/**

 * 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 <codecvt>

#include <vector>

#include <sstream>

#include <iomanip>

#include <libxml++-2.6/libxml++/libxml++.h>

#include <cbor.h>

#include <relpipe/writer/RelpipeWriterException.h>

#include "XMLNameCodec.h"

namespace relpipe {

namespace in {

namespace xmltable {

class XMLDocumentConstructor {

private:

	std::istream* input = nullptr;

	xmlpp::DomParser* parser = nullptr;

	XMLNameCodec nameCodec;

	enum class Mode {

		ROOT,

		ARRAY,

		MAP_KEY,

		MAP_VALUE,

		CHAR_STRING,

		BYTE_STRING

	};

	Glib::ustring rootName = "cbor";

	Glib::ustring itemName;

	xmlpp::Element* current;

	std::vector<Mode> mode;

	/**

	 * number of remainin items in the fixed-size container (map or array) at current tree-level

	 */

	std::vector<ssize_t> remainingItems;

#define INDEFINITE -1

	std::stringstream currentIndefiniteString;

	uint64_t currentTag;

	bool currentTagPresent = false;

	cbor_callbacks callbacks = cbor_empty_callbacks;

	/**

	 * Both CBOR and XML strings are in UTF-8.

	 */

	static std::string c2x(cbor_data value, uint64_t length) {

		return value && length > 0 ? std::string((const char*) value, length) : "";

	}

	xmlpp::Element* parentOrSelf(xmlpp::Element* current) {

		return current->get_parent() == nullptr ? current : current->get_parent();

	}

	void checkRemainingItems() {

		if (mode.back() == Mode::ARRAY || mode.back() == Mode::MAP_KEY) {

			if (remainingItems.back() != INDEFINITE) {

				remainingItems.back()--;

				if (remainingItems.back() < 1) containerEnd();

			}

		}

	}

	void writeCurrentTag(xmlpp::Element* element) {

		if (currentTagPresent) {

			currentTagPresent = false;

		}

	}

	void appendScalarValue(Glib::ustring value, Glib::ustring cborType) {

		if (mode.back() == Mode::ARRAY) {

			xmlpp::Element* element = current->add_child(nameCodec.encode(itemName));

			element->add_child_text(value);

			writeCurrentTag(element);

		} else if (mode.back() == Mode::MAP_KEY) {

			current = current->add_child(nameCodec.encode(value));

			writeCurrentTag(current);

			mode.push_back(Mode::MAP_VALUE);

		} else if (mode.back() == Mode::MAP_VALUE) {

			current->add_child_text(value);

			writeCurrentTag(current);

			current = parentOrSelf(current);

			mode.pop_back();

		} else if (mode.back() == Mode::ROOT) {

			current->add_child_text(value);

			writeCurrentTag(current);

		} else if (mode.back() == Mode::BYTE_STRING || mode.back() == Mode::CHAR_STRING) {

			currentIndefiniteString << value;

		} else {

			// TODO: throw exception?

		}

		checkRemainingItems();

	}

	void arrayStart(ssize_t size) {

		if (mode.back() == Mode::ROOT) {

			itemName = "item";

		} else if (mode.back() == Mode::ARRAY) {

			current = current->add_child(nameCodec.encode(itemName));

			itemName = "item";

		} else if (mode.back() == Mode::MAP_VALUE) {

			xmlpp::Element* parent = current->get_parent();

			itemName = current->get_name();

			parent->remove_child(current);

			current = parent;

			mode.pop_back();

		} else {

			// Mode::BYTE_STRING and Mode::CHAR_STRING – make no sense

			// Mode::MAP_KEY – currently not supported

			throw relpipe::writer::RelpipeWriterException(L"Unsupported mode in arrayStart(): " + std::to_wstring((int) mode.back()));

		}

		mode.push_back(Mode::ARRAY);

		remainingItems.push_back(size);

		writeCurrentTag(current);

		if (size == 0) containerEnd();

	}

	void mapStart(ssize_t size) {

		if (mode.back() == Mode::ROOT) {

		} else if (mode.back() == Mode::ARRAY) {

			current = current->add_child(nameCodec.encode(itemName));

		} else if (mode.back() == Mode::MAP_VALUE) {

			mode.pop_back();

			// TODO: remainingItems

		} else {

			// TODO: map might be a key of another map → wrap/nest

			// …probably not

		}

		mode.push_back(Mode::MAP_KEY);

		remainingItems.push_back(size);

		writeCurrentTag(current);

		if (size == 0) containerEnd();

	}

	void flushCurrentIndefiniteString(Glib::ustring cborType) {

		appendScalarValue(currentIndefiniteString.str(), cborType);

		currentIndefiniteString = std::stringstream();

	}

	void containerEnd() {

		Mode m = mode.back();

		mode.pop_back();

		remainingItems.pop_back();

		if (m == Mode::MAP_KEY || m == Mode::MAP_VALUE || m == Mode::ARRAY) current = parentOrSelf(current);

		else if (m == Mode::BYTE_STRING) flushCurrentIndefiniteString("byte-string");

		else if (m == Mode::CHAR_STRING) flushCurrentIndefiniteString("string");

	}

public:

	XMLDocumentConstructor(std::istream* input, xmlpp::DomParser* parser) : input(input), parser(parser) {

#define CBOR_CALLBACK_START if (XMLDocumentConstructor* instance = static_cast<XMLDocumentConstructor*> (context)) {

