local NULL = function () end

---@class BUTTON.button
---@field name string
---@field x number
---@field y number
---@field w number
---@field h number
---
---@field borderWidth? number
---@field borderJoin? "bevel"|"milter"|"none"
---@field borderStyle? "rough"|"smooth"
---
---@field font? love.Font
---
---@field codeWhenPressed?  function
---@field codeWhenReleased? function
---@field drawingTextFunc?  function
---
---@field _hovering? boolean
---
---@field draw? function
---@field update? function
local button = {
    name = "NEW BUTTON",
    x = 0, y = 0, w = 0, h = 0,

    backgroundColor = {0,0,0,0},
    hoverColor = {1,1,1,0.5},
    borderColor = {1,1,1},
    textColor = {1,1,1},

    font = love.graphics.newFont(15),

    borderWidth = 1,
    borderJoin = "none",
    borderStyle = "smooth",

    drawingBackgroundFunc = function(self)
        love.graphics.setLineWidth(self.borderWidth)
        love.graphics.setLineStyle(self.borderStyle)
        love.graphics.setLineJoin(self.borderJoin)

        love.graphics.setColor(unpack(self.backgroundColor))
        love.graphics.rectangle('fill', self.x, self.y, self.w, self.h)

        if self._hovering then
            love.graphics.setColor(unpack(self.hoverColor))
            love.graphics.rectangle('fill', self.x, self.y, self.w, self.h)
        end

        love.graphics.setColor(unpack(self.borderColor))
        love.graphics.rectangle('line', self.x, self.y, self.w, self.h)
    end,
    drawingTextFunc = function(self)
        love.graphics.setFont(self.font)
        love.graphics.printf(self.name, self.x, self.y + (self.h * 0.25), self.w, "center")
    end,
    codeWhenPressed  = NULL,
    codeWhenReleased = NULL,

    _hovering = false
}; button.__index = button
function button:draw()
    self:drawingBackgroundFunc()
    self:drawingTextFunc()
end
function button:isHovering(x,y)
    if
        x >= self.x and
        y >= self.y and
        x <= self.x + self.w and
        y <= self.y + self.h
    then
        self._hovering = true
    else
        self._hovering = false
    end
end
---@param touch? boolean @ If the button is touched, remember to pass true into touch param
function button:press(touch)
    if touch or self._hovering then
        self.codeWhenPressed()
    end
end
---@param touch? boolean @ If the button is touched, remember to pass true into touch param
function button:release(touch)
    if touch or self._hovering then
        self.codeWhenReleased()
    end
end


local BUTTON = {}

---@param D BUTTON.newData
---Validate the provided data, will be called by ``BUTTON.new`` and ``BUTTON.setDefaultOption``<br>
---***WARNING! THIS FUNCTION WILL RAISE EXCEPTION IF DATA IS INVALID!***
function BUTTON.checkDataValidation(D)
    assert(type(D.name) == "string", "[name] is missing or not valid")

    assert(type(D.x) == "number" and D.x > 0, "[x] must be a positive integer")
    assert(type(D.y) == "number" and D.y > 0, "[y] must be a positive integer")
    assert(type(D.w) == "number" and D.w > 0, "[w] must be a positive integer")
    assert(type(D.h) == "number" and D.h > 0, "[h] must be a positive integer")
    assert((type(D.borderWidth) == "number" and D.borderWidth > 0) or D.drawingTextFunc == nil, "[borderWidth] must be a postive integer")
    assert(table.contains({"bevel", "milter", "none"}, D.borderJoin) or D.borderJoin == nil, "[borderJoin] must be 'bevel', 'milter' or 'none")
    assert(table.contains({"rough", "smooth"}, D.borderStyle) or D.borderStyle == nil, "[borderStyle] must be 'rough' or 'smooth'")
    assert((D.font and D.font.typeOf and D.font:typeOf("Font")) or D.font == nil, "[font] must be love.Font")

    local red_flag = false
    if D.backgroundColor then
        if type(D.backgroundColor) == "table" then
            if #D.backgroundColor == 3 or #D.backgroundColor == 4 then
                for _, v in pairs(D.backgroundColor) do
                    if type(v) ~= "number" or v<0 or v>1 then red_flag = true end
                end
            else
                red_flag = true
            end
        else
            red_flag = true
        end
    end
    if red_flag then error("[backgroundColor] must be a table with r, g, b (, a) values, all of them must be integers between 0 and 1") end
    
