Actor.lua

-- A few persistent-state options used
RAIL.Validate.TempFriendRange = {"number",-1,-1}

RAIL.Event["AI CYCLE"]:Register(-44,                      -- Priority
                                "Actor specialization",   -- Handler name
                                1,                        -- Max runs
                                function()                -- Handler function

  -- Track HP and SP
  do
    local update = RAIL.Owner.Update
    
    -- An extended variant of Update() to track HP and SP values
    RAIL.Owner.Update = function(self,...)
      -- First, call the regular update
      update(self,unpack(arg))
      
      -- Update the HP and SP tables
      History.Update(self.HP,GetV(V_HP,self.ID))
      History.Update(self.SP,GetV(V_SP,self.ID))

      return self
    end
    RAIL.Self.Update = RAIL.Owner.Update
    
    RAIL.Owner.GetMaxHP = function(self) return GetV(V_MAXHP,self.ID) end
    RAIL.Owner.GetMaxSP = function(self) return GetV(V_MAXSP,self.ID) end
    RAIL.Self.GetMaxHP = RAIL.Owner.GetMaxHP
    RAIL.Self.GetMaxSP = RAIL.Owner.GetMaxSP
    
    -- Use the maximum values as default, but don't calculate sub-update values
    RAIL.Owner.HP = History.New(GetV(V_MAXHP,RAIL.Owner.ID),false)
    RAIL.Owner.SP = History.New(GetV(V_MAXSP,RAIL.Owner.ID),false)
    RAIL.Self.HP = History.New(GetV(V_MAXHP,RAIL.Self.ID),false)
    RAIL.Self.SP = History.New(GetV(V_MAXSP,RAIL.Self.ID),false)
  end

  -- Never show up as either enemies or friends
  RAIL.Owner.IsEnemy  = function() return false end
  RAIL.Owner.IsFriend = function() return false end
  RAIL.Self.IsEnemy   = function() return false end
  RAIL.Self.IsFriend  = function() return false end

  -- Don't allow owner or self to expire
  RAIL.Owner.ExpireTimeout[1] = false
  RAIL.Owner.Active = true
  RAIL.Self.ExpireTimeout[1] = false
  RAIL.Self.Active = true

  -- Add a function to the AI's self
  RAIL.Self.GetUsableSP = function(self,skill)
    local state = RAIL.State.SkillOptions[skill.ID]
    local reserved_sp = state.ReservedSP

    if state.ReservedSPisPercent then
      reserved_sp = math.ceil(reserved_sp / 100 * self:GetMaxSP())
    end

    return self.SP[0] - reserved_sp
  end
end)

-- Actor data-collection
do
  -- This unique table ID will be used as a key to identify Actor tables
  local actor_key = {}

  RAIL.IsActor = function(actor)
    if type(actor) ~= "table" then return false end
    if actor[actor_key] == nil then return false end
    return true
  end

  -- The Actor "class" is private, because they're generated by referencing Actors
  local Actor = { }

  -- Metatables
  local Actor_mt = {
    __eq = function(self,other)
      if not RAIL.IsActor(other) then return false end

      return self.ID == other.ID
    end,

    __index = Actor,

    -- When tostring() is called on Actors, we want sensible output
    __tostring = function(self)
      local buf = StringBuffer.New()
        :Append(self.ActorType):Append(" #"):Append(self.ID)
        :Append(" [Loc:(")
          :Append(self.X[0]):Append(","):Append(self.Y[0])
        :Append(")")

      if self.Type ~= -2 then
        buf:Append(", Type:"):Append(self.Type)
      end

      if self.BattleOpts.Name ~= RAIL.State.ActorOptions.Default.Name then
        buf:Append(", Name:"):Append(self.BattleOpts.Name)
      end

      return buf:Append("]"):Get()
    end
  }

  -- Private key for keeping closures
  local closures = {}

  -- Private key of TargetOf, to keep the time of last table update
  local targeted_time = {}

  -- Position tracking uses a specialty "diff" function
  local pos_diff = function(a_value,a_time,b_value,b_time)
    -- If a tile changed, then the position is different
    if math.abs(a_value-b_value) >= 1 then return true end

    -- If enough time has passed, count the position as different
    --  Note: This ensures that subvalues will be accurately calculated
    --  Note: This isn't really needed...
    --if math.abs(a_time-b_time) > 500 then return true end

    -- Otherwise, the position is still the same
    return false
  end

  -- BattleOpts metatable
  local battleopts_parent = {}
  local seen_types = {
    ["NPC"] = true,
    [45] = true,
  }
  local battleopts_mt = {
    __index = function(self,key)
      self = self[battleopts_parent]

      -- First, check ByID table
      local ret = RAIL.State.ActorOptions.ByID[self.ID][key]
      if ret ~= nil then
        return ret
      end

      -- Then, check ByType table
      if self.Type ~= -2 then
        -- Get the table for this type
        local type_state = rawget(RAIL.State.ActorOptions.ByType,self.Type)

        -- If there was no table yet, log it and then generate it
        if not type_state then
          -- Generate the table automatically
          type_state = RAIL.State.ActorOptions.ByType[self.Type]
          
