/* ********* ShiftSort module---implementation ********* */



#include <stdio.h>

#include <stdlib.h>

#include "kwic.h"

#include "LineStorage.h"

#include "ShiftSort.h"



/* **** local constants **** */



/* **** local types **** */



typedef struct {

        int lineNum;

        int shiftNum;

} LineList,*LineListPtr;



/* **** local variables **** */



static LineListPtr lineList;

static int lineCount;



/***** state invariant *****



1. lineCount >= 0



2. if lineCount == 0 then

	lineList == NULL



3. if lineCount > 0

	lineList is a pointer to an array of lineCount lineLists's



4. forall i in [0..lineCount-1]

	lineList[i].lineNum in [0..LSNumLines()-1]

	lineList[i].shiftNum in [0..LSNumWords(lineList[i].lineNum)-1]



*/



/* **** local functions **** */



/*  return word wordNum from the shifted LineStorage line specified by linePtr  */

static const char* getWord(LineListPtr linePtr,int wordNum)

{

        int shiftedWordNum;



        shiftedWordNum = (wordNum+linePtr->shiftNum) %

		LSNumWords(linePtr->lineNum);

        return LSGetWord(linePtr->lineNum,shiftedWordNum);

}



/*

* if line0 < line1

*       return a negative value

* else if line0 == line1

*       return 0

* else

*       return a positive value

*/

static int lineCompare(LineListPtr line0,LineListPtr line1)

{

        int i,j,minNumWords,minLine;



        if (LSNumWords(line0->lineNum) < LSNumWords(line1->lineNum))

                minNumWords = LSNumWords(line0->lineNum);

        else

                minNumWords = LSNumWords(line1->lineNum);

        for (i = 0; i < minNumWords; i++) {

                j = strcmp(getWord(line0,i),getWord(line1,i));

                if (j != 0)

                        return j;

        }

        /*  assert: line0 and line1 are equal for the first min words  */

        return LSNumWords(line0->lineNum) - LSNumWords(line1->lineNum);

}



/* ****exported functions**** */



void SSInit(void)

{

        lineList = NULL;

        lineCount = 0;

}



void SSReset(void)

{

        if (lineList != NULL)

                free(lineList);

        lineList = NULL;

        lineCount = 0;

}



KWStatus SSShiftSort(void)

{

        int i,j,k;



        /*  compute the size of lineList  */

        lineCount = 0;

        for (i = 0; i < LSNumLines(); i++) {

		for (j = 0; j < LSNumWords(i); j++) {

			/*  exclude lines that start with a noise word  */

			if (!WTIsMember(LSGetWord(i,j)))

				lineCount++;

		}

        }



        /*  allocate space for lineList  */

        lineList = calloc(lineCount, sizeof(LineList));

        if (lineList == NULL) {

		lineCount = 0;

                return KWMEMORYERROR;

	}



        /*  fill lineList  */

        k = 0;

        for (i = 0; i < LSNumLines(); i++) {

                for (j = 0; j < LSNumWords(i); j++) {

			/*  exclude lines that start with a noise word  */

			if (!WTIsMember(LSGetWord(i,j))) {

				lineList[k].lineNum = i;

				lineList[k].shiftNum = j;

				k++;

			}

                }

        }



        /*  sort the shifted lines  */

        qsort(lineList,lineCount,sizeof(LineList),

                (int (*)(void *,void *))lineCompare);



        return KWSUCCESS;

}



const char* SSGetWord(int lineNum,int wordNum)

{

        if (lineNum < 0 || lineNum >= lineCount || wordNum < 0 ||

			wordNum >= LSNumWords(lineList[lineNum].lineNum))

                return NULL;

        else

                return getWord(&lineList[lineNum],wordNum);

}



int SSNumWords(int lineNum)

{

        if (lineNum < 0 || lineNum >= lineCount)

                return(KWRANGEERROR);

        else

                return(LSNumWords(lineList[lineNum].lineNum));

}



int SSGetShiftNum(int lineNum)

{

        if (lineNum < 0 || lineNum >= lineCount)

                return(KWRANGEERROR);

        else

                return(lineList[lineNum].shiftNum);

}



int SSNumLines(void)

{

        return(lineCount);

}



void SSPrintState(void)

{

        int i;



        for (i = 0; i < lineCount; i++)

                printf("lineList[%d]: lineNum=%d shiftNum=%d\n",

                        i,lineList[i].lineNum,lineList[i].shiftNum);

}