-- Alien Text Generator
-- Save as main.lua, run with Love2D
-- First it show you the alphabet
-- Then press any key to get a page of filled-up random alien text
-- Then press any key twice more to get a page of random alien text with spacing

local CharParams={Width=3,Height=4}
local CharSheets={}
local Space={}

local State=0
local Matrix={}

--
--  ^
--  |        ^
--  |  j,v,y |
--  |
--  |    #
--  |   # #
--  |   ###
--  |   # #
--  |          i,u,x ->
--  +-------------------->
--

local xor = function(a,b) return (a and not b) or (b and not a) end

local function Shuffle(list)
    for k=#list,1,-1 do
        list[#list]=table.remove(list,math.random(k))
    end
end

local function isCharCorrect(c,u,v)

    -- Forbids 2x2 blobs of pixels
    for i=2,u do
        for j=2,v do
            if c[i][j] and c[i][j-1] and c[i-1][j] and c[i-1][j-1] then
                return false
            end
        end
    end

    -- Must have a pixel on the bottom
    local hasPixel=false
    for i=1,u do
        if c[i][1] then
            hasPixel=true
        end
    end
    if not hasPixel then
        return false
    end

    -- Must be centered
    for i=1,math.floor(u/2) do
        local hasPixel=false
        for j=1,v do
            if c[i][j] then
                hasPixel=true
            end
        end
        if hasPixel then
            hasPixel=false
            for j=1,v do
                if c[u-i][j] or c[u-i+1][j] then
                    hasPixel=true
                end
            end
            if not hasPixel then
                return false
            end
        else
            for j=1,v do
                if c[u-i+1][j] then
                    return false
                end
            end
        end
    end

    -- Must not have disjoint pixels
    local d={}
    local k=1
    for i=1,u do
        d[i]={}
        for j=1,v do
            if c[i][j] then
                d[i][j]=k
                k=k+1
            end
        end
    end
    local retry=true
    while retry do
        retry=false
        local merges={}
        for i=1,u do
            for j=1,v do
                if d[i][j] then
                    for x=math.max(1,i-1),math.min(u,i+1) do
                        for y=math.max(1,j-1),math.min(v,j+1) do
                            if d[x][y] and not (d[x][y]==d[i][j]) then
                                d[x][y]=math.min(d[x][y],d[i][j])
                                d[i][j]=d[x][y]
                                retry=true
                            end
                        end
                    end
                end
            end
        end
    end
    local n=0
    for i=1,u do
        for j=1,v do
            n=math.max(n,d[i][j] or n)
        end
    end
    if not (n==1) then
        return false
    end

    return true
end

local function MakeCharSheets(u,v)
    Space={}
    for i=1,u do
        Space[i]={}
    end
    local s={}
    local b={}
    for n=1,2^(u*v) do
        local r=false
        for k=1,u*v do
            if b[k] then
                b[k]=not b[k]
            else
                b[k]=true
                break
            end
        end
        local c={}
        for i=1,u do
            c[i]={}
            for j=1,v do
                c[i][j]=b[i+u*v-u*j]
            end
        end
        if isCharCorrect(c,u,v) then
            table.insert(s,c)
        end
    end
    return s
end

function love.load()
    love.graphics.setCaption("Alien Letters")
    love.graphics.setMode(512,768)
    love.graphics.setBlendMode("alpha")
    love.graphics.setBackgroundColor(0,0,0)
    love.graphics.setColor(32,255,32,255)
    Font12 = love.graphics.newFont(12)
    Font24 = love.graphics.newFont(24)
    Font48 = love.graphics.newFont(48)
    love.graphics.setFont(Font12)
    CharSheets=MakeCharSheets(CharParams.Width,CharParams.Height)
    --love.mouse.setVisible(false) -- make default mouse invisible
    --love.mouse.setGrab(true)
    State=0
end


local function DrawText(text,x,y)
    love.graphics.print(text,x,love.graphics.getHeight()-y-12)
end

local function DrawPoint(x,y)
    love.graphics.point(0.5+x,0.5+love.graphics.getHeight()-y)
end

local function DrawCharOverRec(c,x,y)
    for i=1,CharParams.Width do
        for j=1,CharParams.Height do
            if c[i][j] then
                love.graphics.setColor(32,255,32,255)
            else
                love.graphics.setColor(96,32,32,255)
            end
            DrawPoint(x+2*i-1,y+2*j-1)
            DrawPoint(x+2*i-1,y+2*j-2)
            DrawPoint(x+2*i-2,y+2*j-1)
            DrawPoint(x+2*i-2,y+2*j-2)
        end
    end
end

local function DrawChar(c,x,y)
    for i=1,CharParams.Width do
        for j=1,CharParams.Height do
            if c[i][j] then
                DrawPoint(x+2*i-1,y+2*j-1)
                DrawPoint(x+2*i-1,y+2*j-2)
                DrawPoint(x+2*i-2,y+2*j-1)
                DrawPoint(x+2*i-2,y+2*j-2)
            end
        end
    end
end

function love.draw()
    love.graphics.setColor(32,255,32,255)
    ;(({[0]=function()
        local k=1
        for y=love.graphics.getHeight()-20,16,-2*(CharParams.Height+1) do
            for x=8,love.graphics.getWidth()-16,2*(CharParams.Width+1) do
                if CharSheets[k] then
                    DrawCharOverRec(CharSheets[k],x,y)
                end
                k=k+1
            end
        end
    end,
    [2]=function()
        local k=0
        for y=love.graphics.getHeight()-20,16,-2*(CharParams.Height+1) do
            for x=8,love.graphics.getWidth()-16,2*(CharParams.Width+1) do
                k=k+1
                if not Matrix[k] then
                    Matrix[k]=CharSheets[math.random(1,#CharSheets)]
                end
                if Matrix[k]=="\n" then
                    break
                end
                DrawChar(Matrix[k],x,y)
            end
        end
    end
    })[State]or(function() end))()
end

function love.keypressed(key,unicode)
    if key=="escape" then
        if love.event.quit then
            love.event.quit() -- 0.8.0
        else
            love.event.push('q') -- 0.7.2
        end
    end
    State=State+1
    if State>=1 then
        if Matrix["2"]==2 then
            for k=1,#CharSheets*12/100 do
                table.insert(CharSheets,Space)
            end
            for k=1,#CharSheets*12/1000 do
                table.insert(CharSheets,"\n")
            end
        end
        Shuffle(CharSheets)
        Matrix={["2"]=(Matrix["2"] or 0)+1}
        State=2
    end
end



function love.update(dt)
    if love.event.quit then
        love.timer.sleep(0.030) -- 0.8.0
    else
        love.timer.sleep(30) -- 0.7.2
    end
    if #(Matrix or {})>1 then
        Matrix[math.random(1,#Matrix)]=CharSheets[math.random(1,#CharSheets)]
    end
end