SudokuGen V3

----------------------------------------------MISC FUNCS
if fs.exists("console") then
    shell.run("delete console")
end


local debug = true
local h = fs.open("console","a")
function log(t)
    if debug then
  if type(t) == "table" then
    for i,v in pairs(t) do
      h.write("i = ")
      h.write(i)
      h.write(" v = ")
      h.write(v)
      h.write("\n")
    end

  else
    h.write(t)
    h.write("\n")
  end
  h.flush()
  end
end

function logBoard(board, currentPos, futurePos)
    if debug then
        for y = 1, 9 do
        term.setCursorPos(1, y + math.ceil(y/3) - 1)
            for x = 1, 9 do
                if tonumber(board[y][x]) then
                    term.setTextColor(colors.red)
                    write(board[y][x])
                else
                    term.setTextColor(colors.white)
                    write("0")
                end
                if x == 3 or x == 6 then
                    write(" ")
                end
            end
        end
        if currentPos then
            term.setTextColor(colors.orange)
            term.setCursorPos(currentPos[1] + math.floor((currentPos[1]-1)/3), currentPos[2] + math.floor((currentPos[2]-1)/3))
            term.write(board[currentPos[2]][currentPos[1]])
        end
        if futurePos then
            term.setTextColor(colors.lime)
            term.setCursorPos(futurePos[1] + math.floor((futurePos[1]-1)/3), currentPos[2] + math.floor((futurePos[2]-1)/3))
            term.write("*")
            os.pullEvent("mouse_click")
        end
        print("")
        sleep(.1)
    end
end

function printBoard(board, num)
    for y = 1, 9 do
    term.setCursorPos(1, y + math.ceil(y/3) - 1)
        for x = 1, 9 do
            if board[y][x][num] == 1 then
                term.setTextColor(colors.red)
                write(num)
            else
                term.setTextColor(colors.white)
                write("0")
            end
            if x == 3 or x == 6 then
                write(" ")
            end
        end
    end
    print("")
end

----------------------------------------------GENERATION
function initializeBoard(board)
    for y = 1, 9 do
        board[y] = {}
        for x = 1, 9 do
            board[y][x] = {1, 1, 1, 1, 1, 1, 1, 1, 1}
        end
    end
end

function generatePuzzle(board)
    log("-=-=-=-=-=-=-=-Starting Generation Algorithm-=-=-=-=-=-=-=-")
    for n = 1, 9 do
        log("Filling in " .. n .. " --------------")
        local scanRef = {1, 1, 1, 1, 1, 1, 1, 1, 1}
        for q = 1, 9 do
            log("Quadrant " .. q .. "...")
            scanRef = scanPatterns(board, n, scanRef)
            local cells = getAvailableCells(board, q, n)
            local c = cells[math.random(1, #cells)]
            isolateNumber(board, c[1], c[2], n)
            log("Quadrant " .. q .. " isolated>>")
        end
    end
    finalizeBoard(board)
end

function isolateNumber(board, x, y, num)
    for i = 1, 9 do
        board[i][x][num] = 0 --whole row
        board[y][i][num] = 0 --whole column
        board[(math.ceil(y/3)-1)*3+(i-1)%3+1][(math.ceil(x/3)-1)*3+(i-1)%3+1][num] = 0
                             --whole box (holy crap! what a line of code!)
    end
    for i = 1, 9 do
        board[y][x][i] = 0
    end
    board[y][x][num] = 1
end

function scanPatterns(board, num, refTab)
    local flag = true
    while flag do
        flag = false
        for i = 1, 9 do
            local cells = getAvailableCells(board, i, num)
            if #cells < 1 then
                --convertBoard(board)
                printBoard(board, num)
                error("ERROR: No avilable places for number " .. num .. " in quadrant " .. i)
            elseif #cells <= 3 and refTab[i] == 1 then
                if #cells == 1 then
                    isolateNumber(board, cells[1][1], cells[1][2], num)
                else
                    local rays = detectLine(cells)
                    for _, v in ipairs(rays) do
                        log("Row?: " .. tostring(v[1]) .. " Slice:" .. v[2] .. "  | Q" .. i)
                        eliminateLine(board, v[1], v[2], i, num)
                    end
                end
                refTab[i] = 0
                flag = true
                break;
            end
        end
    end
    return refTab
end

