/*      $OpenBSD: paste.c,v 1.27 2022/12/04 23:50:49 cheloha Exp $      */

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam S. Moskowitz of Menlo Consulting.
 *
 * 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. 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/queue.h>
#include <sys/types.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char *delim;
int delimcnt;

int     tr(char *);
__dead void usage(void);
void    parallel(char **);
void    sequential(char **);

int
main(int argc, char *argv[])
{
        extern char *optarg;
        extern int optind;
        int ch, seq;

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

        seq = 0;
        while ((ch = getopt(argc, argv, "d:s")) != -1) {
                switch (ch) {
                case 'd':
                        delimcnt = tr(delim = optarg);
                        break;
                case 's':
                        seq = 1;
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc == 0)
                usage();

        if (delim == NULL) {
                delimcnt = 1;
                delim = "\t";
        }

        if (seq)
                sequential(argv);
        else
                parallel(argv);
        return 0;
}

struct list {
        SIMPLEQ_ENTRY(list) entries;
        FILE *fp;
        int cnt;
        char *name;
};

void
parallel(char **argv)
{
        SIMPLEQ_HEAD(, list) head = SIMPLEQ_HEAD_INITIALIZER(head);
        struct list *lp;
        char *line, *p;
        size_t linesize;
        ssize_t len;
        int cnt;
        int opencnt, output;
        char ch;

        for (cnt = 0; (p = *argv) != NULL; ++argv, ++cnt) {
                if ((lp = malloc(sizeof(*lp))) == NULL)
                        err(1, NULL);

                if (p[0] == '-' && p[1] == '\0')
                        lp->fp = stdin;
                else if ((lp->fp = fopen(p, "r")) == NULL)
                        err(1, "%s", p);
                lp->cnt = cnt;
                lp->name = p;
                SIMPLEQ_INSERT_TAIL(&head, lp, entries);
        }

        line = NULL;
        linesize = 0;

        for (opencnt = cnt; opencnt;) {
                output = 0;
                SIMPLEQ_FOREACH(lp, &head, entries) {
                        if (lp->fp == NULL) {
                                if (output && lp->cnt &&
                                    (ch = delim[(lp->cnt - 1) % delimcnt]))
                                        putchar(ch);
                                continue;
                        }
                        if ((len = getline(&line, &linesize, lp->fp)) == -1) {
                                if (ferror(lp->fp))
                                        err(1, "%s", lp->fp == stdin ?
                                            "getline" : lp->name);
                                if (--opencnt == 0)
                                        break;
                                if (lp->fp != stdin)
                                        fclose(lp->fp);
                                lp->fp = NULL;
                                if (output && lp->cnt &&
                                    (ch = delim[(lp->cnt - 1) % delimcnt]))
                                        putchar(ch);
                                continue;
                        }
                        if (line[len - 1] == '\n')
                                line[len - 1] = '\0';
                        /*
                         * make sure that we don't print any delimiters
                         * unless there's a non-empty file.
                         */
                        if (!output) {
                                output = 1;
                                for (cnt = 0; cnt < lp->cnt; ++cnt)
                                        if ((ch = delim[cnt % delimcnt]))
                                                putchar(ch);
                        } else if ((ch = delim[(lp->cnt - 1) % delimcnt]))
                                putchar(ch);
                        fputs(line, stdout);
                }
                if (output)
                        putchar('\n');
        }
        free(line);
}

void
sequential(char **argv)
{
        FILE *fp;
        char *line, *p;
        size_t linesize;
        ssize_t len;
        int cnt;

        line = NULL;
        linesize = 0;
        for (; (p = *argv) != NULL; ++argv) {
                if (p[0] == '-' && p[1] == '\0')
                        fp = stdin;
                else if ((fp = fopen(p, "r")) == NULL) {
                        warn("%s", p);
                        continue;
                }
                cnt = -1;
                while ((len = getline(&line, &linesize, fp)) != -1) {
                        if (line[len - 1] == '\n')
                                line[len - 1] = '\0';
                        if (cnt >= 0)
                                putchar(delim[cnt]);
                        if (++cnt == delimcnt)
                                cnt = 0;
                        fputs(line, stdout);
                }
                if (ferror(fp))
                        err(1, "%s", fp == stdin ? "getline" : p);
                if (cnt >= 0)
                        putchar('\n');
                if (fp != stdin)
                        fclose(fp);
        }
        free(line);
}

int
tr(char *arg)
{
        int cnt;
        char ch, *p;

        for (p = arg, cnt = 0; (ch = *p++) != '\0'; ++arg, ++cnt) {
                if (ch == '\\') {
                        switch (ch = *p++) {
                        case 'n':
                                *arg = '\n';
                                break;
                        case 't':
                                *arg = '\t';
                                break;
                        case '0':
                                *arg = '\0';
                                break;
                        default:
                                *arg = ch;
                                break;
                        }
                } else
                        *arg = ch;
        }

        if (cnt == 0)
                errx(1, "no delimiters specified");
        return cnt;
}

__dead void
usage(void)
{
        extern char *__progname;
        fprintf(stderr, "usage: %s [-s] [-d list] file ...\n", __progname);
        exit(1);
}