#include <Elementary.h>
#include "elm_priv.h"

#define SMART_NAME "elm_pan"
#define API_ENTRY Smart_Data *sd; sd = evas_object_smart_data_get(obj); if ((!obj) || (!sd) || (evas_object_type_get(obj) && strcmp(evas_object_type_get(obj), SMART_NAME)))
#define INTERNAL_ENTRY Smart_Data *sd; sd = evas_object_smart_data_get(obj); if (!sd) return;
typedef struct _Smart_Data Smart_Data;

struct _Smart_Data
{
   Evas_Object *smart_obj;
   Evas_Object *child_obj;
   Evas_Coord   x, y, w, h;
   Evas_Coord   child_w, child_h, px, py;
   double       gravity_x, gravity_y;
   Evas_Coord   prev_cw, prev_ch, delta_posx, delta_posy;
};

/* local subsystem functions */
static void _smart_child_del_hook(void *data, Evas *e, Evas_Object *obj, void *event_info);
static void _smart_child_resize_hook(void *data, Evas *e, Evas_Object *obj, void *event_info);

static void _smart_reconfigure(Smart_Data *sd);
static void _smart_add(Evas_Object *obj);
static void _smart_del(Evas_Object *obj);
static void _smart_move(Evas_Object *obj, Evas_Coord x, Evas_Coord y);
static void _smart_resize(Evas_Object *obj, Evas_Coord w, Evas_Coord h);
static void _smart_show(Evas_Object *obj);
static void _smart_hide(Evas_Object *obj);
static void _smart_color_set(Evas_Object *obj, int r, int g, int b, int a);
static void _smart_clip_set(Evas_Object *obj, Evas_Object * clip);
static void _smart_clip_unset(Evas_Object *obj);
static void _smart_init(void);

/* local subsystem globals */
static Evas_Smart *_smart = NULL;

/* externally accessible functions */
Evas_Object *
_elm_smart_pan_add(Evas *evas)
{
   _smart_init();
   return evas_object_smart_add(evas, _smart);
}

void
_elm_smart_pan_child_set(Evas_Object *obj, Evas_Object *child)
{
   API_ENTRY return;
   if (child == sd->child_obj) return;
   if (sd->child_obj)
     {
        evas_object_clip_unset(sd->child_obj);
        evas_object_smart_member_del(sd->child_obj);
        evas_object_event_callback_del_full(sd->child_obj, EVAS_CALLBACK_FREE, _smart_child_del_hook, sd);
        evas_object_event_callback_del_full(sd->child_obj, EVAS_CALLBACK_RESIZE, _smart_child_resize_hook, sd);
        sd->child_obj = NULL;
     }
   if (child)
     {
        Evas_Coord w, h;
        int r, g, b, a;

        sd->child_obj = child;
        evas_object_smart_member_add(sd->child_obj, sd->smart_obj);
        evas_object_geometry_get(sd->child_obj, NULL, NULL, &w, &h);
        sd->child_w = w;
        sd->child_h = h;
        evas_object_event_callback_add(child, EVAS_CALLBACK_FREE, _smart_child_del_hook, sd);
        evas_object_event_callback_add(child, EVAS_CALLBACK_RESIZE, _smart_child_resize_hook, sd);
        evas_object_color_get(sd->smart_obj, &r, &g, &b, &a);
        evas_object_color_set(sd->child_obj, r, g, b, a);
        evas_object_clip_set(sd->child_obj, evas_object_clip_get(sd->smart_obj));
        if (evas_object_visible_get(sd->smart_obj)) evas_object_show(sd->child_obj);
        else evas_object_hide(sd->child_obj);
        _smart_reconfigure(sd);
     }
   evas_object_smart_callback_call(sd->smart_obj, "changed", NULL);
}

Evas_Object *
_elm_smart_pan_child_get(Evas_Object *obj)
{
   API_ENTRY return NULL;
   return sd->child_obj;
}

void
_elm_smart_pan_set(Evas_Object *obj, Evas_Coord x, Evas_Coord y)
{
   API_ENTRY return;
   //   if (x > (sd->child_w - sd->w)) x = sd->child_w - sd->w;
   //   if (y > (sd->child_h - sd->h)) y = sd->child_h - sd->h;
   //   if (x < 0) x = 0;
   //   if (y < 0) y = 0;
   if ((x == sd->px) && (y == sd->py)) return;
   sd->px = x;
   sd->py = y;
   _smart_reconfigure(sd);
   evas_object_smart_callback_call(sd->smart_obj, "changed", NULL);
}

void
_elm_smart_pan_get(Evas_Object *obj, Evas_Coord *x, Evas_Coord *y)
{
   API_ENTRY return;
   if (x) *x = sd->px;
   if (y) *y = sd->py;
}

void
_elm_smart_pan_max_get(Evas_Object *obj, Evas_Coord *x, Evas_Coord *y)
{
   API_ENTRY return;
   if (x)
     {
        if (sd->w < sd->child_w) *x = sd->child_w - sd->w;
        else *x = 0;
     }
   if (y)
     {
        if (sd->h < sd->child_h) *y = sd->child_h - sd->h;
        else *y = 0;
     }
}

void
_elm_smart_pan_min_get(Evas_Object *obj, Evas_Coord *x, Evas_Coord *y)
{
   API_ENTRY return;
   if (x)
      *x = 0;
   if (y)
      *y = 0;
}

