rain_minimal

--[[
    A minimal version of rain.
    For those who don't need all the fancy options.
]]

local component = require("component")
local event     = require("event")
local gpu = component.gpu

local wid, hig = gpu.getResolution()

local args = {...}
local ii = 1
for i=1,#args do
    if args[ii] == "-v" or args[ii] == "--version" then
        print("Rain (minimal) v1.0")
        print("By minater247")
        os.exit()
    elseif args[ii] == "-h" or args[ii] == "--help" then
        print("usage: rain_minimal [-v|--version] [-h|--help]")
        os.exit()
    else
        print("arg_error: unknown argument " .. args[ii])
        print("usage: rain_minimal [-v|--version] [-h|--help]")
        os.exit()
    end
    ii = ii + 1
end



local function genchars(len)
    local str = ""
    for i=1, len do
        local s = string.char(math.random(32, 126))
        if s == " " then
            s = "&"
        end
        str = str .. s
    end
    return str
end
local charset = genchars(1000)
local charsetlen = 1000
local currchar = 1


local Drops = {}
local function createDrop()
    local drop = {}
    drop.x = math.random(1, wid)
    if math.random() < 0.33 then
        drop.y = math.random(1, math.floor(hig / 2))
    else
        drop.y = 1
    end
    drop.char = charset:sub(currchar, currchar)
    currchar = currchar + 1
    if currchar > charsetlen then
        currchar = 1
    end
    table.insert(Drops, drop)
end

local function moveDropsDown()
    for i, drop in ipairs(Drops) do
        drop.y = drop.y + 1
        if drop.y > hig then
            table.remove(Drops, i)
        end
    end
end

local Screen = {}
for y=1, hig do
    Screen[y] = {}
    for x=1, wid do
        Screen[y][x] = 0
    end
end

local emptyScreen = Screen
local drawableScreen = Screen

local function subtractOne()
    for y=1, hig do
        for x=1, wid do
            if Screen[y][x] > 0 then
                Screen[y][x] = Screen[y][x] - 1
            end
        end
    end
end

local screencolors = {
    0x000000,
    0x002400,
    0x004900,
    0x006d00,
    0x009200,
    0x00b600,
    0x00db00,
    0x00ff00
}

local function drawScreen()
    gpu.setBackground(0x000000)
    for y=1, hig do
        for x=1, wid do
            if Screen[y][x] > 0 then
                if Screen[y][x] > #screencolors then
                    gpu.setForeground(screencolors[#screencolors])
                else
                    gpu.setForeground(screencolors[Screen[y][x]])
                end
                gpu.set(x, y, charset:sub(currchar, currchar))
                currchar = currchar + 1
            else
                gpu.set(x, y, " ")
            end
        end
    end
end


local function addDropsToScreen()
    for i, drop in ipairs(Drops) do
        Screen[drop.y][drop.x] = math.random(4, math.floor(hig / 2))
    end
end

local function drawDrops()
    gpu.setForeground(0xFFFFFF)
    for i, drop in ipairs(Drops) do
        gpu.set(drop.x, drop.y, drop.char)
    end
end

local iter = 0
while true do
    moveDropsDown()
    subtractOne()
    if #Drops < 50 then
        createDrop()
    end
    addDropsToScreen()
    drawScreen()
    drawDrops()
    local ev = event.pull(0.035, "key_down")
    if ev then
        gpu.fill(1, 1, wid, hig, " ")
        io.write("\x1b[1;1H") --terminal escape to 1,1
        break
    end
    iter = iter + 1
end