Apollo Mun Circulization

@clobberbuiltins on.
clearscreen.
main().

function main {
    lock steering to prograde.
    wait 5.
    unlock steering.
    unlock throttle.
    set ship:control:roll to 0.05.
    wait 1.
    set ship:control:roll to 0.
    set status1 to "All controls are unlocked.Awaiting to enter Mun sphere of influence".
    set now to time:seconds.
    set ti to time:seconds-now.
    until ship:body:name = "Mun" {
        printing().
        set ti to time:seconds-now.
        print "Left to enter Mun Sphere of Influence: " + (orbit:nextpatcheta/60) + " Minutes".
        wait 0.1.
    }

    set n to time:seconds+eta:periapsis.
    lock ti to n-time:seconds.
    set status1 to "Entered sphere of influence, awaiting for burn".
    wait 1.
    set maneuvertime to time:seconds + eta:periapsis. // when the burn should start
    set myvel to velocityat(ship,maneuvertime):orbit.
    set ap to ship:body:altitudeOf(positionAt(ship,maneuvertime))+body:radius. // altitude on burn point
    set TargetAp to ap.. // your target apoapsis.
    set smja to (ap + TargetAp) / 2. // your final semimajoraxis
    set targetvel to sqrt(body:mu*((2/ap)-(1/smja))). // target speed
    set apvel to myvel:mag. // burn point speed
    set needvel to abs(targetvel-apvel). // needed speed
    list engines in engList.
    set thr to engList[0]:maxthrust. // Engine Thrust
    set m to ship:mass.  // Mass
    set e to constant():E. // E constant
    set p to engList[0]:isp. // ISP
    set g to constant:g0. // Gravitational acceleration constant.
    set burn_duration to  abs(g * m * p * (1 - e^(-needvel/(g*p))) / thr). // burn duration
    print "Crude Estimated burn duration: " + round(burn_duration) + "s".
    print "Needed dv: " + abs(needvel) + " m/s".
    lock steering to retrograde.
    wait 1.

    until ti-burn_duration/2 <= 60 and ti-burn_duration/2 > 0 {
        print "To maneuver left: " + (ti-burn_duration/2) + " Seconds".
        print "Needed dv: " + abs(needvel) + " m/s".
        wait 0.1.
        printing().
    }

    set status1 to "One Minute Till Burn".
    lock steering to retrograde.
    //now we need to wait until the burn vector and ship's facing are aligned
    until vang(-ship:velocity:orbit, ship:facing:vector) < 0.25 {
        print "To maneuver left: " + (ti-burn_duration/2) + " Seconds".
        print "Needed dv: " + abs(needvel) + " m/s".
        wait 0.1.
        printing().
    }

    until ti-(burn_duration/2) <= 10 {
        print "To maneuver left: " + (ti-(burn_duration/2)) + " Seconds".
        print "Needed dv: " + abs(needvel) + " m/s".
        wait 0.1.
        printing().
    }

    set ship:control:fore to 0.5.
    set status1 to "RCS activated for ullage".
    until ti-(burn_duration/2) <= 1 {
        print "To maneuver left: " + (ti-(burn_duration/2)) + " Seconds".
        print "Needed dv: " + abs(needvel) + " m/s".
        wait 0.1.
        printing().
    }

    set ship:control:fore to 0.
    until ti-(burn_duration/2) <= 0.5 {
        print "To maneuver left: " + (ti-(burn_duration/2)) + " Seconds".
        wait 0.1.
        printing().
    }

    set now to time:seconds.
    lock ti to time:seconds - now.
    set myvel1 to ship:velocity:orbit:mag.
    set tvel to targetvel.
    lock throttle to 1.
    set status1 to "SM Engine Activated".
    until ti > burn_duration {
        set myvel1 to ship:velocity:orbit:mag.
        print "Time left: " + (burn_duration-ti) + " Seconds".
        print "Speed left: " + (tvel-myvel1) + " m/s".
        wait 0.1.
        printing().
    }

    lock throttle to max(0, 1-t/0.3).
    set status1 to "Circulization burn has completed.All controls are unlocked".
    set ship:control:fore to -1.
    wait 1.
    set ship:control:fore to 0.
    wait 5.
    unlock steering.
    unlock throttle.
}

function printing {
    clearscreen.
    set t to (time:seconds - now1)/60.
    print "T+: " + t + " Minutes".
    print "Status: " + status1.
    wait 0.1.
}