          -- Check if this is the first instance
          if not seen_types[self.Type] and not seen_types[self.ActorType] then
            local type_name = ""
            if
              type(type_state.Name) == "string" and
              type_state.Name ~= RAIL.State.ActorOptions.Default.Name
            then
              type_name = " (" .. type_state.Name .. ")"
            end
            -- Log it
            RAIL.LogT(55,
                      "Actor type #{1}{2} not in state-file; only logging first occurrence.",
                      self.Type,
                      type_name)

            -- Set this type as seen
            seen_types[self.Type] = true
          end
        end
        ret = type_state[key]
        if ret ~= nil then
          return ret
        end
      end

      -- If all else fails, use the defaults
      return RAIL.State.ActorOptions.Default[key]
    end,
  }

  -- Initialize a new Actor
  Actor.New = function(self,ID)
    local ret = { }
    setmetatable(ret,Actor_mt)

    ret.ActorType = "Actor"
    ret.ID = ID
    ret.Active = false            -- false = expired; true = active
    ret.Type = -1                 -- "fixed" type (homus don't overlap players)
    ret.Hide = false              -- hidden?
    ret.LastCycle  = RAIL.CycleID -- Unique cycle to see if actor was updated this round
    ret.LastUpdate = -1           -- GetTick() of last :Update() call
    ret.FullUpdate = false        -- Track position, motion, target, etc?
    ret.TargetOf = Table:New()    -- Other Actors that are targeting this one
    ret.IgnoreTime = -1           -- Actor isn't currently ignored
    ret.BattleOpts = { }          -- Battle options
    ret.BattleOpts[battleopts_parent] = ret

    -- Set defaults for battle options
    setmetatable(ret.BattleOpts,battleopts_mt)

    -- The following have their histories tracked
    ret.Target = History.New(-1,false)
    ret.Motion = History.New(MOTION_STAND,false)

    -- And they'll also predict sub-history positions
    ret.X = History.New(-1,true,pos_diff)
    ret.Y = History.New(-1,true,pos_diff)

    -- Set initial position
    local x,y = GetV(V_POSITION,ret.ID)
    if x ~= -1 or y ~= nil then
      -- Hiding?
      if
        (x ==  0 and y ==  0) or
        (x == -1 and y == -1)
      then
        ret.Hide = true
      else
        History.Update(ret.X,RoundNumber(x))
        History.Update(ret.Y,RoundNumber(y))
      end
    end

    -- Set up the expiration timeout for 2.5 seconds...
    --  (it will be updated in Actor.Update)
    ret.ExpireTimeout = RAIL.Timeouts:New(2500,false,Actor.Expire,ret,"timeout")

    -- Create tables to hold the closures
    ret[closures] = {
      DistanceTo = {},
      BlocksTo = {},
      AngleTo = {},
      AngleFrom = {},
      AnglePlot = {},
    }

    -- Initialize the type
    Actor[actor_key](ret)

    -- Log
    if ID ~= -1 then
      RAIL.LogT(40,"Actor class generated for {1}.",ret)
      -- Extra data displayed for mercenary AIs
      if false and RAIL.Mercenary then
        -- Mercenaries should log extra information for Actors and NPCs
        if ret.ActorType == "Actor" or ret.ActorType == "NPC" then
          RAIL.LogT(40,"   --> {1}",StringBuffer.New()
            --:Append("V_TYPE="):Append(GetV(V_TYPE,ret.ID)):Append("; ")
            --:Append("V_HOMUNTYPE="):Append(GetV(V_HOMUNTYPE,ret.ID)):Append("; ")
            --:Append("V_MERTYPE="):Append(GetV(V_MERTYPE,ret.ID)):Append("; ")
            --:Append("V_MOTION="):Append(GetV(V_MOTION,ret.ID)):Append("; ")
            --:Append("V_TARGET="):Append(GetV(V_TARGET,ret.ID)):Append("; ")
            --:Append("IsMonster="):Append(IsMonster(ret.ID)):Append("; ")
            :Get()
          )
        end
      end
    end

    return ret
  end

  -- A temporary "false" return for IsEnemy, as long as an actor is a specific type
  local ret_false = function() return false end

  -- A "private" function to initialize new actor types
  do
    Actor[actor_key] = {
      [true] = function(self,t,notnpc)
        -- Set the new type
        self[actor_key] = t
        self.Type = t

        -- Check the type for sanity
        if (self.ID < 100000 or self.ID > 110000000) and
          -- Homunculus types
          ((1 <= self.Type and self.Type <= 16) or
          -- Mercenary types
          (17 <= self.Type and self.Type <= 46)) and
          -- Not a portal
          (self.Type ~= 45 or notnpc)
        then
          self.Type = self.Type + 6000
        end
  
        -- Initialize differently based upon type
        if self.Type == -1 then
          -- Unknowns are never enemies, but track data
          return "Unknown",false,true
  
        -- Portals
        elseif self.Type == 45 then
          -- Portals are never enemies and shouldn't be tracked
          return "Portal",false,false
  
