#pragma once

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

struct CacheEntry {
    std::string key;     /* hex hash of the URL */
    std::string url;
    std::string path;    /* full SD card path */
    size_t      size;    /* file size in bytes, 0 if unknown */
};

class CacheManager {
public:
    CacheManager();

    /* Returns the SD-card path for url if cached, or empty string if not. */
    std::string getCachedPath(const std::string& url) const;

    /* Enqueue an async FreeRTOS task that downloads url and caches it.
     * onComplete is called (from the download task) when done or on error. */
    void downloadAsync(const std::string& url, std::function<void(bool success)> onComplete = nullptr);

    /* List all cached entries. */
    std::vector<CacheEntry> listEntries() const;

    /* Delete a single cache entry by key (hex hash). Returns true if deleted. */
    bool deleteEntry(const std::string& key);

    /* Delete the entire cache directory. */
    void deleteAll();

    /* Total bytes used by cache. */
    size_t totalBytes() const;

private:
    static constexpr const char* CACHE_DIR = "/sdcard/cache";

    std::string urlToKey(const std::string& url) const;
    std::string urlExtension(const std::string& url) const;
    std::string keyToPath(const std::string& key, const std::string& ext) const;
    std::string findFileByKey(const std::string& key) const;

    static void downloadTask(void* arg);
};