--[[ my move entity script

The player can move an entity up, down, forward or backward and turn it left and right.
To see which keys are used how, see the function loadScancodeMap.

Set the entity properties for "Static Mode = No", "Always Active? = Yes"
and this script for "AI System => Main".  Name this script and/or the init and main functions accordingly!

Features and Phenomena:

The player can "ride" the entity (TransportToIfUsed is called for this).
Unfortunately, the player cannot look up nor down so shooting while riding is an issue.
The player can "exit" the entity using the key defined (L to Land).  The landing
can take a while for high values of y.  One can go so high that the map is no longer visible.
Water landings are to be avoided due to drowning.
Physics must be off, and therefore the entity will plow through terrain, buildings and other entities.

The player was pulled through the buildings tested with; however, the player is pulled *over* terrain
and is not pulled under ground.  The entity goes through the hill; the player goes over it.
An entity can be "flown" into water; the player will drown if riding along.

For simulating flight, a momentum variable is turned on, and the entity will continue moving
in the chosen direction, even when no keys are pressed.  The player can disable this effect.

The player can fly the entity outside of the map boundaries.  If the player is riding along and
leaves the entity while outside the map boundaries, then the player will drown in invisible water.

The Panel displays the initial speed before use, and it displays the current speed setting when hovering.
In other words, it shows "speed" when stationary.  This could use some work...

The toggles donT work correctly.  :-(  It seems that the scan code is passed in more than once for each key pressed.
This applies to speed up and down too.  The speed will increase/decrease more than the increment set. 
]]


local activated = {}
local horizontal_vector = {}  -- forward or backward
local vertical_vector = {}  -- up or down
local yaw_angle = {}  -- a.k.a. turn angle
local Speed = {}
local Speed_change = {}  -- amount for speeding up or slowing down
local PlayerRides = {}   -- boolean for when player is riding the entity
local MomentumToggle = {}  -- if momentum is on, the entity will continue moving without player input.
local ScancodeMapToFunction = {}  -- function table for each key we use
local PanelToggle = {}  -- Toggle display of x,y,z, speed, distance.


function move_e_init(e)
  -- physics need to be off:
  GravityOff(e)
  CollisionOff(e)
  
  activated = 0
  horizontal_vector = "stationary"
  vertical_vector   = "stationary"
  yaw_angle = 40  -- a.k.a. turn angle
  Speed = 200
  Speed_change = 100
  PlayerRides = 0
  KeyPressed = 0
  
  PanelToggle = 1  -- display of x,y,z, speed, distance.
  
  MomentumToggle = 1  -- turn momentum off (set = 0) for finer control (or use M key).
  
  loadScancodeMap(e)  -- map keys to functions
  
end  -- init


function move_e_main(e)

  local KeyInput = {}
  local KeyPressed = {}

  if GetPlayerDistance(e) < 400 and activated == 0 then
    -- you might want to change how this script gets activated...
    activated = 1
	PromptDuration("Press PageUp for lift off or press g to Go, etc....", 5)
  end

  if activated == 1 then
  
    KeyInput = 0
	KeyPressed = 0
    KeyInput = GetScancode() -- get user input, if any
	if KeyInput > 0 then
	  KeyPressed = 1
	end
	
    if ScancodeMapToFunction[KeyInput] ~= nil and KeyPressed == 1 then
	  ScancodeMapToFunction[KeyInput](e)  -- call this matching function from our table
	end

	if  MomentumToggle == 1 then -- if momentum is on, then continue moving even if no key is pressed
      moveThis(e)
	end

    if PlayerRides == 1 then  -- if player is riding this entity
      TransportToIfUsed(e)    -- then drag the player along...
    end
	
    if PanelToggle == 1 then  -- display speed, location and distance:
      displayPanel(e)
    end	
  end  -- end if activated


end  -- main


function loadScancodeMap(e)

--[[ Map some keys to their functions.

   ScancodeMapToFunction is a table of scancodes and matching functions.
   Use this table like:  "ScancodeMapToFunction[KeyInput](e)" where KeyInput = GetScancode()
   and the appropriate function will execute.  Also:  "ScancodeMapToFunction[GetScancode()](e)".
   Encapsulate the call inside an "if ScancodeMapToFunction[KeyInput] ~= nil" to avoid an error.
   (If no function is defined for a key, a runtime error will otherwise be generated.)
   Example:
     KeyInput = GetScancode()
     if ScancodeMapToFunction[KeyInput] ~= nil then
       ScancodeMapToFunction[KeyInput](e)
     end
]]


