/*      $OpenBSD: units.c,v 1.23 2022/12/26 18:52:10 florian Exp $      */
/*      $NetBSD: units.c,v 1.6 1996/04/06 06:01:03 thorpej Exp $        */

/*
 * units.c   Copyright (c) 1993 by Adrian Mariano (adrian@cam.cornell.edu)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * Disclaimer:  This software is provided by the author "as is".  The author
 * shall not be liable for any damages caused in any way by this software.
 *
 * I would appreciate (though I do not require) receiving a copy of any
 * improvements you might make to this program.
 */

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>

#define UNITSFILE "/usr/share/misc/units.lib"

#define VERSION "1.0"

#define MAXUNITS 1000
#define MAXPREFIXES 100

#define MAXSUBUNITS 500

#define PRIMITIVECHAR '!'

char *powerstring = "^";

struct {
        char *uname;
        char *uval;
} unittable[MAXUNITS];

struct unittype {
        char *numerator[MAXSUBUNITS];
        char *denominator[MAXSUBUNITS];
        double factor;
};

struct {
        char *prefixname;
        char *prefixval;
} prefixtable[MAXPREFIXES];


char *NULLUNIT = "";

int unitcount;
int prefixcount;

char *dupstr(char *);
void readunits(char *);
void initializeunit(struct unittype *);
int addsubunit(char *[], char *);
void showunit(struct unittype *);
void zeroerror(void);
int addunit(struct unittype *, char *, int);
int compare(const void *, const void *);
void sortunit(struct unittype *);
void cancelunit(struct unittype *);
char *lookupunit(char *);
int reduceproduct(struct unittype *, int);
int reduceunit(struct unittype *);
int compareproducts(char **, char **);
int compareunits(struct unittype *, struct unittype *);
int completereduce(struct unittype *);
void showanswer(struct unittype *, struct unittype *);
void usage(void);

char *
dupstr(char *str)
{
        char *ret;

        ret = strdup(str);
        if (!ret) {
                fprintf(stderr, "Memory allocation error\n");
                exit(3);
        }
        return (ret);
}


void
readunits(char *userfile)
{
        char line[512], *lineptr;
        int len, linenum, i;
        FILE *unitfile;

        linenum = 0;

        if (userfile) {
                unitfile = fopen(userfile, "r");
                if (!unitfile) {
                        fprintf(stderr, "Unable to open units file '%s'\n",
                            userfile);
                        exit(1);
                }
        } else {
                unitfile = fopen(UNITSFILE, "r");
                if (!unitfile) {
                        fprintf(stderr, "Can't find units file '%s'\n",
                            UNITSFILE);
                        exit(1);
                }
        }
        while (!feof(unitfile)) {
                if (!fgets(line, sizeof(line), unitfile))
                        break;
                linenum++;
                lineptr = line;
                if (*lineptr == '/')
                        continue;
                lineptr += strspn(lineptr, " \n\t");
                len = strcspn(lineptr, " \n\t");
                lineptr[len] = 0;
                if (!strlen(lineptr))
                        continue;
                if (lineptr[strlen(lineptr) - 1] == '-') { /* it's a prefix */
                        if (prefixcount == MAXPREFIXES) {
                                fprintf(stderr,
                                    "Memory for prefixes exceeded in line %d\n",
                                    linenum);
                                continue;
                        }

                        lineptr[strlen(lineptr) - 1] = 0;
                        for (i = 0; i < prefixcount; i++) {
                                if (!strcmp(prefixtable[i].prefixname, lineptr))
                                        break;
                        }
                        if (i < prefixcount) {
                                fprintf(stderr, "Redefinition of prefix '%s' "
                                    "on line %d ignored\n", lineptr, linenum);
                                continue;       /* skip duplicate prefix */
                        }

                        prefixtable[prefixcount].prefixname = dupstr(lineptr);
                        lineptr += len + 1;
                        lineptr += strspn(lineptr, " \n\t");
                        len = strcspn(lineptr, "\n\t");
                        if (len == 0) {
                                fprintf(stderr, "Unexpected end of prefix on "
                                    "line %d\n", linenum);
                                free(prefixtable[prefixcount].prefixname);
                                continue;
                        }
                        lineptr[len] = 0;
                        prefixtable[prefixcount++].prefixval = dupstr(lineptr);
                } else {                /* it's not a prefix */
                        if (unitcount == MAXUNITS) {
                                fprintf(stderr,
                                    "Memory for units exceeded in line %d\n",
                                    linenum);
                                continue;
                        }