        -- Player Jobs
        elseif 
          (0    <= self.Type and self.Type <= 25) or
          (161  <= self.Type and self.Type <= 181) or
          (4001 <= self.Type and self.Type <= 4049)
        then
          -- Players are potential enemies and should be tracked
          return "Player",true,true

        -- AI-controlled (homunc, mercenary)
        --  TODO: Find what the cap for AI-controlled actors should properly be.
        elseif 6000 < self.Type and self.Type <= 6046 then
          -- AIs are similar to players: potential enemies, should be tracked
          return "AI",true,true

        -- NPCs (non-player jobs that are below 1000)
        elseif self.Type < 1000 then
          -- NPCs are never enemies and shouldn't be tracked
          return "NPC",false,false
  
        -- All other types
        else
          -- All other actors are probably monsters or homunculi
          return "Actor",true,true
        end
      end,
      [false] = function(self,t,notnpc)
        self[actor_key] = t
        self.Type = t

        -- Find players based on ID
        if self.ID >= 100000 and self.ID <= 110000000 then
          -- Likely a player
          return "Player",true,true

        -- NPCs and Portals stand still and are never monsters
        elseif
          not notnpc and
          IsMonster(self.ID) == 0 and
          not self.WasMonster and
          GetV(V_MOTION,self.ID) == MOTION_STAND and
          GetV(V_TARGET,self.ID) == 0
        then
          -- Likely an NPC
          return "NPC",false,false

        -- All other types
        else
          return "Actor",true,true
        end
      end,
    }
    setmetatable(Actor[actor_key],{
      __call = function(self,actor,...)
        -- Get the type from MobID handler
        local t = RAIL.MobID[actor.ID]

        -- Pass it to the proper function
        local possibleEnemy
        actor.ActorType,possibleEnemy,actor.FullUpdate = self[t ~= -2](actor,t,unpack(arg))

        if possibleEnemy then
          if rawget(actor,"IsEnemy") == ret_false then
            rawset(actor,"IsEnemy",nil)
          end
        else
          actor.IsEnemy = ret_false
        end
      end,
    })
  end

  -- Update information about the actor
  Actor.Update = function(self)
    -- Check if the actor is dead
    if GetV(V_MOTION,self.ID) == MOTION_DEAD then
      -- If the actor is still active, cause it to expire
      if self.ExpireTimeout[1] then
        self:Expire("death")
      end
      return self
    end

    -- Check for a type change
    if RAIL.MobID[self.ID] ~= self[actor_key] then
      -- Pre-log
      local str = tostring(self)

      -- Call the private type changing function
      Actor[actor_key](self)

      -- Log
      RAIL.LogT(40,"{1} changed type to {2}.",str,tostring(self))
    elseif self.Type == 45 and GetV(V_MOTION,self.ID) ~= MOTION_STAND then
      -- Call the private type changing function
      Actor[actor_key](self,true)

      -- Log
      RAIL.LogT(40,"Incorrectly identified {1} as a Portal; fixed.",self)
    elseif self.Type == -2 and self.ActorType == "NPC" and GetV(V_MOTION,self.ID) ~= MOTION_STAND then
      -- Call the private type changing function
      Actor[actor_key](self,true)

      -- Log
      RAIL.LogT(40,"Incorrectly identified {1} as an NPC; fixed.",self)
    end

    -- Update ignore time
    if self.IgnoreTime > 0 then
      self.IgnoreTime = self.IgnoreTime - (GetTick() - self.LastUpdate)
    end
    
    -- Update the expiration timeout
    self.ExpireTimeout[2] = GetTick()
    if not self.ExpireTimeout[1] and not self.Active then
      self.ExpireTimeout[1] = true
      RAIL.Timeouts:Insert(self.ExpireTimeout)
      
      -- Add the X and Y position
      local x,y = GetV(V_POSITION,self.ID)
      if x ~= -1 then
        History.Update(self.X,x)
        History.Update(self.Y,y)
      end

      -- Log its reactivation
      RAIL.LogT(40,"Reactivating {1}.",self)
    end

    -- Update the LastUpdate and LastCycle fields
    self.LastUpdate = GetTick()
    self.LastCycle  = RAIL.CycleID

    -- The actor is active unless it expires
    self.Active = true

    -- Some actors don't require everything tracked
    if not self.FullUpdate then
      return self
    end

    -- Update the motion
    History.Update(self.Motion,GetV(V_MOTION,self.ID))

    -- Update the actor location
    local x,y = GetV(V_POSITION,self.ID)
    if x ~= -1 or y ~= nil then
      -- Check for hidden
      if
        (x ==  0 and y ==  0) or
        (x == -1 and y == -1)
      then
        if not self.Hide then
          -- Log it
          RAIL.LogT(60,"{1} became invisible.",self)
          self.Hide = true
        end
      else
        -- Make sure the X,Y integers are even
        x,y = RoundNumber(x,y)

        if self.Hide then
          -- Log it
          RAIL.LogT(60,"{1} is no longer invisible.",self)
          self.Hide = false
        end
        History.Update(self.X,x)
        History.Update(self.Y,y)
      end
    end
    
