--[[
    fire effect
    code by GopherAtl, 2013

    No rights reserved, DWYW.
    --]]

    local w,h=term.getSize()

    local dithers={
     " ",
     ".",
     "-",
     "+",
     "%",
     "*",
     "#",
     "@",
    }


    local ranges= {
      { colors.black, colors.gray, },
      { colors.gray, colors.red, },
      { colors.red, colors.orange, },
      { colors.orange, colors.yellow, },
    }

    local coolWeight=75

    if not term.isColor() then
      ranges={
        { colors.black,colors.white },
      }
      coolWeight=25
    end

    local numDithers=(#dithers*2-1)
    local max_bright=#ranges*numDithers


    function genShaded(brightness)
      --break into color group
      local bgColor=colors.black
      local fgColor=colors.black
      local char=" "

      if brightness>=max_bright then
        bgColor=ranges[#ranges][2]
        fgColor=ranges[#ranges][1]
      else
        local dither=brightness%numDithers
        local range=(brightness-dither)/numDithers
        local inv=false
        bgColor=ranges[range+1][1]
        fgColor=ranges[range+1][2]
        if dither>=#dithers then
          dither=2*#dithers-dither-1
          local t=bgColor
          bgColor=fgColor
          fgColor=t
        end
        char=dithers[dither+1]
      end

      --[[term.setBackgroundColor(bgColor)
      term.setTextColor(fgColor)
      term.write(char)--]]
      return bgColor,fgColor,char
    end

    local precalc_shade={}

    for i=0,max_bright do
      precalc_shade[i]={genShaded(i)}
    end

    dither=false

    function drawShaded(bright)
      bright=math.floor(bright+.5)
      if bright>max_bright then
        bright=max_bright
      elseif bright<0 then
        bright=0
      end
      local shading=precalc_shade[bright]
      if shading==nil then
        error("brightness "..bright.." invalid!")
      end
      term.setBackgroundColor(shading[1])
      term.setTextColor(shading[2])
      term.write(dither and shading[3] or " ")
    end

    local grid, gridB={},{}

    for y=1,h+1 do
      grid[y]={}
      gridB[y]={}
      for x=1,w do
        grid[y][x]=0
      end
    end

    local coolingGrid={}

    for y=1,h*4 do
      coolingGrid[y]={}
      for x=1,w*2 do
        coolingGrid[y][x]=0
      end
    end

    function smooth(grid)
      for y=0,(h*4-1) do
        local up=(y-1)%(h*4)+1
        local down=(y+1)%(h*4)+1
        for x=0,(w*2-1) do
          local left=(x-1)%(w*2)+1
          local right=(x+1)%(w*2)+1
          grid[y+1][x+1]=(grid[y+1][left]+grid[y+1][right]+grid[up][x+1]+grid[down][x+1])/4
        end
      end
    end

    for i=1,1.6*w*h do
      coolingGrid[math.random(1,h*4)][math.random(1,w*2)]=coolWeight
    end

    for i=1,5 do
      smooth(coolingGrid)
    end

    coolingOffsetY=0
    coolingOffsetX=0


    function smoothFlame(grid)
      for y=1,h do
        local up=math.max(0,y-1)+1
        local down=math.min((h-1),(y+1))+1
        for x=0,(w-1) do
          local left=(x-1)%w+1
          local right=(x+1)%w+1
          grid[y][x+1]=(grid[y+1][left]+grid[y+1][right]+grid[up][x+1]+grid[down][x+1])/4-coolingGrid[math.floor((y-1+coolingOffsetY)%(h*4))+1][math.floor((x+coolingOffsetX)%(w*2))+1]
        end
      end
    end

    function draw()
      for y=1,h do
        for x=1,w do
          term.setCursorPos(x,y)
          drawShaded(grid[y][x]/2)
        end
      end
    end




    for x=1,w do
      grid[h+1][x]=max_bright*2
    end

    for i=1,w do
      local x=math.random(1,w)
      grid[h+1][x]=max_bright*3
    end

    for i=1,h+1 do
      smoothFlame(grid)
    end


    local tick=os.startTimer(0)
    while true do
      local e={os.pullEvent()}
      if e[1]=="timer" then
        draw()
        smoothFlame(grid)
        for i=1,1 do
          grid[h+1][math.random(1,w)]=max_bright*3
        end
        coolingOffsetY=(coolingOffsetY+1)%(h*4)
        coolingOffsetX=(coolingOffsetX+math.random(-2,3)/2)%(w*2)
        tick=os.startTimer(0)
      elseif e[1]=="char" then
        local ch=e[2]:lower()
        if ch=="d" then
          dither=not dither
        elseif ch=="q" then
          break
        end
      elseif e[1]=="monitor_touch" then
        shell.run("rename <startup> <startup1>")
        shell.run("rename <startup2> <startup>")
		shell.run("reboot")
      end
    end