// See header for documentation.

#include <string>
#include <vector>

#include "ui/ui.h"
#include "gfx/texture_atlas.h"
#include "gfx_es2/draw_buffer.h"

DrawBuffer ui_draw2d;
DrawBuffer ui_draw2d_front;
UIState uistate;

// Theme.
static const Atlas *themeAtlas;
static int themeUIFont;
static int themeButtonImage;
static int themeCheckOnImage;
static int themeCheckOffImage;

void UIInit(const Atlas *atlas, int uiFont, int buttonImage, int checkOn, int checkOff) {
	ui_draw2d.SetAtlas(atlas);
  ui_draw2d_front.SetAtlas(atlas);
	themeAtlas = atlas;
	themeUIFont = uiFont;
	themeButtonImage = buttonImage;
	themeCheckOnImage = checkOn;
	themeCheckOffImage = checkOff;
}

void UIUpdateMouse(float x, float y, int buttons) {
	if ((buttons & 1) && !uistate.mousedown) {
		uistate.mousepressed = 1;
		uistate.mouseStartX = x;
		uistate.mouseStartY = y;
	} else {
		uistate.mousepressed = 0;
	}
  uistate.mousex = x;
  uistate.mousey = y;
  uistate.mousedown = buttons & 1;
}

bool UIRegionHit(int x, int y, int w, int h, int margin) {
  if (uistate.mousex < x - margin ||
      uistate.mousey < y - margin ||
      uistate.mousex >= x + w + margin ||
      uistate.mousey >= y + h + margin) {
    return false;
  } else {
    return true;
  }
}

void UIBegin() {
  uistate.hotitem = 0;
  ui_draw2d.Begin();
	ui_draw2d_front.Begin();
}

void UIEnd() {
  if (uistate.mousedown == 0) {
    uistate.activeitem = 0;
  } else {
    if (uistate.activeitem == 0) {
      uistate.activeitem = -1;
    }
  }
	ui_draw2d.End();
  ui_draw2d_front.End();

	uistate.lastx = uistate.mousex;
	uistate.lasty = uistate.mousey;
}

void UIText(int x, int y, const char *text, uint32_t color, float scale, int align) {
	UIText(themeUIFont, x, y, text, color, scale, align);
}

void UIText(int font, int x, int y, const char *text, uint32_t color, float scale, int align) {
	ui_draw2d.SetFontScale(scale, scale);
	ui_draw2d.DrawTextShadow(font, text, x, y, color, align);
	ui_draw2d.SetFontScale(1.0f, 1.0f);
}

int UIButton(int id, const LayoutManager &layout, float w, const char *text, int button_align) {
  float h = themeAtlas->images[themeButtonImage].h;
	
	float x, y;
	layout.GetPos(&w, &h, &x, &y);

	if (button_align & ALIGN_HCENTER) x -= w / 2;
	if (button_align & ALIGN_VCENTER) y -= h / 2;
	if (button_align & ALIGN_RIGHT) x -= w;
	if (button_align & ALIGN_BOTTOMRIGHT) y -= h;

  // Check whether the button should be hot, use a generous margin for touch ease
  if (UIRegionHit(x, y, w, h, 8)) {
    uistate.hotitem = id;
    if (uistate.activeitem == 0 && uistate.mousedown)
      uistate.activeitem = id;
  }
    
  // Render button 

  int txOffset = 0;
  if (uistate.hotitem == id) {
    if (uistate.activeitem == id) {
      // Button is both 'hot' and 'active'
      txOffset = 2;
    } else {
      // Button is merely 'hot'
    }
  } else {
    // button is not hot, but it may be active    
  }
  ui_draw2d.DrawImage2GridH(themeButtonImage, x, y, x + w);
  ui_draw2d.DrawTextShadow(themeUIFont, text, x + w/2, y + h/2 + txOffset, 0xFFFFFFFF, ALIGN_HCENTER | ALIGN_VCENTER);

