/* Delete shapes of insufficient size from shapefile */

/*  gcc shpchop.c libdbf.c dbfopen.c shpopen.c -lm */


#include <stdio.h>
#include <math.h>
#include "shapefil.h"
#include "libdbf.h"	/* My own DBF functions */


/* Function for getting length of pline */
double shpLen(SHPObject* s){
	double d = 0.0;
	if(s != NULL){
		int i, fin;
		double thisX, thisY, xOff, yOff;
		double lastX = s->padfX[0];
		double lastY = s->padfY[0];
		for(i=1, fin=s->nVertices; i<fin; i++){
			thisX = s->padfX[i];
			thisY = s->padfY[i];
			xOff = thisX - lastX;
			yOff = thisY - lastY;
			if(thisX != 0.0 && thisY != 0.0){

				d += sqrt(xOff * xOff + yOff * yOff);
			} else {
				/* Either X or Y is 0, no need for trig */
				xOff = fabs(xOff);
				yOff = fabs(yOff);
				d += xOff + yOff;
			}
			lastX = thisX;
			lastY = thisY;
		}
	}
	return d; 
}


/* Main function*/
int main(int argc, char** argv){
	char * shpName, *ofName;
	double cutoffLen = 0.0;	/* Minimum length of shape */

	SHPHandle inSHP = NULL, outSHP = NULL;
	DBFHandle inDBF = NULL, outDBF = NULL;
	SHPObject *mySHP; 
	DBFRecord *myDBF;

	int i=0,j=0;	/* in/out indexes */

/* Take input */
	if(argc < 2){
		/* TODO: Real error message */
		fprintf(stderr, "FATAL: Not enough args.\n");
		exit(0);
	} else {
		/* TODO: Real input handling */
		char * myArg;
		double myD; 
		while(--argc > 0){
			myArg = argv[argc];
			/* Use outSHP as generic (SHPObject*) */
			if(inSHP == NULL && (outSHP = SHPOpen(myArg, "rb")) != NULL){
				/* File found, keep inSHP */
				shpName = myArg;
				inDBF = DBFOpen(myArg, "rb");
				inSHP = outSHP;
				outSHP = NULL;	/* reset outSHP */
/* NOTE: atof is buggy in Cygwin */
			} else if( (myD = atof(myArg)) > 0.0){
				if(isnan(myD)){
					fprintf(stderr, "NOTE: %s is NaN\n",myArg);
				} else {
					fprintf(stderr, "NOTE: Using length %f\n",myD);
					cutoffLen = myD;
				}
			} else {
				fprintf(stderr, "WARN: Arg %s neither double nor shapefile\n",myArg);
			}
		}

	}
	/* Check input */
	if(inDBF == NULL || inSHP == NULL){
		fprintf(stderr, "FATAL: Could not open SHP and DBF\n");
		exit(0);
	}
	if(cutoffLen <= 0.0){ 
		fprintf(stderr, "FATAL: No input \n");
		exit(0);
	}

/* Create new shpfile and dbf*/
	ofName = (char*)malloc(sizeof(char) * (strlen(shpName) + 8));
	strcpy(ofName, shpName);
	strcat(ofName, "trimmed");
	outDBF = DBFCreate(ofName);
	outSHP = SHPCreate(ofName, inSHP->nShapeType);

	DBFCopyFields(outDBF, inDBF);

	/* Check each shape's length */
	while((mySHP = SHPReadObject(inSHP, i)) != NULL){
		double myLen = shpLen(mySHP);
		if(myLen > cutoffLen){
			myDBF = DBFGetRecord(inDBF,i);
			/* Copy shp and dbf */
			/* Use -1 for append for shapes */
			SHPWriteObject(outSHP, -1, mySHP);
			DBFWriteRecord(outDBF, j, myDBF);
			j++;
			DBFRecordFree(myDBF);
		} else {
			/* debug:
			fprintf(stderr, "%f <= %f\n",myLen, cutoffLen);
			*/
		}
		i++;
		SHPDestroyObject(mySHP);		/* Dealloc */
	}


/* Write new shpfile and dbf */
	DBFClose(inDBF); DBFClose(outDBF);
	SHPClose(inSHP); SHPClose(outSHP);
}