--- **Ops** - Enhanced Naval Group.
-- 
-- **Main Features:**
--
--    * Dynamically add and remove waypoints.
--    * Let the group steam into the wind.
--    * Command a full stop.
--    * Let a submarine dive and surface.
--     
-- ===
--
-- ### Author: **funkyfranky**
-- @module Ops.NavyGroup
-- @image OPS_NavyGroup.png


--- NAVYGROUP class.
-- @type NAVYGROUP
-- @field #boolean turning If true, group is currently turning.
-- @field #NAVYGROUP.IntoWind intowind Into wind info.
-- @field #table Qintowind Queue of "into wind" turns.
-- @field #number depth Ordered depth in meters.
-- @field #boolean collisionwarning If true, collition warning.
-- @field #boolean pathfindingOn If true, enable pathfining.
-- @field #boolean ispathfinding If true, group is currently path finding.
-- @extends Ops.OpsGroup#OPSGROUP

--- *Something must be left to chance; nothing is sure in a sea fight above all.* -- Horatio Nelson
--
-- ===
--
-- ![Banner Image](..\Presentations\NAVYGROUP\NavyGroup_Main.jpg)
--
-- # The NAVYGROUP Concept
-- 
-- This class enhances naval groups.
-- 
-- @field #NAVYGROUP
NAVYGROUP = {
  ClassName       = "NAVYGROUP",
  turning         = false,
  intowind        = nil,
  intowindcounter = 0,
  Qintowind       = {},
}

--- Navy group element.
-- @type NAVYGROUP.Element
-- @field #string name Name of the element, i.e. the unit.
-- @field #string typename Type name.

--- Navy group element.
-- @type NAVYGROUP.IntoWind
-- @field #number Tstart Time to start.
-- @field #number Tstop Time to stop.
-- @field #boolean Uturn U-turn.
-- @field #number Speed Speed in knots.
-- @field #number Offset Offset angle in degrees.
-- @field #number Id Unique ID of the turn.
-- @field Ops.OpsGroup#OPSGROUP.Waypoint waypoint Turn into wind waypoint.
-- @field Core.Point#COORDINATE Coordinate Coordinate where we left the route.
-- @field #number Heading Heading the boat will take in degrees.
-- @field #boolean Open Currently active.
-- @field #boolean Over This turn is over.


--- NavyGroup version.
-- @field #string version
NAVYGROUP.version="0.1.0"

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- TODO list
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

-- TODO: Collision warning.
-- DONE: Detour, add temporary waypoint and resume route.
-- DONE: Stop and resume route.
-- DONE: Add waypoints.
-- DONE: Add tasks.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Constructor
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Create a new NAVYGROUP class object.
-- @param #NAVYGROUP self
-- @param #string GroupName Name of the group.
-- @return #NAVYGROUP self
function NAVYGROUP:New(GroupName)

  -- Inherit everything from FSM class.
  local self=BASE:Inherit(self, OPSGROUP:New(GroupName)) -- #NAVYGROUP
  
  -- Set some string id for output to DCS.log file.
  self.lid=string.format("NAVYGROUP %s | ", self.groupname)
  
  -- Defaults
  self:SetDetection()
  self:SetPatrolAdInfinitum(true)
  self:SetPathfinding(false)

  -- Add FSM transitions.
  --                 From State  -->   Event      -->     To State
  self:AddTransition("*",             "FullStop",         "Holding")     -- Hold position.
  self:AddTransition("*",             "Cruise",           "Cruising")    -- Hold position.
  
  self:AddTransition("*",             "TurnIntoWind",     "IntoWind")    -- Command the group to turn into the wind.
  self:AddTransition("*",             "TurnIntoWindOver", "Cruising")    -- Turn into wind is over.
  
  self:AddTransition("*",             "TurningStarted",   "*")           -- Group started turning.
  self:AddTransition("*",             "TurningStopped",   "*")           -- Group stopped turning.
  
  self:AddTransition("*",             "Detour",           "OnDetour")    -- Make a detour to a coordinate and resume route afterwards.
  self:AddTransition("OnDetour",      "DetourReached",    "Cruising")    -- Group reached the detour coordinate.
  
  self:AddTransition("*",             "CollisionWarning", "*")           -- Collision warning.
  self:AddTransition("*",             "ClearAhead",       "*")           -- Clear ahead.
  
  self:AddTransition("*",             "Dive",             "Diving")      -- Command a submarine to dive.
  self:AddTransition("Diving",        "Surface",          "Cruising")    -- Command a submarine to go to the surface.
  
  ------------------------
  --- Pseudo Functions ---
  ------------------------

  --- Triggers the FSM event "Stop". Stops the NAVYGROUP and all its event handlers.
  -- @param #NAVYGROUP self

  --- Triggers the FSM event "Stop" after a delay. Stops the NAVYGROUP and all its event handlers.
  -- @function [parent=#NAVYGROUP] __Stop
  -- @param #NAVYGROUP self
  -- @param #number delay Delay in seconds.
  
  -- TODO: Add pseudo functions.


  -- Init waypoints.
  self:InitWaypoints()
  
  -- Initialize the group.
  self:_InitGroup()

  -- Debug trace.
  if false then
    self.Debug=true
    BASE:TraceOnOff(true)
    BASE:TraceClass(self.ClassName)
    BASE:TraceLevel(1)
  end
  
  -- Handle events:
  self:HandleEvent(EVENTS.Birth,      self.OnEventBirth)
  self:HandleEvent(EVENTS.Dead,       self.OnEventDead)
  self:HandleEvent(EVENTS.RemoveUnit, self.OnEventRemoveUnit)  
  
  -- Start the status monitoring.
  self:__CheckZone(-1)
  self:__Status(-2)
  self:__QueueUpdate(-3)
   
  return self  
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- User Functions
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Group patrols ad inifintum. If the last waypoint is reached, it will go to waypoint one and repeat its route.
-- @param #NAVYGROUP self
-- @param #boolean switch If true or nil, patrol until the end of time. If false, go along the waypoints once and stop.
-- @return #NAVYGROUP self
function NAVYGROUP:SetPatrolAdInfinitum(switch)
  if switch==false then
    self.adinfinitum=false
  else
    self.adinfinitum=true
  end
  return self
end

