/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.> See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

#include "adw-widget-utils-private.h"

typedef struct _CompareInfo CompareInfo;

enum Axis {
  HORIZONTAL = 0,
  VERTICAL   = 1
};

struct _CompareInfo
{
  GtkWidget *widget;
  int x;
  int y;
  guint reverse : 1;
  guint axis : 1;
};

static inline void
get_axis_info (const graphene_rect_t *bounds,
               int                    axis,
               int                   *start,
               int                   *end)
{
  if (axis == HORIZONTAL) {
    *start = bounds->origin.x;
    *end = bounds->size.width;
  } else if (axis == VERTICAL) {
    *start = bounds->origin.y;
    *end = bounds->size.height;
  } else {
    g_assert_not_reached ();
  }
}

/* Utility function, equivalent to g_list_reverse */
static void
reverse_ptr_array (GPtrArray *arr)
{
  int i;

  for (i = 0; i < arr->len / 2; i ++) {
    void *a = g_ptr_array_index (arr, i);
    void *b = g_ptr_array_index (arr, arr->len - 1 - i);

    arr->pdata[i] = b;
    arr->pdata[arr->len - 1 - i] = a;
  }
}

static int
tab_sort_func (gconstpointer a,
               gconstpointer b,
               gpointer      user_data)
{
  graphene_rect_t child_bounds1, child_bounds2;
  GtkWidget *child1 = *((GtkWidget **) a);
  GtkWidget *child2 = *((GtkWidget **) b);
  GtkTextDirection text_direction = GPOINTER_TO_INT (user_data);
  float y1, y2;

  if (!gtk_widget_compute_bounds (child1, gtk_widget_get_parent (child1), &child_bounds1) ||
      !gtk_widget_compute_bounds (child2, gtk_widget_get_parent (child2), &child_bounds2))
    return 0;

  y1 = child_bounds1.origin.y + (child_bounds1.size.height / 2.0f);
  y2 = child_bounds2.origin.y + (child_bounds2.size.height / 2.0f);

  if (y1 == y2) {
    const float x1 = child_bounds1.origin.x + (child_bounds1.size.width / 2.0f);
    const float x2 = child_bounds2.origin.x + (child_bounds2.size.width / 2.0f);

    if (text_direction == GTK_TEXT_DIR_RTL)
      return (x1 < x2) ? 1 : ((x1 == x2) ? 0 : -1);
    else
      return (x1 < x2) ? -1 : ((x1 == x2) ? 0 : 1);
  }

  return (y1 < y2) ? -1 : 1;
}

static void
focus_sort_tab (GtkWidget        *widget,
                GtkDirectionType  direction,
                GPtrArray        *focus_order)
{
  GtkTextDirection text_direction = gtk_widget_get_direction (widget);

  g_ptr_array_sort_with_data (focus_order, tab_sort_func, GINT_TO_POINTER (text_direction));

  if (direction == GTK_DIR_TAB_BACKWARD)
    reverse_ptr_array (focus_order);
}

/* Look for a child in @children that is intermediate between
 * the focus widget and container. This widget, if it exists,
 * acts as the starting widget for focus navigation.
 */
static GtkWidget *
find_old_focus (GtkWidget *widget,
                GPtrArray *children)
{
  int i;

  for (i = 0; i < children->len; i ++) {
    GtkWidget *child = g_ptr_array_index (children, i);
    GtkWidget *child_ptr = child;

    while (child_ptr && child_ptr != widget) {
      GtkWidget *parent = gtk_widget_get_parent (child_ptr);

      if (parent && (gtk_widget_get_focus_child (parent) != child_ptr)) {
        child = NULL;
        break;
      }

      child_ptr = parent;
    }

    if (child)
      return child;
  }

  return NULL;
}

static gboolean
old_focus_coords (GtkWidget       *widget,
                  graphene_rect_t *old_focus_bounds)
{
  GtkWidget *old_focus;

  old_focus = gtk_root_get_focus (gtk_widget_get_root (widget));
  if (old_focus)
    return gtk_widget_compute_bounds (old_focus, widget, old_focus_bounds);

  return FALSE;
}

static int
axis_compare (gconstpointer a,
              gconstpointer b,
              gpointer      user_data)
{
  graphene_rect_t bounds1;
  graphene_rect_t bounds2;
  CompareInfo *compare = user_data;
  int start1, end1;
  int start2, end2;

  if (!gtk_widget_compute_bounds (*((GtkWidget **) a), compare->widget, &bounds1) ||
      !gtk_widget_compute_bounds (*((GtkWidget **) b), compare->widget, &bounds2))
    return 0;

  get_axis_info (&bounds1, compare->axis, &start1, &end1);
  get_axis_info (&bounds2, compare->axis, &start2, &end2);

  start1 = start1 + (end1 / 2);
  start2 = start2 + (end2 / 2);

  if (start1 == start2) {
    int x1, x2;

