#include "CacheManager.h"

#include <filesystem>
#include <fstream>
#include <iostream>
#include <ctime>

#include <thread>
#include <chrono>

CacheManager::CacheManager(const char* cache_path) : CacheManager(std::string(cache_path)) { }
CacheManager::CacheManager(std::string cache_path) {
	this->cache_path = cache_path;
	this->verify_cache();
}

CacheManager::~CacheManager() {
	for (std::fstream* file : this->files) {
		if (file != nullptr) {
			file->close();
			delete file;
			file = nullptr;
		}
	}
}

void CacheManager::verify_cache() {
	if (!std::filesystem::is_directory(this->cache_path)) this->init_cache();
	this->update_cache();
}

void CacheManager::init_cache() {
	std::filesystem::create_directory(this->cache_path);
	this->update_cache();
}

void CacheManager::update_cache() {
	std::fstream& date = *cache_get("date");
	this->age = std::time(nullptr);
	date << this->age;
	date.close();
}

void CacheManager::retry(std::string label, bool check_pre, std::function<void()> action, std::function<bool()> retry_if) {
	for (unsigned int i = 0; i < max_tries; i++) {
		if (check_pre && retry_if() == false) return;
		action();
		std::this_thread::sleep_for(std::chrono::milliseconds(1));
		if (!check_pre && retry_if() == false) return;
	}
	std::cout << "retry " << label << " failed after " << max_tries << " tries" << std::endl;
}

std::fstream* CacheManager::cache_get(const char* filename) {
	std::filesystem::path fixed_path = prefix_cache_path(filename); // fix duplicate slashes and add prefix
	retry_if("mkdir", [&] {
		std::filesystem::create_directories(fixed_path.parent_path()); // make sure folder exists
	}, [&] {
		return !std::filesystem::exists(fixed_path.parent_path());
	});

	retry_if("touch file", [&] {
		std::fstream(fixed_path, std::ios::trunc | std::ios::out).close(); // touch file
	}, [&] {
		return !std::filesystem::exists(fixed_path);
	});

	std::fstream* file = nullptr;
	retry_while("get file handle", [&] {
		delete file;
		file = new std::fstream(fixed_path.c_str(), std::ios::out | std::ios::in); // open file
	}, [&] {
		return !file->is_open();
	});

	this->files.push_back(file); // add file pointer (for closing all files on exit)
	return file;
}

bool CacheManager::cache_exists(const char* filename) {
	return std::filesystem::exists(prefix_cache_path(filename));
}

std::string CacheManager::prefix_cache_path(const char* filename) {
	return this->cache_path + "/" + std::string(filename);
}