/* 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 <iostream>
#include <simdjson.h>
#include <string_view>
#include <filesystem>
#include <vector>
#include <unordered_map>
#include <cstdint>
#include <stdexcept>
#include <numeric>
#include <utility>

namespace fs = std::filesystem;

namespace {
#define BASE_PATH "/run/media/duckz/Sabrent/deleme/remarkable_20210324/xochitl/"
//#define BASE_PATH "/home/duckz/dev/code/cpp/remarkable_tool/lib/lines-are-beautiful/share/rmlab/examples/"

struct NotebookInfo {
	std::string visible_name;
	std::string parent;
	std::string type;
	std::vector<std::string> files;
	std::uint64_t version = 0;
	std::uintmax_t total_size = 0;
	bool deleted = false;
	bool isolated = true;
};

struct Node {
	Node() :
		info(nullptr),
		parent(nullptr)
	{ }

	Node (std::string_view name, const NotebookInfo* payload, Node* parent) :
		name(name),
		info(payload),
		parent(parent)
	{ }

	std::vector<Node> children;
	std::string_view name;
	const NotebookInfo* info;
	const Node* parent;
};

typedef std::unordered_map<std::string, NotebookInfo> NotebookMapType;

std::ostream& operator<< (std::ostream& str, const NotebookMapType::value_type& v) {
	auto& key = v.first;
	auto& val = v.second;
	str << key << " (\"" << val.visible_name << "\", " << val.type <<
		"): deleted=" << std::boolalpha << val.deleted <<
		", parent=\"" << val.parent <<
		"\", version=" << val.version <<
		", files=";

	std::string_view sep("");
	for (const auto& f : val.files) {
		str << sep << f;
		sep = ";";
	}

	str << ", size=" << std::setprecision(2) <<
		static_cast<double>(val.total_size) / (1024.0 * 1024.0) << "MiB";
	return str;
}

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;
}

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);
			dst_node->children.push_back(std::move(node));
			grouped_nodes[dst_node->children.back().name] = &dst_node->children.back();
		}
		else {
			roots.push_back(std::move(node));
			grouped_nodes[node.name] = &roots.back();
		}
	}

	return roots;
}

void print_tree (const Node& tree, std::string_view desc={}, std::string indent={}) {
	std::cout << indent << desc << " (\"" << tree.name << "\")";
	if (tree.info && tree.info->isolated)
		std::cout << " ISOLATED";
	else if (tree.info and tree.info->deleted)
		std::cout << " DELETED";
	std::cout << '\n';

	for (const auto& child : tree.children) {
		print_tree(child, child.info->visible_name, indent + "\t");
	}
}

std::uintmax_t recursive_size (const Node& tree) {
	std::uintmax_t retval = 0;
	if (tree.info)
		retval = tree.info->total_size;

	for (const auto& child : tree.children) {
		retval += recursive_size(child);
	}
	return retval;
}

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

int main() {
	using std::string_view;

	auto notebooks = build_notebook_infos(BASE_PATH);

	//naive linear delete
	//std::uintmax_t total = 0;
	//std::uintmax_t freed = 0;
	//std::set<std::string_view> dele_list;
	//for (auto& nb : notebooks) {
	//	if (nb.second.deleted) {
	//		dele_list.insert(nb.first);
	//		for (const auto& file : nb.second.files) {
	//			std::cout << BASE_PATH << file << '\n';
	//		}
	//		freed += nb.second.total_size;
	//	}
	//	total += nb.second.total_size;
	//}

	//for (auto& nb : notebooks) {
	//	if (dele_list.count(nb.second.parent) and not nb.second.deleted) {
	//		std::cerr << "Warning: " << nb.second.parent << " deleted but it's the parent of " << nb.first << "!\n";
	//	}
	//}
    //
	//std::cout << "Found " << notebooks.size() << " notebooks\n";
	//std::cout << "Total size " << std::setprecision(2) <<
	//	static_cast<double>(total) / (1024.0 * 1024.0 * 1024.0) << "GiB\n";
	//std::cout << "Would delete " << dele_list.size() << " notebooks\n";
	//std::cout << "Would free " << std::setprecision(2) <<
	//	static_cast<double>(freed) / (1024.0 * 1024.0 * 1024.0) << "GiB\n";

	std::vector<Node> roots = to_tree(notebooks);
	//std::cout << "Found " << notebooks.size() << " notebooks\n";
	//std::cout << "Collection has " << roots.size() << " roots\n";
	//std::cout << "    ---------\n";
	//for (const auto& root : roots) {
	//	std::cout << "\tTree \"" << root.name << "\" has " << root.children.size() << " nodes\n\n";
	//}

	//std::uintmax_t total_mem1 = 0;
	std::vector<const NotebookInfo*> dele_list;
	for (const auto& root : roots) {
		//std::string_view desc;
		//if (root.name == "trash")
		//	desc = "rubbish bin";
		//else if (root.name == "")
		//	desc = "root";

		//print_tree(root, desc);
		//total_mem1 += recursive_size(root);
		dele_list += make_dele_list(root);
	}

	//std::cout << "Total size 1: " << total_mem1 << " bytes\n";
	//const std::uintmax_t total_mem2 = std::accumulate(notebooks.cbegin(), notebooks.cend(), std::uintmax_t{}, [](std::uintmax_t a, const auto& b) {return a + b.second.total_size;});
	//std::cout << "Total size 2: " << total_mem2 << " bytes\n";

	for (const NotebookInfo* nb : dele_list) {
		for (const auto& f : nb->files) {
			std::cout << "/home/root/.local/share/remarkable/xochitl/" << f << '\n';
		}
	}
	return 0;
}