    -- Check if the actor is able to have a target
    if self.Motion[0] ~= MOTION_SIT then
      -- Get the current target
      local targ = GetV(V_TARGET,self.ID)

      -- Normalize it...
      if targ == 0 then
        targ = -1
      end

      -- Keep a history of it
      History.Update(self.Target,targ)

      -- Tell the other actor that it's being targeted
      if targ ~= -1 then
        Actors[targ]:TargetedBy(self)
      end
    else
      -- Can't target, so it should be targeting nothing
      History.Update(self.Target,-1)
    end

    -- Clear the targeted-by table if it's old
    if math.abs((self.TargetOf[targeted_time] or 0) - GetTick()) > 50 then
      self.TargetOf = Table:New()
    end

    return self
  end

  -- Track when other actors target this one
  Actor.TargetedBy = function(self,actor)
    -- If something targets an NPC, it isn't an NPC
    if self.Type == -2 and self.ActorType == "NPC" then
      -- Call the private type changing function
      Actor[actor_key](self,true)

      -- Log
      RAIL.LogT(40,"Incorrectly identified {1} as an NPC; fixed.",self)
    elseif self.Type == 45 then
      -- Call the private type changing function
      Actor[actor_key](self,true)

      -- Log
      RAIL.LogT(40,"Incorrectly identified {1} as a Portal; fixed.",self)
    end

    -- Use a table to make looping through and counting it faster
    --  * to determine if an actor is targeting this one, use Actors[id].Target[0] == self.ID
    if math.abs((self.TargetOf[targeted_time] or 0) - GetTick()) > 50 then
      self.TargetOf = Table:New()
      self.TargetOf[targeted_time] = GetTick()
    end

    self.TargetOf:Insert(actor)
    return self
  end

  -- Clear out memory
  Actor.Expire = function(self,reason)
    -- Check if the reason is supposed to be timeout, but the actor was
    -- updated this cycle
    if reason == "timeout" and self.LastCycle == RAIL.CycleID then
      -- Don't actually expire; something just caused the script to lag hard
      return
    end

    -- Log
    RAIL.LogT(40,"Clearing history for {1} due to {2}.",self,reason)

    -- Unset any per-actor battle options
    for k,v in pairs(self.BattleOpts) do
      self.BattleOpts[k] = nil
    end
    self.BattleOpts[battleopts_parent] = self

    -- Clear the histories
    History.Clear(self.Motion)
    History.Clear(self.Target)
    History.Clear(self.X)
    History.Clear(self.Y)

    -- Disable the timeout
    self.ExpireTimeout[1] = false

    -- Disable the active flag
    self.Active = false
  end

  -------------
  -- Support --
  -------------
  -- The following functions support other parts of the script

  -- Check if the actor is an enemy (monster/pvp-player)
  Actor.IsEnemy = {
    ["Actor"] = function(self)
      -- Check if the actor ever had IsMonster() return 1
      if not self.WasMonster then
        -- Check if it's a monster
        if IsMonster(self.ID) ~= 1 then
          return false
        end
        
        -- Make sure this is counted as an enemy until AI resets
        self.WasMonster = true
      end

      -- Check if it should be defended against only
      if self.BattleOpts.DefendOnly then
        -- Check if its target is owner, self, other, or a friend
        local target = Actors[self.Target[0]]
        if
          target ~= RAIL.Owner and
          target ~= RAIL.Self and
          target ~= RAIL.Other and
          not target:IsFriend()
        then
          -- Not attacking a friendly, so not an enemy
          return false
        end
      end
  
      -- Check if the monster is dead
      if self.Motion[0] == MOTION_DEAD then
        return false
      end
  
      -- Check if the monster is in a sane location
      if self.X[0] == -1 or self.Y[0] == -1 then
        return false
      end
  
      -- Default to true
      return true
    end,
    ["Player"] = function(self)
      -- Check if the player is set as a friend
      if self:IsFriend() then
        -- Friends are never enemies
        return false
      end
      
      -- Otherwise, act like a regular actor
      return Actor.IsEnemy["Actor"](self)
    end,
  }
  setmetatable(Actor.IsEnemy,{
    __call = function(self,...)
      -- Note: when calling actor:IsEnemy, self will be Actor.IsEnemy table and
      --  arg[1] will be actor (true "self")
      local true_self = arg[1]
      
      -- Get the function based on the actor type
      local f
      if type(true_self) == "table" then
        f = self[true_self.ActorType]
      end
      if not f then
        f = self["Actor"]
      end
      
      -- Call the actual function
      return f(unpack(arg))
    end,
  })

  -- Check if the actor is a friend
  Actor.IsFriend = {
    ["Actor"] = function(self,no_temp)
      -- Non-players and non-AIs should never ocunt as friends
      return false
    end,
    ["Player"] = function(self,no_temp)
      -- Check for temporary friends (players within <opt> range of owner)
      if
        not no_temp and
        RAIL.Owner:DistanceTo(self) <= RAIL.State.TempFriendRange
      then
        return true
      end

