/*
 * Copyright (c) 2009-2011 Alex Hornung <alex@alexhornung.com>.
 * 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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 <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <err.h>
#include "parser.h"

#define _iswhitespace(X)        ((((X) == ' ') || ((X) == '\t'))?1:0)


static int line_no = 1;

static int iswhitespace(char c)
{
        return _iswhitespace(c);
}

static int iscomma(char c)
{
        return (c == ',');
}

void
syntax_error(const char *fmt, ...)
{
        char buf[1024];
        va_list ap;

        va_start(ap, fmt);
        vsnprintf(buf, sizeof(buf), fmt, ap);
        va_end(ap);
        errx(1, "syntax error on line %d: %s\n", line_no, buf);
}


int
entry_check_num_args(char **tokens, int num)
{
        int i;

        for (i = 0; tokens[i] != NULL; i++)
                ;

        if (i < num) {
                syntax_error("at least %d tokens were expected but only %d "
                    "were found", num, i);
                return 1;
        }
        return 0;
}

static int
line_tokenize(char *buffer, int (*is_sep)(char), char comment_char, char **tokens)
{
        int c, n, i;
        int quote = 0;

        i = strlen(buffer) + 1;
        c = 0;

        /* Skip leading white-space */
        while ((_iswhitespace(buffer[c])) && (c < i)) c++;

        /*
         * If this line effectively (after indentation) begins with the comment
         * character, we ignore the rest of the line.
         */
        if (buffer[c] == comment_char)
                return 0;

        tokens[0] = &buffer[c];
        for (n = 1; c < i; c++) {
                if (buffer[c] == '"') {
                        quote = !quote;
                        if (quote) {
                                if ((c >= 1) && (&buffer[c] != tokens[n-1])) {
#if 0
                                        syntax_error("stray opening quote not "
                                            "at beginning of token");
                                        /* NOTREACHED */
#endif
                                } else {
                                        tokens[n-1] = &buffer[c+1];
                                }
                        } else {
                                if ((c < i-1) && (!is_sep(buffer[c+1]))) {
#if 0
                                        syntax_error("stray closing quote not "
                                            "at end of token");
                                        /* NOTREACHED */
#endif
                                } else {
                                        buffer[c] = '\0';
                                }
                        }
                }

                if (quote) {
                        continue;
                }

                if (is_sep(buffer[c])) {
                        buffer[c++] = '\0';
                        while ((_iswhitespace(buffer[c])) && (c < i)) c++;
                        tokens[n++] = &buffer[c--];
                }
        }
        tokens[n] = NULL;

        if (quote) {
                tokens[0] = NULL;
                return 0;
        }

        return n;
}

static int
process_line(FILE* fd, parser_t parser, void *arg)
{
        char buffer[4096];
        char *tokens[256];
        int c, n, i = 0;
        int ret = 0;

        while (((c = fgetc(fd)) != EOF) && (c != '\n')) {
                buffer[i++] = (char)c;
                if (i == (sizeof(buffer) -1))
                        break;
        }
        buffer[i] = '\0';

        if (feof(fd) || ferror(fd))
                ret = 1;


        n = line_tokenize(buffer, &iswhitespace, '#', tokens);

        /*
         * If there are not enough arguments for any function or it is
         * a line full of whitespaces, we just return here. Or if a
         * quote wasn't closed.
         */
        if ((n < 1) || (tokens[0][0] == '\0'))
                return ret;

        parser(arg, tokens);

        return ret;
}

int
parse_options(char *str, char **options)
{
        int i;

        i = line_tokenize(str, &iscomma, '#', options);
        if (i == 0)
                syntax_error("Invalid expression in options token");
                /* NOTREACHED */

        return i;
}

int
process_file(const char *file, parser_t parser, void *arg, int *nlines)
{
        FILE *fd;

        line_no = 0;

        fd = fopen(file, "r");
        if (fd == NULL)
                err(1, "fopen");
                /* NOTREACHED */

        while (process_line(fd, parser, arg) == 0)
                ++line_no;

        fclose(fd);

        if (nlines != NULL)
                *nlines = line_no;

        return 0;
}