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#include <stdio.h>
#include <stdlib.h>
#include "storage_mgr.h"
#include "dberror.h"
#include <sys/stat.h>

void initStorageManager (void) {

}

/************************************************************
 *              manipulating page files                     *
 ************************************************************/


/*******************************************************************
* NAME :            RC createPageFile (char *fileName)
*
* DESCRIPTION :     Create a new page file fileName. The initial size is one page.
*					This method fills this single page with '\0' bytes.
*
* PARAMETERS:
*            char *  fileName                Name of the file to be created
*
* RETURN :
*            Type:   RC                     Returned code:
*            Values: RC_OK                  file created successfully
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-01	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC createPageFile (char *fileName) {
	// Open a new file for writing
	FILE *pageFile = fopen(fileName, "wb");

	// Allocate one PAGE_SIZE space in memory and fill with \0 characters
	char *buffer = (char *) calloc(PAGE_SIZE, sizeof(char));

	// Write the buffer of zeroes to into the file
	fwrite (buffer, sizeof(char), PAGE_SIZE, pageFile);

	// Free memory and close
	free(buffer);
	fclose(pageFile);

	return RC_OK;
}

/*******************************************************************
* NAME :            RC openPageFile (char *fileName, SM_FileHandle *fHandle)
*
* DESCRIPTION :     Opens an existing page file. If opening the file is successful,
*                   then the fields of this file handle should be initialized with
*                   the information about the opened file.
*
* PARAMETERS:
*            char *  fileName                Name of the file to be created
*            SM_Filehandle * fHandle         An existing file handle
*
* RETURN :
*            Type:   RC                     Returned code:
*            Values: RC_OK                  file created successfully
*		     RC_FILE_NOT_FOUND      file does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-01	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC openPageFile (char *fileName, SM_FileHandle *fHandle) {
	// Open an existing file for both reading and writing
	FILE *pageFile = fopen(fileName, "rb+");

	// Check if file exists
	if (pageFile == NULL) {
		return RC_FILE_NOT_FOUND;
	} else {
		// Calculate size of the file
		struct stat st;
		stat(fileName, &st);
		int size = st.st_size;

		// Obtain number of pages
		int nPages = (int) size / PAGE_SIZE;

		// Initialize fields of file handle
		fHandle->fileName = fileName;
		fHandle->totalNumPages = nPages;
		fHandle->curPagePos = 0;
		fHandle->mgmtInfo = pageFile;
	}
	return RC_OK;
}

/*******************************************************************
* NAME :            closePageFile (SM_FileHandle *fHandle)
*
* DESCRIPTION :     Close page file which already opened stored information in fHandle.
*                   If closing the file is successful, then return RC_OK,
*                   else return error.
*
* PARAMETERS
*            SM_Filehandle * fHandle         An existing file handle
*
* RETURN :
*            Type:   RC                     Returned code:
*            Values: RC_OK                  file created successfully
*		     RC_FILE_NOT_FOUND      file does not exist
*
* AUTHOR :
*			 Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>
*
* HISTORY :
*            DATE       	  WHO     				                                      DETAIL
*            -----------    -----------------------------------------------------      ---------------------------------
*            2016-02-01	    Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>      Initialization
*            2016-02-06     Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>      Added comments and header comment
*
*******************************************************************/
RC closePageFile (SM_FileHandle *fHandle) {

	//Check and close file return error if any
	int close = fclose(fHandle->mgmtInfo);
	if (close == 0)
	{
		return RC_OK;
	}
	else
	{
		return RC_FILE_NOT_FOUND;
	}
}

/*******************************************************************
* NAME :            RC destroyPageFile (char *fileName)
*
* DESCRIPTION :     Destroys an existing page file.
*
* PARAMETERS:
*            char *  fileName                Name of the file to be created
*
* RETURN :
*            Type:   RC                     Returned code:
*            Values: RC_OK                  file destroyed successfully
*		     RC_FILE_NOT_FOUND      file does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-01	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC destroyPageFile (char *fileName) {
	// Check if file is removed successfully
	int removed = remove(fileName);
	if (removed == 0) {
		return RC_OK;
	} else {
		return RC_FILE_NOT_FOUND;
	}
}