--- Enable/disable pathfinding.
-- @param #NAVYGROUP self
-- @param #boolean Switch If true, enable pathfinding.
-- @return #NAVYGROUP self
function NAVYGROUP:SetPathfinding(Switch)
  self.pathfindingOn=Switch
end

--- Add a *scheduled* task.
-- @param #NAVYGROUP self
-- @param Core.Point#COORDINATE Coordinate Coordinate of the target.
-- @param #string Clock Time when to start the attack.
-- @param #number Radius Radius in meters. Default 100 m.
-- @param #number Nshots Number of shots to fire. Default 3.
-- @param #number WeaponType Type of weapon. Default auto.
-- @param #number Prio Priority of the task.
-- @return Ops.OpsGroup#OPSGROUP.Task The task data.
function NAVYGROUP:AddTaskFireAtPoint(Coordinate, Radius, Nshots, WeaponType, Clock, Prio)

  local DCStask=CONTROLLABLE.TaskFireAtPoint(nil, Coordinate:GetVec2(), Radius, Nshots, WeaponType)

  local task=self:AddTask(DCStask, Clock, nil, Prio)

  return task
end

--- Add a *waypoint* task.
-- @param #NAVYGROUP self
-- @param Core.Point#COORDINATE Coordinate Coordinate of the target.
-- @param Ops.OpsGroup#OPSGROUP.Waypoint Waypoint Where the task is executed. Default is next waypoint.
-- @param #number Radius Radius in meters. Default 100 m.
-- @param #number Nshots Number of shots to fire. Default 3.
-- @param #number WeaponType Type of weapon. Default auto.
-- @param #number Prio Priority of the task.
-- @return Ops.OpsGroup#OPSGROUP.Task The task table.
function NAVYGROUP:AddTaskWaypointFireAtPoint(Coordinate, Waypoint, Radius, Nshots, WeaponType, Prio)

  Waypoint=Waypoint or self:GetWaypointNext()

  local DCStask=CONTROLLABLE.TaskFireAtPoint(nil, Coordinate:GetVec2(), Radius, Nshots, WeaponType)

  local task=self:AddTaskWaypoint(DCStask, Waypoint, nil, Prio)

  return task
end


--- Add a *scheduled* task.
-- @param #NAVYGROUP self
-- @param Wrapper.Group#GROUP TargetGroup Target group.
-- @param #number WeaponExpend How much weapons does are used.
-- @param #number WeaponType Type of weapon. Default auto.
-- @param #string Clock Time when to start the attack.
-- @param #number Prio Priority of the task.
-- @return Ops.OpsGroup#OPSGROUP.Task The task data.
function NAVYGROUP:AddTaskAttackGroup(TargetGroup, WeaponExpend, WeaponType, Clock, Prio)

  local DCStask=CONTROLLABLE.TaskAttackGroup(nil, TargetGroup, WeaponType, WeaponExpend, AttackQty, Direction, Altitude, AttackQtyLimit, GroupAttack)

  local task=self:AddTask(DCStask, Clock, nil, Prio)
  
  return task
end

--- Add aircraft recovery time window and recovery case.
-- @param #NAVYGROUP self
-- @param #string starttime Start time, e.g. "8:00" for eight o'clock. Default now.
-- @param #string stoptime Stop time, e.g. "9:00" for nine o'clock. Default 90 minutes after start time.
-- @param #number speed Speed in knots during turn into wind leg.
-- @param #boolean uturn If true (or nil), carrier wil perform a U-turn and go back to where it came from before resuming its route to the next waypoint. If false, it will go directly to the next waypoint.
-- @param #number offset Offset angle in degrees, e.g. to account for an angled runway. Default 0 deg.
-- @return #NAVYGROUP.IntoWind Recovery window.
function NAVYGROUP:CreateTurnIntoWind(starttime, stoptime, speed, uturn, offset)

  -- Absolute mission time in seconds.
  local Tnow=timer.getAbsTime()

  -- Convert number to Clock.
  if starttime and type(starttime)=="number" then
    starttime=UTILS.SecondsToClock(Tnow+starttime)
  end

  -- Input or now.
  starttime=starttime or UTILS.SecondsToClock(Tnow)

  -- Set start time.
  local Tstart=UTILS.ClockToSeconds(starttime)

  -- Set stop time.
  local Tstop=Tstart+90*60

  if stoptime==nil then
    Tstop=Tstart+90*60
  elseif type(stoptime)=="number" then
    Tstop=Tstart+stoptime
  else
    Tstop=UTILS.ClockToSeconds(stoptime)
  end


  -- Consistancy check for timing.
  if Tstart>Tstop then
    self:E(string.format("ERROR:Into wind stop time %s lies before start time %s. Input rejected!", UTILS.SecondsToClock(Tstart), UTILS.SecondsToClock(Tstop)))
    return self
  end
  if Tstop<=Tnow then
    self:I(string.format("WARNING: Into wind stop time %s already over. Tnow=%s! Input rejected.", UTILS.SecondsToClock(Tstop), UTILS.SecondsToClock(Tnow)))
    return self
  end

  -- Increase counter.
  self.intowindcounter=self.intowindcounter+1

  -- Recovery window.
  local recovery={} --#NAVYGROUP.IntoWind
  recovery.Tstart=Tstart
  recovery.Tstop=Tstop
  recovery.Open=false
  recovery.Over=false
  recovery.Speed=speed or 20
  recovery.Uturn=uturn and uturn or false
  recovery.Offset=offset or 0
  recovery.Id=self.intowindcounter

  return recovery
end

--- Add aircraft recovery time window and recovery case.
-- @param #NAVYGROUP self
-- @param #string starttime Start time, e.g. "8:00" for eight o'clock. Default now.
-- @param #string stoptime Stop time, e.g. "9:00" for nine o'clock. Default 90 minutes after start time.
-- @param #number speed Speed in knots during turn into wind leg.
-- @param #boolean uturn If true (or nil), carrier wil perform a U-turn and go back to where it came from before resuming its route to the next waypoint. If false, it will go directly to the next waypoint.
-- @param #number offset Offset angle in degrees, e.g. to account for an angled runway. Default 0 deg.
-- @return #NAVYGROUP.IntoWind Recovery window.
function NAVYGROUP:AddTurnIntoWind(starttime, stoptime, speed, uturn, offset)

  local recovery=self:CreateTurnIntoWind(starttime, stoptime, speed, uturn, offset)
  
  --TODO: check if window is overlapping with an other and if extend the window.
  