    if D.hoverColor then
        if type(D.hoverColor) == "table" then
            if #D.hoverColor == 3 or #D.hoverColor == 4 then
                for _, v in pairs(D.hoverColor) do
                    if type(v) ~= "number" or v<0 or v>1 then red_flag = true end
                end
            else
                red_flag = true
            end
        else
            red_flag = true
        end
    end
    if red_flag then error("[hoverColor] must be a table with r, g, b (, a) values, all of them must be integers between 0 and 1") end

    if D.borderColor then
        if type(D.borderColor) == "table" then
            if #D.borderColor == 3 or #D.borderColor == 4 then
                for _, v in pairs(D.borderColor) do
                    if type(v) ~= "number" or v<0 or v>1 then red_flag = true end
                end
            else
                red_flag = true
            end
        else
            red_flag = true
        end
    end
    if red_flag then error("[borderColor] must be a table with r, g, b (, a) values, all of them must be integers between 0 and 1") end

    if D.textColor then
        if type(D.textColor) == "table" then
            if #D.textColor == 3 or #D.textColor == 4 then
                for _, v in pairs(D.textColor) do
                    if type(v) ~= "number" or v<0 or v>1 then red_flag = true end
                end
            else
                red_flag = true
            end
        else
            red_flag = true
        end
    end
    if red_flag then error("[textColor] must be a table with r, g, b (, a) values, all of them must be integers between 0 and 1") end

    assert(type(D.codeWhenPressed)  == "function" or D.codeWhenPressed  == nil, "[codeWhenPressed] must be a function or nil")
    assert(type(D.codeWhenReleased) == "function" or D.codeWhenReleased == nil, "[codeWhenReleased] must be a function or nil")
    assert(type(D.drawingTextFunc)  == "function" or D.drawingTextFunc  == nil, "[drawingTextFunc] must be a function or nil")
end


---@class BUTTON.newData
---@field name string # Name of the button, will be shown
---@field x number
---@field y number
---@field w number
---@field h number
---
---@field borderWidth? number|1 # Line width will be used to draw button
---@field borderJoin? "bevel"|"milter"|"none"
---@field borderStyle? "rough"|"smooth"
---
---@field font? love.Font
---
---@field backgroundColor? table<[r,g,b,a]>
---@field hoverColor? table<[r,g,b,a]>
---@field borderColor? table<[r,g,b,a]>
---@field textColor? table<[r,g,b,a]>
---
---@field codeWhenPressed? function|nil # Code will be execute when pressed
---@field codeWhenReleased? function|nil # Code will be execute when released
---@field drawingTextFunc? function|defaultDrawingTextFunc

---@param D BUTTON.newData
---@return BUTTON.button
---Create a new button, provide you a table with 2 functions inside: draw and update<br>
---You need to put them into intended callbacks :)
function BUTTON.new(D)
    BUTTON.checkDataValidation(D)
    return setmetatable({
        name = D.name,
        x = D.x,
        y = D.y,
        w = D.w,
        h = D.h,

        borderWidth = D.borderWidth,
        borderJoin = D.borderJoin,
        borderStyle = D.borderStyle,

        backgroundColor = D.backgroundColor,
        hoverColor = D.hoverColor,
        borderColor = D.borderColor,
        textColor = D.textColor,

        codeWhenPressed  = D.codeWhenPressed,
        codeWhenReleased = D.codeWhenReleased,
        drawingTextFunc  = D.drawingTextFunc,
    }, button)
end

--- Set the default funciton used to drawing text, will be passed name, x, y, w and h
function BUTTON.setDefaultDrawingTextFunction(f)
    assert(type(f) == "function", "[f] must be a function!")
    button.drawingTextFunc = f
end

---@param D BUTTON.newData
function BUTTON.setDefaultOption(D)
    BUTTON.checkDataValidation(D)
    for k, v in pairs(D) do
        if button[k] ~= nil then
            button[k] = v
        else
            error("There is no "..k.." parameter in BUTTON!")
        end
    end
end

return BUTTON