/*
 * Calculate the gear ratios and shifting patterns for bicycles.
 * 
 * From: speed@etecnw.com (Paul W. Laudon x7241 (sun))
 * Date: 17 Aug 1994 23:21:36 GMT
 * Newsgroups: rec.bicycles.tech
 * Subject: Gear Shift Tables Made Easy ...
 * 
 * This programs expects an input file as an argument.
 *
 * The file needs to have pairs of lines of numbers.  Blank lines or lines
 *  that start with a '#' are allowed before or after the line pairs.
 *
 * The first line of a pair specifies the number of teeth on the ring gears.
 * The second line of a pair specifies the number of teeth on the cog gears.
 *
 * The numbers in the set of numbers on either line can appear in any order,
 *  including random, as long as the numbers are delimited by spaces.
 *
 * This program supports up to three ring gears and up to eight cog gears.
 *  If you specify more than this the excess will be ignored!
 *
 * If you do not want each gear spec to appear on a separate page you can
 *  comment out the printf that prints a 'Ctl-L' on line 127.
 * 
 * 
 * 08/04/98	m.e.sherman	start to add log graphing
 * 08/05/98	m.e.sherman	complete log graphing
 * 08/06/98	m.e.sherman	add crank, wheel size, more help, and
 *				Sheldon Brown's gear charting
 *                              up max cogs to 10 - who knows...
 * 08/10/98	m.e.sherman	add display option
 * 08/11/98	m.e.sherman	display crank arm length.
 * 09/23/99	m.e.sherman	change numbers displayed in semilog graph
 *				so they are in the right order (line 363)
 * 11/16/99	m.e.sherman	remove newline in print of comment and add to
 *				newline
 * 05/04/02	m.e.sherman	make room for campy 10sp with tripple
 * 05/25/02	m.e.sherman	132 col display for log graph
 * 
 */

#include <stdio.h>
#include <math.h>

extern double log(double);

void lower(char *string);
int LookupWheel(char *ptr);
void ShowUsage();

#define RATIO_CONSTANT  27.0            /* MAGIC RATIO Multiplier        */
#define NUMBER_OF_RATIOS 30		/* campy 10x3			 */

char    lbuf[128];      /* Input Line Buffer                            */

int     rings[3];       /* Main Ring Gear Teeth Counts                  */
int     cogs[10];        /* Cog Gear Teeth Counts                        */

/* log graph limits */
int p1 = 78;		/* paper is 78 characters wide */
int p2 = 77;
double n1;		/* lower limit for log graph */
double n2;		/* upper limit for log graph */
char line[132];		/* a line of the log graph */
char tmps[80];		/* a temp string */

struct  ratio   {
    int         gear;   /* Initialize from 1 to NUMBER_OF_RATIOS        */
    float       value;  /* Gear Ratio times RATIO_CONSTANT              */
    int		ring;	/* which chainring				*/
    float	ratio;	/* Sheldon Brown's radius ratio			*/
} ratios[NUMBER_OF_RATIOS];


char    *spc = "                        ";      /* Printing Spaces      */
char    *dsh = "------------------------";      /* Printing Dashes      */