  -- Add to table
  table.insert(self.Qintowind, recovery)

  return recovery
end


--- Check if the group is currently holding its positon.
-- @param #NAVYGROUP self
-- @return #boolean If true, group was ordered to hold.
function NAVYGROUP:IsHolding()
  return self:Is("Holding")
end

--- Check if the group is currently cruising.
-- @param #NAVYGROUP self
-- @return #boolean If true, group cruising.
function NAVYGROUP:IsCruising()
  return self:Is("Cruising")
end

--- Check if the group is currently on a detour.
-- @param #NAVYGROUP self
-- @return #boolean If true, group is on a detour
function NAVYGROUP:IsOnDetour()
  return self:Is("OnDetour")
end


--- Check if the group is currently diving.
-- @param #NAVYGROUP self
-- @return #boolean If true, group is currently diving.
function NAVYGROUP:IsDiving()
  return self:Is("Diving")
end

--- Check if the group is currently turning.
-- @param #NAVYGROUP self
-- @return #boolean If true, group is currently turning.
function NAVYGROUP:IsTurning()
  return self.turning
end

--- Check if the group is currently steaming into the wind.
-- @param #NAVYGROUP self
-- @return #boolean If true, group is currently steaming into the wind.
function NAVYGROUP:IsSteamingIntoWind()
  if self.intowind then
    return true
  else
    return false    
  end
end


-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Status
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

---- Update status.
-- @param #NAVYGROUP self
function NAVYGROUP:onbeforeStatus(From, Event, To)

  if self:IsDead() then  
    self:I(self.lid..string.format("Onbefore Status DEAD ==> false"))
    return false   
  elseif self:IsStopped() then
    self:I(self.lid..string.format("Onbefore Status STOPPED ==> false"))
    return false
  end

  return true
end

--- Update status.
-- @param #NAVYGROUP self
function NAVYGROUP:onafterStatus(From, Event, To)

  -- FSM state.
  local fsmstate=self:GetState()
  
  if self:IsAlive() then
  
    ---
    -- Detection
    ---  
  
    -- Check if group has detected any units.
    if self.detectionOn then
      self:_CheckDetectedUnits()
    end

    -- Current heading and position of the carrier.
    local hdg=self:GetHeading()
    local pos=self:GetCoordinate()
    local speed=self.group:GetVelocityKNOTS()
    
    -- Check if group started or stopped turning.
    self:_CheckTurning()
    
    local freepath=UTILS.NMToMeters(10)
    
    -- Only check if not currently turning.
    if not self:IsTurning() then
    
      -- Check free path ahead.
      freepath=self:_CheckFreePath(freepath, 100)
      
      if freepath<5000 then
      
        if not self.collisionwarning then
          -- Issue a collision warning event.
          self:CollisionWarning(freepath)
        end
    
        if self.pathfindingOn and not self.ispathfinding then
          self.ispathfinding=self:_FindPathToNextWaypoint()
        end
        
      end
      
      -- Check water is ahead.
      --collision=self:_CheckCollisionCoord(pos:Translate(freepath+100, hdg))
      
    end
    
    -- Check into wind queue.
    self:_CheckTurnsIntoWind()
    
    -- Check if group got stuck.
    self:_CheckStuck()    
  
    -- Get number of tasks and missions.
    local nTaskTot, nTaskSched, nTaskWP=self:CountRemainingTasks()
    local nMissions=self:CountRemainingMissison()

    local intowind=self:IsSteamingIntoWind() and UTILS.SecondsToClock(self.intowind.Tstop-timer.getAbsTime(), true) or "N/A"    
    local turning=tostring(self:IsTurning())
    local alt=pos.y
    local speedExpected=UTILS.MpsToKnots(self.speed or 0)
    
    local wpidxCurr=self.currentwp
    local wpuidCurr=0
    local wpidxNext=self:GetWaypointIndexNext()
    local wpuidNext=0
    local wpDist=UTILS.MetersToNM(self:GetDistanceToWaypoint())
    local wpETA=UTILS.SecondsToClock(self:GetTimeToWaypoint(), true)
    local roe=self:GetROE() or 0
    local als=self:GetAlarmstate() or 0
  
    -- Info text.
    local text=string.format("%s [ROE=%d,AS=%d, T/M=%d/%d]: Wp=%d[%d]-->%d[%d] (of %d) Dist=%.1f NM ETA=%s - Speed=%.1f (%.1f) kts, Depth=%.1f m, Hdg=%03d, Turn=%s Collision=%d IntoWind=%s", 
    fsmstate, roe, als, nTaskTot, nMissions, wpidxCurr, wpuidCurr, wpidxNext, wpuidNext, #self.waypoints, wpDist, wpETA, speed, speedExpected, alt, hdg, turning, freepath, intowind)
    self:I(self.lid..text)
    
  else

    -- Info text.
    local text=string.format("State %s: Alive=%s", fsmstate, tostring(self:IsAlive()))
    self:I(self.lid..text)
  
  end


  ---
  -- Tasks & Missions
  ---

  self:_PrintTaskAndMissionStatus()


  -- Next status update in 30 seconds.
  self:__Status(-30)
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- FSM Events
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- On after "ElementSpawned" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #NAVYGROUP.Element Element The group element.
function NAVYGROUP:onafterElementSpawned(From, Event, To, Element)
  self:I(self.lid..string.format("Element spawned %s", Element.name))

  -- Set element status.
  self:_UpdateStatus(Element, OPSGROUP.ElementStatus.SPAWNED)

end

--- On after "ElementDead" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #NAVYGROUP.Element Element The group element.
function NAVYGROUP:onafterElementDead(From, Event, To, Element)
  self:T(self.lid..string.format("Element dead %s.", Element.name))

