/*
 * Copyright (C) 2003 Sean Chittenden <seanc@FreeBSD.org>
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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/types.h>
#include <sys/param.h>

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

#include "randomize_fd.h"

static struct rand_node *rand_root;
static struct rand_node *rand_tail;

static struct rand_node *
rand_node_allocate(void)
{
        struct rand_node *n;

        n = (struct rand_node *)malloc(sizeof(struct rand_node));
        if (n == NULL)
                err(1, "malloc");

        n->len = 0;
        n->cp = NULL;
        n->next = NULL;
        return(n);
}

static void
rand_node_free(struct rand_node *n)
{
        if (n != NULL) {
                if (n->cp != NULL)
                        free(n->cp);

                free(n);
        }
}

static void
rand_node_free_rec(struct rand_node *n)
{
        if (n != NULL) {
                if (n->next != NULL)
                        rand_node_free_rec(n->next);

                rand_node_free(n);
        }
}

static void
rand_node_append(struct rand_node *n)
{
        if (rand_root == NULL)
                rand_root = rand_tail = n;
        else {
                rand_tail->next = n;
                rand_tail = n;
        }
}

int
randomize_fd(int fd, int type, int unique, double denom)
{
        u_char *buf;
        u_int slen;
        u_long i, j, numnode, selected;
        struct rand_node *n, *prev;
        int bufleft, eof, fndstr, ret;
        size_t bufc, buflen;
        ssize_t len;

        rand_root = rand_tail = NULL;
        bufc = i = 0;
        bufleft = eof = fndstr = numnode = 0;

        if (type == RANDOM_TYPE_UNSET)
                type = RANDOM_TYPE_LINES;

        buflen = sizeof(u_char) * MAXBSIZE;
        buf = (u_char *)malloc(buflen);
        if (buf == NULL)
                err(1, "malloc");

        while (!eof) {
                /* Check to see if we have bits in the buffer */
                if (bufleft == 0) {
                        len = read(fd, buf, buflen);
                        if (len == -1)
                                err(1, "read");
                        else if (len == 0) {
                                eof++;
                                break;
                        } else if ((size_t)len < buflen)
                                buflen = (size_t)len;

                        bufleft = (int)len;
                }

                /* Look for a newline */
                for (i = bufc; i <= buflen && bufleft >= 0; i++, bufleft--) {
                        if (i == buflen) {
                                if (fndstr) {
                                        if (!eof) {
                                                memmove(buf, &buf[bufc], i - bufc);
                                                i -= bufc;
                                                bufc = 0;
                                                len = read(fd, &buf[i], buflen - i);
                                                if (len == -1)
                                                        err(1, "read");
                                                else if (len == 0) {
                                                        eof++;
                                                        break;
                                                } else if (len < (ssize_t)(buflen - i))
                                                        buflen = i + (size_t)len;

                                                bufleft = (int)len;
                                                fndstr = 0;
                                        }
                                } else {
                                        buflen *= 2;
                                        buf = (u_char *)realloc(buf, buflen);
                                        if (buf == NULL)
                                                err(1, "realloc");

                                        if (!eof) {
                                                len = read(fd, &buf[i], buflen - i);
                                                if (len == -1)
                                                        err(1, "read");
                                                else if (len == 0) {
                                                        eof++;
                                                        break;
                                                } else if (len < (ssize_t)(buflen - i))
                                                        buflen = i + (size_t)len;

                                                bufleft = (int)len;
                                        }

                                }
                        }

                        if ((type == RANDOM_TYPE_LINES && buf[i] == '\n') ||
                            (type == RANDOM_TYPE_WORDS && isspace(buf[i])) ||
                            (eof && i == buflen - 1)) {
make_token:
                                if (numnode == UINT32_MAX - 1) {
                                        errno = EFBIG;
                                        err(1, "too many delimiters");
                                }
                                numnode++;
                                n = rand_node_allocate();
                                if (-1 != (int)i) {
                                        slen = i - (u_long)bufc;
                                        n->len = slen + 2;
                                        n->cp = (u_char *)malloc(slen + 2);
                                        if (n->cp == NULL)
                                                err(1, "malloc");

                                        memmove(n->cp, &buf[bufc], slen);
                                        n->cp[slen] = buf[i];
                                        n->cp[slen + 1] = '\0';
                                        bufc = i + 1;
                                }
                                rand_node_append(n);
                                fndstr = 1;
                        }
                }
        }

        /* Necessary evil to compensate for files that don't end with a newline */
        if (bufc != i) {
                i--;
                goto make_token;
        }

        (void)close(fd);

        free(buf);

        for (i = numnode; i > 0; i--) {
                selected = arc4random_uniform(numnode);

                for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
                        if (j == selected) {
                                if (n->cp == NULL)
                                        break;

                                if (random_uniform_denom(denom)) {
                                        ret = printf("%.*s",
                                                (int)n->len - 1, n->cp);
                                        if (ret < 0)
                                                err(1, "printf");
                                }
                                if (unique) {
                                        if (n == rand_root)
                                                rand_root = n->next;
                                        if (n == rand_tail)
                                                rand_tail = prev;

                                        prev->next = n->next;
                                        rand_node_free(n);
                                        numnode--;
                                }
                                break;
                        }
                }
        }

        fflush(stdout);

        if (!unique)
                rand_node_free_rec(rand_root);

        return(0);
}