/* the Sheldon Brown gearing method */
/* wheel radius' taken from his web page */
int	wheel_index;		/* index into wheels table */
#define DEFAULT_WHEEL_INDEX 1
#define NUMBER_OF_WHEELS 26
struct wheel_table{
    char	wheel[20];	/* wheel size name */
    char	alt[20];	/* alternate name */
    int		radius;		/* wheel radius in cm */
    float	diameter;	/* wheel diameter in inches */
} wheels[NUMBER_OF_WHEELS] = {
    "27 x 1 3/8",   "",               345, (float)(345*2)/25.4,
    "27 x 1 1/4",   "",               343, (float)(343*2)/25.4,
    "27 x 1 1/8",   "",               342, (float)(342*2)/25.4,
    "27 x 1",       "",               340, (float)(340*2)/25.4,
    "700 x 44",     "",               354, (float)(354*2)/25.4,
    "700 x 38",     "",               347, (float)(347*2)/25.4,
    "700 x 35",     "",               345, (float)(345*2)/25.4,
    "700 x 32",     "",               342, (float)(342*2)/25.4,
    "700 x 28",     "",               336, (float)(336*2)/25.4,
    "700 x 25",     "",               335, (float)(335*2)/25.4,
    "700 x 20",     "",               332, (float)(332*2)/25.4,
    "26 x 2.125",   "",               330, (float)(330*2)/25.4,
    "26 x 1.9",     "",               324, (float)(324*2)/25.4,
    "26 x 1.5",     "",               312, (float)(312*2)/25.4,
    "26 x 1.25",    "",               311, (float)(311*2)/25.4,
    "26 x 1.0",     "559mm",          305, (float)(305*2)/25.4,
    "650c",         "26 x 1",         311, (float)(311*2)/25.4,
    "wide tubular", "",               338, (float)(338*2)/25.4,
    "tubular",      "narrow tubular", 335, (float)(335*2)/25.4,
    "26 x 1 3/8",   "590mm",          330, (float)(330*2)/25.4,
    "24",           "",               305, (float)(305*2)/25.4,
    "24 x 1",       "520mm",          279, (float)(279*2)/25.4,
    "20 x 1.75",    "406mm",          254, (float)(254*2)/25.4,
    "20 x 1 1/4",   "451mm",          257, (float)(257*2)/25.4,
    "17 x 1 1/4",   "369mm",          211, (float)(211*2)/25.4,
    "16 x 1 3/8",   "349mm",          204, (float)(204*2)/25.4
};

int int_compare( int *a, int *b )
{
    return( *a - *b );
}


int rat_compare( struct ratio *a, struct ratio *b )
{
    if      ( a->value > b->value )
        return( 1 );
    else if ( a->value < b->value )
        return( -1 );
    else
        return( 0 );
}


main( int argc, char *argv[ ] ) {

    FILE        *fs;                    /* File Stream Pointer          */
    int         num_rings, num_cogs;    /* Number of rings & cogs       */
    int         i, j, k, l;             /* Loopers                      */
    int         t, z;                   /* Temp Vars                    */
    int         first = 0;              /* Have we printed first page?  */
    char	*sptr;			/* a string pointer		*/
    int		crank;			/* crank arm length		*/
    float	wheel_size;		/* in inches			*/
    float	radius_ratio;		/* Sheldon Brown's radius Ratio */
    int		gear, logs, sheldon;    /* display option flags	*/
    int		pat, wide;
    
    if ( argc != 2 ) {
        fprintf( stderr, "Usage: %s gear_file\n", argv[0] );
	ShowUsage();
        exit( -5 );
    }
    
    if ( (fs = fopen( argv[1], "r" )) == (FILE *)NULL ) {
        fprintf( stderr, "Could not open gear spec file '%s'\n", argv[1] );
        exit( -1 );
    }
    
    printf("\nGearing for %s\n", argv[1]);
    
    /* defaults */
    wheel_index = DEFAULT_WHEEL_INDEX;	/* 27 x 1 1/4 */
    crank = 170;
    gear = 1;				/* all displays on */
    logs = 1;
    sheldon = 1;
    pat = 1;

    while ( fgets( &lbuf[0], 128, fs ) != (char *)NULL ) {

	if(first == 1){
	    first = 2;
	    printf( "\014\n" );  /* Ctl-L */
	}

	/* skip blank lines */
        if (lbuf[0] == '\n')
            continue;
	
	/* print comments */
        if (lbuf[0] == '#'){
	    printf("%s", lbuf);
            continue;
	}

	/* ---=== crank length ===--- */
        if(lbuf[0] == 'c'){
	    (int)sptr = strstr(lbuf, "=");
	    sptr++;
	    crank = atoi(sptr);
            continue;
	}

	/* ---=== wheel size ===--- */
	if(lbuf[0] == 'w'){
	    (int)sptr = strstr(lbuf, "=");
	    sptr++;
	    wheel_index = LookupWheel(sptr);
            continue;
	}