/*******************************************************************
* NAME :            readBlock (int pageNum, SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Seek into specific page and perform read page in to memory if it valid
*
* PARAMETERS
*            int pageNum                     The pageNumth block needed to be read
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Memory which wanted to load data into
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file created successfully
*		     RC_READ_NON_EXISTING_PAGE      page file does not exist
*
* AUTHOR :
*			 Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>
*
* HISTORY :
*            DATE       	  WHO     				                                      DETAIL
*            -----------    -----------------------------------------------------      ---------------------------------
*            2016-02-01	    Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>      Initialization
*            2016-02-06     Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>      Add missing fseek
*            2016-02-06     Patipat Duangchalomnin <pduangchalomnin@hawk.iit.edu>      Added comments and header comment
*	     	 2016-02-08     Adrian Tirados <atirados@hawk.iit.edu>		       Added check for opened file
*
*******************************************************************/
RC readBlock (int pageNum, SM_FileHandle *fHandle, SM_PageHandle memPage) {
	int pageFirstByte = pageNum * PAGE_SIZE * sizeof(char);

	// Check if file is opened
	if (fHandle->mgmtInfo == NULL) {
		return RC_FILE_NOT_FOUND;
	}
	//Check if page does exist
	if (0 > pageNum || fHandle->totalNumPages < pageNum)
	{
		printf("FLAG1!!\n");
		return RC_READ_NON_EXISTING_PAGE;
	}
	else
	{
		//Read and write block to memPage (Expected number of element read should be return)
		if(fseek(fHandle->mgmtInfo, pageFirstByte, SEEK_SET) != 0) {
			printf("FLAG2!!\n");
			return RC_READ_NON_EXISTING_PAGE;
		}

		unsigned long size = fread(memPage, sizeof(char), PAGE_SIZE, fHandle->mgmtInfo);

		if (size == PAGE_SIZE)
		{
			//Set current page position
			fHandle->curPagePos = pageNum;
			return RC_OK;
		}
		else
		{
			printf("FLAG3!!\n");
			printf("%zu\n", size);
			printf("%d\n", pageNum);
			return RC_READ_NON_EXISTING_PAGE;
		}
	}
}

/*******************************************************************
* NAME :            int getBlockPos (SM_FileHandle *fHandle)
*
* DESCRIPTION :     Return the current page position in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*
* RETURN :
*            Type:   int                    Current page position
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
int getBlockPos (SM_FileHandle *fHandle) {
	// Get the current page from the file handle information
	return fHandle->curPagePos;
}

/*******************************************************************
* NAME :            RC readFirstBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Read the first page in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file read successfully
*		     RC_READ_NON_EXISTING_PAGE      page does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC readFirstBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Call readBlock to read page '0' and return its RC
	return readBlock(0, fHandle, memPage);
}

/*******************************************************************
* NAME :            RC readPreviousBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Read the previous page to the current position in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file read successfully
*		     RC_READ_NON_EXISTING_PAGE      page does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC readPreviousBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Calculate previous page
	int previousBlock = fHandle->curPagePos - 1;

	// Call readBlock to read previousBlock and return its RC
	return readBlock(previousBlock, fHandle, memPage);
}

/*******************************************************************
* NAME :            RC readCurrentBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Read the current page in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file read successfully
*		     RC_READ_NON_EXISTING_PAGE      page does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC readCurrentBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Call readBlock to read current page and return its RC
	return readBlock(fHandle->curPagePos, fHandle, memPage);
}

/*******************************************************************
* NAME :            RC readNextBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Read the next page to the current position page in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file read successfully
*	  	     RC_READ_NON_EXISTING_PAGE      page does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC readNextBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Calculate next page
	int nextBlock = fHandle->curPagePos + 1;

	// Call readBlock to read nextBlock and return its RC
	return readBlock(nextBlock, fHandle, memPage);
}

/*******************************************************************
* NAME :            RC readLastBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Read the last page in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file read successfully
*		     RC_READ_NON_EXISTING_PAGE      page does not exist
*
* AUTHOR :
*			 Adrian Tirados <atirados@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02	    Adrian Tirados <atirados@hawk.iit.edu>   Initialization
*            2016-02-06     Adrian Tirados <atirados@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC readLastBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Call readBlock to read last page (totalNumPages) and return its RC
	int lastBlock = fHandle->totalNumPages-1;
	return readBlock(lastBlock, fHandle, memPage);
}

/************************************************************
 *            writing blocks to a page file                 *
 ************************************************************/

/*******************************************************************
* NAME :            RC writeBlock (int pageNum, SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Write a page to disk using an absolute position.
*
* PARAMETERS:
* 	     int pageNum		     The pageNumth block that the method writes
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file write successfully
*		     RC_WRITE_FAILED                failed to write
*
* AUTHOR :
*			Yung Chi Shih <yshih2@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-08		Yung Chi Shih <yshih2@hawk.iit.edu>       Initialization
*            2016-02-08     	Yung Chi Shih <yshih2@hawk.iit.edu>       Added comments and header comment
*	     2016-02-08		Adrian Tirados <atirados@hawk.iit.edu>	  Fixed return code after running test
*
*******************************************************************/
RC writeBlock (int pageNum, SM_FileHandle *fHandle, SM_PageHandle memPage) {