function getAvailableNum(board, quadrant, num)
    local cells = {}
    for i = 1, 3 do
        for j = 1, 3 do
            if board[(math.ceil(quadrant/3)-1)*3 + i][(quadrant-1)%3 + j][num] == 1 then
                table.insert(cells, {(quadrant-1)%3 + j, (math.ceil(quadrant/3)-1)*3 + i})
            end
        end
    end
    return cells
end

function detectLine(cells)
    local xList = {}
    local yList = {}
    for i, v in ipairs(cells) do
        table.insert(xList, v[1])
        table.insert(yList, v[2])
    end
    local rays = {}
    table.sort(xList)
    table.sort(yList)
    for i = 1, #xList-1 do
        if xList[i] == xList[i+1] then
            table.insert(rays, {true, xList[i]})
            break;
        end
    end
    for i = 1, #yList-1 do
        if yList[i] == yList[i+1] then
            table.insert(rays, {false, yList[i]})
            break;
        end
    end
    return rays
end

function eliminateLine(board, row, slice, homeQuadrant, num) --num: the current number
    --int[][][]board: the board, boolean row: whether it is a row or a column
    --int slice: row/col being altered, homeQuadrant: unnaffected quadrant
    if row then
        for i = 1, 9 do
            if math.ceil(i/3) ~= (homeQuadrant-1)%3 + 1 then
                board[slice][i][num] = 0
            end
        end
    else
        for i = 1, 9 do
            if math.ceil(i/3) ~= math.ceil(homeQuadrant/3) then
                board[i][slice][num] = 0
            end
        end
    end
end

function convertBoard(board)
    for y = 1, 9 do
        for x = 1, 9 do
            local num = 0
            for i = 1, 9 do
                if board[y][x][i] == 1 then
                    if num ~= 0 then
                        --error("ERROR: Multiple answers at " .. x .. ":" .. y)
                        board[y][x] = 0
                        break;
                    else
                        num = i
                    end
                end
            end
            if num == 0 then
                --error("ERROR: No answers at " .. x .. ":" .. y)
                board[y][x] = {}
            else
                board[y][x] = num
            end
        end
    end
end

function finalizeBoard(board)
    for y = 1, 9 do
        for x = 1, 9 do
            local num = 0
            for i = 1, 9 do
                if board[y][x][i] == 1 then
                    if num ~= 0 then
                        error("ERROR: Multiple answers at " .. x .. ":" .. y)
                    end
                    num = i
                end
            end
            if num == 0 then
                error("ERROR: No answers at " .. x .. ":" .. y)
            end
            board[y][x] = num
        end
    end
end

function getAvailableCells(board, quadrant, num)
    local result = {}
    for y = (math.ceil(quadrant/3)-1)*3 + 1, (math.ceil(quadrant/3)-1)*3 + 3 do
        for x = ((quadrant-1)%3)*3 + 1, ((quadrant-1)%3)*3 + 3 do
            if board[y][x][num] == 1 then
                table.insert(result, {x, y})
            end
        end
    end
    return result
end

function iLocate(i, quadrantX, quadrantY, board)
    for y =  1, 3 do
        for x = 1, 3 do
            if board[y + (quadrantY-1)*3][x + (quadrantX-1)*3] == i then
                return {x, y}, {x + (quadrantX-1)*3, y + (quadrantY-1)*3}
            end
        end
    end
    printBoard(board)
    error("iLocate Failed")
end
----------------------------------------------SOLUTION

----------------------------------------------ENGINE
local tArgs = {...}
term.setBackgroundColor(colors.black)
term.setTextColor(colors.white)
term.clear()

if tArgs[1] == "generate" or tArgs[1] == "gen" then
    local board = {}
    initializeBoard(board)
    generatePuzzle(board)
    printBoard(board)
elseif tArgs[1] == "solve" then

end