/* Copyright 2021, Michele Santullo
 * This file is part of remarkable_tool.
 *
 * remarkable_tool 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Remarkable_tool 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 remarkable_tool.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "notebook_tree.hpp"
#include <unordered_map>
#include <utility>
#include <stdexcept>
#include <filesystem>
#include <simdjson.h>
#include <cassert>

namespace fs = std::filesystem;

namespace duck {
namespace {
typedef std::unordered_map<std::string, NotebookInfo> NotebookMapType;

template <typename T>
std::vector<T>& operator+= (std::vector<T>& dst, const std::vector<T>& src) {
	dst.insert(dst.end(), src.begin(), src.end());
	return dst;
}

NotebookMapType build_notebook_infos (
	const fs::path& from_path
) {
	simdjson::dom::parser parser;
	NotebookMapType retval;

	for (const auto& entry : fs::directory_iterator(from_path)) {
		NotebookInfo& curr_info = retval[entry.path().stem()];

		if (entry.path().extension() == ".metadata") {
			simdjson::dom::object json_doc = parser.load(entry.path());

			curr_info.deleted = json_doc["deleted"];
			curr_info.parent = json_doc["parent"];
			curr_info.type = json_doc["type"];
			curr_info.version = json_doc["version"];
			curr_info.visible_name = json_doc["visibleName"];
			curr_info.isolated = false;
		}
		else if (fs::is_directory(entry)) {
			for (const auto& subentry : fs::recursive_directory_iterator(entry)) {
				curr_info.files.push_back(fs::relative(subentry, from_path));
				if (fs::is_regular_file(subentry))
					curr_info.total_size += fs::file_size(subentry);
			}
		}

		curr_info.files.push_back(fs::relative(entry, from_path));
		if (fs::is_regular_file(entry))
			curr_info.total_size += fs::file_size(entry);
	}

	return retval;
}

void assert_parents_correct (const Node* node) {
#if !defined(NDEBUG)
	for (const auto& child : node->children) {
		assert(child.parent == node);
		assert_parents_correct(&child);
	}
#else
	static_cast<void>(node);
#endif
}

std::vector<Node> to_tree (const NotebookMapType& nbs) {
	std::unordered_map<std::string_view, std::pair<unsigned int, Node>> parents;
	for (const auto& nb : nbs) {
		auto it_ins = parents.emplace(nb.second.parent, std::make_pair(0U, Node{nb.second.parent, nullptr, nullptr}));
		it_ins.first->second.first++;
	}
	for (const auto& nb : nbs) {
		auto it_parent = parents.find(nb.first);
		if (parents.cend() != it_parent) {
			Node& node = it_parent->second.second;
			node.info = &nb.second;
		}
	}
	for (auto& par : parents) {
		Node& node = par.second.second;
		const unsigned int children_count = par.second.first;
		node.children.reserve(children_count);
	}

	for (const auto& nb : nbs) {
		if (0 == parents.count(nb.first)) {
			Node& parent = parents[nb.second.parent].second;
			parent.children.emplace_back(nb.first, &nb.second, &parent);
		}
	}

	std::vector<Node> roots;
	std::unordered_map<std::string_view, Node*> grouped_nodes;
	for (auto it = parents.begin(), it_end = parents.end(); it != it_end; it = parents.erase(it)) {
		auto& node = it->second.second;
		if (node.info) {
			auto it_parent = parents.find(node.info->parent);
			Node* dst_node = (parents.end() == it_parent ? grouped_nodes[node.info->parent] : &it_parent->second.second);
			node.parent = dst_node;
			assert(dst_node->children.capacity() > dst_node->children.size());
			dst_node->children.push_back(std::move(node));
			for (auto& child : dst_node->children.back().children) {
				child.parent = &dst_node->children.back();
			}
			grouped_nodes[dst_node->children.back().name] = &dst_node->children.back();
		}
		else {
			node.parent = nullptr;
			roots.push_back(std::move(node));
			grouped_nodes[node.name] = &roots.back();
		}
	}

	for (auto& root : roots) {
		for (auto& child : root.children) {
			child.parent = &root;
		}
	}

	return roots;
}

std::vector<const NotebookInfo*> to_flat_notebook_list (const Node& tree) {
	std::vector<const NotebookInfo*> retval;
	for (const auto& child : tree.children) {
		retval += to_flat_notebook_list(child);
	}
	if (tree.info)
		retval.push_back(tree.info);
	return retval;
}

std::vector<const NotebookInfo*> make_dele_list (const Node& tree) {
	if (tree.info and (tree.info->deleted or tree.info->isolated))
		return to_flat_notebook_list(tree);

	std::vector<const NotebookInfo*> retval;
	for (const auto& child : tree.children) {
		retval += make_dele_list(child);
	}
	return retval;
}
} //unnamed namespace

struct Notebooks::LocalData {
	NotebookMapType nb_map;
};

Notebooks::Notebooks (std::string_view base_path) :
	m_local(std::make_unique<LocalData>())
{
	m_local->nb_map = build_notebook_infos(base_path);
}

Notebooks::~Notebooks() noexcept = default;

std::vector<Node> Notebooks::build_tree() const {
	auto tree = to_tree(m_local->nb_map);
	for (const auto& root : tree) {
		assert_parents_correct(&root);
	}
	return tree; //to_tree(m_local->nb_map);
}

std::vector<const NotebookInfo*> make_list_of_deleted (const std::vector<Node>& roots) {
	std::vector<const NotebookInfo*> dele_list;
	for (const auto& root : roots) {
		dele_list += make_dele_list(root);
	}
	return dele_list;
}
} //namespace duck