void
_elm_smart_pan_child_size_get(Evas_Object *obj, Evas_Coord *w, Evas_Coord *h)
{
   API_ENTRY return;
   if (w) *w = sd->child_w;
   if (h) *h = sd->child_h;
}

void
_elm_smart_pan_gravity_set(Evas_Object *obj, double x, double y)
{
   API_ENTRY return;
   sd->gravity_x = x;
   sd->gravity_y = y;
   sd->prev_cw = sd->child_w;
   sd->prev_ch = sd->child_h;
   sd->delta_posx = 0;
   sd->delta_posy = 0;
}

void
_elm_smart_pan_gravity_get(Evas_Object *obj, double *x, double *y)
{
   API_ENTRY return;
   if (x) *x = sd->gravity_x;
   if (y) *y = sd->gravity_y;
}

/* local subsystem functions */
static void
_smart_child_del_hook(void *data, Evas *e __UNUSED__, Evas_Object *obj __UNUSED__, void *event_info __UNUSED__)
{
   Smart_Data *sd;

   sd = data;
   sd->child_obj = NULL;
   evas_object_smart_callback_call(sd->smart_obj, "changed", NULL);
}

static void
_smart_child_resize_hook(void *data, Evas *e __UNUSED__, Evas_Object *obj __UNUSED__, void *event_info __UNUSED__)
{
   Smart_Data *sd;
   Evas_Coord w, h;

   sd = data;
   evas_object_geometry_get(sd->child_obj, NULL, NULL, &w, &h);
   if ((w != sd->child_w) || (h != sd->child_h))
     {
        sd->child_w = w;
        sd->child_h = h;
        _smart_reconfigure(sd);
     }
   evas_object_smart_callback_call(sd->smart_obj, "changed", NULL);
}

static void
_smart_reconfigure(Smart_Data *sd)
{
   if (sd->gravity_x || sd->gravity_y)
     {
        if ((!sd->px) && (!sd->py))
          {
             sd->px = sd->delta_posx*sd->gravity_x;
             sd->py = sd->delta_posy*sd->gravity_y;
          }
        sd->delta_posx += sd->child_w - sd->prev_cw;
        sd->prev_cw = sd->child_w;
        sd->delta_posy += sd->child_h - sd->prev_ch;
        sd->prev_ch = sd->child_h;

        evas_object_move(sd->child_obj, sd->x - sd->px, sd->y - sd->py);
        sd->px = sd->delta_posx*sd->gravity_x;
        sd->py = sd->delta_posy*sd->gravity_y;

     }
   else
     evas_object_move(sd->child_obj, sd->x - sd->px, sd->y - sd->py);
}

static void
_smart_add(Evas_Object *obj)
{
   Smart_Data *sd;

   sd = calloc(1, sizeof(Smart_Data));
   if (!sd) return;
   sd->smart_obj = obj;
   sd->x = 0;
   sd->y = 0;
   sd->w = 0;
   sd->h = 0;
   sd->gravity_x = 0.0;
   sd->gravity_y = 0.0;
   evas_object_smart_data_set(obj, sd);
}

static void
_smart_del(Evas_Object *obj)
{
   INTERNAL_ENTRY;
   _elm_smart_pan_child_set(obj, NULL);
   free(sd);
}

static void
_smart_move(Evas_Object *obj, Evas_Coord x, Evas_Coord y)
{
   INTERNAL_ENTRY;
   sd->x = x;
   sd->y = y;
   _smart_reconfigure(sd);
}

static void
_smart_resize(Evas_Object *obj, Evas_Coord w, Evas_Coord h)
{
   INTERNAL_ENTRY;
   sd->w = w;
   sd->h = h;
   _smart_reconfigure(sd);
   evas_object_smart_callback_call(sd->smart_obj, "changed", NULL);
}

static void
_smart_show(Evas_Object *obj)
{
   INTERNAL_ENTRY;
   if (sd->child_obj)
     evas_object_show(sd->child_obj);
}

static void
_smart_hide(Evas_Object *obj)
{
   INTERNAL_ENTRY;
   if (sd->child_obj)
     evas_object_hide(sd->child_obj);
}

static void
_smart_color_set(Evas_Object *obj, int r, int g, int b, int a)
{
   INTERNAL_ENTRY;
   if (sd->child_obj)
     evas_object_color_set(sd->child_obj, r, g, b, a);
}

static void
_smart_clip_set(Evas_Object *obj, Evas_Object *clip)
{
   INTERNAL_ENTRY;
   if (sd->child_obj)
     evas_object_clip_set(sd->child_obj, clip);
}

static void
_smart_clip_unset(Evas_Object *obj)
{
   INTERNAL_ENTRY;
   if (sd->child_obj)
     evas_object_clip_unset(sd->child_obj);
}

/* never need to touch this */

static void
_smart_init(void)
{
   if (_smart) return;
     {
        static const Evas_Smart_Class sc =
          {
             SMART_NAME,
             EVAS_SMART_CLASS_VERSION,
             _smart_add,
             _smart_del,
             _smart_move,
             _smart_resize,
             _smart_show,
             _smart_hide,
             _smart_color_set,
             _smart_clip_set,
             _smart_clip_unset,
             NULL,
             NULL,
             NULL,
             NULL,
             NULL,
             NULL,
             NULL
          };
        _smart = evas_smart_class_new(&sc);
     }
}