--Добавить сортировку по цветам
--Переменная библиотеки
local doubleBufferLib = {}
local component = require("component")
local gpu = component.gpu
--Символ пробела
local charSpace = ' '
local prevBuffer

doubleBufferLib.widthScreen, doubleBufferLib.heightScreen = gpu.getResolution()

--Очищает экран
doubleBufferLib.clearScreen = function()
    gpu.setForeground(0xffffff)
    gpu.setBackground(0x000000)
    gpu.fill(1, 1, doubleBufferLib.widthScreen, doubleBufferLib.heightScreen, charSpace)
end

--Копирует таблицу
doubleBufferLib.getCopyTable = function(table)
    local copyTable = {}
    for k, v in pairs(table) do
        copyTable[k] = v
    end
    return copyTable
end

--Вовзращает пустой буфер
local function setEmptyBuffer()
    local emptyBuffer = {}
    for i = 1, doubleBufferLib.heightScreen do
        for j = 1, doubleBufferLib.widthScreen do
            table.insert(emptyBuffer, charSpace)
            table.insert(emptyBuffer, 0xffffff)
            table.insert(emptyBuffer, 0x000000)
        end
    end
    return emptyBuffer
end

--Меняет цвет переднего фона
doubleBufferLib.setForeColor = function(color)
    if gpu.getForeground() == color then
        return false
    else
        gpu.setForeground(color)
        return true
    end
end

--Меняет цвет заднего фона
doubleBufferLib.setBackColor = function(color)
    if gpu.getBackground() == color then
        return false
    else
        gpu.setBackground(color)
        return true
    end
end

--Возвращает индекс пикселя в буфере по координатам, кол-ву переменных, принадлежащих 1 пикселю, и ширине буфера
doubleBufferLib.getIndexByCoords = function(x, y, numberItems, width)
    width = width or doubleBufferLib.widthScreen
    numberItems = numberItems or 1
    return (y * width - width + x) * numberItems - numberItems
end

--Функция сравнивает активный буфер экрана с заданным. Возвращает массив изменений
local function compareBuffer(buffer)
    local changedPix = {}
    local char, foreColor, backColor
    local curChar, curForeColor, curBackColor
    local index
    for i = 1, doubleBufferLib.heightScreen do
        for j = 1, doubleBufferLib.widthScreen do
            index = doubleBufferLib.getIndexByCoords(j, i, 3)
            char, foreColor, backColor = buffer[index + 1], buffer[index + 2], buffer[index + 3]
            curChar, curForeColor, curBackColor = prevBuffer[index + 1], prevBuffer[index + 2], prevBuffer[index + 3] -- gpu.get(j, i)
            if not(char == curChar and foreColor == curForeColor and backColor == curBackColor) then
                table.insert(changedPix, j)
                table.insert(changedPix, i)
                table.insert(changedPix, char)
                table.insert(changedPix, foreColor)
                table.insert(changedPix, backColor)
            end
        end
    end
    return changedPix
end

--Функция групирует пиксели по цвету
local function groupByColor(changedPix)
    if changedPix == nil then
        return
    end

    local colorArr = {} --Массив цветов и принадлежащих им пикселей

    local x, y, char
    local foreColor, backColor
    for i = 0, #changedPix - 1, 5 do
        x, y, char = changedPix[i + 1], changedPix[i + 2], changedPix[i + 3]
        foreColor, backColor = changedPix[i + 4], changedPix[i + 5]

        --Проверяет наличие пары переднего и заднего цвета
        if i == 0 then
            table.insert(colorArr, foreColor)
            table.insert(colorArr, backColor)
            table.insert(colorArr, {x, y, char})
        else
            local isColorExist = false
            for j = 0, #colorArr - 1, 3 do
                local curForeColor, curBackColor = colorArr[j + 1], colorArr[j + 2]
                if curForeColor == foreColor and curBackColor == backColor then
                    table.insert(colorArr[j + 3], x)
                    table.insert(colorArr[j + 3], y)
                    table.insert(colorArr[j + 3], char)
                    isColorExist = true
                    break
                end
            end

            if not(isColorExist) then
                table.insert(colorArr, foreColor)
                table.insert(colorArr, backColor)
                table.insert(colorArr, {x, y, char})
            end
        end
    end

    return colorArr
end

--Функция возвращает пустую строку указанной длины
local function isOneChar(str)
    if #str == 1 then
        return true
    end
    local isOneChar = false
    for i = 2, #str do
        if str:sub(i,i) == str:sub(i-1,i-1) then
            isOneChar = true
            break
        end
    end
    return isOneChar
end