	/* ---=== display options ===--- */
        if(lbuf[0] == 'd'){
	    (int)sptr = strstr(lbuf, "=");
	    gear = 0;
	    logs = 0;
	    sheldon = 0;
	    pat = 0;
	    wide = 0;
	    sptr++;
	    if(strstr(sptr, "g") > 0){
		gear = 1;
	    }
	    if(strstr(sptr, "l") > 0){
		logs = 1;
	    }
	    if(strstr(sptr, "s") > 0){
		sheldon = 1;
	    }
	    if(strstr(sptr, "p") > 0){
		pat = 1;
	    }
	    if(strstr(sptr, "w") > 0){
		wide = 1;
	    }
            continue;
	}


	/* ---=== set the wheel size ===--- */

	printf(" wheel size = %s", wheels[wheel_index].wheel);
	if(strlen(wheels[wheel_index].alt)>0){
	    printf(", %s", wheels[wheel_index].alt);
	}
	printf(" (radius = %d)\n", wheels[wheel_index].radius);

	wheel_size = wheels[wheel_index].diameter;
	radius_ratio = (float)wheels[wheel_index].radius / (float)crank;

	printf(" crank arm = %dmm\n", crank);

	/* ---=== clear the variables ===--- */

        rings[0] = rings[1] = rings[2] = 0;

        cogs[0] = cogs[1] = cogs[2] = cogs[3] = cogs[4] = 
        cogs[5] = cogs[6] = cogs[7] = cogs[8] = cogs[9] = 0;

        for ( i = 0;  i < NUMBER_OF_RATIOS;  i++ ) {
            ratios[i].gear = 0;
            ratios[i].value = 0.0;
            ratios[i].ring = 0;
            ratios[i].ratio = 0.0;
        }

	/* ---=== scan in the chainrings ===--- */
	/*                                      */
	/* if the line didn't contain any of    */
	/* the above, it must be the chainrings */
	/*                                      */
	/* ---==============================--- */
        num_rings = sscanf( &lbuf[0], "%d%d%d",
                &rings[0], &rings[1], &rings[2] );

        if ( num_rings == 0 ) {
            fprintf( stderr, "Could not parse the ring gear spec\n" );
            exit( -2 );
        }

	/* ---=== read the cogs from the file ===--- */

        if ( fgets( &lbuf[0], 80, fs ) == (char *)NULL ) {
            fprintf( stderr, "Missing cog gear spec\n" );
            exit( -3 );
        }

	/* ---=== and scan them in to the program ===--- */

        num_cogs = sscanf( &lbuf[0], "%d%d%d%d%d%d%d%d%d%d",
			   &cogs[0], &cogs[1], &cogs[2], &cogs[3], &cogs[4], 
			   &cogs[5], &cogs[6], &cogs[7], &cogs[8], &cogs[9]);

        if ( num_cogs == 0 ) {
            fprintf( stderr, "Could not parse the cog gear spec\n" );
            exit( -4 );
        }

	/* ---=== sort the gears by teeth ===--- */

        qsort( &rings[0], num_rings, sizeof(int), int_compare );
        qsort( &cogs[0],  num_cogs,  sizeof(int), int_compare );

	/* ---=== calculate gears and ratios ===--- */

        for ( j = 0;  j < num_rings;  j++ ){
            for ( i = 0;  i < num_cogs;  i++ ) {
                ratios[(j*num_cogs)+i].gear = ((j + 1) * num_cogs) - i;
                ratios[(j*num_cogs)+i].value =
                        ((float)rings[j] / (float)cogs[i]) * wheel_size;
                ratios[(j*num_cogs)+i].ring = rings[j];
		/* Sheldon Brown's radius ratio */
		ratios[(j*num_cogs)+i].ratio = radius_ratio * 
		    (float)rings[j] / (float)cogs[i];
            }
	}

	/* ---=== now draw the charts and graphs ===--- */

	/* ========== */
	/* Gear Chart */
	/* ========== */

	if(gear == 1){
	    printf( "\n\n Gear Ratio Chart\n\n" );
	    
	    printf( "    |" );
	    for ( i = 0;  i < num_cogs;  i++ ) printf( "    %2d", cogs[i] );
	    printf( "\n----+" );
	    for ( i = 0;  i < num_cogs;  i++ ) printf( "%0.6s", dsh );
	    printf( "-\n" );
	    
	    for ( j = (num_rings - 1);  j >= 0;  j-- ) {
		printf( " %2d |", rings[j] );
		for ( i = 0;  i < num_cogs;  i++ )
		    printf( " %5.1f", ratios[(j*num_cogs)+i].value );
		printf( "\n" );
	    }
	}

