// ═══════════════════════════════════════════════════════════
// staging.ks
// Utility functions related to staging and the effects of changing stages
//
// Usage:
//   basicStaging()
//   calcBurnTime(dvNeeded: scalar)
// ═══════════════════════════════════════════════════════════


declare function basicStaging {
  when ship:maxThrust = 0 then {
    print "Staging".
    stage.
    preserve.
  }.
}

function calcBurnTime {
  parameter dvNeeded.

  local totalTime   to 0.
  local dvRemaining to dvNeeded.
  local stageNum    to ship:stagenum.

  until dvRemaining <= 0 or stageNum < 0 {
    local stageDv   to ship:stagedeltav(stageNum):current.
    local stageTime to ship:stagedeltav(stageNum):duration.

    if stageDv <= 0 {
        set stageNum to stageNum - 1.
    } else if stageDv >= dvRemaining {
        set totalTime   to totalTime + stageTime * (dvRemaining / stageDv).
        set dvRemaining to 0.
    } else {
        set totalTime   to totalTime + stageTime.
        set dvRemaining to dvRemaining - stageDv.
        set stageNum    to stageNum - 1.
    }
  }

  if dvRemaining > 0 {
    print "WARNING: Insufficient dV. Short by " + round(dvRemaining, 1) + " m/s.".
  }

  return totalTime.
}