--Группирует массив по строкам
local function groupByRow(colorArr)
    if colorArr == nil then
        return
    end

    local rowArr = {}
    local foreColor, backColor
    local pixArr
    for i = 0, #colorArr - 1, 3 do
        local sequenceArr = {}
        foreColor, backColor = colorArr[i + 1], colorArr[i + 2]
        table.insert(rowArr, foreColor)
        table.insert(rowArr, backColor)

        pixArr = colorArr[i + 3]

        local prevX, prevY
        local sequence
        for j = 0, #pixArr - 1, 3 do
            local curX, curY, curChar = pixArr[j + 1], pixArr[j + 2], pixArr[j + 3]
            if curX - 1 == prevX and curY == prevY then
                sequence[3] = curX
                sequence[5] = sequence[5] .. curChar

            else
                if sequence ~= nil then
                    table.insert(sequenceArr, sequence)
                end
                sequence = {}
                sequence[1], sequence[3] = curX, curX
                sequence[2], sequence[4] = curY, curY
                sequence[5] = curChar
            end
            --Последний или единтсвенный элемент в массиве
            if j + 3 == #pixArr then
                table.insert(sequenceArr, sequence)
            end

            prevX, prevY = curX, curY
        end

        --Групировка по Y
        if sequenceArr ~= nil then
            local delSequinceIndexArr = {}
            local prevSequence
            local countSequence = 0
            for j = 1, #sequenceArr do
                local curSequence = sequenceArr[j]
                local sequenceHeight = {}
                if prevSequence ~= nil then
                    if prevSequence[4] == curSequence[4] - 1 and prevSequence[5] == curSequence[5] then
                        countSequence = countSequence + 1
                        prevSequence[4] = curSequence[4]
                        prevSequence[2] = curSequence[4] - countSequence
                        sequenceArr[j] = prevSequence

                        table.insert(delSequinceIndexArr, j - 1)

                        prevSequence = curSequence
                    else
                        countSequence = 0
                        prevSequence = curSequence
                    end
                else
                    if isOneChar(curSequence[5]) then
                        prevSequence = curSequence
                        countSequence = 0
                    end
                end
            end

            if delSequinceIndexArr ~= nil then
                for j = #delSequinceIndexArr, 1, - 1 do
                    table.remove(sequenceArr, delSequinceIndexArr[j])
                end
            end
        end
        table.insert(rowArr, sequenceArr)
    end

    return rowArr
end

local function group(changedPix)
    local colorArr = groupByColor(changedPix)
    local rowArr = groupByRow(colorArr)

    return rowArr
end

--Отрисовывает указанный буфер
doubleBufferLib.draw = function(buffer)
    local changedPix = compareBuffer(buffer)
    local rowArr = group(changedPix)
    local colorOperation, drawOperation = 0, 0
    if rowArr == nil then
        return
    end

    for i = 0, #rowArr - 1, 3 do
        if doubleBufferLib.setForeColor(rowArr[i + 1]) then
            colorOperation = colorOperation + 1
        end
        if doubleBufferLib.setBackColor(rowArr[i + 2]) then
            colorOperation = colorOperation + 1
        end

        local sequenceArr = rowArr[i + 3]

        for j = 1, #sequenceArr do
            local sequence = sequenceArr[j]

            local x1, y1, x2, y2, str = sequence[1], sequence[2], sequence[3], sequence[4], sequence[5]
            --print(x1, y1, x2, y2)
            if y1 ~= y2 then
                local char = sequence[5]:sub(1, 1)
                local width, height = x2 - x1 + 1, y2 - y1 + 1
                gpu.fill(x1, y1, width, height, char)
            else
                gpu.set(x1, y1, str)
            end
            drawOperation = drawOperation + 1
        end
    end

    --print("DRAWNING -", drawOperation, "COLOR -", colorOperation)

    prevBuffer = doubleBufferLib.getCopyTable(buffer)
end

doubleBufferLib.getEmptyBuffer = function()
    return doubleBufferLib.getCopyTable(doubleBufferLib.emptyBuffer)
end

--Инициализация
local function init()
    doubleBufferLib.emptyBuffer = setEmptyBuffer()
    prevBuffer = doubleBufferLib.getCopyTable(doubleBufferLib.emptyBuffer)
end

init()

--Возвращает библиотеку
return doubleBufferLib