UI

local UDim2 = require("UDim2")
local Enum  = require("Enum")
local InputService = require("InputService")
local Signal = require("Signal")

local focusedTextbox = nil

local UI = {}

UI.__index = UI

UI.Windows = {}
UI.Focused = Signal.new()
UI.FocusLost = Signal.new()

function UI.new()
    local self = {
        Size = UDim2.fromOffset(0, 0),
        Position = UDim2.fromOffset(0, 0),
        AnchorPoint = {X = .5, Y = .5},
        TextXAlign = Enum.TextXAlign.Center,
        TextYAlign = Enum.TextYAlign.Center,
        Text = "",
        BackgroundColor = colors.white,
        TextColor = colors.black,

        TextEditable = false,
        MultiLine = false,

        Focused = Signal.new(),
        FocusLost = Signal.new(),

        Clicked = Signal.new()
    }

    return setmetatable(self, UI)
end

function UI:Init(optionalParent)
    if (self.Window) then
        printError("UI already initialized")
        return
    end

    local terminalSizeX, terminalSizeY = term.getSize()
    local sizeX = self.Size.X.Offset + terminalSizeX * self.Size.X.Scale
    local sizeY = self.Size.Y.Offset + terminalSizeY * self.Size.Y.Scale
    local positionX = (self.Position.X.Offset + terminalSizeX * self.Position.X.Scale) - sizeX * self.AnchorPoint.X
    local positionY = (self.Position.Y.Offset + terminalSizeY * self.Position.Y.Scale) - sizeY * self.AnchorPoint.Y

    local newUI = window.create(optionalParent or term.current(), positionX, positionY, sizeX, sizeY)
    UI.Windows[newUI] = self
    self.Window = newUI
    self:Update()
end

function UI:Update()
    if (not self) then
        return printError("Self not assigned")
    end
    if (not self.Window) then
        return printError("Missing Window")
    end

    local terminalSizeX, terminalSizeY = term.getSize()
    local sizeX = self.Size.X.Offset + (terminalSizeX + 1) * self.Size.X.Scale
    local sizeY = self.Size.Y.Offset + (terminalSizeY + 1) * self.Size.Y.Scale
    local positionX = (self.Position.X.Offset + terminalSizeX * self.Position.X.Scale) - sizeX * self.AnchorPoint.X
    local positionY = (self.Position.Y.Offset + terminalSizeY * self.Position.Y.Scale) - sizeY * self.AnchorPoint.Y

    self.Window.reposition(positionX, positionY, sizeX, sizeY)

    local cursorX = 0 do
        if (self.TextXAlign == Enum.TextXAlign.Center) then
            cursorX = (sizeX / 2) - (#self.Text / 2) + 1
        elseif (self.TextXAlign == Enum.TextXAlign.Right) then
            cursorX = sizeX - #self.Text
        end
    end
    local cursorY = 0 do
        if (self.TextYAlign == Enum.TextYAlign.Center) then
            cursorY = (sizeY / 2) + 1
        elseif (self.TextYAlign == Enum.TextYAlign.Botom) then
            cursorY = sizeY
        end
    end

    self.Window.setBackgroundColor(self.BackgroundColor)
    self.Window.setTextColor(self.TextColor)
    self.Window.clear()
    self.Window.setCursorPos(cursorX, cursorY)
    self.Window.write(self.Text)
end

function UI:CleanUp()
    self.Window.setVisible(false)
    self.Window.clear()
    UI.Windows[self.Window] = nil

    for _, signal in next, {UI.FocusLost, UI.Focused, UI.Clicked} do
        for _, c in next, signal.__Connections do
            c:Disconnect()
        end
    end

    for k in next, self do
        self[k] = nil
    end
end

function UI.UpdateAll()
    term.clear()
    for _, ui in next, UI.Windows do
        UI.Update(ui)
    end
end

local function appendCharacter(char)
    if (not focusedTextbox) then
        return
    end
    focusedTextbox.Text = focusedTextbox.Text .. char
    UI.Update(focusedTextbox)
end

InputService.MouseDown:Connect(function (mouseKey, X, Y)
    if (focusedTextbox) then
        UI.FocusLost:Fire(false)
        focusedTextbox = nil
        return
    end
    for uiWindow, ui in next, UI.Windows do
        local sizeX, sizeY = uiWindow.getSize()
        local positionX, positionY = uiWindow.getPosition()
        if (mouseKey == Enum.MouseButton.Left and X > positionX and X < positionX + sizeX and Y > positionY and Y < positionY + sizeY) then
            if (ui.TextEditable) then
                focusedTextbox = ui
                UI.Focused:Fire(ui)
                ui.Focused:Fire()
                uiWindow.setCursorBlink(true)
            else
                ui.Clicked:Fire(X, Y)
            end
            return
        end
    end
end)

InputService.Writing:Connect(appendCharacter)
InputService.Paste:Connect(appendCharacter)

InputService.KeyDown:Connect(function (keyCode)
    if (not focusedTextbox) then
        return
    end

    local key = keys.getName(keyCode)
    if (key == "enter") then
        if (focusedTextbox.MultiLine) then
            appendCharacter("\n")
        else
            UI.FocusLost:Fire(true)
            focusedTextbox = nil
            return
        end
    elseif (key == "backspace") then
        focusedTextbox.Text = string.sub(focusedTextbox.Text, 1, -2)
    end

    UI.Update(focusedTextbox)
end)

UI.FocusLost:Connect(function (enterPressed)
    if (not focusedTextbox or not focusedTextbox.Window) then
        return
    end
    focusedTextbox.Window.setCursorBlink(false)
    focusedTextbox.FocusLost:Fire(enterPressed)
end)

return UI