  -- Set element status.
  self:_UpdateStatus(Element, OPSGROUP.ElementStatus.DEAD)
end

--- On after "Spawned" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterSpawned(From, Event, To)
  self:I(self.lid..string.format("Group spawned!"))

  if self.ai then
 
    -- Set default ROE.
    if self.option.ROE then
      self:SwitchROE(self.option.ROE)
    else
      self:SwitchROE(ENUMS.ROE.ReturnFire)
    end
    
    -- Set default Alarm State.
    if self.option.Alarm then
      self:SwitchAlarmstate(self.option.Alarm)
    else
      self:SwitchAlarmstate(0)
    end
    
    -- Turn TACAN beacon on.
    if self.tacan.On then
      self:_SwitchTACAN(self.tacan)
    end
    
    -- Turn ICLS on.
    if self.icls.On then
      self:_SwitchICLS(self.icls)
    end    

    -- Turn on the radio.
    if self.radio.On then
      self:SwitchRadio(self.radio.Freq, self.radio.Modu)
    else
      self.radio.On=true -- Radio is always on for ships. If not set, it is default.
    end
    
  end
  
  -- Get orientation.
  self.Corientlast=self.group:GetUnit(1):GetOrientationX()
  
  -- Update route.
  self:Cruise()
  
end

--- On after "UpdateRoute" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number n Waypoint number. Default is next waypoint.
-- @param #number Speed Speed in knots to the next waypoint.
-- @param #number Depth Depth in meters to the next waypoint.
function NAVYGROUP:onafterUpdateRoute(From, Event, To, n, Speed, Depth)

  -- Update route from this waypoint number onwards.
  n=n or self:GetWaypointIndexNext()
  
  -- Debug info.
  self:T(self.lid..string.format("FF Update route n=%d", n))
  
  -- Update waypoint tasks, i.e. inject WP tasks into waypoint table.
  self:_UpdateWaypointTasks(n)

  -- Waypoints.
  local waypoints={}
  
  -- Add remaining waypoints to route.
  local depth=nil
  for i=n, #self.waypoints do
  
    -- Waypoint.
    local wp=self.waypoints[i]  --Ops.OpsGroup#OPSGROUP.Waypoint

    -- Check if next wp.
    if i==n then
    
      -- Speed.
      if Speed then
        -- Take speed specified.
        wp.speed=UTILS.KnotsToMps(Speed)
      else
        -- Take default waypoint speed.
      end
      
      if Depth then
        wp.alt=-Depth
      elseif self.depth then
        wp.alt=-self.depth
      else
        -- Take default waypoint alt.
      end
      
      -- Current set speed in m/s.
      self.speed=wp.speed
      
      -- Current set depth.
      depth=wp.alt
    
    else
      
      -- Dive depth is applied to all other waypoints.
      if self.depth then
        wp.alt=-self.depth
      else
        -- Take default waypoint depth.
      end      
      
    end

    -- Add waypoint.
    table.insert(waypoints, wp)
  end
  
  -- Current waypoint.
  local current=self:GetCoordinate():WaypointNaval(UTILS.MpsToKmph(self.speed), depth)
  table.insert(waypoints, 1, current)  

  
  if #waypoints>1 then

    self:I(self.lid..string.format("Updateing route: WP %d-->%d-->%d (#%d), Speed=%.1f knots, Depth=%d m", 
    self.currentwp, n, #self.waypoints, #waypoints-1, UTILS.MpsToKnots(self.speed), depth))


    -- Route group to all defined waypoints remaining.
    self:Route(waypoints)
    
  else
  
    ---
    -- No waypoints left ==> Full Stop
    ---
  
    self:E(self.lid..string.format("WARNING: No waypoints left ==> Full Stop!"))    
    self:FullStop()
    
  end

end

--- On after "Detour" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param Core.Point#COORDINATE Coordinate Coordinate where to go.
-- @param #number Speed Speed in knots. Default cruise speed.
-- @param #number Depth Depth in meters. Default 0 meters.
-- @param #number ResumeRoute If true, resume route after detour point was reached. If false, the group will stop at the detour point and wait for futher commands.
function NAVYGROUP:onafterDetour(From, Event, To, Coordinate, Speed, Depth, ResumeRoute)
    
  -- Depth for submarines.
  Depth=Depth or 0

  -- Speed in knots.
  Speed=Speed or self:GetSpeedCruise()
  
  -- ID of current waypoint.
  local uid=self:GetWaypointCurrent().uid
  
  -- Add waypoint after current.
  local wp=self:AddWaypoint(Coordinate, Speed, uid, Depth, true)
  
  -- Set if we want to resume route after reaching the detour waypoint.
  if ResumeRoute then
    wp.detour=1
  else
    wp.detour=0
  end

end

--- On after "DetourReached" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterDetourReached(From, Event, To)
  self:I(self.lid.."Group reached detour coordinate.")
end

--- On after "TurnIntoWind" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #NAVYGROUP.IntoWind Into wind parameters.
function NAVYGROUP:onafterTurnIntoWind(From, Event, To, IntoWind)

  IntoWind.Heading=self:GetHeadingIntoWind(IntoWind.Offset)
  
  IntoWind.Open=true
  
  IntoWind.Coordinate=self:GetCoordinate()

  self.intowind=IntoWind
  
  -- Wind speed in m/s.
  local _,vwind=self:GetWind()
  
  -- Convert to knots.
  vwind=UTILS.MpsToKnots(vwind)

  -- Speed of carrier relative to wind but at least 2 knots.
  local speed=math.max(IntoWind.Speed-vwind, 2)

  -- Debug info.
  self:I(self.lid..string.format("Steaming into wind: Heading=%03d Speed=%.1f Vwind=%.1f Vtot=%.1f knots, Tstart=%d Tstop=%d", IntoWind.Heading, speed, vwind, speed+vwind, IntoWind.Tstart, IntoWind.Tstop))
  
  local distance=UTILS.NMToMeters(1000)
  
  local coord=self:GetCoordinate()
  local Coord=coord:Translate(distance, IntoWind.Heading)

