/*      $NetBSD: printching.c,v 1.5 2011/08/31 16:24:55 plunky Exp $    */

/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Guy Harris.
 *
 * 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. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1988, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)ching.phx.c 8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: printching.c,v 1.5 2011/08/31 16:24:55 plunky Exp $");
#endif
#endif /* not lint */

/*
 * printching - Print NROFF/TROFF source of change, given the line values.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ching.h"
#include "pathnames.h"

static int changes(void);
static int codem(int a);
static int doahex(void);
static void phx(int hexagram, int flag);

static const struct {
        int     lines;          /* encoded value of lines */
        int     trinum;         /* trigram number */
} table[] = {
        { 777, 0 },             /* 1 */
        { 887, 1 },             /* 4 */
        { 878, 2 },             /* 6 */
        { 788, 3 },             /* 7 */
        { 888, 4 },             /* 8 */
        { 778, 5 },             /* 5 */
        { 787, 6 },             /* 3 */
        { 877, 7 },             /* 2 */
};

/*
 * Gives hexagram number from two component trigrams.
 */
static const int crosstab[8][8] = {
        {1,  34, 5,  26, 11, 9,  14, 43},
        {25, 51, 3,  27, 24, 42, 21, 17},
        {6,  40, 29, 4,  7,  59, 64, 47},
        {33, 62, 39, 52, 15, 53, 56, 31},
        {12, 16, 8,  23, 2,  20, 35, 45},
        {44, 32, 48, 18, 46, 57, 50, 28},
        {13, 55, 63, 22, 36, 37, 30, 49},
        {10, 54, 60, 41, 19, 61, 38, 58}
};

static int trigrams[6];
static int moving[6];

static FILE *chingf;            /* stream to read the hexagram file */

/*ARGSUSED*/
int
main(int argc, char **argv)
{
        char *hexptr;           /* pointer to string of lines */
        char hexstr[6+1];       /* buffer for reading lines in */
        int i;

        if (argc < 2)
                hexptr = fgets(hexstr, 6+1, stdin);
        else
                hexptr = argv[1];
        if (hexptr == NULL || strlen(hexptr) != 6) {
                fprintf(stderr, "What kind of a change is THAT?!?\n");
                exit(1);
        }
        for (i = 0; i < 6; i++) {
                trigrams[i] = hexptr[i] - '0';
                if (trigrams[i] == 6 || trigrams[i] == 9)
                        moving[i] = 1;
                else
                        moving[i] = 0;
        }
        if ((chingf = fopen(_PATH_HEX, "r")) == NULL) {
                fprintf(stderr, "ching: can't read %s\n", _PATH_HEX);
                exit(2);
        }
        phx(doahex(), 0);
        if (changes())
                phx(doahex(), 1);
        exit(0);
}

/*
 * Compute the hexagram number, given the trigrams.
 */
static int
doahex(void)
{
        int lower, upper;       /* encoded values of lower and upper trigrams */
        int lnum = 0, unum = 0; /* indices of upper and lower trigrams */
        int i;

        lower = codem(0);
        upper = codem(3);
        for (i = 0; i < 8; i++) {
                if (table[i].lines == lower)
                         lnum = table[i].trinum;
                if (table[i].lines == upper)
                         unum = table[i].trinum;
        }
        return(crosstab[lnum][unum]);
}

/*
 * Encode a trigram as a 3-digit number; the digits, from left to right,
 * represent the lines.  7 is a solid (yang) line, 8 is a broken (yin) line.
 */
static int
codem(int a)
{
        int code, i;
        int factor[3];

        factor[0] = 1;
        factor[1] = 10;
        factor[2] = 100;
        code = 0;

        for (i = a; i < a + 3; i++) {
                switch(trigrams[i]) {

                case YYANG:
                case OYANG:
                        code += factor[i%3]*7;
                        break;

                case OYIN:
                case YYIN:
                        code += factor[i%3]*8;
                        break;
                }
        }
        return(code);
}

/*
 * Compute the changes based on moving lines; return 1 if any lines moved,
 * 0 if no lines moved.
 */
static int
changes(void)
{
        int cflag;
        int i;

        cflag = 0;
        for (i = 0; i < 6; i++) {
                if (trigrams[i] == OYIN) {
                        trigrams[i] = YYANG;
                        cflag++;
                } else if (trigrams[i] == OYANG) {
                        trigrams[i] = YYIN;
                        cflag++;
                }
        }
        return(cflag);
}

/*
 * Print the NROFF/TROFF source of a hexagram, given the hexagram number;
 * if flag is 0, print the entire source; if flag is 1, ignore the meanings
 * of the lines.
 */
static void
phx(int hexagram, int flag)
{
        char textln[128+1];             /* buffer for text line */
        char *lp;                       /* pointer into buffer */
        int thishex;                    /* number of hexagram just read */
        int lineno;                     /* number of line read in */
        int allmoving;                  /* 1 if all lines are moving */
        int i;

        /*
         * Search for the hexagram; it begins with a line of the form
         * .H <hexagram number> <other data>.
         */
        rewind(chingf);
        for (;;) {
                if (fgets(textln, sizeof(textln), chingf) == NULL) {
                        fprintf(stderr, "ching: Hexagram %d missing\n",
                            hexagram);
                        exit(3);
                }
                lp = &textln[0];
                if (*lp++ != '.' || *lp++ != 'H')
                        continue;
                while (*lp++ == ' ')
                        ;
                lp--;
                thishex = atoi(lp);
                if (thishex < 1 || thishex > 64)
                        continue;
                if (thishex == hexagram)
                        break;
        }

        /*
         * Print up to the line commentary, which ends with a line of the form
         * .L <position> <value>
         */
        fputs(textln, stdout);
        for (;;) {
                if (fgets(textln, sizeof(textln), chingf) == NULL) {
                        fprintf(stderr, "ching: Hexagram %d malformed\n",
                            hexagram);
                        exit(3);
                }
                lp = &textln[0];
                if (*lp++ == '.') {
                        if (*lp++ == 'L')
                                break;
                }
                fputs(textln, stdout);
        }

        /*
         * Now print the line commentaries, if this is the first hexagram.
         */
        if (flag)
                return;

        /*
         * If a line is moving, print its commentary.
         * The text of the commentary ends with a line either of the form
         * .L <position> <value>
         * or of the form
         * .LA <value>
         * or of the form
         * .H <hexagram number> <other arguments>
         */
        allmoving = 1;
        for (i = 0; i < 6; i++) {
                while (*lp++ == ' ')
                        ;
                lp--;
                lineno = atoi(lp);
                if (i + 1 != lineno) {
                        fprintf(stderr, "ching: Hexagram %d malformed\n",
                            hexagram);
                        exit(3);
                }
                if (moving[i])
                        fputs(textln, stdout);
                else
                        allmoving = 0;
                for (;;) {
                        if (fgets(textln, sizeof(textln), chingf) == NULL)
                                break;
                        lp = &textln[0];
                        if (*lp++ == '.' && (*lp == 'L' || *lp == 'H')) {
                                lp++;
                                break;
                        }
                        if (moving[i])
                                fputs(textln, stdout);
                }
        }

        /*
         * If all the lines are moving, print the commentary for that; it
         * ends with a line of the form
         * .H <hexagram number> <other arguments>
         */
        if (*lp == 'A' && allmoving) {
                fputs(textln, stdout);
                for (;;) {
                        if (fgets(textln, sizeof(textln), chingf) == NULL)
                                break;
                        lp = &textln[0];
                        if (*lp++ == '.' || *lp++ == 'H')
                                break;
                        fputs(textln, stdout);
                }
        }
}