context.h

// context.h — Global system state container.
//
// Header-only by design (the manifest lists no context.c): the struct
// definitions and the two tiny accessors below are small enough to live as
// `static inline` functions. Storage for g_context itself is defined once,
// in main.c.

#ifndef CONTEXT_H
#define CONTEXT_H

#include <stdint.h>
#include <stdbool.h>

// Top-level states for the hierarchical state machine. Each maps to an
// Enter/Update/Draw triplet dispatched from main.c's loop.
typedef enum {
    SCREEN_BOOT = 0,
    SCREEN_MENU,
    SCREEN_SETTINGS,
    SCREEN_GAME_LAUNCHER,
    SCREEN_NAME_ENTRY,
    SCREEN_GAME_SNAKE,
    SCREEN_GAME_TETRIS,
    SCREEN_GAME_BRICKS,
} ScreenState;

#define GAME_ID_SNAKE   0
#define GAME_ID_TETRIS  1
#define GAME_ID_BRICKS  2

// Live, user-adjustable settings, edited from the Settings screen.
typedef struct {
    uint8_t brightness; // 0-100 (%) -> drives backlight.c's software PWM
    uint8_t volume;     // 0-100 (%) -> TODO: not yet wired into audio.c's
                         //              output duty; see audio.c.
} SystemSettings;

// Single global state container threaded through every state handler.
typedef struct {
    ScreenState screen;         // state currently being dispatched
    ScreenState nextScreen;     // requested transition target
    bool        screenEntered;  // true once the current screen's Enter() ran

    uint32_t    lastTickMs;     // systemGetTimeMs() at the last frame
    uint16_t    deltaMs;        // ms elapsed since the previous frame
    
    // Global state shared across screens
    uint8_t     selectedGameId;
    bool        hasState[3];    // snake, tetris, bricks

    SystemSettings settings;
} SystemContext;

extern SystemContext g_context; // defined once, in main.c

static inline void contextInit(void) {
    g_context.screen        = SCREEN_BOOT;
    g_context.nextScreen    = SCREEN_BOOT;
    g_context.screenEntered = false;
    g_context.lastTickMs    = 0;
    g_context.deltaMs       = 0;
    g_context.selectedGameId = 0;
    g_context.settings.brightness = 50;
    g_context.settings.volume     = 75;
}

// ----------------------------------------------------------------------------
// Screen Management
// ----------------------------------------------------------------------------
// Any state handler calls this to ask main.c's loop to switch screens on
// the next frame. Transition itself (calling the new screen's Enter()) is
// handled centrally in main.c so it only ever happens once per switch.
static inline void contextRequestScreen(ScreenState next) {
    g_context.nextScreen = next;
}

#endif // CONTEXT_H