      -- Check if the actor is set as a permanent friend
      return self.BattleOpts.Friend
    end,
    ["AI"] = function(self,no_temp)
      -- If disallowing temporary friends, AIs should never count
      if no_temp then
        return false
      end

      -- Only friend if within a certain range
      return RAIL.Owner:DistanceTo(self) <= RAIL.State.TempFriendRange
    end,
  }
  -- IsEnemy and IsFriend function essentially the same way
  setmetatable(Actor.IsFriend,getmetatable(Actor.IsEnemy))

  -- Set actor as a friend
  Actor.SetFriend = {
    ["Actor"] = function(self,bool)
      -- Normal actors shouldn't be put on the permanent friend list
      return
    end,
    ["Player"] = function(self,bool)
      -- Check if there is already a ByID field for this actor
      if not RAIL.State.ActorOptions.ByID[self.ID] then
        -- No table exists for this actor, create it
        RAIL.State.ActorOptions.ByID[self.ID] = {
          ["Friend"] = bool,
        }
      else
        -- Table exists, update the friend value
        RAIL.State.ActorOptions.ByID[self.ID].Friend = bool
      end
    end,
  }
  -- SetFriend and IsFriend function the same way
  setmetatable(Actor.SetFriend,getmetatable(Actor.IsFriend))

  -- Check if the actor is ignored
  Actor.IsIgnored = function(self)
    return self.IgnoreTime > 0
  end

  -- Ignore the actor for a specific amount of time
  Actor.Ignore = function(self,ticks)
    -- Use default ticks if needed
    if type(ticks) ~= "number" then
      ticks = self.BattleOpts.DefaultIgnoreTicks
    end

    -- If it's already ignored, do nothing
    if self:IsIgnored() then
      -- Update the ignore time to whichever is higher
      self.IgnoreTime = math.max(ticks,self.IgnoreTime)

      return self
    end

    RAIL.LogT(20,"{1} ignored for {2} milliseconds.",self,ticks)

    self.IgnoreTime = ticks
  end

  -- Estimate Movement Speed (in milliseconds per cell) and Direction
  local estimate_key = {}
  Actor.EstimateMove = function(self)
    -- Ensure we have a place to store estimation data
    if not self[estimate_key] then
      self[estimate_key] = {
        -- Default move-speed to regular walk
        --  according to http://forums.roempire.com/archive/index.php/t-137959.html:
        --    0.15 sec per cell at regular speed
        --    0.11 sec per cell w/ agi up
        --    0.06 sec per cell w/ Lif's emergency avoid
        --
        -- Default move-direction to straight north; the same as the server seems to
        speed = 150,
        angle = 90,

        -- Last time calculated was never
        last = 0,
        last_move = 0,
        last_non_move = 0,

        -- And the distance used to calculate speed was 1
        --  Note: Greater or equal distances will recalculate,
        --    to prevent infinite speeds (0 distance)
        dist = 1,
      }
    end

    -- Get the estimation data table
    local estimate = self[estimate_key]

    -- Don't estimate too often
    if GetTick() - estimate.last <= 250 then
      return estimate.speed, estimate.angle
    end

    -- Get the list of motions for the actor
    local motion_list = History.GetConstList(self.Motion)

    -- Loop from the most recent to the oldest
    local move
    local non_move
    for i=motion_list.last,motion_list.first,-1 do
      -- Check for a movement motion
      if motion_list[i][1] == MOTION_MOVE then
        -- Get the time of the motion start
        move = motion_list[i][2]

        -- Check if we're at the most recent motion
        if i == motion_list.last then
          -- Get the current time
          non_move = GetTick()
        else
          -- Get the time of the more-recent motion start
          non_move = motion_list[i+1][2]
        end

        -- Ensure that the motions are sufficiently far apart (in time or distance)
        local move_delta = GetTick() - move
        local non_move_d = GetTick() - non_move
        if
          non_move - move >= 100 or
          BlockDistance(self.X[non_move_d],self.Y[non_move_d],self.X[move_delta],self.Y[non_move_d]) > 0
        then
          -- Use these values
          break
        end

        -- Don't use these values
        move = nil
        non_move = nil
      end
    end

    -- If no new moves were found, return from estimate
    if
      -- No move found
      move == nil or
      -- Move is same as last estimation
      (move == estimate.last_move and non_move == estimate.last_non_move)
    then
      return estimate.speed, estimate.angle
    end

    -- Store the move and non_move times we're using
    estimate.last_move = move
    estimate.last_non_move = non_move

    -- Get the X and Y position lists
    local x_list = History.GetConstList(self.X)
    local y_list = History.GetConstList(self.Y)

    -- Find the position (in list) closest to non_move
    local begin_x = x_list:BinarySearch(non_move)
    local begin_y = y_list:BinarySearch(non_move)

    -- Begin searching backward into history
    local i_x,i_y = begin_x,begin_y
    while true do
      -- Get the X,Y coords
      local x = x_list[i_x][1]
      local y = y_list[i_y][1]