    /* Now use origin/bounds to compare the 2 widgets on the other axis */
    get_axis_info (&bounds1, 1 - compare->axis, &start1, &end1);
    get_axis_info (&bounds2, 1 - compare->axis, &start2, &end2);

    x1 = abs (start1 + (end1 / 2) - compare->x);
    x2 = abs (start2 + (end2 / 2) - compare->x);

    if (compare->reverse)
      return (x1 < x2) ? 1 : ((x1 == x2) ? 0 : -1);
    else
      return (x1 < x2) ? -1 : ((x1 == x2) ? 0 : 1);
  }

  return (start1 < start2) ? -1 : 1;
}

static void
focus_sort_left_right (GtkWidget        *widget,
                       GtkDirectionType  direction,
                       GPtrArray        *focus_order)
{
  CompareInfo compare_info;
  GtkWidget *old_focus = gtk_widget_get_focus_child (widget);
  graphene_rect_t old_bounds;

  compare_info.widget = widget;
  compare_info.reverse = (direction == GTK_DIR_LEFT);

  if (!old_focus)
    old_focus = find_old_focus (widget, focus_order);

  if (old_focus && gtk_widget_compute_bounds (old_focus, widget, &old_bounds)) {
    float compare_y1;
    float compare_y2;
    float compare_x;
    int i;

    /* Delete widgets from list that don't match minimum criteria */

    compare_y1 = old_bounds.origin.y;
    compare_y2 = old_bounds.origin.y + old_bounds.size.height;

    if (direction == GTK_DIR_LEFT)
      compare_x = old_bounds.origin.x;
    else
      compare_x = old_bounds.origin.x + old_bounds.size.width;

    for (i = 0; i < focus_order->len; i++) {
      GtkWidget *child = g_ptr_array_index (focus_order, i);

      if (child != old_focus) {
        graphene_rect_t child_bounds;

        if (gtk_widget_compute_bounds (child, widget, &child_bounds)) {
          const float child_y1 = child_bounds.origin.y;
          const float child_y2 = child_bounds.origin.y + child_bounds.size.height;

          if ((child_y2 <= compare_y1 || child_y1 >= compare_y2) /* No vertical overlap */ ||
              (direction == GTK_DIR_RIGHT && child_bounds.origin.x + child_bounds.size.width < compare_x) || /* Not to left */
              (direction == GTK_DIR_LEFT && child_bounds.origin.x > compare_x)) /* Not to right */ {
            g_ptr_array_remove_index (focus_order, i);
            i --;
          }
        } else {
          g_ptr_array_remove_index (focus_order, i);
          i --;
        }
      }
    }

    compare_info.y = (compare_y1 + compare_y2) / 2;
    compare_info.x = old_bounds.origin.x + (old_bounds.size.width / 2.0f);
  } else {
    /* No old focus widget, need to figure out starting x,y some other way
     */
    graphene_rect_t bounds;
    GtkWidget *parent;
    graphene_rect_t old_focus_bounds;

    parent = gtk_widget_get_parent (widget);
    if (!gtk_widget_compute_bounds (widget, parent ? parent : widget, &bounds))
      graphene_rect_init (&bounds, 0, 0, 0, 0);

    if (old_focus_coords (widget, &old_focus_bounds)) {
      compare_info.y = old_focus_bounds.origin.y + (old_focus_bounds.size.height / 2.0f);
    } else {
      if (!GTK_IS_NATIVE (widget))
        compare_info.y = bounds.origin.y + bounds.size.height;
      else
        compare_info.y = bounds.size.height / 2.0f;
    }

    if (!GTK_IS_NATIVE (widget))
      compare_info.x = (direction == GTK_DIR_RIGHT) ? bounds.origin.x : bounds.origin.x + bounds.size.width;
    else
      compare_info.x = (direction == GTK_DIR_RIGHT) ? 0 : bounds.size.width;
  }