	/* ============== */
	/* Semi-Log Graph */
	/* ============== */

	if(logs == 1){
	    if(wide == 1){
	      p1 = 130;
	      p2 = 129;
	    }
	    printf( "\n\n Semi-Log Graph\n\n" );
	    n1 = log((double)20);	/* draw gears from 20" */
	    n2 = log((double)120);	/*  to 120" */
	    
	    /* clear the line */
	    for(l=0; l<p1+1; l++){
		line[l] = ' ';
	    }
	    
	    /* draw the log scale */
	    for(j=20; j<121; j+=10){
		l = (int)((log((double)j) - n1) * (p2/(n2 - n1)) + 1);
		sprintf(tmps, "%d", j);
		line[l] = tmps[0];
	    }
	    
	    printf("%s\n", line);
	    
	    /* draw a line */
	    for(j=0; j<p1; j++){
		printf("-");
	    }
	    printf("\n");
	    
	    /* draw the gears */
	    /* for each chainring */
	    for(j=0; j<num_rings; j++){
		/* clear the line */
		for(l=0; l<p1+1; l++){
		    line[l] = ' ';
		}
		/* for each cog */
		for ( i = 0;  i < num_cogs;  i++ ){
		    l = (int)((log((double)
				   (((float)rings[j] / (float)cogs[i]) * 
				    wheel_size)) - n1) * (p2/(n2 - n1)) + 1);
		    sprintf(tmps, "%d", num_cogs - i);
		    line[l] = tmps[0];
		}
		printf("%s\n", line);
	    }
	}


	/* ==================== */
	/* Sheldon's Gear Chart */
	/* ==================== */

	if(sheldon == 1){
	    printf( "\n\n Sheldon's Gear Ratio Chart\n\n" );
	    printf( "    |" );
	    for ( i = 0;  i < num_cogs;  i++ ) printf( "    %2d", cogs[i] );
	    printf( "\n----+" );
	    for ( i = 0;  i < num_cogs;  i++ ) printf( "%0.6s", dsh );
	    printf( "-\n" );
	    /* for ( j = 0;  j < num_rings;  j++ ){ */
	    for ( j = (num_rings - 1);  j >= 0;  j-- ) {
		printf( " %2d |", rings[j] );
		for ( i = 0;  i < num_cogs;  i++ ) {
		    printf("  %1.2f", ratios[(j*num_cogs)+i].ratio);
		}
		printf( "\n" );
	    }
	}

	/* =================== */
	/* Shift Pattern Chart */
	/* =================== */

	if(pat == 1){
	    /* ---=== resort by gears ===--- */
	    qsort( &ratios[0], (num_cogs * num_rings),
		   sizeof(struct ratio), rat_compare );
	    
	    
	    printf( "\n Shift Pattern Chart (with ratio value changes)\n\n" );
	    t = (num_rings - 1) * 2;
	    printf( "    |%0.*s Gear %0.*s   Value  Ratio   Step", 
		    t, spc, t, spc );
	    if ( num_rings > 1 ) printf( "   Main Ring Steps" );
	    printf( "\n----+-------------%0.*s", ((t * 2) + 16), dsh );
	    if ( num_rings > 1 ) printf( "----%0.*s", (num_rings * 7), dsh );
	    printf( "\n" );
	    
	    /* for each chainring */
	    for ( j = 0;  j < num_rings;  j++ ){
		/* for each cog */
		for ( i = 0;  i < num_cogs;  i++ ) {
		    
		    z = (j * num_cogs) + i;
		    t = ratios[z].gear;
		    
		    /* gear# | gear  value */
		    printf( " %2d | %0.*s %2d %0.*s    %5.1f   %4.2f",
			    (z + 1), (((t - 1) / num_cogs) * 4), spc, t,
			    (((num_rings - 1)* 4) - (((t - 1) / num_cogs)* 4)),
			    spc, ratios[z].value, ratios[z].ratio);
		    