  -- ID of current waypoint.
  local uid=self:GetWaypointCurrent().uid
  
  local wptiw=self:AddWaypoint(Coord, speed, uid)
  wptiw.intowind=true
  
  IntoWind.waypoint=wptiw
  
  if IntoWind.Uturn and self.Debug then
    IntoWind.Coordinate:MarkToAll("Return coord")
  end
  
end

--- On after "TurnIntoWindOver" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number Duration Duration in seconds.
-- @param #number Speed Speed in knots.
-- @param #boolean Uturn Return to the place we came from.
function NAVYGROUP:onafterTurnIntoWindOver(From, Event, To)

  env.info("FF Turn Into Wind Over!")

  self.intowind.Over=true
  self.intowind.Open=false
  
  -- Remove additional waypoint.
  self:RemoveWaypointByID(self.intowind.waypoint.uid)

  if self.intowind.Uturn then
    env.info("FF Turn Into Wind Over Uturn!")
    self:Detour(self.intowind.Coordinate, self:GetSpeedCruise(), 0, true)
  else
    env.info("FF Turn Into Wind Over Next WP!")
    local indx=self:GetWaypointIndexNext()
    local speed=self:GetWaypointSpeed(indx)
    self:__UpdateRoute(-1, indx, speed)
  end
  
  self.intowind=nil

end

--- On after "FullStop" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterFullStop(From, Event, To)

  -- Get current position.
  local pos=self:GetCoordinate()
  
  -- Create a new waypoint.
  local wp=pos:WaypointNaval(0)
  
  -- Create new route consisting of only this position ==> Stop!
  self:Route({wp})

end

--- On after "Cruise" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number Speed Speed in knots until next waypoint is reached. Default is speed set for waypoint.
function NAVYGROUP:onafterCruise(From, Event, To, Speed)

  -- No set depth.
  self.depth=nil

  self:__UpdateRoute(-1, nil, Speed)

end

--- On after "Dive" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number Depth Dive depth in meters. Default 50 meters.
-- @param #number Speed Speed in knots until next waypoint is reached.
function NAVYGROUP:onafterDive(From, Event, To, Depth, Speed)

  Depth=Depth or 50

  self:I(self.lid..string.format("Diving to %d meters", Depth))
  
  self.depth=Depth
  
  self:__UpdateRoute(-1, nil, Speed)

end

--- On after "Surface" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number Speed Speed in knots until next waypoint is reached.
function NAVYGROUP:onafterSurface(From, Event, To, Speed)

  self.depth=0

  self:__UpdateRoute(-1, nil, Speed)

end

--- On after "TurningStarted" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterTurningStarted(From, Event, To)
  self.turning=true
end

--- On after "TurningStarted" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterTurningStopped(From, Event, To)
  self.turning=false
  self.collisionwarning=false
end

--- On after "CollisionWarning" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
-- @param #number Distance Distance in meters where obstacle was detected.
function NAVYGROUP:onafterCollisionWarning(From, Event, To, Distance)
  self:I(self.lid..string.format("Iceberg ahead in %d meters!", Distance or -1))
  self.collisionwarning=true
end

--- On after "Dead" event.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterDead(From, Event, To)
  self:I(self.lid..string.format("Group dead!"))

  -- Delete waypoints so they are re-initialized at the next spawn.
  self.waypoints=nil
  self.groupinitialized=false

  -- Cancel all mission.
  for _,_mission in pairs(self.missionqueue) do
    local mission=_mission --Ops.Auftrag#AUFTRAG

    self:MissionCancel(mission)
    mission:GroupDead(self)

  end

  -- Stop
  self:Stop()
end

--- On after Start event. Starts the NAVYGROUP FSM and event handlers.
-- @param #NAVYGROUP self
-- @param #string From From state.
-- @param #string Event Event.
-- @param #string To To state.
function NAVYGROUP:onafterStop(From, Event, To)

  -- Check if group is still alive.
  if self:IsAlive() then
    -- Destroy group. No event is generated.
    self.group:Destroy(false)
  end

  -- Handle events:
  self:UnHandleEvent(EVENTS.Birth)
  self:UnHandleEvent(EVENTS.Dead)
  self:UnHandleEvent(EVENTS.RemoveUnit)

  self.CallScheduler:Clear()

  self:I(self.lid.."STOPPED! Unhandled events, cleared scheduler and removed from database.")
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Events DCS
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Event function handling the birth of a unit.
-- @param #NAVYGROUP self
-- @param Core.Event#EVENTDATA EventData Event data.
function NAVYGROUP:OnEventBirth(EventData)

  -- Check that this is the right group.
  if EventData and EventData.IniGroup and EventData.IniUnit and EventData.IniGroupName and EventData.IniGroupName==self.groupname then
    local unit=EventData.IniUnit
    local group=EventData.IniGroup
    local unitname=EventData.IniUnitName
    
    if self.respawning then
    
      local function reset()
        self.respawning=nil
      end
      
      -- Reset switch in 1 sec. This should allow all birth events of n>1 groups to have passed.
      -- TODO: Can I do this more rigorously?
      self:ScheduleOnce(1, reset)
    
    else
          
      -- Get element.
      local element=self:GetElementByName(unitname)

      -- Set element to spawned state.
      self:T3(self.lid..string.format("EVENT: Element %s born ==> spawned", element.name))            
      self:ElementSpawned(element)
      
    end    
    
  end

end

--- Flightgroup event function handling the crash of a unit.
-- @param #NAVYGROUP self
-- @param Core.Event#EVENTDATA EventData Event data.
function NAVYGROUP:OnEventDead(EventData)

  -- Check that this is the right group.
  if EventData and EventData.IniGroup and EventData.IniUnit and EventData.IniGroupName and EventData.IniGroupName==self.groupname then
    self:T(self.lid..string.format("EVENT: Unit %s dead!", EventData.IniUnitName))
    
    local unit=EventData.IniUnit
    local group=EventData.IniGroup
    local unitname=EventData.IniUnitName