                        for (i = 0; i < unitcount; i++) {
                                if (!strcmp(unittable[i].uname, lineptr))
                                        break;
                        }
                        if (i < unitcount) {
                                fprintf(stderr, "Redefinition of unit '%s' "
                                    "on line %d ignored\n", lineptr, linenum);
                                continue;       /* skip duplicate unit */
                        }

                        unittable[unitcount].uname = dupstr(lineptr);
                        lineptr += len + 1;
                        lineptr += strspn(lineptr, " \n\t");
                        if (!strlen(lineptr)) {
                                fprintf(stderr, "Unexpected end of unit on "
                                    "line %d\n", linenum);
                                free(unittable[unitcount].uname);
                                continue;
                        }
                        len = strcspn(lineptr, "\n\t");
                        lineptr[len] = 0;
                        unittable[unitcount++].uval = dupstr(lineptr);
                }
        }
        fclose(unitfile);
}

void
initializeunit(struct unittype *theunit)
{
        theunit->factor = 1.0;
        theunit->numerator[0] = theunit->denominator[0] = NULL;
}


int
addsubunit(char *product[], char *toadd)
{
        char **ptr;

        for (ptr = product; *ptr && *ptr != NULLUNIT; ptr++);
        if (ptr >= product + MAXSUBUNITS) {
                fprintf(stderr, "Memory overflow in unit reduction\n");
                return 1;
        }
        if (!*ptr)
                *(ptr + 1) = 0;
        *ptr = dupstr(toadd);
        return 0;
}


void
showunit(struct unittype *theunit)
{
        char **ptr;
        int printedslash;
        int counter = 1;

        printf("\t%.8g", theunit->factor);
        for (ptr = theunit->numerator; *ptr; ptr++) {
                if (ptr > theunit->numerator && **ptr &&
                    !strcmp(*ptr, *(ptr - 1)))
                        counter++;
                else {
                        if (counter > 1)
                                printf("%s%d", powerstring, counter);
                        if (**ptr)
                                printf(" %s", *ptr);
                        counter = 1;
                }
        }
        if (counter > 1)
                printf("%s%d", powerstring, counter);
        counter = 1;
        printedslash = 0;
        for (ptr = theunit->denominator; *ptr; ptr++) {
                if (ptr > theunit->denominator && **ptr &&
                    !strcmp(*ptr, *(ptr - 1)))
                        counter++;
                else {
                        if (counter > 1)
                                printf("%s%d", powerstring, counter);
                        if (**ptr) {
                                if (!printedslash)
                                        printf(" /");
                                printedslash = 1;
                                printf(" %s", *ptr);
                        }
                        counter = 1;
                }
        }
        if (counter > 1)
                printf("%s%d", powerstring, counter);
        printf("\n");
}


void
zeroerror(void)
{
        fprintf(stderr, "Unit reduces to zero\n");
}

/*
   Adds the specified string to the unit.
   Flip is 0 for adding normally, 1 for adding reciprocal.

   Returns 0 for successful addition, nonzero on error.
*/

int
addunit(struct unittype *theunit, char *toadd, int flip)
{
        char *scratch, *savescr;
        char *item;
        char *divider, *slash;
        int doingtop;

        savescr = scratch = dupstr(toadd);
        for (slash = scratch + 1; *slash; slash++)
                if (*slash == '-' &&
                    (tolower((unsigned char)*(slash - 1)) != 'e' ||
                    !strchr(".0123456789", *(slash + 1))))
                        *slash = ' ';
        slash = strchr(scratch, '/');
        if (slash)
                *slash = 0;
        doingtop = 1;
        do {
                item = strtok(scratch, " *\t\n/");
                while (item) {
                        if (strchr("0123456789.", *item)) { /* item is a number */
                                double num;

                                divider = strchr(item, '|');
                                if (divider) {
                                        *divider = 0;
                                        num = atof(item);
                                        if (!num) {
                                                zeroerror();
                                                free(savescr);
                                                return 1;
                                        }
                                        if (doingtop ^ flip)
                                                theunit->factor *= num;
                                        else
                                                theunit->factor /= num;
                                        num = atof(divider + 1);
                                        if (!num) {
                                                zeroerror();
                                                free(savescr);
                                                return 1;
                                        }
                                        if (doingtop ^ flip)
                                                theunit->factor /= num;
                                        else
                                                theunit->factor *= num;
                                } else {
                                        num = atof(item);
                                        if (!num) {
                                                zeroerror();
                                                free(savescr);
                                                return 1;
                                        }
                                        if (doingtop ^ flip)
                                                theunit->factor *= num;
                                        else
                                                theunit->factor /= num;

