/*-
 * Copyright (c) 2008 Tim Kientzle
 * 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
 *    in this position and unchanged.
 * 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 AUTHOR(S) ``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 AUTHOR(S) 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 "lafe_platform.h"
__FBSDID("$FreeBSD$");

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "err.h"
#include "line_reader.h"

#if defined(_WIN32) && !defined(__CYGWIN__)
#define strdup _strdup
#endif

/*
 * Read lines from file and do something with each one.  If option_null
 * is set, lines are terminated with zero bytes; otherwise, they're
 * terminated with newlines.
 *
 * This uses a self-sizing buffer to handle arbitrarily-long lines.
 */
struct lafe_line_reader {
    FILE *f;
    char *buff, *buff_end, *line_start, *line_end, *p;
    char *pathname;
    size_t buff_length;
    int nullSeparator; /* Lines separated by null, not CR/CRLF/etc. */
    int ret;
};

struct lafe_line_reader *
lafe_line_reader(const char *pathname, int nullSeparator)
{
    struct lafe_line_reader *lr;

    lr = calloc(1, sizeof(*lr));
    if (lr == NULL)
        lafe_errc(1, ENOMEM, "Can't open %s", pathname);

    lr->nullSeparator = nullSeparator;
    lr->pathname = strdup(pathname);

    if (strcmp(pathname, "-") == 0)
        lr->f = stdin;
    else
        lr->f = fopen(pathname, "r");
    if (lr->f == NULL)
        lafe_errc(1, errno, "Couldn't open %s", pathname);
    lr->buff_length = 8192;
    lr->buff = malloc(lr->buff_length);
    if (lr->buff == NULL)
        lafe_errc(1, ENOMEM, "Can't read %s", pathname);
    lr->line_start = lr->line_end = lr->buff_end = lr->buff;

    return (lr);
}

const char *
lafe_line_reader_next(struct lafe_line_reader *lr)
{
    size_t bytes_wanted, bytes_read, new_buff_size;
    char *line_start, *p;

    for (;;) {
        /* If there's a line in the buffer, return it immediately. */
        while (lr->line_end < lr->buff_end) {
            if (lr->nullSeparator) {
                if (*lr->line_end == '\0') {
                    line_start = lr->line_start;
                    lr->line_start = lr->line_end + 1;
                    lr->line_end = lr->line_start;
                    return (line_start);
                }
            } else if (*lr->line_end == '\x0a' || *lr->line_end == '\x0d') {
                *lr->line_end = '\0';
                line_start = lr->line_start;
                lr->line_start = lr->line_end + 1;
                lr->line_end = lr->line_start;
                if (line_start[0] != '\0')
                    return (line_start);
            }
            lr->line_end++;
        }

        /* If we're at end-of-file, process the final data. */
        if (lr->f == NULL) {
            /* If there's more text, return one last line. */
            if (lr->line_end > lr->line_start) {
                *lr->line_end = '\0';
                line_start = lr->line_start;
                lr->line_start = lr->line_end + 1;
                lr->line_end = lr->line_start;
                return (line_start);
            }
            /* Otherwise, we're done. */
            return (NULL);
        }

        /* Buffer only has part of a line. */
        if (lr->line_start > lr->buff) {
            /* Move a leftover fractional line to the beginning. */
            memmove(lr->buff, lr->line_start,
                lr->buff_end - lr->line_start);
            lr->buff_end -= lr->line_start - lr->buff;
            lr->line_end -= lr->line_start - lr->buff;
            lr->line_start = lr->buff;
        } else {
            /* Line is too big; enlarge the buffer. */
            new_buff_size = lr->buff_length * 2;
            if (new_buff_size <= lr->buff_length)
                lafe_errc(1, ENOMEM,
                    "Line too long in %s", lr->pathname);
            lr->buff_length = new_buff_size;
            p = realloc(lr->buff, new_buff_size);
            if (p == NULL)
                lafe_errc(1, ENOMEM,
                    "Line too long in %s", lr->pathname);
            lr->buff_end = p + (lr->buff_end - lr->buff);
            lr->line_end = p + (lr->line_end - lr->buff);
            lr->line_start = lr->buff = p;
        }

        /* Get some more data into the buffer. */
        bytes_wanted = lr->buff + lr->buff_length - lr->buff_end;
        bytes_read = fread(lr->buff_end, 1, bytes_wanted, lr->f);
        lr->buff_end += bytes_read;

        if (ferror(lr->f))
            lafe_errc(1, errno, "Can't read %s", lr->pathname);
        if (feof(lr->f)) {
            if (lr->f != stdin)
                fclose(lr->f);
            lr->f = NULL;
        }
    }
}

void
lafe_line_reader_free(struct lafe_line_reader *lr)
{
    free(lr->buff);
    free(lr->pathname);
    free(lr);
}
