/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file stringfilter.cpp Searching and filtering using a stringterm. */

#include "stdafx.h"
#include "string_func.h"
#include "strings_func.h"
#include "stringfilter_type.h"
#include "gfx_func.h"

#include "safeguards.h"

static const WChar STATE_WHITESPACE = ' ';
static const WChar STATE_WORD = 'w';
static const WChar STATE_QUOTE1 = '\'';
static const WChar STATE_QUOTE2 = '"';

/**
 * Set the term to filter on.
 * @param str Filter term
 */
void StringFilter::SetFilterTerm(const char *str)
{
	this->word_index.clear();
	this->word_index.shrink_to_fit();
	this->word_matches = 0;
	free(this->filter_buffer);

	assert(str != nullptr);

	char *dest = MallocT<char>(strlen(str) + 1);
	this->filter_buffer = dest;

	WChar state = STATE_WHITESPACE;
	const char *pos = str;
	WordState *word = nullptr;
	size_t len;
	for (;; pos += len) {
		WChar c;
		len = Utf8Decode(&c, pos);

		if (c == 0 || (state == STATE_WORD && IsWhitespace(c))) {
			/* Finish word */
			if (word != nullptr) {
				*(dest++) = '\0';
				word = nullptr;
			}
			state = STATE_WHITESPACE;
			if (c != 0) continue; else break;
		}

		if (state == STATE_WHITESPACE) {
			/* Skip whitespace */
			if (IsWhitespace(c)) continue;
			state = STATE_WORD;
		}

		if (c == STATE_QUOTE1 || c == STATE_QUOTE2) {
			if (state == c) {
				/* Stop quoting */
				state = STATE_WORD;
				continue;
			} else if (state == STATE_WORD) {
				/* Start quoting */
				state = c;
				continue;
			}
		}

		/* Add to word */
		if (word == nullptr) {
			word = &this->word_index.emplace_back(WordState{ dest, false });
		}

		memcpy(dest, pos, len);
		dest += len;
	}
}

/**
 * Reset the matching state to process a new item.
 */
void StringFilter::ResetState()
{
	this->word_matches = 0;
	for (WordState &ws : this->word_index) {
		ws.match = false;
	}
}

/**
 * Pass another text line from the current item to the filter.
 *
 * You can call this multiple times for a single item, if the filter shall apply to multiple things.
 * Before processing the next item you have to call ResetState().
 *
 * @param str Another line from the item.
 */
void StringFilter::AddLine(const char *str)
{
	if (str == nullptr) return;

	bool match_case = this->case_sensitive != nullptr && *this->case_sensitive;
	for (WordState &ws : this->word_index) {
		if (!ws.match) {
			if ((match_case ? strstr(str, ws.start) : strcasestr(str, ws.start)) != nullptr) {
				ws.match = true;
				this->word_matches++;
			}
		}
	}
}

/**
 * Pass another text line from the current item to the filter.
 *
 * You can call this multiple times for a single item, if the filter shall apply to multiple things.
 * Before processing the next item you have to call ResetState().
 *
 * @param str Another line from the item.
 */
void StringFilter::AddLine(StringID str)
{
	char buffer[DRAW_STRING_BUFFER];
	GetString(buffer, str, lastof(buffer));
	AddLine(buffer);
}