/*
	Copyright 2019 flyinghead

	This file is part of reicast.

    reicast 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 2 of the License, or
    (at your option) any later version.

    reicast 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 reicast.  If not, see <https://www.gnu.org/licenses/>.
 */
#include "gui_util.h"
#include <string>
#include <vector>
#include <algorithm>
#include <stdlib.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/stat.h>

#include "types.h"
#include "stdclass.h"
#include "imgui/imgui.h"

extern int screen_width, screen_height;

static std::string select_current_directory;
static std::vector<std::string> select_subfolders;
static bool subfolders_read;
#ifdef _WIN32
static const std::string separators = "/\\";
static const std::string native_separator = "\\";
#else
static const std::string separators = "/";
static const std::string native_separator = "/";
#endif

void select_directory_popup(const char *prompt, float scaling, StringCallback callback)
{
	if (select_current_directory.empty())
	{
#if defined(_ANDROID)
		const char *home = getenv("REICAST_HOME");
		if (home != NULL)
			select_current_directory = home;
#elif HOST_OS == OS_LINUX || HOST_OS == OS_DARWIN
		const char *home = getenv("HOME");
		if (home != NULL)
			select_current_directory = home;
#elif HOST_OS == OS_WINDOWS
		const char *home = getenv("HOMEPATH");
		if (home != NULL)
			select_current_directory = home;
#endif
		if (select_current_directory.empty())
		{
			select_current_directory = get_writable_config_path("");
			if (select_current_directory.empty())
				select_current_directory = ".";
		}
	}

	ImGui::SetNextWindowPos(ImVec2(0, 0));
	ImGui::SetNextWindowSize(ImVec2(screen_width, screen_height));
	ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0);

	if (ImGui::BeginPopupModal(prompt, NULL, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize ))
	{
		std::string path = select_current_directory;
		int last_sep = path.find_last_of(separators);
		if (last_sep == path.size() - 1)
			path.pop_back();

		static std::string error_message;

		if (!subfolders_read)
		{
			select_subfolders.clear();
			error_message.clear();
#ifdef _WIN32
			if (select_current_directory.empty())
			{
				// List all the drives
				u32 drives = GetLogicalDrives();
				for (int i = 0; i < 32; i++)
					if ((drives & (1 << i)) != 0)
						select_subfolders.push_back(std::string(1, (char)('A' + i) + ":\\");
			}
			else
#endif
			{
				DIR *dir = opendir(select_current_directory.c_str());
				if (dir == NULL)
				{
					error_message = "Cannot read " + select_current_directory;
					select_subfolders.push_back("..");
				}
				else
				{
					bool dotdot_seen = false;
					while (true)
					{
						struct dirent *entry = readdir(dir);
						if (entry == NULL)
							break;
						std:string name(entry->d_name);
						if (name == ".")
							continue;
						if (name == "..")
							dotdot_seen = true;
						std::string child_path = path + "/" + name;
						if (entry->d_type == DT_UNKNOWN || entry->d_type == DT_LNK)
						{
							struct stat st;
							if (stat(child_path.c_str(), &st) != 0)
								continue;
							if (S_ISDIR(st.st_mode))
								entry->d_type = DT_DIR;
						}
						if (entry->d_type == DT_DIR && access(child_path.c_str(), R_OK) == 0)
							select_subfolders.push_back(name);
					}
					closedir(dir);
#ifdef _WIN32
					if (!dotdot_seen)
						select_subfolders.push_back("..");
#endif
				}
			}

			std::stable_sort(select_subfolders.begin(), select_subfolders.end());
			subfolders_read = true;
		}

		ImGui::Text("%s", error_message.empty() ? select_current_directory.c_str() : error_message.c_str());
		ImGui::BeginChild(ImGui::GetID("dir_list"), ImVec2(0, -ImGui::CalcTextSize("Cancel").y - ImGui::GetStyle().FramePadding. y * 2 - ImGui::GetStyle().ItemSpacing.y), true);

		ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(8 * scaling, 20 * scaling));		// from 8, 4


		for (auto name : select_subfolders)
		{
			std::string child_path;
			if (name == "..")
			{
				std::string::size_type last_sep = path.find_last_of(separators);
				if (last_sep == std::string::npos)
				{
					if (path.empty())
						// Root folder
						continue;
#ifdef _WIN32
					if (path.size() == 2 && path[1] == ':')
						child_path = "";
					else
#endif
					if (path == ".")
						child_path = "..";
					else if (path == "..")
						child_path = ".." + native_separator + "..";
					else
						child_path = ".";
				}
				else if (last_sep == 0)
					child_path = native_separator;
				else if (path.size() >= 2 && path.substr(path.size() - 2) == "..")
					child_path = path + native_separator + "..";
				else
					child_path = path.substr(0, last_sep);
			}
			else
			{
				if (!path.empty())
				{
					std::string::size_type last_sep = path.find_last_of(separators);
					if (last_sep == path.size() - 1)
						path.pop_back();
				}
				child_path = path + native_separator + name;
			}
			if (ImGui::Selectable(name.c_str()))
			{
				subfolders_read = false;
				select_current_directory = child_path;
			}
		}
		ImGui::PopStyleVar();
		ImGui::EndChild();
		if (ImGui::Button("Select Current Directory"))
		{
			subfolders_read = false;
			callback(false, select_current_directory);
			ImGui::CloseCurrentPopup();
		}
		ImGui::SameLine();
		if (ImGui::Button("Cancel"))
		{
			subfolders_read = false;
			callback(true, "");
			ImGui::CloseCurrentPopup();
		}

		ImGui::EndPopup();
	}
	ImGui::PopStyleVar();
}