MinecraftConsoles/MCAuth/include/MCAuthManager.h

#pragma once
/*
 * MCAuthManager - Thread-safe singleton that wraps JavaAuthManager with
 * multi-account and per-slot session support (for splitscreen).
 *
 * Architecture:
 *
 *   - Account list (m_javaAccounts) is SHARED — one global list of saved accounts.
 *   - Each player slot (0..XUSER_MAX_COUNT-1) has its own AuthSlot containing:
 *       - A shared_ptr<JavaAuthManager> (ownership shared with background worker)
 *       - Its own session, mutex, generation counter
 *   - Slot 0 is the primary player.  Slots 1-3 are splitscreen.
 *
 *   Thread model (fire-and-forget):
 *     - Background workers are detached threads that capture a shared_ptr copy
 *       of the auth engine they operate on.
 *     - To cancel: increment generation + RequestCancel on the old auth engine,
 *       then create a fresh shared_ptr<JavaAuthManager> for the slot.
 *     - The old thread runs to completion harmlessly — generation mismatch causes
 *       it to discard results, and the old auth engine is freed when the thread
 *       exits (shared_ptr ref-count drops to zero).
 *     - The main thread NEVER calls join(). No blocking. Ever.
 *
 * Usage:
 *   auto& mgr = MCAuthManager::Get();
 *   mgr.LoadJavaAccountIndex();
 *   mgr.TryRestoreActiveJavaAccount();       // restore slot 0
 *
 *   mgr.SetAccountForSlot(0, accountIndex);  // switch slot 0's account
 *   auto session = mgr.GetSlotSession(0);    // get slot 0's session
 */

#include "MCAuth.h"
#include <functional>
#include <mutex>
#include <atomic>
#include <string>
#include <vector>
#include <memory>
#include <condition_variable>

#ifndef XUSER_MAX_COUNT
#define XUSER_MAX_COUNT 4
#endif

class MCAuthManager {
public:
    enum class State {
        Idle,
        WaitingForCode,   // device code displayed, waiting for user
        Authenticating,   // polling / running auth chain
        Success,
        Failed,
    };

    // Per-account info stored in the index.
    struct JavaAccountInfo {
        std::string username;      // Minecraft username
        std::string uuid;          // Player UUID (dashed)
        std::string tokenFile;     // e.g. "java_auth_0.json" (empty for offline)
        bool        isOffline = false;
        std::string authProvider;  // "mojang", "elyby", "offline" (default: "mojang")
    };

    // Per-player-slot auth state.  Each slot has its own auth engine + session.
    struct AuthSlot {
        // Auth engine is heap-allocated and shared with background worker threads.
        // When we cancel, we abandon the old shared_ptr and create a fresh one.
        // The old thread's copy prevents use-after-free; it finishes harmlessly.
        std::shared_ptr<MCAuth::JavaAuthManager> auth;

        MCAuth::ElybyTokens       elybyTokens;      // Ely.by tokens (no engine class needed)
        MCAuth::JavaSession       session;           // current session data
        std::atomic<int>          accountIndex{-1};  // index into m_javaAccounts (-1 = none)
        mutable std::mutex        mutex;
        std::atomic<uint32_t>     generation{0};     // invalidates stale workers
        std::atomic<State>        state{State::Idle};
        mutable std::condition_variable cv;          // signals when state changes
        std::string               lastError;

        // No std::thread member — workers are detached (fire-and-forget).

        bool hasSession() const { return !session.uuid.empty(); }

        AuthSlot() : auth(std::make_shared<MCAuth::JavaAuthManager>()) {}
    };

    using DeviceCodeCb      = MCAuth::DeviceCodeCallback;
    using JavaCompleteCb    = std::function<void(bool, const MCAuth::JavaSession&, const std::string&)>;

    static MCAuthManager& Get();

    MCAuthManager(const MCAuthManager&) = delete;
    MCAuthManager& operator=(const MCAuthManager&) = delete;

    // ---- Java Edition — Account Index ----

    bool LoadJavaAccountIndex();
    bool SaveJavaAccountIndex() const;

    std::vector<JavaAccountInfo> GetJavaAccounts() const;

    // ---- Java Edition — Per-Slot Session Management ----

    // Get the auth slot for a player index (0 = primary, 1-3 = splitscreen).
    const AuthSlot& GetSlot(int slot) const;