      -- Check to see if we can search further back
      local next_i_x = i_x
      if i_x-1 >= x_list.first and x_list[i_x-1][2] >= move then
        next_i_x = i_x - 1
      end
      local next_i_y = i_y
      if i_y-1 >= y_list.first and y_list[i_y-1][2] >= move then
        next_i_y = i_y - 1
      end

      -- Check if we've reached the back
      if next_i_x == i_x and next_i_y == i_y then
        break
      end

      -- Find the next changed point
      if x_list[next_i_x][2] > y_list[next_i_y][2] and next_i_x ~= i_x then
        next_i_y = i_y
      elseif x_list[next_i_x][2] < y_list[next_i_y][2] and next_i_y ~= i_y then
        next_i_x = i_x
      end

      -- Get the angle of the two adjacent points
      local angle = GetAngle(
        x_list[next_i_x][1],y_list[next_i_y][1],
        x,y
      )

      -- Get the angle of the beginning to our current point
      local angle2 = GetAngle(
        x,y,
        x_list[begin_x][1],y_list[begin_y][1]
      )

      -- If x,y are still at beginning position, move to next
      if angle ~= -1 and angle2 ~= -1 then
        -- Check to see if the angle is within 45 degrees either way
        if not CompareAngle(angle,angle2+45,90) then
          -- Doesn't match
          break
        end

        -- Check if the distance is great enough
        local blocks = BlockDistance(x,y,x_list[begin_x][1],y_list[begin_y][1])
        if blocks >= 6 then
          break
        end
      end

      i_x = next_i_x
      i_y = next_i_y
    end

    -- Get the beginning position and end position
    --  Note: begin refers to the most recent, so it becomes x2,y2
    local x2,y2 = x_list[begin_x][1],y_list[begin_y][1]
    local x1,y1 = x_list[i_x][1],y_list[i_y][1]

    -- Get the angle and the block distance
    local angle = GetAngle(x1,y1,x2,y2)
    local dist = BlockDistance(x1,y1,x2,y2)

    -- Ensure we're still sane
    --  Note: And don't repeat logs for the same angle
    if angle ~= -1 and angle ~= estimate.angle then
      -- Store our estimated angle
      estimate.angle = angle

      -- Log it
      RAIL.LogT(80,"Movement angle for {1} estimated at {2} degrees.",
        self,RoundNumber(estimate.angle))
    end

    -- Check if we've calculated a better speed than before
    if dist >= estimate.dist then
      -- Store our speed and distance

      estimate.dist = dist

      -- Get the tick delta
      local tick_delta_x = x_list[begin_x][2] - x_list[i_x][2]
      local tick_delta_y = y_list[begin_y][2] - y_list[i_y][2]
      local tick_delta = math.max(tick_delta_x,tick_delta_y)

      estimate.speed = tick_delta / dist

      -- Store the time of last estimation
      estimate.last = GetTick()

      -- Log it
      RAIL.LogT(80,"Movement speed for {1} estimated at {2}ms/tile (dist={3}).",
        self,RoundNumber(estimate.speed),estimate.dist)
    end

    -- And return
    return estimate.speed, estimate.angle
  end

  --------------------
  -- Battle Options --
  --------------------

  -- RAIL allowed to attack monster?
  Actor.IsAttackAllowed = function(self)
    -- Determine if we are allowed to attack the monster
    if not self:IsEnemy() then
      return false
    end

    if not self.BattleOpts.AttackAllowed then
      return false
    end

    local last_attack = self.BattleOpts.LastAttack or 0
    if GetTick() < last_attack + self.BattleOpts.TicksBetweenAttack then
      return false
    end
    
    return true
  end

  -- RAIL allowed to cast against monster?
  Actor.IsSkillAllowed = function(self,level)
    -- Check if skills are allowed
    if not self:IsEnemy() or not self.BattleOpts.SkillsAllowed then
      return false
    end

    -- Check that the skill level is high enough
    if level < self.BattleOpts.MinSkillLevel then
      return false
    end

    -- Check if we've reached max cast count
    if
      (self.BattleOpts.CastsAgainst or 0) >= self.BattleOpts.MaxCastsAgainst and
      self.BattleOpts.MaxCastsAgainst >= 0
    then
      return false
    end

    -- Check if we should wait before casting against this actor
    if RAIL.SkillState:CompletedTime() + self.BattleOpts.TicksBetweenSkills > GetTick() then
      return false
    end

    -- Skills are allowed (and hint at the max skill level)
    return true,math.min(self.BattleOpts.MaxSkillLevel,level)
  end

  -- Determine if attacking this actor would be kill-stealing
  Actor.WouldKillSteal = function(self)
    -- Free-for-all monsters are never kill-stealed
    if self.BattleOpts.FreeForAll then
      return false
    end

    -- Check if it's an enemy
    if not self:IsEnemy() then
      return false
    end

    -- Check if this actor is targeting anything
    local targ = self.Target[0]
    if targ ~= -1 then
      -- Owner and self don't count
      if targ == RAIL.Self.ID or targ == RAIL.Owner.ID then
        return false
      end

      local targ = Actors[targ]

