)message);
      return NOTOK;
    }

    String dummy;
    if(files->Put(0, newname, dummy, 0) != 0)
      return NOTOK;
    words->Meta()->SetSerial(WORD_META_SERIAL_FILE, serial);
  }
  if(locking) words->Meta()->Unlock("cache", lock);

  return OK;
}

int WordDBCaches::Merge(const String& filea, const String& fileb, const String& tmpname)
{
  FILE* ftmp = fopen((const char*)tmpname, "w");
  FILE* fa = fopen((const char*)filea, "r");
  FILE* fb = fopen((const char*)fileb, "r");

  unsigned int buffertmp_size = 128;
  unsigned char* buffertmp = (unsigned char*)malloc(buffertmp_size);
  unsigned int buffera_size = 128;
  unsigned char* buffera = (unsigned char*)malloc(buffera_size);
  unsigned int bufferb_size = 128;
  unsigned char* bufferb = (unsigned char*)malloc(bufferb_size);

  unsigned int entriesa_length;
  if(ber_file2value(fa, entriesa_length) < 1) return NOTOK;
  unsigned int entriesb_length;
  if(ber_file2value(fb, entriesb_length) < 1) return NOTOK;

  if(ber_value2file(ftmp, entriesa_length + entriesb_length) < 1) return NOTOK;

  WordDBCacheEntry entrya;
  WordDBCacheEntry entryb;

  if(entriesa_length > 0 && entriesb_length > 0) {
    
    if(ReadEntry(fa, entrya, buffera, buffera_size) != OK) return NOTOK;
    if(ReadEntry(fb, entryb, bufferb, bufferb_size) != OK) return NOTOK;

    while(entriesa_length > 0 && entriesb_length > 0) {
      if(WordKey::Compare(words->GetContext(), (const unsigned char*)entrya.key, entrya.key_size, (const unsigned char*)entryb.key, entryb.key_size) < 0) {
	if(WriteEntry(ftmp, entrya, buffertmp, buffertmp_size) != OK) return NOTOK;
	if(--entriesa_length > 0)
	  if(ReadEntry(fa, entrya, buffera, buffera_size) != OK) return NOTOK;
      } else {
	if(WriteEntry(ftmp, entryb, buffertmp, buffertmp_size) != OK) return NOTOK;
	if(--entriesb_length > 0)
	  if(ReadEntry(fb, entryb, bufferb, bufferb_size) != OK) return NOTOK;
      }
    }
  }

  if(entriesa_length > 0 || entriesb_length > 0) {
    FILE* fp = entriesa_length > 0 ? fa : fb;
    unsigned int& entries_length = entriesa_length > 0 ? entriesa_length : entriesb_length;
    WordDBCacheEntry& entry = entriesa_length > 0 ? entrya : entryb;
    while(entries_length > 0) {
      if(WriteEntry(ftmp, entry, buffertmp, buffertmp_size) != OK) return NOTOK;
      if(--entries_length > 0)
	if(ReadEntry(fp, entry, buffera, buffera_size) != OK) return NOTOK;
    }
  }

  free(buffera);
  free(bufferb);
  free(buffertmp);

  fclose(fa);
  fclose(fb);
  fclose(ftmp);

  return OK;
}

int WordDBCaches::Merge(WordDB& db)
{
  int locking = 0;
  if(!lock) {
    words->Meta()->Lock("cache", lock);
    locking = 1;
  }
  if(Merge() != OK) return NOTOK;

  String filename;
  String dummy;
  WordDBCursor* cursor = files->Cursor();
  if(cursor->Get(filename, dummy, DB_FIRST) != 0) {
    delete cursor;
    return NOTOK;
  }
  cursor->Del();
  delete cursor;

  FILE* fp = fopen((char*)filename, "r");

  unsigned int buffer_size = 128;
  unsigned char* buffer = (unsigned char*)malloc(buffer_size);

  unsigned int entries_length;
  if(ber_file2value(fp, entries_length) < 1) return NOTOK;

