local field = {}
local cX,cY = 1,1
local width,height,mines
local running = true
local cursorSwap = true
local updateTimer

local function getField(x,y)
    if field[x] == nil then field[x] = {} end
    if field[x][y] == nil then field[x][y] = { fType = "unknown", x=x, y=y } end
    return field[x][y]
end

local function getNum(cField)
    if not cField.x or not cField.y then return " " end
    local nums = 0
    for dX=-1,1,1 do
        for dY=-1,1,1 do
            if dX ~= 0 or dY ~= 0 then
                if field[cField.x+dX] and field[cField.x+dX][cField.y+dY] then
                    if field[cField.x+dX][cField.y+dY].mine then
                        nums=nums+1
                    end
                end
            end
        end
    end
    return (nums==0 and " " or string.format("%d",nums))
end

local function getChar(field)
    if field == nil then field = { fType = "unknown" } end
    local tab = { flag="F", unknown="#", openMine = "X" }
    if field.fType == "open" then
        return getNum(field)
    else
        return tab[field.fType]
    end
end

local function readNum(min,max,intOnly)
    local tX,tY = term.getCursorPos()

    while true do
        term.setCursorPos(tX,tY)
        term.clearLine()

        local inp = tonumber(read())
        if inp and (intOnly == false or (math.abs(inp)==inp)) then
            if (min == nil or inp >= min) and (max == nil or inp <= max) then
                return inp
            end
        end

    end
end

local function putMine(x,y)
    local field = getField(x,y)
    if field.mine == true then return false end
    field.mine = true
    return true
end

local function drawSpace(x,y)
    term.setCursorPos(x,y)
    if field[x] and field[x][y] then
        term.write(getChar(getField(x,y)))
    else
        term.write(getChar(nil))
    end
end

local function drawField()
    term.clear()
    for x=1,width,1 do
        for y=1,height,1 do
            drawSpace(x,y)
        end
    end
end

term.clear()
term.setCursorPos(1,1)
print("Width of field?")
width = readNum(1,30,true)
print("Height of field?")
height = readNum(1,30,true)
print("Number of mines?")
mines = readNum(1,width*height,true)
term.setCursorBlink(false)

do
    local minesPut = 0
    while minesPut < mines do
        if putMine(math.random(1,width),math.random(1,height)) then
            minesPut = minesPut + 1
        end
    end
end

local function updateCursor()
    cursorSwap = not cursorSwap
    if cursorSwap then
        term.setCursorPos(cX,cY)
        term.write("|")
    else
        drawSpace(cX,cY)
    end
    updateTimer = os.startTimer(0.3)
end

local function moveCursor(nX,nY)
    nX = math.min(width,math.max(1,nX))
    nY = math.min(height,math.max(1,nY))
    drawSpace(cX,cY)
    cX,cY = nX,nY
    cursorSwap = false
    updateCursor()
end

local function sweep(originField)
    local sweepList = { originField }
    local function sweepCheck(x,y)
        if x >= 1 and x <= width and y >= 1 and y <= height then
            local pField = getField(x,y)
            if pField.fType == "unknown" then
                pField.fType = "open"
                if getNum(pField) == " " then
                    table.insert(sweepList,pField)
                end
            end
        end
    end
    while #sweepList > 0 do
        local sweepField = table.remove(sweepList,1)
        for dX=-1,1,1 do
            for dY=-1,1,1 do
                if dX ~= 0 or dY ~= 0 then
                    sweepCheck(sweepField.x+dX,sweepField.y+dY)
                end
            end
        end
    end
    drawField()
end

local function drawMines()
    for x=1,width,1 do
        for y=1,height,1 do
            if field[x] and field[x][y] then
                local fld = getField(x,y)
                if fld.mine then
                    fld.fType = "openMine"
                end
            end
        end
    end
end

local function checkWin()
    for x=1,width,1 do
        for y=1,height,1 do
            if not field[x] or not field[x][y] or (field[x][y].fType == "unknown" and field[x][y].mine == false) then
                return false
            end
        end
    end
    return true
end

drawField()
updateTimer = os.startTimer(0.3)
while running do
    local evData = {os.pullEvent()}

    if evData[1] == "timer" and evData[2] == updateTimer then
        updateCursor()
    elseif evData[1] == "key" then
        if evData[2] == keys.f4 then
            running = false
        elseif evData[2] == keys.left then
            moveCursor(cX-1,cY)
        elseif evData[2] == keys.right then
            moveCursor(cX+1,cY)
        elseif evData[2] == keys.down then
            moveCursor(cX,cY+1)
        elseif evData[2] == keys.up then
            moveCursor(cX,cY-1)
        elseif evData[2] == keys.f then
            local field = getField(cX,cY)
            if field.fType == "unknown" then
                field.fType = "flag"
            elseif field.fType == "flag" then
                field.fType = "unkown"
            end
            cursorSwap = true
            updateCursor()
        elseif evData[2] == keys.enter then
            local field = getField(cX,cY)
            if field.fType == "unknown" or field.fType == "flag" then
                if field.mine then
                    drawMines()
                    drawField()
                    print("GAME OVER")
                    sleep(5)
                    running = false
                else
                    field.fType = "open"
                    if getNum(field) == " " then
                        sweep(field)
                    end
                    if checkWin() then
                        drawField()
                        print("YOU WON")
                        sleep(5)
                        running = false
                    end
                end
            end
        end
    end
end

term.clear()
term.setCursorPos(1,1)
term.setCursorBlink(true)