/**

 * Relational pipes

 * Copyright © 2019 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 <iomanip>

#include <stdexcept>

#include <glibmm-2.4/glibmm/ustring.h>

namespace relpipe {

namespace in {

namespace xmltable {

class XMLNameCodec {

private:

	static const char DEFAULT_ESCAPING_CHARACTER = '_';

	const char esc;

	const bool namespaceAware;

	bool between(gunichar codepoint, gunichar start, gunichar end) {

		return codepoint >= start && codepoint <= end;

	}

	/**

	 * https://www.w3.org/TR/REC-xml/#NT-NameStartChar

	 *

	 * @param codepoint unicode character

	 * @return whether this character is allowed at the beginning of a XML name

	 */

	bool isValidNameStartChar(gunichar codepoint) {

		// NameStartChar  ::= ":" | [A-Z] | "_" | [a-z] 

		//   | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF]

		//   | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF]

		//   | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]

		return (codepoint == ':' && !namespaceAware) || between(codepoint, 'A', 'Z') || codepoint == '_' || between(codepoint, 'a', 'z')

				|| between(codepoint, 0xC0, 0xD6) || between(codepoint, 0xD8, 0xF6) || between(codepoint, 0xF8, 0x2FF) || between(codepoint, 0x370, 0x37D) || between(codepoint, 0x37F, 0x1FFF)

				|| between(codepoint, 0x200C, 0x200D) || between(codepoint, 0x2070, 0x218F) || between(codepoint, 0x2C00, 0x2FEF) || between(codepoint, 0x3001, 0xD7FF)

				|| between(codepoint, 0xF900, 0xFDCF) || between(codepoint, 0xFDF0, 0xFFFD) || between(codepoint, 0x10000, 0xEFFFF);

	}

	/**

	 * https://www.w3.org/TR/REC-xml/#NT-NameChar

	 *

	 * @param codepoint unicode character

	 * @return whether this character is allowed in a XML name

	 */

	bool isValidNameChar(gunichar codepoint) {

		// NameChar       ::= NameStartChar | "-" | "." | [0-9] 

		//   | #xB7

		//   | [#x0300-#x036F] | [#x203F-#x2040]

		return isValidNameStartChar(codepoint) || codepoint == '-' || codepoint == '.' || between(codepoint, '0', '9')

				|| codepoint == 0xB7

				|| between(codepoint, 0x0300, 0x036F) || between(codepoint, 0x203F, 0x2040);

	}

public:

	XMLNameCodec() : XMLNameCodec(DEFAULT_ESCAPING_CHARACTER, true) {

	}

	/**

	 * @param escapingCharacter must be valid character allowed not only in the middle of the XML name but also as the

	 * first character of the name

	 * @param namespaceAware colon character is reserved as a separator of the prefix and the local name, see

	 * https://www.w3.org/TR/REC-xml-names/#NT-NCName

	 * @throws std::invalid_argument if escapingCharacter is not valid

	 */

	XMLNameCodec(const char escapingCharacter, const bool namespaceAware) : esc(escapingCharacter), namespaceAware(namespaceAware) {

		// TODO: allow also characters like #xB7 and add another escaping if they occur at the beginning of the name?

		if (!isValidNameStartChar(esc)) {

			throw std::invalid_argument("The character „" + std::to_string(escapingCharacter) + "“ is not allowed at the beginning of a XML name and thus not usable for escaping");

		}

	}

	virtual ~XMLNameCodec() {

	}

	/**

	 * @param name any string

	 * @return valid name of XML element or attribute

	 */

	Glib::ustring encode(Glib::ustring name) {

		if (name.empty()) {

			return Glib::ustring(1, esc);

		} else {

			std::stringstream result;

			for (int i = 0; i < name.size(); i++) {

				gunichar codepoint = name[i];

				if (codepoint == esc) {

					result.put(esc);

					result.put(esc);

					continue;

				} else if ((i == 0 && isValidNameStartChar(codepoint)) || (i > 0 && isValidNameChar(codepoint))) {

					result << Glib::ustring(1, codepoint);

					continue;

				}

				result.put(esc);

				result << Glib::ustring::format(std::hex, std::setfill(L'0'), std::setw(2), codepoint);

				result.put(esc);

			}

			return result.str();

		}

	}

};

}

}

}