  WordDBCacheEntry entry;

  unsigned int i;
  for(i = 0; i < entries_length; i++) {
    if(ReadEntry(fp, entry, buffer, buffer_size) != OK) return NOTOK;
    void* user_data = words->GetContext();
    WORD_DBT_INIT(rkey, (void*)entry.key, entry.key_size);
    WORD_DBT_INIT(rdata, (void*)entry.data, entry.data_size);
    db.db->put(db.db, 0, &rkey, &rdata, 0);
  }

  if(unlink((char*)filename) != 0) {
    const String message = String("WordDBCaches::Merge: unlink ") + filename;
    perror((const char*)message);
    return NOTOK;
  }

  words->Meta()->SetSerial(WORD_META_SERIAL_FILE, 0);
  if(locking) words->Meta()->Unlock("cache", lock);
  size = 0;
  free(buffer);
  fclose(fp);

  return OK;
}

int WordDBCaches::CacheWrite(const String& filename)
{
  FILE* fp = fopen(filename, "w");
  if(!fp) {
    String message;
    message << "WordDBCaches::CacheWrite()" << filename << "): ";
    perror((char*)message);
    return NOTOK;
  }

  int entries_length;
  WordDBCacheEntry* entries;
  int ret;
  if((ret = cache.Entries(entries, entries_length)) != 0)
    return ret;

  if(ber_value2file(fp, entries_length) < 1) return NOTOK;

  unsigned int buffer_size = 1024;
  unsigned char* buffer = (unsigned char*)malloc(buffer_size);
  int i;
  for(i = 0; i < entries_length; i++) {
    if(WriteEntry(fp, entries[i], buffer, buffer_size) != OK) return NOTOK;
  }
  free(buffer);
  fclose(fp);

  cache.Flush();

  return OK;
}

int WordDBCaches::WriteEntry(FILE* fp, WordDBCacheEntry& entry, unsigned char*& buffer, unsigned int& buffer_size)
{
    if(entry.key_size + entry.data_size + 64 > buffer_size) {
      buffer_size = entry.key_size + entry.data_size + 64;
      buffer = (unsigned char*)realloc(buffer, buffer_size);
    }

    int p_size = buffer_size;
    unsigned char* p = buffer;

    int ber_len;
    if((ber_len = ber_value2buf(p, p_size, entry.key_size)) < 1) {
      fprintf(stderr, "WordDBCaches::WriteEntry: BER failed for key %d\n", entry.key_size);
      return NOTOK;
    }
    p += ber_len;
    memcpy(p, entry.key, entry.key_size);
    p += entry.key_size;

    p_size -= ber_len + entry.key_size;

    if((ber_len = ber_value2buf(p, p_size, entry.data_size)) < 1) {
      fprintf(stderr, "WordDBCaches::WriteEntry: BER failed for data %d\n", entry.data_size);
      return NOTOK;
    }
    p += ber_len;
    memcpy(p, entry.data, entry.data_size);
    p += entry.data_size;
    
    if(fwrite((void*)buffer, p - buffer, 1, fp) != 1) {
      perror("WordDBCaches::WriteEntry: cannot write entry ");
      return NOTOK;
    }

    return OK;
}

int WordDBCaches::ReadEntry(FILE* fp, WordDBCacheEntry& entry, unsigned char*& buffer, unsigned int& buffer_size)
{
  if(ber_file2value(fp, entry.key_size) < 1) return NOTOK;

  if(entry.key_size > buffer_size) {
    buffer_size += entry.key_size;
    if(!(buffer = (unsigned char*)realloc(buffer, buffer_size))) return NOTOK;
  }
    
  if(fread((void*)buffer, entry.key_size, 1, fp) != 1) {
    perror("WordDBCaches::ReadEntry(): cannot read key entry ");
    return NOTOK;
  }

  if(ber_file2value(fp, entry.data_size) < 1) return NOTOK;

  if(entry.data_size > 0) {
    if(entry.data_size + entry.key_size > buffer_size) {
      buffer_size += entry.data_size;
      if(!(buffer = (unsigned char*)realloc(buffer, buffer_size))) return NOTOK;
    }

    if(fread((void*)(buffer + entry.key_size), entry.data_size, 1, fp) != 1) {
      perror("WordDBCaches::ReadEntry(): cannot read data entry ");
      return NOTOK;
    }
  }

  entry.key = (char*)buffer;
  entry.data = (char*)(buffer + entry.key_size);

  return OK;
}