      -- Can't kill steal friends
      if targ:IsFriend() then
        return false
      end

      -- Determine if it's not targeting another enemy
      if not targ:IsEnemy() then

        -- Determine if the target has been updated recently
        if targ.Active then
          -- It would be kill stealing
          return true
        end

      end
    end

    -- Check if this actor is the target of anything
    -- Note: TargetOf table will always be fresh by the time this is called
    for i=1,self.TargetOf:Size(),1 do
      targ = self.TargetOf[i]

      -- Determine if the targeter is...
      if
        targ ~= RAIL.Owner and        -- not the owner
        targ ~= RAIL.Self and       -- not ourself
        not targ:IsEnemy() and        -- not an enemy
        not targ:IsFriend() and       -- not a friend
        true
      then
        -- Likely kill-stealing
        return true
      end
    end

    -- Check if the monster is probably part of a mob-train
    -- TODO: Check for monster chasing another

    -- Default is not kill-steal
    return false
  end



  -- Kite / Attack**
  --  **- based partially on shared table, based partially on homu's current HP?

  --------------------
  -- Utils Wrappers --
  --------------------

  -- The following wrappers are fairly complex, so here are some examples:
  --
  --  RAIL.Owner:DistanceTo(x,y)
  --    Returns the pythagorean distance between owner and (x,y)
  --
  --  RAIL.Owner:DistanceTo(-500)(x,y)
  --    Returns the pythagorean distance between (x,y) and the owner's
  --    estimated position at 500 milliseconds into the future
  --
  --  RAIL.Owner:DistanceTo(RAIL.Self)
  --    Returns the pythagorean distance between owner and homu/merc
  --
  --  RAIL.Owner:DistanceTo(500)(RAIL.Self)
  --    Returns the pythagorean distance between owner's position
  --    500 milliseconds ago, and the homu/merc's position 500 milliseconds ago
  --
  --  RAIL.Owner:DistanceTo(RAIL.Self.X[500],RAIL.Self.Y[500])
  --    Returns the pythagorean distance between owner's current position
  --    and the homu/merc's position 500 milliseconds ago
  --
  --  RAIL.Owner:DistanceTo(-500)(RAIL.Self.X[0],RAIL.Self.Y[0])
  --    Returns the pythagorean distance between owner's estimated position
  --    (500ms into future), and homu/merc's current position.
  --
  -- Remember:
  --  - negative values represent future (estimated)
  --  - positive values represent past (recorded)
  --
  --

  -- Closures will timeout and be removed after 10 seconds of non-use
  local closure_timeout = 10000

  -- Pythagorean Distance
  Actor.DistanceTo = function(self,a,b)
    -- Check if a specific closure is requested
    if type(a) == "number" and b == nil then

      -- Check if a closure already exists
      if not self[closures].DistanceTo[a] then

        -- Create table to hold the closure
        local table = {}
        self[closures].DistanceTo[a] = table

        -- Create closure
        table.func = function(x,y)
          -- Main function logic follows

          -- Check if "x" is an actor table
          if RAIL.IsActor(x) then
            y = x.Y[a]
            x = x.X[a]
          end

          return PythagDistance(self.X(a),self.Y(a),x,y)

        end -- function(x,y)

        -- Add a timeout to remove the table
        table.timeout = RAIL.Timeouts:New(closure_timeout,false,function()
          self[closures].DistanceTo[a] = nil
        end)

      end -- not self[closures].DistanceTo[a]

      -- Update the timeout
      self[closures].DistanceTo[a].timeout[2] = GetTick()

      -- Return the requested closure
      return self[closures].DistanceTo[a].func
    end

    -- Not requesting specific closure, so use 0
    return Actor.DistanceTo(self,0)(a,b)
  end

  -- Straight-line Block Distance
  Actor.BlocksTo = function(self,a,b)
    -- Check if a specific closure is requested
    if type(a) == "number" and b == nil then

      -- Check if a closure already exists
      if not self[closures].BlocksTo[a] then

        -- Create table to hold the closure
        local table = {}
        self[closures].BlocksTo[a] = table

        -- Create closure
        table.func = function(x,y)
          -- Main function logic follows

          -- Check if "x" is an actor table
          if RAIL.IsActor(x) then
            y = x.Y[a]
            x = x.X[a]
          end

          return BlockDistance(self.X[a],self.Y[a],x,y)

        end -- function(x,y)

        -- Add a timeout to remove the table
        table.timeout = RAIL.Timeouts:New(closure_timeout,false,function()
          self[closures].BlocksTo[a] = nil
        end)

      end -- not self[closures].BlocksTo[a]

      -- Update the timeout
      self[closures].BlocksTo[a].timeout[2] = GetTick()

      -- Return the requested closure
      return self[closures].BlocksTo[a].func
    end

    -- Not requesting specific closure, so use 0
    return Actor.BlocksTo(self,0)(a,b)
  end

  -- Angle from actor to point
  Actor.AngleTo = function(self,a,b)
    -- Check if a specific closure is requested
    if type(a) == "number" and b == nil then