		    /* the step */
		    if ( ((j + 1) * (i + 1)) != (num_rings * num_cogs) )
			printf( "   %4.1f", (ratios[z + 1].value -
					     ratios[z].value) );
		    
		    /* ring steps */
		    if((num_rings > 1) && ((ratios[z].gear % num_cogs) != 0)){
			
			for ( k = z + 1;  k < NUMBER_OF_RATIOS;  k++ )
			    if ( (ratios[z].gear + 1) == ratios[k].gear )
				break;
			
			printf( "%0.*s%4.1f",
				(((ratios[z].gear / num_cogs) + 1) * 7),
				spc, (ratios[k].value - ratios[z].value) );
			
		    }
		    printf( "\n" );
		}

	    }
	}/* end of if(pat) */

	if(first == 0 || first == 2 ){
	    first = 1; 
	}
    }
    exit( 0 );
}


int LookupWheel(char *ptr){
    int i, l;
    char string[80], stringn[80];
    
    strncpy(string, ptr, 80);
    lower(string);
    for(i=0; i<NUMBER_OF_WHEELS; i++){
	/* compare wheel names */
	strncpy(stringn, wheels[i].wheel, 80);
	lower(stringn);
	l = strlen(stringn);
	if(strlen(string) > l){
	    l = strlen(string);
	}
	if(strncmp(string, stringn, l) == 0){
	    return(i);
	}

	/* check the alt name */
	strncpy(stringn, wheels[i].alt, 80);
	lower(stringn);
	l = strlen(stringn);
	if(strlen(string) > l){
	    l = strlen(string);
	}
	if(strncmp(string, stringn, l) == 0){
	    printf(" alt index = %d\n", i);	    
	    return(i);
	}
    }
    printf("no wheel size match found for %s, %d\n",string,i);	    
    return(DEFAULT_WHEEL_INDEX);
}
    
void lower(char *string){
    int i;
    char *iptr, *optr;

    iptr = string;
    optr = iptr;
    for(i=0; i<strlen(string); i++, iptr++){
	if(*iptr != ' '){
	    if(*iptr >='A' && *iptr <='Z'){
		*optr = *iptr+32;
	    }else if(*iptr == 0x0d || *iptr == 0x0a){
		*optr = '\0';
	    }else{
		*optr = *iptr;
	    }
	    optr++;
	}
    }
    *optr = '\0';
}

void ShowUsage(){
    int i;
    fprintf(stderr, "Where the gear_file is an ASCII file containing pairs ");
    fprintf(stderr, "of lines of numbers.\n");
    fprintf(stderr, "The first line of a pair specifies the number of ");
    fprintf(stderr, "teeth on the ring gears.\n");
    fprintf(stderr, "The second line of a pair specifies the number of ");
    fprintf(stderr, "teeth on the cog gears.\n");
    fprintf(stderr, "Numbers on each line are separated by spaces.\n");
    fprintf(stderr, "Blank lines are ignored.\n");
    fprintf(stderr, "Lines that start with a '#' are considered comments.\n");
    fprintf(stderr, "Optional inputs are:\n");
    fprintf(stderr, " c = nnn   Inputs crank arm length in mm ");
    fprintf(stderr, "(for Sheldon Brown's raitios).\n");
    fprintf(stderr, "           Default crank size is 170mm.\n");
    fprintf(stderr, " w = sss   Inputs wheel size\n");
    fprintf(stderr, "           Default wheel size is 27 x 1 1/4\n");
    fprintf(stderr, "Valid wheel sizes are:\n");
    for(i=0; i<NUMBER_OF_WHEELS; i++){
	fprintf(stderr, "      %s, %s\n", wheels[i].wheel, wheels[i].alt);
    }
    fprintf(stderr, "White space and case are ignored in the wheel size ");
    fprintf(stderr, "entry\n");
    fprintf(stderr, " d = glsp  Controls the display.  Where:\n");
    fprintf(stderr, "           g = draw gear table\n");
    fprintf(stderr, "           l = draw log table\n");
    fprintf(stderr, "           s = draw Sheldons ratios\n");
    fprintf(stderr, "           p = draw shift pattern\n");
    fprintf(stderr, "           w = 132 column log table\n");
    fprintf(stderr, "by default, all outputs are drawn.\n");
}