Missile Interceptor

-- Missile Interceptor by Saldor010
-- Patch #1
-- See the forum post below for more details
-- http://www.computercraft.info/forums2/index.php?/topic/28897-missile-interceptor/

local GAMEOVER = false
local GAMESTARTED = false
local args = {...}
local difficulty = tonumber(args[1])
if not difficulty then difficulty = 1 end
if difficulty < 1 or difficulty > 2 then difficulty = 1 end

if not fs.exists("cobalt") and not args[2] then
    term.setTextColor(colors.red)
    print("Cobalt could not be found on this machine. Cobalt is required to run this game.")
    term.setTextColor(colors.lime)
    print("To download cobalt, please press the Y key now.")
    term.setTextColor(colors.blue)
    print("If you already have cobalt, and we just can't find it, please supply the path as the second argument.")
    local ev,p1,p2,p3,p4,p5 = os.pullEvent("char")
    if string.lower(p1) == "y" then
        shell.run("pastebin","run","h5h4fm3t")
    else
        term.setTextColor(colors.red)
        print("Cancelled installation of Cobalt.")
    end
    error()
end

local cobalt = nil
if fs.exists("cobalt") then
    cobalt = dofile("cobalt")
elseif args[2] then
    cobalt = dofile(args[2])
end

local smokeGrid = {}
local smokeColors = {
    [4] = colors.yellow,
    [3] = colors.orange,
    [2] = colors.red,
    [1] = colors.gray,
}
local missileGrid = {}
local missileTimer = 1
local tick = 0

local points = 0

local function spawnMissile()
    local x = math.random(3,49)
    table.insert(missileGrid,{
        ["x"] = x,
        ["y"] = 1,
        ["speed"] = math.random(1)
    })
end

function cobalt.update( dt )
    if GAMESTARTED then
        if GAMEOVER then
            GAMEOVER = GAMEOVER - dt
            if GAMEOVER <= 0 then
                cobalt.exit()
            end
            return
        end
        missileTimer = missileTimer - dt
        tick = tick - dt

        if missileTimer <= 0 then
            spawnMissile()
            missileTimer = math.random(1,3)
        end

        if tick <= 0 then
            local toRemove = {}
            for k,v in pairs(smokeGrid) do
                v["ct"] = v["ct"] - 1
                if v["ct"] <= 0 then
                    toRemove[k] = true
                end
            end
            for k,v in pairs(toRemove) do
                table.remove(smokeGrid,k)
            end

            for k,v in pairs(missileGrid) do
                v["y"] = v["y"] + v["speed"]

                for i=1,v["speed"] do
                    table.insert(smokeGrid,{
                        ["x"] = v["x"],
                        ["y"] = v["y"]-i,
                        ["ct"] = 4
                    })
                end

                if v["y"] >= 19 then
                    GAMEOVER = 2
                    return
                end
            end

            tick = 0.2
        end
    end
end

function cobalt.draw()
    if GAMESTARTED then
        for k,v in pairs(missileGrid) do
            if v["speed"] == 2 then
                cobalt.graphics.print("V",v["x"],v["y"],colors.black,colors.red)
            else
                cobalt.graphics.print("V",v["x"],v["y"],colors.black,colors.white)
            end
        end

        for k,v in pairs(smokeGrid) do
            cobalt.graphics.print("@",v["x"],v["y"],colors.black,smokeColors[v["ct"]] or colors.gray)
        end

        if GAMEOVER then
            cobalt.graphics.center("GAME OVER",9,0,20,colors.black,colors.red)
            cobalt.graphics.center("Missiles Intercepted: "..points,11,0,50,colors.black,colors.gray)
            if difficulty == 1 then
                cobalt.graphics.center("On Easy Difficulty",12,0,50,colors.black,colors.yellow)
            else
                cobalt.graphics.center("On Hard Difficulty",12,0,50,colors.black,colors.red)
            end
        end

        local scoreDigit = 0
        if points and points > 0 then
        scoreDigit = tostring(points)
        scoreDigit = #scoreDigit-1
        end
        --cobalt.graphics.print(math.log(points),1,1,colors.black,colors.white)
        cobalt.graphics.print(points,51-scoreDigit,1,colors.black,colors.gray)
    else
        cobalt.graphics.center("MISSILE INTERCEPTOR",9,0,50,colors.black,colors.orange)
        if difficulty == 2 then
            cobalt.graphics.center("- = HARDCORE = -",10,0,50,colors.black,colors.red)
        end
        cobalt.graphics.center("Press any key to start",10+difficulty,0,50,colors.black,colors.gray)
    end
end

local function check(x,y,vx,vy)
    if difficulty == 1 then
        for i=-1,1 do
            for j=-1,1 do
                if vx == x+i and vy == y+j then return true end
            end
        end
        return false
    elseif difficulty == 2 then
        if vx == x and vy == y then return true else return false end
    end
end

function cobalt.mousepressed( x, y, button )
    if not GAMEOVER then
        local toRemove = {}
        for k,v in pairs(missileGrid) do
            if check(v["x"],v["y"],x,y) then
                points = points + 1
                toRemove[k] = true
                for i=-1,1 do
                    if true then --v["x"]+i >= 1 and v["x"]+i <= 51 then
                        for j=-1,1 do
                            if true then --v["y"]+j >= 1 and v["y"]+j <= 19 then
                                table.insert(smokeGrid,{
                                    ["x"] = v["x"]+i,
                                    ["y"] = v["y"]+j,
                                    ["ct"] = math.random(3,4)
                                })
                            end
                        end
                    end
                end
            end
        end
        for k,v in pairs(toRemove) do
            table.remove(missileGrid,k)
        end
    end
end

function cobalt.mousereleased( x, y, button )

end

function cobalt.keypressed( keycode, key )
    if not GAMESTARTED then GAMESTARTED = true end
end

function cobalt.keyreleased( keycode, key )

end

function cobalt.textinput( t )

end

cobalt.initLoop()