	int clicked = 0;
  // If button is hot and active, but mouse button is not
  // down, the user must have clicked the button.
  if (uistate.mousedown == 0 && 
      uistate.hotitem == id && 
      uistate.activeitem == id) {
    clicked = 1;
  }

	uistate.lastwidget = id;
	return clicked;
}

int UIImageButton(int id, const LayoutManager &layout, float w, int image, int button_align) {
	float h = 64;
	float x, y;
	layout.GetPos(&w, &h, &x, &y);

	if (button_align & ALIGN_HCENTER) x -= w / 2;
	if (button_align & ALIGN_VCENTER) y -= h / 2;
	if (button_align & ALIGN_RIGHT) x -= w;
	if (button_align & ALIGN_BOTTOMRIGHT) y -= h;

	// Check whether the button should be hot, use a generous margin for touch ease
	if (UIRegionHit(x, y, w, h, 8)) {
		uistate.hotitem = id;
		if (uistate.activeitem == 0 && uistate.mousedown)
			uistate.activeitem = id;
	}

	// Render button 

	int txOffset = 0;
	if (uistate.hotitem == id) {
		if (uistate.activeitem == id) {
			// Button is both 'hot' and 'active'
			txOffset = 2;
		} else {
			// Button is merely 'hot'
		}
	} else {
		// button is not hot, but it may be active    
	}
	ui_draw2d.DrawImage2GridH(themeButtonImage, x, y, x + w);
	ui_draw2d.DrawImage(image, x + w/2, y + h/2 + txOffset, 0xFFFFFFFF, ALIGN_HCENTER | ALIGN_VCENTER);

	int clicked = 0;
	// If button is hot and active, but mouse button is not
	// down, the user must have clicked the button.
	if (uistate.mousedown == 0 && 
		uistate.hotitem == id && 
		uistate.activeitem == id) {
			clicked = 1;
	}

	uistate.lastwidget = id;
	return clicked;
}


int UICheckBox(int id, int x, int y, const char *text, int align, bool *value) {
  const int h = 64;
	float tw, th;
	ui_draw2d.MeasureText(themeUIFont, text, &tw, &th);
	int w = themeAtlas->images[themeCheckOnImage].w + UI_SPACE + tw;
	if (align & ALIGN_HCENTER) x -= w / 2;
	if (align & ALIGN_VCENTER) y -= h / 2;
	if (align & ALIGN_RIGHT) x -= w;
	if (align & ALIGN_BOTTOMRIGHT) y -= h;

  // Check whether the button should be hot
  if (UIRegionHit(x, y, w, h, 8)) {
    uistate.hotitem = id;
    if (uistate.activeitem == 0 && uistate.mousedown)
      uistate.activeitem = id;
  }
    
  // Render button 

  int txOffset = 0;
  if (uistate.hotitem == id) {
    if (uistate.activeitem == id) {
      // Button is both 'hot' and 'active'
      txOffset = 2;
    } else {
      // Button is merely 'hot'
    }
  } else {
    // button is not hot, but it may be active    
  }

	ui_draw2d.DrawImage((*value) ? themeCheckOnImage : themeCheckOffImage, x, y+h/2, 1.0f, 0xFFFFFFFF, ALIGN_LEFT | ALIGN_VCENTER);
  ui_draw2d.DrawTextShadow(themeUIFont, text, x + themeAtlas->images[themeCheckOnImage].w + UI_SPACE, y + txOffset + h/2, 0xFFFFFFFF, ALIGN_LEFT | ALIGN_VCENTER);

	int clicked = 0;
  // If button is hot and active, but mouse button is not
  // down, the user must have clicked the button.
  if (uistate.mousedown == 0 && 
      uistate.hotitem == id && 
      uistate.activeitem == id) {
    *value = !(*value);
		clicked = 1;
  }

	uistate.lastwidget = id;
	return clicked;
}

void StringVectorListAdapter::drawItem(int item, int x, int y, int w, int h, bool selected) const
{
	ui_draw2d.DrawImage2GridH(themeButtonImage, x, y, x + w);
	ui_draw2d.DrawTextShadow(themeUIFont, (*items_)[item].c_str(), x + UI_SPACE , y, 0xFFFFFFFF, ALIGN_LEFT | ALIGN_VCENTER);
}

int UIList(int id, int x, int y, int w, int h, UIListAdapter *adapter, UIListState *state) {
  const int item_h = 64;
	
