/**
 * 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;
};

}
}
}