  compare_info.axis = HORIZONTAL;
  g_ptr_array_sort_with_data (focus_order, axis_compare, &compare_info);

  if (compare_info.reverse)
    reverse_ptr_array (focus_order);
}

static void
focus_sort_up_down (GtkWidget        *widget,
                    GtkDirectionType  direction,
                    GPtrArray        *focus_order)
{
  CompareInfo compare_info;
  GtkWidget *old_focus = gtk_widget_get_focus_child (widget);
  graphene_rect_t old_bounds;

  compare_info.widget = widget;
  compare_info.reverse = (direction == GTK_DIR_UP);

  if (!old_focus)
    old_focus = find_old_focus (widget, focus_order);

  if (old_focus && gtk_widget_compute_bounds (old_focus, widget, &old_bounds)) {
    float compare_x1;
    float compare_x2;
    float compare_y;
    int i;

    /* Delete widgets from list that don't match minimum criteria */

    compare_x1 = old_bounds.origin.x;
    compare_x2 = old_bounds.origin.x + old_bounds.size.width;

    if (direction == GTK_DIR_UP)
      compare_y = old_bounds.origin.y;
    else
      compare_y = old_bounds.origin.y + old_bounds.size.height;

    for (i = 0; i < focus_order->len; i++) {
      GtkWidget *child = g_ptr_array_index (focus_order, i);

      if (child != old_focus) {
        graphene_rect_t child_bounds;

        if (gtk_widget_compute_bounds (child, widget, &child_bounds)) {
          const float child_x1 = child_bounds.origin.x;
          const float child_x2 = child_bounds.origin.x + child_bounds.size.width;

          if ((child_x2 <= compare_x1 || child_x1 >= compare_x2) /* No horizontal overlap */ ||
              (direction == GTK_DIR_DOWN && child_bounds.origin.y + child_bounds.size.height < compare_y) || /* Not below */
              (direction == GTK_DIR_UP && child_bounds.origin.y > compare_y)) /* Not above */ {
            g_ptr_array_remove_index (focus_order, i);
            i --;
          }
        } else {
          g_ptr_array_remove_index (focus_order, i);
          i --;
        }
      }
    }

    compare_info.x = (compare_x1 + compare_x2) / 2;
    compare_info.y = old_bounds.origin.y + (old_bounds.size.height / 2.0f);
  } else {
    /* No old focus widget, need to figure out starting x,y some other way
     */
    GtkWidget *parent;
    graphene_rect_t bounds;
    graphene_rect_t old_focus_bounds;

    parent = gtk_widget_get_parent (widget);
    if (!gtk_widget_compute_bounds (widget, parent ? parent : widget, &bounds))
      graphene_rect_init (&bounds, 0, 0, 0, 0);

    if (old_focus_coords (widget, &old_focus_bounds)) {
      compare_info.x = old_focus_bounds.origin.x + (old_focus_bounds.size.width / 2.0f);
    } else {
      if (!GTK_IS_NATIVE (widget))
        compare_info.x = bounds.origin.x + (bounds.size.width / 2.0f);
      else
        compare_info.x = bounds.size.width / 2.0f;
    }

    if (!GTK_IS_NATIVE (widget))
      compare_info.y = (direction == GTK_DIR_DOWN) ? bounds.origin.y : bounds.origin.y + bounds.size.height;
    else
      compare_info.y = (direction == GTK_DIR_DOWN) ? 0 : + bounds.size.height;
  }

  compare_info.axis = VERTICAL;
  g_ptr_array_sort_with_data (focus_order, axis_compare, &compare_info);

  if (compare_info.reverse)
    reverse_ptr_array (focus_order);
}

static void
focus_sort (GtkWidget        *widget,
            GtkDirectionType  direction,
            GPtrArray        *focus_order)
{
  GtkWidget *child;

  g_assert (focus_order != NULL);

  if (focus_order->len == 0) {
    /* Initialize the list with all visible child widgets */
    for (child = gtk_widget_get_first_child (widget);
         child != NULL;
         child = gtk_widget_get_next_sibling (child)) {
      if (gtk_widget_get_mapped (child) &&
          gtk_widget_get_sensitive (child))
        g_ptr_array_add (focus_order, child);
    }
  }