  // Check whether the button should be hot
  if (UIRegionHit(x, y, w, h, 0)) {
    uistate.hotitem = id;
    if (uistate.activeitem == 0 && uistate.mousedown)
      uistate.activeitem = id;
  }

	// render items
	int itemHeight = adapter->itemHeight(0);
	int numItems = adapter->getCount();
	for (int i = 0; i < numItems; i++) {
		int item_y = y + i * itemHeight - state->scrollY;
		if (uistate.mousedown && adapter->itemEnabled(i) && item_y >= y - itemHeight && item_y <= y + h && UIRegionHit(x, item_y, w, h, 0)) {
			// ultra fast touch response
			state->selected = i;
		}
		adapter->drawItem(i, x, item_y, w, itemHeight, i == state->selected);
	}

	int clicked = 0;

  // If button is hot and active, but mouse button is not
  // down, the user must have clicked the button.
  if (uistate.mousedown == 0 && 
      uistate.hotitem == id && 
      uistate.activeitem == id &&
			state->selected != -1) {
    clicked = 1;
  }

	uistate.lastwidget = id;

	// Otherwise, no clicky.
  return clicked;
}

/*
struct SlideItem {
	const char *text;
	int image;
	uint32_t bgColor;
};

struct SlideState 
{
	float scroll;

};

void UISlideChoice(int id, int y, const SlideItem *items, int numItems, SlideState *state)

}*/

// TODO
int UIHSlider(int id, int x, int y, int w, int max, int *value) {
  // Calculate mouse cursor's relative y offset
  int xpos = ((256 - 16) * *value) / max;

  // Check for hotness
  if (UIRegionHit(x+8, y+8, 16, 255, 0)) {
    uistate.hotitem = id;
    if (uistate.activeitem == 0 && uistate.mousedown)
      uistate.activeitem = id;
  }
  // Render the scrollbar
  ui_draw2d.Rect(x, y, 32, 256+16, 0x777777);
  
  if (uistate.activeitem == id || uistate.hotitem == id) {
    ui_draw2d.Rect(x+8+xpos, y+8, 16, 16, 0xffffff);
  } else {
    ui_draw2d.Rect(x+8+xpos, y+8, 16, 16, 0xaaaaaa);
  }

  // Update widget value
  if (uistate.activeitem == id) {
    int mousepos = uistate.mousey - (y + 8);
    if (mousepos < 0) mousepos = 0;
    if (mousepos > 255) mousepos = 255;
    int v = (mousepos * max) / 255;
    if (v != *value) {
      *value = v;
      return 1;
    }
  }
  
  return 0;
}

// TODO
int UIVSlider(int id, int x, int y, int h, int max, int *value) {
  // Calculate mouse cursor's relative y offset
  int ypos = ((256 - 16) * *value) / max;

  // Check for hotness
  if (UIRegionHit(x+8, y+8, 16, 255, 0)) {
    uistate.hotitem = id;
    if (uistate.activeitem == 0 && uistate.mousedown)
      uistate.activeitem = id;
  }
  // Render the scrollbar
  ui_draw2d.Rect(x, y, 32, 256+16, 0x777777);
  
  if (uistate.activeitem == id || uistate.hotitem == id) {
    ui_draw2d.Rect(x+8, y+8 + ypos, 16, 16, 0xffffff);
  } else {
    ui_draw2d.Rect(x+8, y+8 + ypos, 16, 16, 0xaaaaaa);
  }

  // Update widget value
  if (uistate.activeitem == id) {
    int mousepos = uistate.mousey - (y + 8);
    if (mousepos < 0) mousepos = 0;
    if (mousepos > 255) mousepos = 255;
    int v = (mousepos * max) / 255;
    if (v != *value) {
      *value = v;
      return 1;
    }
  }
  
  return 0;
}