#define CBOR_CALLBACK_END } else throw relpipe::writer::RelpipeWriterException(L"Invalid context in the CBOR callback.");

#define NUMERIC_CALLBACK(type, name) [](void* context, type value) { CBOR_CALLBACK_START instance->appendScalarValue(std::to_string(value), name); CBOR_CALLBACK_END }

		callbacks.array_start = [](void* context, size_t size) {

			CBOR_CALLBACK_START

			instance->arrayStart(size);

			CBOR_CALLBACK_END

		};

		callbacks.boolean = [](void* context, bool value) {

			CBOR_CALLBACK_START

			instance->appendScalarValue(value ? "true" : "false", "boolean");

			CBOR_CALLBACK_END

		};

		callbacks.byte_string = [](void* context, cbor_data value, uint64_t size) {

			CBOR_CALLBACK_START

			std::stringstream hex;

			hex << std::hex << std::setfill('0') << std::setw(2);

			for (uint64_t i = 0; i < size; i++) hex << (int) value[i];

			instance->appendScalarValue(hex.str(), "byte-string");

			CBOR_CALLBACK_END

		};

		callbacks.byte_string_start = [](void* context) {

			CBOR_CALLBACK_START

			instance->mode.push_back(Mode::BYTE_STRING);

			instance->remainingItems.push_back(INDEFINITE);

			CBOR_CALLBACK_END

		};

		callbacks.float2 = NUMERIC_CALLBACK(float, "float2");

		callbacks.float4 = NUMERIC_CALLBACK(float, "float4");

		callbacks.float8 = NUMERIC_CALLBACK(double, "float8");

		callbacks.indef_array_start = [](void* context) {

			CBOR_CALLBACK_START

			instance->arrayStart(INDEFINITE);

			CBOR_CALLBACK_END

		};

		callbacks.indef_map_start = [](void* context) {

			CBOR_CALLBACK_START

			instance->mapStart(INDEFINITE);

			CBOR_CALLBACK_END

		};

		callbacks.indef_break = [](void* context) {

			CBOR_CALLBACK_START

			instance->containerEnd();

			CBOR_CALLBACK_END

		};

		callbacks.map_start = [](void* context, size_t size) {

			CBOR_CALLBACK_START

			instance->mapStart(size);

			CBOR_CALLBACK_END

		};

		callbacks.negint8 = NUMERIC_CALLBACK(uint8_t, "negative-int8");

		callbacks.negint16 = NUMERIC_CALLBACK(uint16_t, "negative-int16");

		callbacks.negint32 = NUMERIC_CALLBACK(uint32_t, "negative-int32");

		callbacks.negint64 = NUMERIC_CALLBACK(uint64_t, "negative-int64");

		callbacks.null = [](void* context) {

			CBOR_CALLBACK_START

			instance->appendScalarValue("", "null");

			CBOR_CALLBACK_END

		};

		callbacks.string = [](void* context, cbor_data value, uint64_t size) {

			CBOR_CALLBACK_START

			instance->appendScalarValue(c2x(value, size), "string");

			CBOR_CALLBACK_END

		};

		callbacks.string_start = [](void* context) {

			CBOR_CALLBACK_START

			instance->mode.push_back(Mode::CHAR_STRING);

			instance->remainingItems.push_back(INDEFINITE);

			CBOR_CALLBACK_END

		};

		callbacks.tag = [](void* context, uint64_t value) {

			CBOR_CALLBACK_START

			instance->currentTag = value;

			instance->currentTagPresent = true;

			CBOR_CALLBACK_END

		};

		callbacks.uint8 = NUMERIC_CALLBACK(uint8_t, "uint8");

		callbacks.uint16 = NUMERIC_CALLBACK(uint16_t, "uint16");

		callbacks.uint32 = NUMERIC_CALLBACK(uint32_t, "uint32");

		callbacks.uint64 = NUMERIC_CALLBACK(uint64_t, "uint64");

		callbacks.undefined = [](void* context) {

			CBOR_CALLBACK_START

			instance->appendScalarValue("", "undefined"); // TODO: throw exception?

			CBOR_CALLBACK_END

		};

	}

	virtual ~XMLDocumentConstructor() {

	}

	void setOption(const std::string& uri, const std::string& value) {

		if (uri == "root-name") rootName = value;

		else throw std::invalid_argument(std::string("Invalid parser option: „") + uri + "“ with value: „" + value + "“");

	}

	void process() {

		current = parser->get_document()->create_root_node(rootName);

		mode.push_back(Mode::ROOT);

		// TODO: better streaming/buffering? (however, we still have to hold whole document in memory and „infinite“ stream processing is impossible)

		std::stringstream bufferStream;

		for (char ch = input->get(); input->good(); ch = input->get()) bufferStream.put(ch);

		std::string buffer = bufferStream.str();

		size_t bytesRead = 0;

		size_t length = buffer.size();

		for (cbor_decoder_result result; bytesRead < length; bytesRead += result.read) {

			result = cbor_stream_decode((cbor_data) buffer.c_str() + bytesRead, length - bytesRead, &callbacks, this);

			if (result.status != cbor_decoder_status::CBOR_DECODER_FINISHED) throw relpipe::writer::RelpipeWriterException(L"CBOR parsing failed: status = " + std::to_wstring(result.status));

		}

		checkRemainingItems();

	}

};

}

}

}