/**

 * 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 <cstdlib>

#include <iostream>

#include <sstream>

#include <string>

#include <vector>

#include <map>

#include <memory>

#include <algorithm>

#include <filesystem>

#include <pwd.h>

#include <grp.h>

#include <sys/stat.h>

#include <sys/xattr.h>

#include <relpipe/writer/typedefs.h>

#include "Configuration.h"

#include "AttributeFinder.h"

#include "FileAttributeFinder.h"

#include "XattrAttributeFinder.h"

#include "StreamletAttributeFinder.h"

namespace relpipe {

namespace in {

namespace filesystem {

namespace fs = std::filesystem;

using namespace relpipe::writer;

class FilesystemWorker {

protected:

	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.	

	std::map<string_t, std::shared_ptr<AttributeFinder>> createAttributeFinders() {

		return {

			{RequestedField::GROUP_FILE, std::make_shared<FileAttributeFinder>()},

			{RequestedField::GROUP_STREAMLET, std::make_shared<StreamletAttributeFinder>()},

			{RequestedField::GROUP_XATTR, std::make_shared<XattrAttributeFinder>()}};

	}

	void reset(std::stringstream& stream) {

		stream.str("");

		stream.clear();

	}

	bool readNext(std::istream& input, std::stringstream& originalName) {

		for (char ch; input.get(ch);) {

			if (ch == 0) return true;

			else originalName << ch;

		}

		return originalName.tellp();

	}

	string_t fetchRelationName(Configuration* configuration) {

		return configuration->relation.empty() ? L"filesystem" : configuration->relation;

	}

	void writeHeader(RelationalWriter* writer, std::map<string_t, std::shared_ptr < AttributeFinder>> attributeFinders, string_t relationName, std::vector<RequestedField>* fields, bool writeHeader = true) {

		std::vector<AttributeMetadata> attributesMetadata;

		for (RequestedField field : *fields) {

			std::shared_ptr<AttributeFinder> finder = attributeFinders[field.group];

			if (finder) for (AttributeMetadata m : finder->toMetadata(writer, relationName, field)) attributesMetadata.push_back(m);

			else throw RelpipeWriterException(L"Unsupported field group: " + field.group);

		}

		writer->startRelation(relationName, attributesMetadata, writeHeader);

	}

	void processSingleFile(std::shared_ptr<RelationalWriter> writer, std::stringstream& originalName, std::map<string_t, std::shared_ptr < AttributeFinder>>&attributeFinders, Configuration& configuration, string_t relationName) {

		fs::path file(originalName.str().empty() ? "." : originalName.str()); // interpret empty string as current directory (e.g. result of: find -printf '%P\0')

		bool exists = false;

		try {

			exists = fs::exists(file);

		} catch (const fs::filesystem_error& e) {

			// we probably do not have permissions to given directory → pretend that the file does not exist

		}

		for (auto& finder : attributeFinders) finder.second->startFile(file, originalName.str(), exists);

		for (RequestedField field : configuration.fields) {

			std::shared_ptr<AttributeFinder> finder = attributeFinders[field.group]; // should not be nullptr, because already checked while writing the relation metadata

			finder->writeField(writer.get(), relationName, field);

		}

		for (auto& finder : attributeFinders) finder.second->endFile();

	}

public:

	virtual ~FilesystemWorker() = default;

};

}

}

}