    -- Get element.
    local element=self:GetElementByName(unitname)

    if element then
      self:I(self.lid..string.format("EVENT: Element %s dead ==> dead", element.name))
      self:ElementDead(element)
    end
    
  end

end

--- Flightgroup event function handling the crash of a unit.
-- @param #NAVYGROUP self
-- @param Core.Event#EVENTDATA EventData Event data.
function NAVYGROUP:OnEventRemoveUnit(EventData)

  -- Check that this is the right group.
  if EventData and EventData.IniGroup and EventData.IniUnit and EventData.IniGroupName and EventData.IniGroupName==self.groupname then
    local unit=EventData.IniUnit
    local group=EventData.IniGroup
    local unitname=EventData.IniUnitName

    -- Get element.
    local element=self:GetElementByName(unitname)

    if element then
      self:I(self.lid..string.format("EVENT: Element %s removed ==> dead", element.name))
      self:ElementDead(element)
    end

  end

end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Routing
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Add an a waypoint to the route.
-- @param #NAVYGROUP self
-- @param Core.Point#COORDINATE Coordinate The coordinate of the waypoint. Use COORDINATE:SetAltitude(altitude) to define the altitude.
-- @param #number Speed Speed in knots. Default is default cruise speed or 70% of max speed.
-- @param #number AfterWaypointWithID Insert waypoint after waypoint given ID. Default is to insert as last waypoint.
-- @param #number Depth Depth at waypoint in meters. Only for submarines.
-- @param #boolean Updateroute If true or nil, call UpdateRoute. If false, no call.
-- @return Ops.OpsGroup#OPSGROUP.Waypoint Waypoint table.
function NAVYGROUP:AddWaypoint(Coordinate, Speed, AfterWaypointWithID, Depth, Updateroute)

  -- Check if a coordinate was given or at least a positionable.
  if not Coordinate:IsInstanceOf("COORDINATE") then
    if Coordinate:IsInstanceOf("POSITIONABLE") or Coordinate:IsInstanceOf("ZONE_BASE") then
      self:I(self.lid.."WARNING: Coordinate is not a COORDINATE but a POSITIONABLE. Trying to get coordinate")
      Coordinate=Coordinate:GetCoordinate()
    else
      self:E(self.lid.."ERROR: Coordinate is neither a COORDINATE nor any POSITIONABLE!")
      return nil
    end
  end
  
  -- Set waypoint index.
  local wpnumber=self:GetWaypointIndexAfterID(AfterWaypointWithID)

  -- Check if final waypoint is still passed.  
  if wpnumber>self.currentwp then
    self.passedfinalwp=false
  end
  
  -- Speed in knots.
  Speed=Speed or self:GetSpeedCruise()

  -- Create a Naval waypoint.
  local wp=Coordinate:WaypointNaval(UTILS.KnotsToKmph(Speed), Depth)

  -- Create waypoint data table.
  local waypoint=self:_CreateWaypoint(wp)

  -- Add waypoint to table.
  self:_AddWaypoint(waypoint, wpnumber)
  
  -- Debug info.
  self:I(self.lid..string.format("Adding NAVAL waypoint index=%d uid=%d, speed=%.1f knots. Last waypoint passed was #%d. Total waypoints #%d", wpnumber, waypoint.uid, Speed, self.currentwp, #self.waypoints))

  -- Update route.
  if Updateroute==nil or Updateroute==true then
    self:_CheckGroupDone(1)
  end
  
  return waypoint
end

--- Initialize group parameters. Also initializes waypoints if self.waypoints is nil.
-- @param #NAVYGROUP self
-- @return #NAVYGROUP self
function NAVYGROUP:_InitGroup()

  -- First check if group was already initialized.
  if self.groupinitialized then
    self:E(self.lid.."WARNING: Group was already initialized!")
    return
  end

  -- Get template of group.
  self.template=self.group:GetTemplate()

  -- Define category.
  self.isAircraft=false
  self.isNaval=true
  self.isGround=false


  -- Helo group.
  --self.isSubmarine=self.group:IsSubmarine()
  
  -- Ships are always AI.
  self.ai=true
  
  -- Is (template) group late activated.
  self.isLateActivated=self.template.lateActivation
  
  -- Naval groups cannot be uncontrolled.
  self.isUncontrolled=false
  
  -- Max speed in km/h.
  self.speedmax=self.group:GetSpeedMax()
  
  -- Cruise speed: 70% of max speed.
  self.speedCruise=self.speedmax*0.7
  
  -- Group ammo.
  self.ammo=self:GetAmmoTot()
  
  self.traveldist=0
  self.traveltime=timer.getAbsTime()
  self.position=self:GetCoordinate()
  
  -- Radio parameters from template.
  self.radio.On=false  -- Radio is always on for ships but we set it to false to check if it has been changed before spawn.
  self.radio.Freq=tonumber(self.template.units[1].frequency)/1000000
  self.radio.Modu=tonumber(self.template.units[1].modulation)
  
  -- Set default formation. No really applicable for ships.
  self.optionDefault.Formation="Off Road"
  self.option.Formation=self.optionDefault.Formation
  
  -- Get all units of the group.
  local units=self.group:GetUnits()
  
  for _,_unit in pairs(units) do
    local unit=_unit --Wrapper.Unit#UNIT
    
    local element={} --#NAVYGROUP.Element
    element.name=unit:GetName()
    element.typename=unit:GetTypeName()
    element.status=OPSGROUP.ElementStatus.INUTERO
    element.unit=unit
    table.insert(self.elements, element)
    
    self:GetAmmoUnit(unit, false)
    
    if unit:IsAlive() then      
      self:ElementSpawned(element)
    end
    
  end

  -- Get first unit. This is used to extract other parameters.
  local unit=self.group:GetUnit(1)
  
  if unit then
    
    self.descriptors=unit:GetDesc()
    
    self.actype=unit:GetTypeName()
    
