/* csv.c : really dumb CSV parser */
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include "csv.h"

#define CSV_MAX_COLS 256
#define CSV_MAX_BUF 4096

struct csv {
	FILE *f;
	int current_row;
	int cols;
	char filename[32];
	char *colptr[CSV_MAX_COLS];
	char buf[CSV_MAX_BUF];
	int error;
};

struct csv *csv_open(const char *filename)
{
	struct csv *st;
	FILE *f;

	f = fopen(filename, "r");
	if (!f) {
		perror(filename);
		return NULL;
	}
	st = calloc(1, sizeof(*st));
	if (!st) {
		fclose(f);
		return NULL;
	}
	st->f = f;
	snprintf(st->filename, sizeof(st->filename), "%s", filename);
	st->cols = 0;
	st->current_row = 0;
	st->colptr[0] = 0;
	st->error = 0;

	return st;
}

void csv_close(struct csv *st)
{
	fclose(st->f);
	st->f = NULL;
	st->filename[0] = 0;
	st->current_row = 0;
	st->cols = 0;
	free(st);
}

/* return 0 on error */
static int csv_parse_row(struct csv *st)
{
	char *in, *out;
	char *start;

	in = out = st->buf;
	st->cols = 0;

	while (*in) {
		while (isspace(*in))
			in++;
		if (*in == '"') { /* start of quoted element */
			in++;
			start = out;
			while (1) {
				if (!*in) {
					st->error++;
					return 0; /* parse error */
				}
				if (*in == '"') { /* is this a double quote? */
					in++;
					if (*in == '"') { /* it it a pair? */
						in++;
						*out++ = '"'; /* insert the quote */
					} else { /* no, it's the end of the element */
						break; /* done! */
					}
				} else {
					*out++ = *in++;
				}
			}
			while (isspace(*in))
				in++;
			if (*in == ',') {
				in++;
			} else if (*in) {
				st->error++;
				return 0; /* parse error */
			}
			*out++ = 0;
			st->colptr[st->cols++] = start;
		} else if (*in == 0) {
			break; /* end of line */
		} else { /* unquoted element */
			start = out;
			while (*in) {
				if (*in == ',') {
					in++;
					break;
				}
				*out++ = *in++;
			}
			*out++ = 0;
			st->colptr[st->cols++] = start;
		}
	}

	return 1; /* no error */
}

static int trimnl(char *buf)
{
	int len;

	len = strlen(buf);
	if (buf[len - 1] == '\n') {
		len--;
		buf[len] = 0;
	}
	return len;
}

/* return 0 on EOF or error */
int csv_next(struct csv *st)
{
	st->cols = 0;
	memset(st->colptr, 0, sizeof(st->colptr));
	if (!fgets(st->buf, sizeof(st->buf), st->f))
		return 0; /* EOF */
	st->current_row++;
	trimnl(st->buf);
	return csv_parse_row(st);
}

int csv_current_row(struct csv *st)
{
	return st->current_row;
}

int csv_cols(struct csv *st)
{
	return st->cols;
}

const char *csv_element(struct csv *st, int elem)
{
	assert(elem < st->cols ? st->colptr[elem] : "dummy");
	return elem < st->cols ? st->colptr[elem] : NULL;
}

int csv_error(struct csv *st)
{
	return st->error;
}