/**
   
    This file handles all of the file I/O for pages.

*/
#include "page.h"
#include "page/slotted.h"
#include <lladd/bufferManager.h>


#include "pageFile.h"
#include <assert.h>
#include "logger/logWriter.h"

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

#define __USE_GNU  /* For O_DIRECT.. */

#include <fcntl.h>
#include <unistd.h>

static int stable = -1;
static pthread_mutex_t stable_mutex;

static long myLseek(int f, long offset, int whence);
static long myLseekNoLock(int f, long offset, int whence);

void pageRead(Page *ret) {

  long pageoffset;
  long offset;

  /** @todo pageRead() is using fseek to calculate the file size on each read, which is inefficient. */
  pageoffset = ret->id * PAGE_SIZE;
  pthread_mutex_lock(&stable_mutex);

  offset = myLseekNoLock(stable, pageoffset, SEEK_SET);
  assert(offset == pageoffset);
  int read_size;
  read_size = read(stable, ret->memAddr, PAGE_SIZE);
  if(read_size != PAGE_SIZE) {
    if (!read_size) { 
      long fileSize = myLseekNoLock(stable, 0, SEEK_END);
      offset = myLseekNoLock(stable, pageoffset, SEEK_SET);
      assert(offset == pageoffset);
      if(fileSize <= pageoffset) { 
	pageInitialize(ret);
	write(stable, ret->memAddr, PAGE_SIZE);
      }
    } else if(read_size == -1) { 
      perror("pageFile.c couldn't read");
      fflush(NULL);
      assert(0);
    } else {
      printf("pageFile.c readfile: read_size = %d, errno = %d\n", read_size, errno);
      abort();
    }
  }
  pthread_mutex_unlock(&stable_mutex);

}

void pageWrite(Page * ret) {

  long pageoffset = ret->id * PAGE_SIZE;
  long offset ;

  /*  assert(ret->pending == 0); */
  
  if(flushedLSN() < pageReadLSN(ret)) {
    DEBUG("pageWrite is calling syncLog()!\n"); 
    syncLog();
  }

  pthread_mutex_lock(&stable_mutex);

  offset = myLseekNoLock(stable, pageoffset, SEEK_SET);
  assert(offset == pageoffset);
  assert(ret->memAddr);

  /*  DEBUG("Writing page %d\n", ret->id); */
  int write_ret = write(stable, ret->memAddr, PAGE_SIZE);
  if(-1 == write_ret) {
    perror("pageFile.c couldn't write");
    fflush(NULL);
    abort();
  } else if(0 == write_ret) {
    /* now what? */
    printf("write_ret is zero\n");
    fflush(NULL);
    abort();
  } else if(write_ret != PAGE_SIZE){
    printf("write_ret is %d\n", write_ret);
    fflush(NULL);
    abort();
  }
  pthread_mutex_unlock(&stable_mutex);
}

void openPageFile() {

  DEBUG("Opening storefile.\n");

  stable = open (STORE_FILE, O_CREAT | O_RDWR | O_DIRECT, S_IRWXU | S_IRWXG | S_IRWXO);

  if(stable == -1) {
    perror("couldn't open storefile");
    fflush(NULL);
    abort();
  }
  
  pthread_mutex_init(&stable_mutex, NULL);

}
void closePageFile() {

  int ret = close(stable);

  if(-1 == ret) { 
    perror("Couldn't close storefile.");
    fflush(NULL);
    abort();
  }
  stable = -1;
}

long myLseek(int f, long offset, int whence) {
  long ret;
  pthread_mutex_lock(&stable_mutex);
  ret = myLseekNoLock(f, offset, whence);
  pthread_mutex_unlock(&stable_mutex);
  return ret;
}

long myLseekNoLock(int f, long offset, int whence) {
  assert(! ( offset % 4096 ));
  long ret = lseek(f, offset, whence);
  if(ret == -1) {
    perror("Couldn't seek.");
    fflush(NULL);
    abort();
  }
  return ret;
}

/*void myFwrite(const void * dat, long size, FILE * f) {
  int nmemb = fwrite(dat, size, 1, f); 
  / * test * /
  if(nmemb != 1) {
    perror("myFwrite");
    abort();
    / *    return FILE_WRITE_OPEN_ERROR; * /
  }
  
}*/

long pageCount() {
  long fileSize = myLseek(stable, 0, SEEK_END);

  assert(! (fileSize % PAGE_SIZE));
  return fileSize / PAGE_SIZE;
}