    -- Debug info.
    local text=string.format("Initialized Navy Group %s:\n", self.groupname)
    text=text..string.format("AC type      = %s\n", self.actype)
    text=text..string.format("Speed max    = %.1f Knots\n", UTILS.KmphToKnots(self.speedmax))
    text=text..string.format("Speed cruise = %.1f Knots\n", UTILS.KmphToKnots(self.speedCruise))
    text=text..string.format("Elements     = %d\n", #self.elements)
    text=text..string.format("Waypoints    = %d\n", #self.waypoints)
    text=text..string.format("Radio        = %.1f MHz %s %s\n", self.radio.Freq, UTILS.GetModulationName(self.radio.Modu), tostring(self.radio.On))
    text=text..string.format("Ammo         = %d (G=%d/R=%d/M=%d/T=%d)\n", self.ammo.Total, self.ammo.Guns, self.ammo.Rockets, self.ammo.Missiles, self.ammo.Torpedos)
    text=text..string.format("FSM state    = %s\n", self:GetState())
    text=text..string.format("Is alive     = %s\n", tostring(self.group:IsAlive()))
    text=text..string.format("LateActivate = %s\n", tostring(self:IsLateActivated()))
    self:I(self.lid..text)
    
    -- Init done.
    self.groupinitialized=true
    
  end
  
  return self
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Option Functions
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Misc Functions
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Check for possible collisions between two coordinates.
-- @param #NAVYGROUP self
-- @param #number DistanceMax Max distance in meters ahead to check. Default 5000.
-- @param #number dx
-- @return #number Free distance in meters.
function NAVYGROUP:_CheckFreePath(DistanceMax, dx)

  local distance=DistanceMax or 5000
  local dx=dx or 100

  -- If the group is turning, we cannot really tell anything about a possible collision.
  if self:IsTurning() then
    return distance
  end
  
  -- Offset above sea level.
  local offsetY=0.1
  
  -- Current bug on Caucasus. LoS returns false.
  if UTILS.GetDCSMap()==DCSMAP.Caucasus then
    offsetY=5.01
  end
  
  -- Current coordinate.
  local coordinate=self:GetCoordinate():SetAltitude(offsetY, true)
  
  -- Current heading.
  local heading=self:GetHeading()
  
  -- Check from 500 meters in front.
  --coordinate=coordinate:Translate(500, heading, true)
  
  local function LoS(dist)
    local checkcoord=coordinate:Translate(dist, heading, true)
    return coordinate:IsLOS(checkcoord, offsetY)
  end

  -- First check if everything is clear.
  if LoS(DistanceMax) then
    return DistanceMax
  end
  
  local function check()
  
    local xmin=0
    local xmax=DistanceMax
    
    local Nmax=100
    local eps=100

    local N=1
    while N<=Nmax do
    
      local d=xmax-xmin
      local x=xmin+d/2
      
      local los=LoS(x)
      
      -- Debug message.
      self:T(self.lid..string.format("N=%d: xmin=%.1f xmax=%.1f x=%.1f d=%.3f los=%s", N, xmin, xmax, x, d, tostring(los)))
      
      if los and d<=eps then
        return x
      end
      
      if los then
        xmin=x
      else
        xmax=x
      end
    
      N=N+1
    end
  
    return 0
  end


  return check()
end

--- Check for possible collisions between two coordinates.
-- @param #NAVYGROUP self
-- @param Core.Point#COORDINATE coordto Coordinate to which the collision is check.
-- @param Core.Point#COORDINATE coordfrom Coordinate from which the collision is check.
-- @return #boolean If true, surface type ahead is not deep water.
-- @return #number Max free distance in meters.
function NAVYGROUP:_CheckCollisionCoord(coordto, coordfrom)

  -- Increment in meters.
  local dx=100

  -- From coordinate. Default 500 in front of the carrier.
  local d=0
  if coordfrom then
    d=0
  else
    d=250
    coordfrom=self:GetCoordinate():Translate(d, self:GetHeading())
  end

  -- Distance between the two coordinates.
  local dmax=coordfrom:Get2DDistance(coordto)

  -- Direction.
  local direction=coordfrom:HeadingTo(coordto)

  -- Scan path between the two coordinates.
  local clear=true
  while d<=dmax do

    -- Check point.
    local cp=coordfrom:Translate(d, direction)

    -- Check if surface type is water.
    if not cp:IsSurfaceTypeWater() then

      -- Debug mark points.
      if self.Debug or true then
        local st=cp:GetSurfaceType()
        cp:MarkToAll(string.format("Collision check surface type %d", st))
      end

      -- Collision WARNING!
      clear=false
      break
    end

    -- Increase distance.
    d=d+dx
  end

  local text=""
  if clear then
    text=string.format("Path into direction %03d° is clear for the next %.1f NM.", direction, UTILS.MetersToNM(d))
  else
    text=string.format("Detected obstacle at distance %.1f NM into direction %03d°.", UTILS.MetersToNM(d), direction)
  end
  self:T(self.lid..text)

  return not clear, d
end

--- Check if group is turning.
-- @param #NAVYGROUP self
function NAVYGROUP:_CheckTurning()

  local unit=self.group:GetUnit(1)
  
  if unit and unit:IsAlive() then

    -- Current orientation of carrier.
    local vNew=unit:GetOrientationX()
  
    -- Last orientation from 30 seconds ago.
    local vLast=self.Corientlast or vNew
  
    -- We only need the X-Z plane.
    vNew.y=0 ; vLast.y=0
  
    -- Angle between current heading and last time we checked ~30 seconds ago.
    local deltaLast=math.deg(math.acos(UTILS.VecDot(vNew,vLast)/UTILS.VecNorm(vNew)/UTILS.VecNorm(vLast)))
  
    -- Last orientation becomes new orientation
    self.Corientlast=vNew
  
    -- Carrier is turning when its heading changed by at least two degrees since last check.
    local turning=math.abs(deltaLast)>=2
  
