/**
 * 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 <vector>
#include <filesystem>

#include <relpipe/writer/typedefs.h>
#include <relpipe/writer/AttributeMetadata.h>
#include <relpipe/writer/RelationalWriter.h>
#include <regex>

#include "RequestedField.h"
#include "SystemProcess.h"
#include "AttributeFinder.h"

namespace relpipe {
namespace in {
namespace filesystem {

namespace fs = std::filesystem;
using namespace relpipe::writer;

class ScriptAttributeFinder : public AttributeFinder {
private:
	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.

	std::string getScriptCommand(const RequestedField& field) {
		return SCRIPT_PREFIX + convertor.to_bytes(field.name);
	}

	std::vector<std::string> toEnvironmentalVariables(const std::vector<string_t>& vector) {
		std::vector<std::string> result;
		for (int i = 0; i < vector.size();) {
			string_t name = vector[i++];
			string_t value = vector[i++];
			if (name.rfind(L"env:" == 0)) {
				result.push_back(convertor.to_bytes(name.substr(4)));
				result.push_back(convertor.to_bytes(value));
			}
		}
		return result;
	}

	TypeId getAttributeType(const RequestedField& field, const string_t& alias) {
		// TODO: put latest supported version in the environmental variable
		// TODO: put alias in the environmental variable
		SystemProcess process({getScriptCommand(field)}, toEnvironmentalVariables(field.options));
		std::string output = process.execute();
		std::regex pattern("(.*)\\n(.*)\\n");
		std::smatch match;
		std::regex_match(output, match, pattern);
		if (match.ready() && match[1] == "1") {
			// TODO: move to a common library
			if (match[2] == "boolean") return TypeId::BOOLEAN;
			if (match[2] == "integer") return TypeId::INTEGER;
			if (match[2] == "string") return TypeId::STRING;
			throw RelpipeWriterException(L"Unsupported script data type – field: „" + field.name + L"“ type: „" + convertor.from_bytes(match[2]) + L"“");
		} else {
			throw RelpipeWriterException(L"Unsupported script version – field: „" + field.name + L"“ output: „" + convertor.from_bytes(output) + L"“");
		}

	}

	string_t getScriptOutput(const fs::path& file, const RequestedField& field, const string_t& alias) {
		try {
			// TODO: put alias in the environmental variable
			SystemProcess process({getScriptCommand(field), currentFileRaw}, toEnvironmentalVariables(field.options));
			return convertor.from_bytes(process.execute());
		} catch (relpipe::cli::RelpipeCLIException& e) {
			// TODO: print warnings?
			// TODO: do not fork/exec if the file is not readable
			return L"";
		}
	}
protected:

	virtual void writeFieldOfExistingFile(RelationalWriter* writer, const RequestedField& field) override {
		// TODO: paralelization?
		if (field.group == RequestedField::GROUP_SCRIPT) {
			for (string_t alias : field.getAliases()) {
				writer->writeAttribute(getScriptOutput(currentFile, field, alias));
			}
		}
	}

public:

	static const std::string SCRIPT_PREFIX;

	virtual vector<AttributeMetadata> toMetadata(const RequestedField& field) override {
		if (field.group == RequestedField::GROUP_SCRIPT) {
			vector<AttributeMetadata> metadata;
			for (string_t alias : field.getAliases()) metadata.push_back(AttributeMetadata{alias, getAttributeType(field, alias)});
			return metadata;
		} else {
			return {};
		}
	}

	virtual ~ScriptAttributeFinder() override {
	}
};

const std::string ScriptAttributeFinder::SCRIPT_PREFIX = "__relpipe_in_filesystem_script_";

}
}
}