                                }
                        } else {        /* item is not a number */
                                int repeat = 1;

                                if (strchr("23456789",
                                    item[strlen(item) - 1])) {
                                        repeat = item[strlen(item) - 1] - '0';
                                        item[strlen(item) - 1] = 0;
                                }
                                for (; repeat; repeat--)
                                        if (addsubunit(doingtop ^ flip
                                            ? theunit->numerator
                                            : theunit->denominator, item)) {
                                                free(savescr);
                                                return 1;
                                        }
                        }
                        item = strtok(NULL, " *\t/\n");
                }
                doingtop--;
                if (slash) {
                        scratch = slash + 1;
                } else
                        doingtop--;
        } while (doingtop >= 0);
        free(savescr);
        return 0;
}


int
compare(const void *item1, const void *item2)
{
        return strcmp(*(char **) item1, *(char **) item2);
}


void
sortunit(struct unittype *theunit)
{
        char **ptr;
        int count;

        for (count = 0, ptr = theunit->numerator; *ptr; ptr++, count++);
        qsort(theunit->numerator, count, sizeof(char *), compare);
        for (count = 0, ptr = theunit->denominator; *ptr; ptr++, count++);
        qsort(theunit->denominator, count, sizeof(char *), compare);
}


void
cancelunit(struct unittype *theunit)
{
        char **den, **num;
        int comp;

        den = theunit->denominator;
        num = theunit->numerator;

        while (*num && *den) {
                comp = strcmp(*den, *num);
                if (!comp) {
                        *den++ = NULLUNIT;
                        *num++ = NULLUNIT;
                } else if (comp < 0)
                        den++;
                else
                        num++;
        }
}




/*
   Looks up the definition for the specified unit.
   Returns a pointer to the definition or a null pointer
   if the specified unit does not appear in the units table.
*/

static char buffer[500];        /* buffer for lookupunit answers with
                                   prefixes */

char *
lookupunit(char *unit)
{
        size_t len;
        int i;
        char *copy;

        for (i = 0; i < unitcount; i++) {
                if (!strcmp(unittable[i].uname, unit))
                        return unittable[i].uval;
        }

        len = strlen(unit);
        if (len == 0)
                return NULL;
        if (unit[len - 1] == '^') {
                copy = dupstr(unit);
                copy[len - 1] = '\0';
                for (i = 0; i < unitcount; i++) {
                        if (!strcmp(unittable[i].uname, copy)) {
                                strlcpy(buffer, copy, sizeof(buffer));
                                free(copy);
                                return buffer;
                        }
                }
                free(copy);
        }
        if (unit[len - 1] == 's') {
                copy = dupstr(unit);
                copy[len - 1] = '\0';
                --len;
                for (i = 0; i < unitcount; i++) {
                        if (!strcmp(unittable[i].uname, copy)) {
                                strlcpy(buffer, copy, sizeof(buffer));
                                free(copy);
                                return buffer;
                        }
                }
                if (len != 0 && copy[len - 1] == 'e') {
                        copy[len - 1] = 0;
                        for (i = 0; i < unitcount; i++) {
                                if (!strcmp(unittable[i].uname, copy)) {
                                        strlcpy(buffer, copy, sizeof(buffer));
                                        free(copy);
                                        return buffer;
                                }
                        }
                }
                free(copy);
        }
        for (i = 0; i < prefixcount; i++) {
                len = strlen(prefixtable[i].prefixname);
                if (!strncmp(prefixtable[i].prefixname, unit, len)) {
                        if (!strlen(unit + len) || lookupunit(unit + len)) {
                                snprintf(buffer, sizeof(buffer), "%s %s",
                                    prefixtable[i].prefixval, unit + len);
                                return buffer;
                        }
                }
        }
        return NULL;
}



/*
   reduces a product of symbolic units to primitive units.
   The three low bits are used to return flags:

     bit 0 (1) set on if reductions were performed without error.
     bit 1 (2) set on if no reductions are performed.
     bit 2 (4) set on if an unknown unit is discovered.
*/


#define ERROR 4

int
reduceproduct(struct unittype *theunit, int flip)
{
        char *toadd, **product;
        int didsomething = 2;

        if (flip)
                product = theunit->denominator;
        else
                product = theunit->numerator;

        for (; *product; product++) {

                for (;;) {
                        if (!strlen(*product))
                                break;
                        toadd = lookupunit(*product);
                        if (!toadd) {
                                printf("unknown unit '%s'\n", *product);
                                return ERROR;
                        }
                        if (strchr(toadd, PRIMITIVECHAR))
                                break;
                        didsomething = 1;
                        if (*product != NULLUNIT) {
                                free(*product);
                                *product = NULLUNIT;
                        }
                        if (addunit(theunit, toadd, flip))
                                return ERROR;
                }
        }
        return didsomething;
}