  /* Now sort that list depending on @direction */
  switch (direction) {
  case GTK_DIR_TAB_FORWARD:
  case GTK_DIR_TAB_BACKWARD:
    focus_sort_tab (widget, direction, focus_order);
    break;
  case GTK_DIR_UP:
  case GTK_DIR_DOWN:
    focus_sort_up_down (widget, direction, focus_order);
    break;
  case GTK_DIR_LEFT:
  case GTK_DIR_RIGHT:
    focus_sort_left_right (widget, direction, focus_order);
    break;
  default:
    g_assert_not_reached ();
  }
}


static gboolean
focus_move (GtkWidget        *widget,
            GtkDirectionType  direction)
{
  GPtrArray *focus_order;
  GtkWidget *focus_child = gtk_widget_get_focus_child (widget);
  int i;
  gboolean ret = FALSE;

  focus_order = g_ptr_array_new ();
  focus_sort (widget, direction, focus_order);

  for (i = 0; i < focus_order->len && !ret; i++) {
    GtkWidget *child = g_ptr_array_index (focus_order, i);

    if (focus_child) {
      if (focus_child == child) {
        focus_child = NULL;
        ret = gtk_widget_child_focus (child, direction);
      }
    } else if (gtk_widget_get_mapped (child) &&
               gtk_widget_is_ancestor (child, widget)) {
      ret = gtk_widget_child_focus (child, direction);
    }
  }

  g_ptr_array_unref (focus_order);

  return ret;
}

gboolean
adw_widget_focus_child (GtkWidget        *widget,
                        GtkDirectionType  direction)
{
  return focus_move (widget, direction);
}

gboolean
adw_widget_grab_focus_self (GtkWidget *widget)
{
  if (!gtk_widget_get_focusable (widget))
    return FALSE;

  gtk_root_set_focus (gtk_widget_get_root (widget), widget);

  return TRUE;
}

gboolean
adw_widget_grab_focus_child (GtkWidget *widget)
{
  GtkWidget *child;

  for (child = gtk_widget_get_first_child (widget);
       child != NULL;
       child = gtk_widget_get_next_sibling (child))
    if (gtk_widget_grab_focus (child))
      return TRUE;

  return FALSE;
}

void
adw_widget_compute_expand (GtkWidget *widget,
                           gboolean  *hexpand_p,
                           gboolean  *vexpand_p)
{
  GtkWidget *child;
  gboolean hexpand = FALSE;
  gboolean vexpand = FALSE;

  for (child = gtk_widget_get_first_child (widget);
       child != NULL;
       child = gtk_widget_get_next_sibling (child)) {
    hexpand = hexpand || gtk_widget_compute_expand (child, GTK_ORIENTATION_HORIZONTAL);
    vexpand = vexpand || gtk_widget_compute_expand (child, GTK_ORIENTATION_VERTICAL);
  }

  *hexpand_p = hexpand;
  *vexpand_p = vexpand;
}

void
adw_widget_compute_expand_horizontal_only (GtkWidget *widget,
                                           gboolean  *hexpand_p,
                                           gboolean  *vexpand_p)
{
  GtkWidget *child;
  gboolean hexpand = FALSE;

  for (child = gtk_widget_get_first_child (widget);
       child != NULL;
       child = gtk_widget_get_next_sibling (child))
    hexpand = hexpand || gtk_widget_compute_expand (child, GTK_ORIENTATION_HORIZONTAL);

  *hexpand_p = hexpand;
  *vexpand_p = FALSE;
}

GtkSizeRequestMode
adw_widget_get_request_mode (GtkWidget *widget)
{
  GtkWidget *child;
  int wfh = 0, hfw = 0;

  for (child = gtk_widget_get_first_child (widget);
       child;
       child = gtk_widget_get_next_sibling (child)) {
    GtkSizeRequestMode mode = gtk_widget_get_request_mode (child);

    switch (mode) {
    case GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH:
      hfw++;
      break;
    case GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT:
      wfh++;
      break;
    case GTK_SIZE_REQUEST_CONSTANT_SIZE:
    default:
      break;
    }
  }

  if (hfw == 0 && wfh == 0)
    return GTK_SIZE_REQUEST_CONSTANT_SIZE;
  else
    return wfh > hfw ?
        GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT :
        GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
}