      -- Check if a closure already exists
      if not self[closures].AngleTo[a] then

        -- Create table to hold the closure
        local table = {}
        self[closures].AngleTo[a] = table

        -- Create closure
        table.func = function(x,y)
          -- Main function logic follows

          -- Check if "x" is an actor table
          if RAIL.IsActor(x) then
            y = x.Y[a]
            x = x.X[a]
          end

          return GetAngle(self.X[a],self.Y[a],x,y)
        end -- function(x,y)

        -- Add a timeout to remove the table
        table.timeout = RAIL.Timeouts:New(closure_timeout,false,function()
          self[closures].AngleTo[a] = nil
        end)

      end -- not self[closures].AngleTo[a]

      -- Update the timeout
      self[closures].AngleTo[a].timeout[2] = GetTick()

      -- Return the requested closure
      return self[closures].AngleTo[a].func
    end

    -- Not requesting specific closure, so use 0
    return Actor.AngleTo(self,0)(a,b)
  end

  -- Angle from point to actor
  Actor.AngleFrom = function(self,a,b)
    -- Check if a specific closure is requested
    if type(a) == "number" and b == nil then

      -- Check if a closure already exists
      if not self[closures].AngleFrom[a] then

        -- Create table to hold the closure
        local table = {}
        self[closures].AngleFrom[a] = table

        -- Create closure
        table.func = function(x,y)
          -- Main function logic follows

          -- Check if "x" is an actor table
          if RAIL.IsActor(x) then
            y = x.Y[a]
            x = x.X[a]
          end

          return GetAngle(x,y,self.X[a],self.Y[a])
        end -- function(x,y)

        -- Add a timeout to remove the table
        table.timeout = RAIL.Timeouts:New(closure_timeout,false,function()
          self[closures].AngleFrom[a] = nil
        end)

      end -- not self[closures].AngleFrom[a]

      -- Update the timeout
      self[closures].AngleFrom[a].timeout[2] = GetTick()

      -- Return the requested closure
      return self[closures].AngleFrom[a].func
    end

    -- Not requesting specific closure, so use 0
    return Actor.AngleFrom(self,0)(a,b)
  end

  -- Plot a point on a circle around this actor
  Actor.AnglePlot = function(self,a,b)
    -- Check if a specific closure is requested
    if type(a) == "number" and b == nil then

      -- Check if a closure already exists
      if not self[closures].AnglePlot[a] then

        -- Create table to hold the closure
        local table = {}
        self[closures].AnglePlot[a] = table

        -- Create closure
        table.func = function(angle,radius)
          -- Main function logic follows

          return PlotCircle(self.X[a],self.Y[a],angle,radius)
        end -- function(angle,radius)

        -- Add a timeout to remove the table
        table.timeout = RAIL.Timeouts:New(closure_timeout,false,function()
          self[closures].AnglePlot[a] = nil
        end)

      end -- not self[closures].AnglePlot[a]

      -- Update the timeout
      self[closures].AnglePlot[a].timeout[2] = GetTick()

      -- Return the requested closure
      return self[closures].AnglePlot[a].func
    end

    -- Not requesting specific closure, so use 0
    return Actor.AnglePlot(self,0)(a,b)
  end

  ------------------
  -- API Wrappers --
  ------------------

  -- These are mainly to allow attacks/skills vs. specific monsters to be
  --  hooked in a more efficient manner than hooking Attack() base API

  Actor.Attack = function(self)
    -- Send the attack
    Attack(RAIL.Self.ID,self.ID)

    -- After sending an attack, this actor can never be kill-stealed (until Actor.Expire)
    self.BattleOpts.FreeForAll = true
    
    -- Set the last attack time to now
    self.BattleOpts.LastAttack = GetTick()
  end

  Actor.SkillObject = function(self,skill)
    -- Send the skill
    skill:Cast(self.ID)

    -- And never see this actor as kill-stealing
    self.BattleOpts.FreeForAll = true

    -- Set the last skill time to now
    self.BattleOpts.LastSkill = GetTick()
  end

  -----------------------
  -- Actors Collection --
  -----------------------

  Actors = {}
  setmetatable(Actors,{
    __index = function(self,idx)
      if type(idx) ~= "number" then
        return self[-1]
      end

      -- Make sure the actor ID is positive
      --  (but -1 is a special value)
      if idx < -1 then
        return self[-idx]
      end

      -- Ensure the actor is sane
      if GetV(V_MOTION,idx) == -1 then
        return self[-1]
      end

      -- Generate a new actor class
      rawset(self,idx,Actor:New(idx))
      return self[idx]
    end
  })

  -- Create Actors[-1], and disable certain features
  rawset(Actors,-1,Actor:New(-1))

  Actors[-1].ExpireTimeout[1] = false

  Actors[-1].Update    = function(self) return self end
  Actors[-1].IsEnemy   = function() return false end
  Actors[-1].IsFriend  = function() return false end
  Actors[-1].IsIgnored = function() return true end
  Actors[-1].IsAllowed = function() return false end
end