/*
   Reduces numerator and denominator of the specified unit.
   Returns 0 on success, or 1 on unknown unit error.
*/

int
reduceunit(struct unittype *theunit)
{
        int ret;

        ret = 1;
        while (ret & 1) {
                ret = reduceproduct(theunit, 0) | reduceproduct(theunit, 1);
                if (ret & 4)
                        return 1;
        }
        return 0;
}


int
compareproducts(char **one, char **two)
{
        while (*one || *two) {
                if (!*one && *two != NULLUNIT)
                        return 1;
                if (!*two && *one != NULLUNIT)
                        return 1;
                if (*one == NULLUNIT)
                        one++;
                else if (*two == NULLUNIT)
                        two++;
                else if (strcmp(*one, *two))
                        return 1;
                else
                        one++, two++;
        }
        return 0;
}


/* Return zero if units are compatible, nonzero otherwise */

int
compareunits(struct unittype *first, struct unittype *second)
{
        return compareproducts(first->numerator, second->numerator) ||
            compareproducts(first->denominator, second->denominator);
}


int
completereduce(struct unittype *unit)
{
        if (reduceunit(unit))
                return 1;
        sortunit(unit);
        cancelunit(unit);
        return 0;
}


void
showanswer(struct unittype *have, struct unittype *want)
{
        if (compareunits(have, want)) {
                printf("conformability error\n");
                showunit(have);
                showunit(want);
        } else
                printf("\t* %.8g\n\t/ %.8g\n", have->factor / want->factor,
                    want->factor / have->factor);
}


void
usage(void)
{
        fprintf(stderr,
            "usage: units [-qv] [-f filename] [[count] from-unit to-unit]\n");
        exit(3);
}


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

        struct unittype have, want;
        char havestr[81], wantstr[81];
        int optchar;
        int quiet = 0, units_read = 0;

        extern char *optarg;
        extern int optind;

        if (pledge("stdio rpath", NULL) == -1)
                err(1, "pledge");

        while ((optchar = getopt(argc, argv, "vqf:")) != -1) {
                switch (optchar) {
                case 'f':
                        units_read = 1;
                        readunits(*optarg == '\0' ? NULL : optarg);
                        break;
                case 'q':
                        quiet = 1;
                        break;
                case 'v':
                        fprintf(stderr,
                            "units version %s Copyright (c) 1993 by Adrian Mariano\n",
                            VERSION);
                        fprintf(stderr,
                            "This program may be freely distributed\n");
                        usage();
                default:
                        usage();
                        break;
                }
        }

        argc -= optind;
        argv += optind;

        if (argc != 3 && argc != 2 && argc != 0)
                usage();

        if (!units_read)
                readunits(NULL);

        if (pledge("stdio", NULL) == -1)
                err(1, "pledge");

        if (argc == 3) {
                strlcpy(havestr, argv[0], sizeof(havestr));
                strlcat(havestr, " ", sizeof(havestr));
                strlcat(havestr, argv[1], sizeof(havestr));
                argc--;
                argv++;
                argv[0] = havestr;
        }

        if (argc == 2) {
                strlcpy(havestr, argv[0], sizeof(havestr));
                strlcpy(wantstr, argv[1], sizeof(wantstr));
                initializeunit(&have);
                addunit(&have, havestr, 0);
                completereduce(&have);
                initializeunit(&want);
                addunit(&want, wantstr, 0);
                completereduce(&want);
                showanswer(&have, &want);
        } else {
                if (!quiet)
                        printf("%d units, %d prefixes\n", unitcount,
                            prefixcount);
                for (;;) {
                        do {
                                initializeunit(&have);
                                if (!quiet)
                                        printf("You have: ");
                                if (!fgets(havestr, sizeof(havestr), stdin)) {
                                        if (!quiet)
                                                putchar('\n');
                                        exit(0);
                                }
                        } while (addunit(&have, havestr, 0) ||
                            completereduce(&have));
                        do {
                                initializeunit(&want);
                                if (!quiet)
                                        printf("You want: ");
                                if (!fgets(wantstr, sizeof(wantstr), stdin)) {
                                        if (!quiet)
                                                putchar('\n');
                                        exit(0);
                                }
                        } while (addunit(&want, wantstr, 0) ||
                            completereduce(&want));
                        showanswer(&have, &want);
                }
        }
        return (0);
}