#pragma once

#include <string>
#include <vector>
#include <chrono>
#include <functional>

/** @brief cache storage manager */
class CacheManager {
private:
	/** @brief currently opened cache location */
	std::string cache_path;
	/** @brief pointers to open file handles */
	std::vector<std::fstream*> files;

	/** @brief max amount of attempts for `retry` */
	const unsigned int max_tries = 100;

	/**
	 * @brief retry `action` as long as `retry_if` returns false, until `max_tries`
	 *
	 * this function runs `action` repeatedly until `retry_if` returns true, or
	 * `action` has been called `max_tries` times. between each try, there is a
	 * blocking 1ms delay, so this function should ideally only be used in
	 * threads, or when `action` has a high probability of succeeding.
	 *
	 * @param label  this label gets printed if retry_count exceeds max_tries
	 * @param check_pre  `true` = check `retry_if` before `action`, `false` = check `retry_if` after `action`
	 * @param action  this gets executed as long as `retry_if` returns false
	 * @param retry_if  this returns whether `action` is successful (boolean)
	 */
	virtual void retry(std::string label, bool check_pre, std::function<void()> action, std::function<bool()> retry_if);
	/** @brief alias for `retry` with `check_pre` = false (check after action) */
	virtual void retry_while(std::string label, std::function<void()> action, std::function<bool()> retry_if) { retry(label, false, action, retry_if); };
	/** @brief alias for `retry` with `check_pre` = true (check before action) */
	virtual void retry_if(std::string label, std::function<void()> action, std::function<bool()> retry_if) { retry(label, true, action, retry_if); };
public:
	/** @brief initialize CacheManager class at `cache_path` */
	CacheManager(const char* cache_path);
	CacheManager(std::string cache_path);
	/** @brief close cache */
	virtual ~CacheManager();
	/** @brief create cache folder structure */
	virtual void init_cache();
	/** @brief update cache date */
	virtual void update_cache();
	/**
	 * @brief check cache file structure
	 *
	 * automatically creates cache when non-existant
	 */
	virtual void verify_cache();

	/** @brief get fstream for file in cache or create file */
	virtual std::fstream* cache_get(const char* filename);
	virtual std::fstream* cache_get(std::string filename) { return cache_get(filename.c_str()); };
	/** @brief check if file exists in cache */
	virtual bool cache_exists(const char* filename);
	virtual bool cache_exists(std::string filename) { return cache_exists(filename.c_str()); };

	/** @brief add cache path before filename */
	virtual std::string prefix_cache_path(const char* filename);

	/** @brief currently opened cache update unix timestamp */
	uint64_t age;
};