ScancodeMapToFunction[23] = function (e)  -- i, player rides this entity.
  TransportToIfUsed(e)
  PlayerRides = 1
end


ScancodeMapToFunction[24] = function (e)  -- o, turn off, deactivate this script.
  activated = 0
  horizontal_vector = "stationary"
  vertical_vector   = "stationary"  
end


ScancodeMapToFunction[25] = function (e)  -- p, toggle Panel Display on/off of x,y,z, speed, distance
  if PanelToggle == 1 then
    PanelToggle = 0
  else
    PanelToggle = 1	
  end  
end


ScancodeMapToFunction[34] = function (e)  -- g, go forward
  MoveForward(e, Speed)
  horizontal_vector = "forward"
end


ScancodeMapToFunction[35] = function ()  -- h, hover
  horizontal_vector = "stationary"
  vertical_vector   = "stationary"
end


ScancodeMapToFunction[38] = function ()  -- l, if player is riding the entity, land the player
  PlayerRides = 0  -- player dismounts
end


ScancodeMapToFunction[44] = function (e)  -- z, turn left
  RotateY(e, -yaw_angle)
end


ScancodeMapToFunction[45] = function (e)  -- x, turn right
  RotateY(e, yaw_angle)
end


ScancodeMapToFunction[48] = function (e)  -- b, go backward
  MoveBackward(e, Speed)
  horizontal_vector = "backward"
end


ScancodeMapToFunction[50] = function ()  -- m, toggle momentum

  if MomentumToggle == 1 then
    MomentumToggle = 0
	PromptDuration("Momentum:  off", 3)	
  else
    MomentumToggle = 1
	PromptDuration("Momentum:  on", 3)	
  end

  -- turn off any vectors:
  horizontal_vector = "stationary"
  vertical_vector   = "stationary"  

end


ScancodeMapToFunction[74] = function ()  -- minus, slow down
  Speed = Speed - Speed_change
  if Speed < 0 then
    Speed = 0
  end
end


ScancodeMapToFunction[78] = function ()  -- +, speed up
  Speed = Speed + Speed_change
  -- might want to set a max-speed limit here...
end


ScancodeMapToFunction[201] = function (e)  -- PageUp, move entity up.
  if vertical_vector == "down" then
    vertical_vector = "level off"
  else
    MoveUp(e, Speed)
    vertical_vector = "up"
  end
end


ScancodeMapToFunction[209] = function (e)  -- PageDown, move entity down
  if vertical_vector == "up" then
    vertical_vector = "level off"
  else
    vertical_vector = "down"
    myMoveDown(e, Speed)
  end
end


end -- function loadScancodeMap


function moveThis(e)

  -- this function should only be called when momentum is on.
  if MomentumToggle == 0 then
    return
  end

  if horizontal_vector == "forward" then
    MoveForward(e, Speed)
  elseif horizontal_vector == "backward" then
    MoveBackward(e, Speed)
  end

  if vertical_vector == "up" then
    MoveUp(e, Speed)  
  elseif vertical_vector == "down" and g_Entity[e]['y'] > 0 then  -- donT drop below 0
    if g_Entity[e]['y'] > Speed then
      myMoveDown(e, Speed)
    else  -- getting deep
      if g_Entity[e]['y'] > 0 then
        myMoveDown(e, g_Entity[e]['y'])
	  
	    if g_Entity[e]['y'] < 0 then  -- settle down at y = 0 in case we missed it.
	      SetPosition(e, g_Entity[e]['x'], 0, g_Entity[e]['z'])
	      ResetPosition(e, g_Entity[e]['x'], 0, g_Entity[e]['z'])
	      vertical_vector = "level off"
        end	  
	  end
    end
  end

end  -- end function moveThis


function displayPanel(e)  -- display speed, location and distance:

  if PanelToggle ~= 1 then
    return  -- this function should only be called when the display is desired.
  end

  local Distance = {}
  Distance = math.floor(GetPlayerDistance(e)+0.5)
  if Distance < 40 then
    Distance = 0  -- setting to 0 flickers less.
  end
  Panel(3,90,80,98)
  Text(5,94,1, "Speed:  " .. math.floor(Speed+0.5))
  TextCenterOnX(40,94,1,  "Location[X][Y][Z]:  [" 
    .. math.floor(g_Entity[e]['x']+0.5) .. "]  [" .. math.floor(g_Entity[e]['y']+0.5)
    .. "]  [" .. math.floor(g_Entity[e]['z']+0.5) .. "]")
  Text(65,94,1, "Distance:  " .. Distance)	

end


function myMoveDown(e,v)
  MoveUp(e, -v)
end