    -- Check if turning stopped.
    if self.turning and not turning then
  
      -- Carrier was turning but is not any more.
      self:TurningStopped()
      
    elseif turning and not self.turning then
  
      -- Carrier was not turning but is now.
      self:TurningStarted()    
  
    end
  
    -- Update turning.
    self.turning=turning
    
  end
  
end

--- Check if group got stuck.
-- @param #NAVYGROUP self
function NAVYGROUP:_CheckStuck()

  if self:IsHolding() then
    return
  end

  local holdtime=0
  if self.holdtimestamp then
    holdtime=timer.getTime()-self.holdtimestamp
  end
  
  local ExpectedSpeed=self:GetExpectedSpeed()
  
  local speed=self:GetVelocity()
  
  if speed<0.5 and ExpectedSpeed>0 then
    if not self.holdtimestamp then
      self:E(self.lid..string.format("WARNING: Group came to an unexpected standstill. Speed=%.1f<%.1f m/s expected", speed, ExpectedSpeed))
      self.holdtimestamp=timer.getTime()
    end
  end
    
end



--- Check queued turns into wind.
-- @param #NAVYGROUP self
function NAVYGROUP:_CheckTurnsIntoWind()

  -- Get current abs time.
  local time=timer.getAbsTime()
  local Cnow=UTILS.SecondsToClock(time)

  -- Debug output:
  local text=string.format(self.lid.."Recovery time windows:")

  -- Handle case with no recoveries.
  if #self.Qintowind==0 then
    text=text.." none!"
  end

  -- Sort windows wrt to start time.
  table.sort(self.Qintowind, function(a, b) return a.Tstart<b.Tstart end)

  -- Loop over all slots.
  for _,_recovery in pairs(self.Qintowind) do
    local recovery=_recovery --#NAVYGROUP.IntoWind

    -- Get start/stop clock strings.
    local Cstart=UTILS.SecondsToClock(recovery.Tstart)
    local Cstop=UTILS.SecondsToClock(recovery.Tstop)

    -- Debug text.
    text=text..string.format("\n- Start=%s Stop=%s Open=%s Closed=%s", Cstart, Cstop, tostring(recovery.Open), tostring(recovery.Over))
  end

  -- Debug output.
  self:T(self.lid..text)


  -- Loop over all slots.
  for _,_recovery in pairs(self.Qintowind) do
    local recovery=_recovery --#NAVYGROUP.IntoWind

    if time>=recovery.Tstart and time<recovery.Tstop and not recovery.Open then
      self:TurnIntoWind(recovery)
      break
    end
    
  end

  -- If into wind, check if over.
  if self.intowind then  
    if timer.getAbsTime()>=self.intowind.Tstop then    
      self:TurnIntoWindOver()      
    end  
  end  
  
end

--- Check queued turns into wind.
-- @param #NAVYGROUP self
-- @return #NAVYGROUP.IntoWind Next into wind data.
function NAVYGROUP:GetNextTurnIntoWind()

  -- Loop over all windows.
  for _,_recovery in pairs(self.Qintowind) do
    local recovery=_recovery --#NAVYGROUP.IntoWind
    
  end

end

--- Get wind direction and speed at current position.
-- @param #NAVYGROUP self
-- @return #number Direction the wind is blowing **from** in degrees.
-- @return #number Wind speed in m/s.
function NAVYGROUP:GetWind()

  -- Current position of the carrier or input.
  local coord=self:GetCoordinate()

  -- Wind direction and speed. By default at 50 meters ASL.
  local Wdir, Wspeed=coord:GetWind(50)

  return Wdir, Wspeed
end

--- Get heading of group into the wind.
-- @param #NAVYGROUP self
-- @param #number Offset Offset angle in degrees, e.g. to account for an angled runway.
-- @return #number Carrier heading in degrees.
function NAVYGROUP:GetHeadingIntoWind(Offset)

  Offset=Offset or 0

  -- Get direction the wind is blowing from. This is where we want to go.
  local windfrom, vwind=self:GetWind()

  -- Actually, we want the runway in the wind.
  local intowind=windfrom-Offset

  -- If no wind, take current heading.
  if vwind<0.1 then
    intowind=self:GetHeading()
  end

  -- Adjust negative values.
  if intowind<0 then
    intowind=intowind+360
  end

  return intowind
end

--- Find free path to next waypoint.
-- @param #NAVYGROUP self
-- @return #boolean If true, a path was found.
function NAVYGROUP:_FindPathToNextWaypoint()

  -- Pathfinding A*
  local astar=ASTAR:New()
  
  -- Current positon of the group.
  local position=self:GetCoordinate()
  
  -- Next waypoint.
  local wpnext=self:GetWaypointNext()
  
  -- Next waypoint coordinate.
  local nextwp=wpnext.coordinate
  
  -- If we are currently turning into the wind...
  if wpnext.intowind then
    local hdg=self:GetHeading()
    nextwp=position:Translate(UTILS.NMToMeters(20), hdg, true)
  end
  
  local speed=UTILS.MpsToKnots(wpnext.speed)

  -- Set start coordinate.    
  astar:SetStartCoordinate(position)
  
  -- Set end coordinate.
  astar:SetEndCoordinate(nextwp)
  
  -- Distance to next waypoint.
  local dist=position:Get2DDistance(nextwp)
  
  local boxwidth=dist*2
  local spacex=dist*0.1
  local delta=dist/10
  
  -- Create a grid of nodes. We only want nodes of surface type water.
  astar:CreateGrid({land.SurfaceType.WATER}, boxwidth, spacex, delta, delta*2, self.Debug)
  
  -- Valid neighbour nodes need to have line of sight.
  astar:SetValidNeighbourLoS(400)
  
  --- Function to find a path and add waypoints to the group.
  local function findpath()
  
    -- Calculate path from start to end node.
    local path=astar:GetPath(true, true)
    
    if path then

      -- Loop over nodes in found path.
      local uid=self:GetWaypointCurrent().uid -- ID of current waypoint.
      
      for i,_node in ipairs(path) do
        local node=_node --Core.Astar#ASTAR.Node
          
        -- Add waypoints along detour path to next waypoint.
        local wp=self:AddWaypoint(node.coordinate, speed, uid)
        wp.astar=true
        
        -- Update id so the next wp is added after this one.
        uid=wp.uid

        -- Debug: smoke and mark path.
        node.coordinate:MarkToAll(string.format("Path node #%d", i))
        
      end
      
      return #path>0 
    else
      return false
    end
    
  end

  return findpath()

end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------