/* hlite.c, generic syntax highlighting, Atto Emacs, Hugh Barney, Public Domain, 2016 */

#include "header.h"

int state = ID_DEFAULT;
int next_state = ID_DEFAULT;
int skip_count = 0;

static char_t get_at(buffer_t *, point_t);
static int is_symbol(char_t);

static char_t get_at(buffer_t *bp, point_t pt)
{
	if (pt >= pos(bp, bp->b_ebuf))
		return '\0';
	return (*ptr(bp, pt));
}

static char_t symbols[] = "{}[]()!'£$%^&*-+=:;@~#<>,.?/\\|";

static int is_symbol(char_t c)
{
	char_t *p = symbols;

	for (p = symbols; *p != '\0'; p++)
		if (*p == c) return 1;
	return 0;
}

void set_parse_state(buffer_t *bp, point_t pt)
{
	point_t po;

	state = ID_DEFAULT;
	next_state = ID_DEFAULT;
	skip_count = 0;

	for (po =0; po < pt; po++)
		parse_text(bp, po);
}

int parse_text(buffer_t *bp, point_t pt)
{
	if (skip_count-- > 0)
		return state;

	char_t c_now = get_at(bp, pt);
	char_t c_next = get_at(bp, pt + 1);
	state = next_state;

	if (state == ID_DEFAULT && c_now == '/' && c_next == '*') {
		skip_count = 1;
		return (next_state = state = ID_BLOCK_COMMENT);
	}

	if (state == ID_BLOCK_COMMENT && c_now == '*' && c_next == '/') {
		skip_count = 1;
		next_state = ID_DEFAULT;
		return ID_BLOCK_COMMENT;
	}

	if (state == ID_DEFAULT && c_now == '/' && c_next == '/') {
		skip_count = 1;
		return (next_state = state = ID_LINE_COMMENT);
	}

	if (state == ID_LINE_COMMENT && c_now == '\n')
		return (next_state = ID_DEFAULT);

	if (state == ID_DEFAULT && c_now == '"')
		return (next_state = ID_DOUBLE_STRING);

	if (state == ID_DOUBLE_STRING && c_now == '\\') {
		skip_count = 1;
		return (next_state = ID_DOUBLE_STRING);
	}

	if (state == ID_DOUBLE_STRING && c_now == '"') {
		next_state = ID_DEFAULT;
		return ID_DOUBLE_STRING;
	}

	if (state == ID_DEFAULT && c_now == '\'')
		return (next_state = ID_SINGLE_STRING);

	if (state == ID_SINGLE_STRING && c_now == '\\') {
		skip_count = 1;
		return (next_state = ID_SINGLE_STRING);
	}

	if (state == ID_SINGLE_STRING && c_now == '\'') {
		next_state = ID_DEFAULT;
		return ID_SINGLE_STRING;
	}

	if (state != ID_DEFAULT)
		return (next_state = state);

	if (state == ID_DEFAULT && c_now >= '0' && c_now <= '9') {
		next_state = ID_DEFAULT;
		return (state = ID_DIGITS);
	}

	if (state == ID_DEFAULT && 1 == is_symbol(c_now)) {
		next_state = ID_DEFAULT;
		return (state = ID_SYMBOL);
	}

	return (next_state = state);
}