/*
 * rofi
 *
 * MIT/X11 License
 * Copyright © 2013-2021 Qball Cow <qball@gmpclient.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "widgets/scrollbar.h"
#include "widgets/icon.h"
#include "widgets/listview.h"
#include "widgets/textbox.h"
#include <glib.h>
#include <xkbcommon/xkbcommon.h>

#include "theme.h"

/** The default width of the scrollbar */
#define DEFAULT_SCROLLBAR_WIDTH 8

static void scrollbar_draw(widget *, cairo_t *);
static void scrollbar_free(widget *);

static int scrollbar_get_desired_height(widget *wid) {
  // Want height we are.
  return wid->h;
}

// TODO
// This should behave more like a real scrollbar.
guint scrollbar_scroll_get_line(const scrollbar *sb, int y) {
  y -= sb->widget.border.top.base.distance;
  if (y < 0) {
    return 0;
  }

  if (y > sb->widget.h) {
    return sb->length - 1;
  }

  short r =
      (sb->length * sb->widget.h) / ((double)(sb->length + sb->pos_length));
  short handle = sb->widget.h - r;
  double sec = ((r) / (double)(sb->length - 1));
  short half_handle = handle / 2;
  y -= half_handle;
  y = MIN(MAX(0, y), sb->widget.h - 2 * half_handle);

  unsigned int sel = ((y) / sec);
  return MIN(sel, sb->length - 1);
}

static void scrollbar_scroll(scrollbar *sb, int y) {
  listview_set_selected((listview *)sb->widget.parent,
                        scrollbar_scroll_get_line(sb, y));
}

static WidgetTriggerActionResult
scrollbar_trigger_action(widget *wid, MouseBindingMouseDefaultAction action,
                         G_GNUC_UNUSED gint x, gint y,
                         G_GNUC_UNUSED void *user_data) {
  scrollbar *sb = (scrollbar *)wid;
  switch (action) {
  case MOUSE_CLICK_DOWN:
    return WIDGET_TRIGGER_ACTION_RESULT_GRAB_MOTION_BEGIN;
  case MOUSE_CLICK_UP:
    scrollbar_scroll(sb, y);
    return WIDGET_TRIGGER_ACTION_RESULT_GRAB_MOTION_END;
  case MOUSE_DCLICK_DOWN:
  case MOUSE_DCLICK_UP:
    break;
  }
  return FALSE;
}

static gboolean scrollbar_motion_notify(widget *wid, G_GNUC_UNUSED gint x,
                                        gint y) {
  scrollbar *sb = (scrollbar *)wid;
  scrollbar_scroll(sb, y);
  return TRUE;
}

scrollbar *scrollbar_create(widget *parent, const char *name) {
  scrollbar *sb = g_malloc0(sizeof(scrollbar));
  widget_init(WIDGET(sb), parent, WIDGET_TYPE_SCROLLBAR, name);
  sb->widget.x = 0;
  sb->widget.y = 0;
  sb->width = rofi_theme_get_distance(WIDGET(sb), "handle-width",
                                      DEFAULT_SCROLLBAR_WIDTH);
  int width = distance_get_pixel(sb->width, ROFI_ORIENTATION_HORIZONTAL);
  sb->widget.w = widget_padding_get_padding_width(WIDGET(sb)) + width;
  sb->widget.h = widget_padding_get_padding_height(WIDGET(sb));

  sb->widget.draw = scrollbar_draw;
  sb->widget.free = scrollbar_free;
  sb->widget.trigger_action = scrollbar_trigger_action;
  sb->widget.motion_notify = scrollbar_motion_notify;
  sb->widget.get_desired_height = scrollbar_get_desired_height;

  sb->length = 10;
  sb->pos = 0;
  sb->pos_length = 4;

  return sb;
}

static void scrollbar_free(widget *wid) {
  scrollbar *sb = (scrollbar *)wid;
  g_free(sb);
}

void scrollbar_set_max_value(scrollbar *sb, unsigned int max) {
  if (sb != NULL) {
    sb->length = MAX(1u, max);
  }
}

void scrollbar_set_handle(scrollbar *sb, unsigned int pos) {
  if (sb != NULL) {
    sb->pos = MIN(sb->length, pos);
  }
}

void scrollbar_set_handle_length(scrollbar *sb, unsigned int pos_length) {
  if (sb != NULL) {
    sb->pos_length = MIN(sb->length, MAX(1u, pos_length));
  }
}

/**
 * The range is the height - handle length.
 * r = h - handle;
 * handle is the element length of the handle* length of one element.
 * handle =  r / ( num ) * hl
 *
 * r = h - r / ( num) *hl
 * r*num = num*h - r*hl
 * r*num+r*hl = num*h;
 * r ( num+hl ) = num*h
 * r = (num*h)/(num+hl)
 */
static void scrollbar_draw(widget *wid, cairo_t *draw) {
  scrollbar *sb = (scrollbar *)wid;
  unsigned int wh = widget_padding_get_remaining_height(wid);
  // Calculate position and size.
  unsigned int r = (sb->length * wh) / ((double)(sb->length + sb->pos_length));
  unsigned int handle = wid->h - r;
  double sec = ((r) / (double)(sb->length - 1));
  unsigned int height = handle;
  unsigned int y = sb->pos * sec;
  // Set max pos.
  y = MIN(y, wh - handle);
  // Never go out of bar.
  height = MAX(2, height);
  // Cap length;
  rofi_theme_get_color(WIDGET(sb), "handle-color", draw);

  cairo_rectangle(draw, widget_padding_get_left(wid),
                  widget_padding_get_top(wid) + y,
                  widget_padding_get_remaining_width(wid), height);
  cairo_fill(draw);
}