os.loadAPI("class")

-- Screen
screen = class.class(function(self, monitor)
            self.monitor = monitor
            self.drawables = {}
            self.clickables = {}
        end)

function screen:addDrawable(component)
    if component == nil then
        print("[Screen] Not adding nil drawable.")
        return self
    end
    local i = #self.drawables + 1
    self.drawables[i] = component

    return self
end

function screen:addClickable(component)
    if component == nil then
        print("[Screen] Not adding nil clickable.")
        return self
    end
    local i = #self.clickables + 1
    self.clickables[i] = component

    return self
end

function screen:addControl(component)
    self:addDrawable(component)
    self:addClickable(component)
end

function screen:handleClickEvent(x, y)
    local arrLength = #self.clickables
    local handled = false
    for i=1, arrLength do
        handled = self.clickables[i]:handleClickEvent(x, y)
        if handled then
            break
        end
    end

    return handled
end

function screen:draw()
    local arrLength = #self.drawables
    for i=1, arrLength do
        self.drawables[i]:draw(self.monitor)
    end
end

-- Program
program = class.class(function(self)
            self.screen = nil
        end)

function program:screen()
    return self.screen
end

function program:setScreen(value)
    self.screen = value
    return self
end

function program:draw()
    mon.clear()
    if self.screen ~= nil then
        self.screen:draw()
    end
end
function program:waitEvent()
    local e,side,x,y = os.pullEvent("monitor_touch")
    local handled = false
    if self.screen ~= nil then
        handled = self.screen:handleClickEvent(x,y)
    end
    if not handled then
        print(string.format("[Program] Unhandled click event at %d, %d", x, y))
    end
end

-- Button
button = class.class(function(self, text, clickEvent, tag)
            self.text = text
            self.x = 0
            self.y = 0
            self.width = 1
            self.height = 1
            self.paddedText = text
            self.emptyRow = ""
            self.tag = tag
            self.clickEvent = clickEvent
            self.isDisabled = false
        end)

function button:pos()
    local t = {}
    t.x = self.x
    t.y = self.y
    return t
end

function button:tag()
    return self.tag
end

function button:setTag(value)
    self.tag = value
end

function button:isDisabled()
    return self.isDisabled
end

function button:setIsDisabled(value)
    self.isDisabled = value
    return self
end

function button:handleClickEvent(x, y)
    local hitX = x >= self.x and x <= self.x + self.width
    local hitY = y >= self.y and y <= self.y + self.height
    if hitX and hitY then
        print(string.format("[Button] Button with name %q at position %d, %d was clicked!", self.text, self.x, self.y))
        if self.isDisabled == false and self.clickEvent ~= nil then
            local data = {}
            data.x = x
            data.y = y
            self.clickEvent(self, data)
        end
        return true
    end

    return false
end

function button:text()
    return self.text
end

function button:setText(text)
    self.text = text
    self:updateTextData()
    return self
end

function button:setPos(x, y)
    self.x = x
    self.y = y
    return self
end

function button:updateTextData()
    local missingLength = self.width - string.len(self.text);
    if missingLength < 0 then
        self.paddedText = self.text
        print("[Button] Error, text too big for button")
    else
        local beg = math.floor(missingLength / 2)
        self.paddedText = string.rep(" ", beg) .. self.text .. string.rep(" ", missingLength - beg)
    end
    if self.height > 1 then
        self.emptyRow = string.rep(" ", self.width)
    end
end

function button:setSize(width, height)
    if width < 1 or height < 1 then
        print("[Button] Error, invalid size")
        return self;
    end
    self.width = width
    self.height = height

    self:updateTextData()

    return self
end

function button:draw(mon)
    if self.isDisabled then
        mon.setBackgroundColor(colors.gray)
        mon.setTextColor(colors.lightGray)
    else
        mon.setBackgroundColor(colors.red)
        mon.setTextColor(colors.white)
    end
    local yText = math.floor(self.height / 2 + self.y)

    for y = self.y, self.y+self.height-1 do
        mon.setCursorPos(self.x, y)
        if y == yText then
            mon.write(self.paddedText)
        else
            mon.write(self.emptyRow)
        end
    end

    return self
end