/**
 * Relational pipes
 * Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)
 *
 * This program 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 3 of the License.
 *
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 */
#pragma once

#include <sstream>

#include "UnescapingProcessor.h"

using namespace std;
using namespace relpipe::writer;

namespace relpipe {
namespace in {
namespace ini {
namespace lib {

class BackspaceUnescapingProcessor : public UnescapingProcessor {
private:
	const bool lastEscaphingPhase = true;
public:

	std::string unescape(const std::string& s, const TextType type) override {
		std::stringstream result;
		for (int i = 0, length = s.size(); i < length; i++) {
			char ch = s[i];
			if (i + 1 < length && ch == ESC) {
				ch = s[i + 1];
				if (ch == ESC) put(result, ESC, i); // unescape \\ to \.
				else if (lastEscaphingPhase) throw std::logic_error(std::string("Unsupported escape sequence: ") + ch);
				else result.put(ESC); // keep the escape sequence for later unescaping phase
			} else if (ch == ESC) {
				throw std::logic_error(std::string("Missing escape sequence")); // this should not happen
			} else {
				result.put(ch);
			}
		}
		return result.str();
	}

	/**
	 * @param lastEscaphingPhase whether this is final unescaping stage.
	 * By default it is set to true, thus no unrecognized escape sequences may left after this stage.
	 * Setting this to false is dangerous and may lead to errors and ambiguous behavior.
	 * It should be used only as a last resort.
	 * Because both "\\ \xxx" and "\ \xxx" will be converted to "\ \xxx" and the information will be lost.
	 * So, it is usually better to keep the "\" escaped as "\\" and process both the escaped backspaces and unrecognized escape sequences later.
	 */
	BackspaceUnescapingProcessor(bool lastEscaphingPhase = true) : lastEscaphingPhase(lastEscaphingPhase) {
	}

};

}
}
}
}