/**

 * 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/>.

 */

#include <vector>

#include <regex>

#include "INIReader.h"

class INIReaderImpl : public INIReader {

private:

	std::istream& input;

	std::vector<INIContentHandler*> handlers;

public:

	INIReaderImpl(std::istream& input) : input(input) {

	}

	void addHandler(INIContentHandler* handler) override {

		handlers.push_back(handler);

	}

	void process() override {

		for (INIContentHandler* handler : handlers) handler->startDocument();

		std::regex whitespacePattrern("\\s*");

		std::regex commentPattrern("\\s*(;|#)\\s*(.*)");

		std::regex sectionPattrern("\\s*\\[\\s*([^\\]]+)\\s*\\]\\s*(\\[\\s*([^\\]]+)\\s*\\])?\\s*((;|#)\\s*(.*))?");

		std::regex entryQuotesPattrern(/***/"\\s*(([^=\\]]+?[^=\\s\\]]*)(\\[([^\\]]+)\\])?)\\s*=\\s*\"([^']+)\"\\s*((;|#)\\s*(.*))?");

		std::regex entryApostrophesPattrern("\\s*(([^=\\]]+?[^=\\s\\]]*)(\\[([^\\]]+)\\])?)\\s*=\\s*'([^']+)'\\s*((;|#)\\s*(.*))?");

		std::smatch match;

		bool inSection = false;

		std::string line;

		int lineNumber = 0;

		int eventNumber = 0;

		while (std::getline(input, line)) {

			lineNumber++;

			if (std::regex_match(line, match, whitespacePattrern)) {

				INIContentHandler::WhitespaceEvent event;

				event.lineNumber = lineNumber;

				event.eventNumber = ++eventNumber;

				event.whitespace = match[0];

				for (INIContentHandler* handler : handlers) handler->whitespace(event);

			} else if (std::regex_match(line, match, commentPattrern)) {

				INIContentHandler::CommentEvent event;

				event.lineNumber = lineNumber;

				event.eventNumber = ++eventNumber;

				event.comment = match[2];

				for (INIContentHandler* handler : handlers) handler->comment(event);

			} else if (std::regex_match(line, match, sectionPattrern)) {

				if (inSection) for (INIContentHandler* handler : handlers) handler->endSection();

				inSection = true;

				INIContentHandler::SectionStartEvent event;

				event.lineNumber = lineNumber;

				event.eventNumber = ++eventNumber;

				event.name = match[1];

				event.comment = match[6];

				// event.tag = match[3];

				// KDE uses some weird INI dialect that allows [section][x] syntax where „x“ is kind of „tag“ that signalizes some properties of given section.

				// see <https://userbase.kde.org/KDE_System_Administration/Configuration_Files>, „[$i]“ means that the section is „locked“

				// We may emit this information somehow later, but for now, it is just ignored.

				for (INIContentHandler* handler : handlers) handler->startSection(event);

			} else if (std::regex_match(line, match, entryQuotesPattrern) || std::regex_match(line, match, entryApostrophesPattrern)) {

				INIContentHandler::EntryEvent event;

				event.lineNumber = lineNumber;

				event.eventNumber = ++eventNumber;

				event.key = match[2];

				event.subKey = match[4];

				event.fullKey = match[1];

				event.value = match[5];

				if (match.size() == 9) event.comment = match[8];

				for (INIContentHandler* handler : handlers) handler->entry(event);

			} else if (std::regex_match(line, match, entryPlainPattrern)) {

				INIContentHandler::EntryEvent event;

				event.lineNumber = lineNumber;

				event.eventNumber = ++eventNumber;

				event.key = match[2];

				event.subKey = match[4];

				event.fullKey = match[1];

				event.value = match[5];

				while (line.back() == '\\' && std::getline(input, line)) {

					line = std::regex_replace(line, std::regex("^\\s+|\\s+$"), ""); // trim the spaces: continuing lines might be aligned to the first line (desired spaces – if any – should be at the line end before the \ character)

					event.value = event.value.substr(0, event.value.size() - 1); // cut the trailing \ backslash

					event.value = event.value + line;

				}

				for (INIContentHandler* handler : handlers) handler->entry(event);

			} else {

				// TODO: warning, error, or support unknown content

			}

			// General feautres:

			// TODO: probably switch to state-machine approach instead of regular expressions or use an existing library

			// TODO: warning/error handler

			// TODO: support also quoted or multiline keys?

			// TODO: support also escaped characters

			// TODO: support also Java .properties and manifest.mf formats?

			// TODO: support also quoted sections ["qoted section"] – useful for hierarchy (the path element may contain the separator character)

			// TODO: support also nested sections – hierarchy

			// TODO: support also nested keys e.g. key.sub.subsub.subsubsub=value – translate them to nested sections

			// TODO: support also option for alternative key-value separator (: instead of =)

			// TODO: support also other encodings (currently only UTF-8 is supported)

			// Lossless conversions:

			// TODO: emit also the quote style ('/"/)

			// TODO: emit also the comment style (;/#) ?

			// TODO: emit also the whitespace before key name, around =, after "values"/'values', around [sections] ?

			// TODO: emit also the line-end type (LF/CRLF) ?

		}

		if (inSection) for (INIContentHandler* handler : handlers) handler->endSection();

		for (INIContentHandler* handler : handlers) handler->endDocument();

	}

};

INIReader* INIReader::create(std::istream& input) {

	return new INIReaderImpl(input);

}