-- Helper function to perform smooth color transitions
local function smoothTransition(colorSequence, delay)
    for _, color in ipairs(colorSequence) do
        term.setBackgroundColor(color)
        term.clear()
        sleep(delay)
    end
end

-- Intro Transition: Fade from white to black
local function introTransition()
    local fadeColors = {
        colors.white, colors.lightGray, colors.gray, colors.darkGray, colors.black
    }
    smoothTransition(fadeColors, 0.1)
end

-- Outro Transition: Fade from black to white
local function outroTransition()
    local fadeColors = {
        colors.black, colors.darkGray, colors.gray, colors.lightGray, colors.white
    }
    smoothTransition(fadeColors, 0.1)
end

-- Additional effect: Slight flicker before locking screen
local function flickerEffect()
    for _ = 1, 3 do
        term.setBackgroundColor(colors.white)
        term.clear()
        sleep(0.05) -- Flicker effect speed
        term.setBackgroundColor(colors.black)
        term.clear()
        sleep(0.05)
    end
end

-- Main Program Execution
introTransition()  -- Fade from white to black
os.pullEvent("key") -- Wait for any key press
outroTransition()  -- Fade back from black to white
sleep(0.1)  -- Optional buffer after outro transition
flickerEffect()  -- Add flicker effect before locking
shell.run("/disk/os/lock")  -- Lock the system