DECLARE FUNCTION throttle_to_twr {
  declare parameter x is 1.5.

  local m is ship:mass.
  local g is 9.81.
  if has_grav_sensor = true {
    set g to ship:sensors:grav:mag.
  }
  print "Locking throttle to: " + min((x*m*g)/ship:availablethrust, 1.0).
  lock throttle to min((x*m*g)/ship:availablethrust, 1.0).
}

DECLARE FUNCTION twr {
  local m is ship:mass.
  local g is 9.81. // fallback to this approximation that doesn't deal with
                   // altitude change.
  if has_grav_sensor = true {
    set g to ship:sensors:grav:mag.
  }
  local t is throttle * ship:availablethrust.
  print "Mass: " + ship:mass.
  print "Throttle: " + throttle.
  print "Thrust (max): " + ship:availablethrust.
  print "TWR = " + t/(m*g).
  return t/(m*g).
}

LOCAL has_grav_sensor is false.
DECLARE FUNCTION sensor_check {
  list sensors in senselist.
  for s in senselist {
    if s:type = "grav" {
      print "Gravometric sensor detected".
      set has_grav_sensor to true.
      return.
    }
  }
  set has_grav_sensor to false.
}

// countdown
sensor_check().
LOCAL done is false.
PRINT "Initiating automated launch sequence".
FROM { local x is 5. } UNTIL x = 0 STEP { set x to x - 1. } DO {
  PRINT "..." + x.
  WAIT 1.
}

// Logic for initial ascent.
SAS OFF.
LOCK throttle to 1.0.
LOCK steering to up.
STAGE.

WHEN ship:altitude > 1000 THEN {
  PRINT "Vectoring away from launchpad".
  LOCK steering to HEADING(90, 88).
  WHEN ship:altitude > 8000 THEN {
    // begin "gravity" curve
    PRINT "Beginning orbital insertion turn".
    LOCK steering to HEADING(90,80).
    WAIT 1.
    LOCK steering to HEADING(90,70).
    WAIT 1.
    LOCK steering to HEADING(90,60).
    WAIT 3.
    LOCK steering to ship:prograde.

    WHEN ship:apoapsis > 70000 THEN {
      LOCK throttle to 0.0.
      // todo: automate orbital insertion.
      PRINT "Initial ascent complete. Manually perform orbital insertion. Good luck, Kerman!".
      SET done to true.
    }
  }
}

// Control rate of ascent to reduce drag.
UNTIL ship:altitude > 32000 {
  if twr() > 1.5 {
    throttle_to_twr(1.5).
  }
  wait 0.001.
}
lock throttle to 1.0.

// throttle_to_twr(1.5).
// WHEN ship:altitude > 32000 THEN {
//   lock throttle to 1.0.
// }

WAIT UNTIL done.