/**
 * Copyright 2013 (c) Anna Schumaker.
 */

#include <core/filter.h>
#include <core/index.h>
#include <core/string.h>

#include <algorithm>

static Index filter_index("", false);

const std::string filter :: add(const std::string &text, unsigned int index)
{
	const std::string lc = string :: lowercase(text);
	size_t begin = 0, end;

	for (end = 1; end <= lc.size(); end++) {
		filter_index.insert(lc.substr(begin, end - begin), index);
		if (lc[end] == ' ')
			begin = ++end;
	}
	return lc;
}

static void do_set_intersection(IndexEntry *entry,
				std::set<unsigned int> &res)
{
	std::set<unsigned int> tmp;

	set_intersection(entry->begin(), entry->end(), res.begin(), res.end(),
			 std::inserter(tmp, tmp.begin()));
	res.swap(tmp);
}

void filter :: search(const std::string &text, std::set<unsigned int> &res)
{
	const std::string lc = string :: lowercase(text);
	size_t begin = 0, end;
	IndexEntry *found;

	res.clear();

	for (end = 1; end <= lc.size(); end++) {
		end = lc.find(' ', begin);
		if (end == std::string::npos)
			end = lc.size();

		found = filter_index.find(lc.substr(begin, end - begin));
		if (!found) {
			res.clear();
			return;
		}

		if (begin == 0)
			std::copy(found->begin(), found->end(),
				  std::inserter(res, res.begin()));
		else
			do_set_intersection(found, res);

		begin = ++end;
	}
}