/**
 * GUI framework
 * 
 * Created on 2020/01/03.
 */

#ifndef REFLOWER_LIQUID_H
#define REFLOWER_LIQUID_H

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

struct Liquid;

enum InputEvent_Kind {
    InputEventKind_Wheel,
    InputEventKind_Button,
};

struct InputEvent {
    enum InputEvent_Kind kind;
    union {
        struct {
            // Wheel delta
            int8_t delta;
        } wheel;
        struct {
            // Button state
            bool state;
        } button;
    };
};

#define InputEvent_Wheel(delta_) ((struct InputEvent) { \
    .kind = InputEventKind_Wheel, \
    .wheel = { .delta = delta_ } \
})

#define InputEvent_Button(state_) ((struct InputEvent) { \
    .kind = InputEventKind_Button, \
    .button = { .state = state_ }, \
})

enum SceneEvent_Kind {
    // Close this scene.
    // The scene is responsible for cleaning up 'private'.
    // 'options' and the scene itself will be freed by the GUI engine.
    SceneEventKind_Close,
    SceneEventKind_OpenChild,
    SceneEventKind_RequestRepaint,
    SceneEventKind_None,
};

struct SceneEvent {
    enum SceneEvent_Kind kind;
    union {
        struct {
            // Status code
            uint32_t status;
            // Return data on heap
            void *data;
        } close;
        struct {
            // Scene (initialized, with options loaded in through the constructor)
            void *scene;
            // Tag used by parent to identify the open child
            uint32_t tag;
        } open;
    };
};

struct Scene;

#define SceneEvent_None() ((struct SceneEvent) { \
    .kind = SceneEventKind_None\
})

#define SceneEvent_Repaint() ((struct SceneEvent) { \
    .kind = SceneEventKind_RequestRepaint\
})

#define SceneEvent_OpenChild(child_, tag_) ((struct SceneEvent) { \
    .kind = SceneEventKind_OpenChild,\
    .open = { .scene = (child_), .tag=tag_ }, \
})

#define SceneEvent_Close(status_, data_) ((struct SceneEvent) { \
    .kind = SceneEventKind_Close,\
    .close = { .status = (status_), .data=(data_) }, \
})

typedef struct SceneEvent (*Scene_onInput_t)(struct Scene *scene, struct InputEvent event);
typedef struct SceneEvent (*Scene_onChildReturn_t)(struct Scene *scene, uint32_t tag, uint32_t status, void *data);
typedef struct SceneEvent (*Scene_onTick_t)(struct Scene *scene);
typedef void (*Scene_repaint_t)(struct Scene *scene);

struct Scene {
    uint32_t tag;
    void *options;
    void *private;
    /** Handle input */
    Scene_onInput_t onInput;
    /** Handle child scene return */
    Scene_onChildReturn_t onChildReturn;
    /** Periodic tick */
    Scene_onTick_t onTick;
    /** Periodic tick */
    Scene_repaint_t paint;
};

/**
 * Allocate scene and the inner private type.
 *
 * Requires <malloc.h>
 *
 * Must be used like:
 *
 * struct Scene *scene = SCENE_SAFE_ALLOC(struct private);
 * scene->onInput = ...
 * return scene;
 */
#define SCENE_SAFE_ALLOC(private_type) \
    calloc(1, sizeof(struct Scene)); \
    if (!scene) return NULL; \
    scene->private = calloc(1, sizeof(private_type)); \
    if (!scene->private) return NULL;

/** return 1 if repaint requested */
bool Liquid_handleInput(struct Liquid *container, struct InputEvent event);

/** return 1 if repaint requested */
bool Liquid_handleTick(struct Liquid *container);

void Liquid_paint(struct Liquid *container);
struct Liquid *Liquid_start();

#endif //REFLOWER_LIQUID_H