	//check if the pageNumth block that the method writes is not less than 0
	if (0 > pageNum || fHandle->totalNumPages < pageNum)
		return RC_WRITE_FAILED;

	//sets the file pointer point to a structure that contains information about the file
	FILE *pageFile = fHandle->mgmtInfo;

	//declares the number of bytes to offset
	long int offset = pageNum * PAGE_SIZE;

	//sets the file position of the stream to beginning of file
	fseek(pageFile, offset, SEEK_SET);

	//check if the write is successful
	if (fwrite(memPage, sizeof(char), PAGE_SIZE, pageFile) != PAGE_SIZE) {
		return RC_WRITE_FAILED;
	} else {
		fHandle->curPagePos = pageNum;
		return RC_OK;
	}
}

/*******************************************************************
* NAME :            RC writeCurrentBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Write the current page in a file.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*            SM_PageHandle memPage           Pointer to an area in memory storing the data of a page
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK                          file write successfully
*		     RC_WRITE_FAILED                failed to write
*
* AUTHOR :
*			Yung Chi Shih <yshih2@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-07		Yung Chi Shih <yshih2@hawk.iit.edu>   Initialization
*            2016-02-07     	Yung Chi Shih <yshih2@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC writeCurrentBlock (SM_FileHandle *fHandle, SM_PageHandle memPage) {
	// Call writeBlock to write current page and return its RC
	return writeBlock(fHandle->curPagePos, fHandle, memPage);
}

/*******************************************************************
* NAME :            RC appendEmptyBlock (SM_FileHandle *fHandle, SM_PageHandle memPage)
*
* DESCRIPTION :     Append a new page at the end of the file
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_WRITE_FAILED                failed to write
*
*
* AUTHOR :
*			 Yung Chi Shih <yshih2@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-02		Yung Chi Shih <yshih2@hawk.iit.edu>   Initialization
*            2016-02-07    	Yung Chi Shih <yshih2@hawk.iit.edu>   Added comments and header comment
*            2016-02-08    	Yung Chi Shih <yshih2@hawk.iit.edu>   Added file pointer declaration
*
*******************************************************************/
RC appendEmptyBlock (SM_FileHandle *fHandle) {

	//sets the file pointer point to a structure that contains information about the file
	FILE *pageFile = fHandle->mgmtInfo;

	char *buffer = (char *) calloc(PAGE_SIZE, sizeof(char));


	struct stat st;
	stat(fHandle->fileName, &st);
	int size = st.st_size;

	//writes data
	fwrite (buffer, sizeof(char), PAGE_SIZE, pageFile);

	stat(fHandle->fileName, &st);
	int newSize = st.st_size;

	//check if a new block of size PAGE_SIZE is appeneded
	if (size + PAGE_SIZE != newSize) {
		free(buffer);
		return RC_WRITE_FAILED;
	}

	free(buffer);

	//increments the total number of pages
	fHandle->totalNumPages++;
	fHandle->curPagePos++;
	return RC_OK;
}

/*******************************************************************
* NAME :            RC ensureCapacity (int numberOfPages, SM_FileHandle *fHandle)
*
* DESCRIPTION :     Increase page size of file to equal numberOfPages if it is less than numberOfPages.
*
* PARAMETERS:
*            SM_Filehandle * fHandle         An existing file handle
*
* RETURN :
*            Type:   RC                             Returned code:
*            Values: RC_OK			    file page size is equal to or more than numberOfPages
*
*
* AUTHOR :
*			 Arpita Rathore <arathore@hawk.iit.edu>
*
* HISTORY :
*            DATE       	WHO     				                 DETAIL
*            -----------    ---------------------------------------  ---------------------------------
*            2016-02-04		Arpita Rathore <arathore@hawk.iit.edu>   Initialization
*            2016-02-07    	Arpita Rathore <arathore@hawk.iit.edu>   Added comments and header comment
*
*******************************************************************/
RC ensureCapacity (int numberOfPages, SM_FileHandle *fHandle) {

	//check if the file page size is less than numberOfPages
	if (fHandle->totalNumPages < numberOfPages) {
		//call appendEmptyBlock to append an empty page, check again if size is still less than numberOfPages, continue appending a page until size is equal to numberOfPages
		do {
			appendEmptyBlock(fHandle);
		} while (fHandle->totalNumPages < numberOfPages);
		//file page size is equal to or more than numberOfPages, appending is not needed
	}
	return RC_OK;
}