#include "ui_defs.lua"
#include "script/common.lua"
#include "ui_object.lua"

function Ui.ScrollableArea(obj)
	local area = Ui.Object:new
	{
		navId = "",

		contentW = 100,
		contentH = 100,

		scrollbarOffset = 5,

		scrollBar = 
		{
			drag = false,
			dragPos = 0,
			delta = 0,
			deltaLerp = 0,
			lerpStartTime = 0,
			lerping = false,

			visibleSize = 100,
			contentSize = 100,
			isShown = false,

			thumbView =
			{
				w = 8,
		    	h = 100,

			    draw = function(self)
			        UiPush()
			            UiTranslate(2, 2)
			            UiColor(1, 1, 1, 1)
			            UiImageBox("common/rect_c#ffffff_o1.00_cr3.png", self.w, self.h, 3, 3)
			        UiPop()
			    end
			},

			bgView = 
			{
				w = 12,
		    	h = 100,

			    draw = function(self)
			        UiPush()
			            UiColor(1, 1, 1, 1)
			            UiImageBox("common/rect_c#525252_o1.00_cr4.png", self.w, self.h, 4, 4)
			        UiPop()
			    end
			},

			draw = function(self)
				if not self.isShown then
					return
				end

				UiPush()
					UiColorFilter(1,1,1,0.5)

					self.bgView:draw()

					UiTranslate(0, self.deltaLerp)

					if not UiIsMouseInRect(self.thumbView.w, self.thumbView.h) and not self.drag then
						UiColorFilter(0.5, 0.5, 0.5, 1)
					elseif not self.drag then
					 	UiColorFilter(0.7, 0.7, 0.7, 1)
					end

					self.thumbView:draw()
				UiPop()
			end,

			update = function(self, visibleSize, contentSize)
                contentSize = isNan(contentSize) and 0 or contentSize

				self.visibleSize = visibleSize
				self.contentSize = contentSize
				self.isShown = contentSize > visibleSize

				if not self.isShown then
					return
				end

                self.bgView.h = visibleSize
                self.thumbView.h = self.bgView.h * visibleSize / contentSize

				self.deltaLerp = lerp(self.deltaLerp, self.delta, (GetTime() - self.lerpStartTime) * 5)
				if self.deltaLerp == self.delta and self.lerping then
					self.lerping = false
				end

                UiPush() 
					UiTranslate(0, self.deltaLerp)

					if InputPressed("lmb") and UiIsMouseInRect(self.thumbView.w, self.thumbView.h) then
						self.drag = true
						_, self.dragPos = UiGetMousePos()
					elseif self.drag and InputDown("lmb") then
						local _, my = UiGetMousePos()
						self.delta = self.delta + my - self.dragPos
						self.delta = clamp(self.delta, 0, self.bgView.h - self.thumbView.h)
						self.deltaLerp = self.delta
					elseif InputReleased("lmb") then
						self.drag = false
					end
				UiPop()

                self.deltaLerp = clamp(self.deltaLerp, 0, (self.bgView.h - self.thumbView.h))
			end,

			getOffset = function(self)
				if self.isShown then
					return -(self.contentSize - self.visibleSize) * self.deltaLerp / (self.bgView.h - self.thumbView.h)
				else
					return 0
				end
			end,

			addOffset = function(self, offset, noLerp)
				if not self.isShown or offset == 0 then
					return
				end

				self.delta = self.delta - offset * (self.bgView.h - self.thumbView.h) / (self.contentSize - self.visibleSize)
				self.delta = clamp(self.delta, 0, (self.bgView.h - self.thumbView.h))
				
				if noLerp then
					self.deltaLerp = self.delta
				else
					self.lerpStartTime = GetTime()
					self.lerping = true
				end
			end,

			getRelativeOffset = function(self)
				return self.deltaLerp / (self.bgView.h - self.thumbView.h)
			end,

			reset = function(self)
				self.delta = 0
				self.deltaLerp = 0
			end
		},

		draw = function(self)
			UiFrameOccupy(self.w, self.h)
			UiFrameSkipItem(true)

			UiPush()
				UiClipRect(self.w, self.h, true)

				if UiIsMouseInRect(self.w, self.h) then
					local mouseScroll = InputValue("mousewheel") * 20
					self.scrollBar:addOffset(mouseScroll, self.h, self.contentH)
				end

				self.navId = UiNavComponent(self.w, self.h)

				if UiIsComponentInFocus(self.navId) then
					local gamepadScroll = (InputValue("menu_up") - InputValue("menu_down")) * 500 * GetTimeStep()
					self.scrollBar:addOffset(gamepadScroll, self.h, self.contentH)
				end

				UiTranslate(0, self.scrollBar:getOffset())
				UiBeginFrame()
				self.children[1]:draw()

				local sx,sy = UiGetScale()
				local cw, ch = UiEndFrame()

				self.contentW, self.contentH = cw / sx , ch / sy
			UiPop()
			UiPush()
				UiTranslate(self.w + self.scrollbarOffset, 0)
				self.scrollBar:update(self.h, self.contentH)
				self.scrollBar:draw()
			UiPop()

			UiFrameSkipItem(false)
		end
	}

	return area:new(obj)
end