    // Set which account a slot uses.  Loads tokens + refreshes in background.
    // The old session remains valid until the new one is ready (no empty window).
    bool SetAccountForSlot(int slot, int accountIndex);

    // Clear a slot (e.g. when a splitscreen player leaves).
    void ClearSlot(int slot);

    // Get the session for a specific slot.
    MCAuth::JavaSession GetSlotSession(int slot) const;

    // Check if a slot has a valid logged-in session.
    bool IsSlotLoggedIn(int slot) const;

    // Check if the slot's token is expiring soon (within 60s).
    bool IsTokenExpiringSoon(int slot) const;

    // Proactively refresh a slot's token in the background.
    void RefreshSlot(int slot);

    // Block until a slot's auth settles (state leaves Authenticating/WaitingForCode).
    // Returns true if login succeeded, false on timeout or failure.
    bool WaitForSlotReady(int slot, int timeoutMs = 15000) const;

    // Check if an online account is already assigned to another slot.
    bool IsAccountInUseByOtherSlot(int slot, int accountIndex) const;

    // ---- Java Edition — Slot 0 Convenience (backward compat) ----

    int  GetActiveJavaAccountIndex() const;
    bool SetActiveJavaAccount(int index) { return SetAccountForSlot(0, index); }
    MCAuth::JavaSession GetJavaSession() const;
    bool IsJavaLoggedIn() const;
    State GetState() const { return m_slots[0].state.load(); }
    State GetSlotState(int slot) const {
        if (slot < 0 || slot >= XUSER_MAX_COUNT) slot = 0;
        return m_slots[slot].state.load();
    }
    bool WaitForAuthReady(int timeoutMs = 15000) const { return WaitForSlotReady(0, timeoutMs); }

    // ---- Java Edition — Account Management ----

    // Add a new account via device code flow (background thread on slot 0).
    void BeginAddJavaAccount(DeviceCodeCb onDeviceCode, JavaCompleteCb onComplete,
                             int timeoutSeconds = 300);

    // Add an Ely.by account via username+password.
    using ElybyCompleteCb = std::function<void(bool ok, const MCAuth::JavaSession& session, const std::string& error)>;
    using Elyby2FACb = std::function<void()>;
    void BeginAddElybyAccount(const std::string& username, const std::string& password,
                              ElybyCompleteCb onComplete, Elyby2FACb on2FA = nullptr);

    // Add an offline account.  Returns new account index or -1.
    int AddOfflineJavaAccount(const std::string& username);

    // Remove an account by index.  Deletes its token file.
    bool RemoveJavaAccount(int index);

    // Restore the active account from disk at startup (slot 0).
    void TryRestoreActiveJavaAccount();

    // ---- Device code info (valid during add-account flow) ----

    std::string GetJavaDeviceCode() const;
    std::string GetJavaDirectUri()  const;
    std::string GetLastError() const;

    // File paths
    static constexpr const char* kJavaAccountsFile = "java_accounts.json";

private:
    MCAuthManager();
    ~MCAuthManager();

    // Generate a unique token filename for a new account.
    std::string AllocTokenFile(const std::string& uuid) const;

    // Synthesize an offline session from account info.
    static MCAuth::JavaSession SynthesizeOfflineSession(const JavaAccountInfo& acct);

    // Abandon the current auth engine for a slot and create a fresh one.
    // Calls RequestCancel on the old engine so its worker exits promptly.
    // Returns the fresh shared_ptr for capturing in the new worker lambda.
    std::shared_ptr<MCAuth::JavaAuthManager> ResetSlotAuth(AuthSlot& s);

    // Shared Ely.by refresh logic used by RefreshSlot and SetAccountForSlot.
    // If failOpen is true, sets state to Success even when refresh fails (fail-open).
    // If alwaysSaveIndex is true, calls SaveJavaAccountIndex even on failure.
    void RunElybyRefresh(int slot, uint32_t gen, const std::string& tokenFile,
                         bool failOpen, bool alwaysSaveIndex);

    // Per-slot auth state
    AuthSlot m_slots[XUSER_MAX_COUNT];

    // Shared account list (protected by m_accountsMutex)
    mutable std::mutex           m_accountsMutex;
    std::vector<JavaAccountInfo> m_javaAccounts;

    // Device code state (for BeginAddJavaAccount, always on slot 0)
    mutable std::mutex           m_deviceCodeMutex;
    std::string                  m_javaDeviceCode;
    std::string                  m_javaDirectUri;

    bool m_javaRestoreAttempted = false;
};