-- oarc_utils.lua
-- Nov 2016
-- 
-- My general purpose utility functions for factorio
-- Also contains some constants and gui styles


--------------------------------------------------------------------------------
-- Useful constants
--------------------------------------------------------------------------------
CHUNK_SIZE = 32
MAX_FORCES = 64
TICKS_PER_SECOND = 60
TICKS_PER_MINUTE = TICKS_PER_SECOND * 60
TICKS_PER_HOUR = TICKS_PER_MINUTE * 60
--------------------------------------------------------------------------------

GAME_SURFACE_NAME="Game"

--------------------------------------------------------------------------------
-- GUI Label Styles
--------------------------------------------------------------------------------
my_fixed_width_style = {
    minimal_width = 450,
    maximal_width = 450
}
my_label_style = {
    minimal_width = 450,
    maximal_width = 450,
    maximal_height = 10,
    font_color = {r=1,g=1,b=1},
    top_padding = 0,
    bottom_padding = 0
}
my_note_style = {
    minimal_width = 450,
    maximal_height = 10,
    font = "default-small-semibold",
    font_color = {r=1,g=0.5,b=0.5},
    top_padding = 0,
    bottom_padding = 0
}
my_warning_style = {
    minimal_width = 450,
    maximal_width = 450,
    maximal_height = 10,
    font_color = {r=1,g=0.1,b=0.1},
    top_padding = 0,
    bottom_padding = 0
}
my_spacer_style = {
    minimal_width = 450,
    maximal_width = 450,
    minimal_height = 20,
    maximal_height = 20,
    font_color = {r=0,g=0,b=0},
    top_padding = 0,
    bottom_padding = 0
}
my_small_button_style = {
    font = "default-small-semibold"
}
my_player_list_fixed_width_style = {
    minimal_width = 200,
    maximal_width = 400,
    maximal_height = 200
}
my_player_list_admin_style = {
    font = "default-semibold",
    font_color = {r=1,g=0.5,b=0.5},
    minimal_width = 200,
    top_padding = 0,
    bottom_padding = 0,
    maximal_height = 15
}
my_player_list_style = {
    font = "default-semibold",
    minimal_width = 200,
    top_padding = 0,
    bottom_padding = 0,
    maximal_height = 15
}
my_player_list_style_spacer = {
    maximal_height = 15
}
my_color_red = {r=1,g=0.1,b=0.1}


--------------------------------------------------------------------------------
-- General Helper Functions
--------------------------------------------------------------------------------

-- Print debug only to me while testing.
function DebugPrint(msg)
    if ((game.players["Oarc"] ~= nil) and (global.oarcDebugEnabled)) then
        game.players["Oarc"].print("DEBUG: " .. msg)
    end
end

-- Prints flying text.
-- Color is optional
function FlyingText(msg, pos, color, surface)
    if color == nil then
        surface.create_entity({ name = "flying-text", position = pos, text = msg })
    else
        surface.create_entity({ name = "flying-text", position = pos, text = msg, color = color })
    end
end

-- Broadcast messages to all connected players
function SendBroadcastMsg(msg)
    for name,player in pairs(game.connected_players) do
        player.print(msg)
    end
end

-- Special case for ensuring that if I create the server, my messages are
-- used instead of the generic insert msg warning.
function SetServerWelcomeMessages()
    if (SERVER_OWNER_IS_OARC) then
        global.welcome_msg = WELCOME_MSG_OARC
        global.welcome_msg_title = WELCOME_MSG_TITLE_OARC
    else
        global.welcome_msg = WELCOME_MSG
        global.welcome_msg_title = WELCOME_MSG_TITLE
    end
end

-- Useful for displaying game time in mins:secs format
function formattime(ticks)
  local seconds = ticks / 60
  local minutes = math.floor((seconds)/60)
  local seconds = math.floor(seconds - 60*minutes)
  return string.format("%dm:%02ds", minutes, seconds)
end

-- Useful for displaying game time in mins:secs format
function formattime_hours_mins(ticks)
  local seconds = ticks / 60
  local minutes = math.floor((seconds)/60)
  local hours   = math.floor((minutes)/60)
  local minutes = math.floor(minutes - 60*hours)
  return string.format("%dh:%02dm", hours, minutes)
end

-- Simple function to get total number of items in table
function TableLength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

-- Chart area for a force
function ChartArea(force, position, chunkDist, surface)
    force.chart(surface,
        {{position.x-(CHUNK_SIZE*chunkDist),
        position.y-(CHUNK_SIZE*chunkDist)},
        {position.x+(CHUNK_SIZE*chunkDist),
        position.y+(CHUNK_SIZE*chunkDist)}})
end

-- Give player these default items.
function GivePlayerItems(player)
    for _,item in pairs(PLAYER_RESPAWN_START_ITEMS) do
        player.insert(item)
    end
end

-- Starter only items
function GivePlayerStarterItems(player)
    for _,item in pairs(PLAYER_SPAWN_START_ITEMS) do
        player.insert(item)
    end

    if ENABLE_POWER_ARMOR_QUICK_START then
        GiveQuickStartPowerArmor(player)
    end
end

-- Cheater's quick start
function GiveQuickStartPowerArmor(player)
    player.insert{name="power-armor", count = 1}

    if player and player.get_inventory(5) ~= nil and player.get_inventory(5)[1] ~= nil then
        local p_armor = player.get_inventory(5)[1].grid --defines.inventory.player_armor = 5?
            if p_armor ~= nil then
                  p_armor.put({name = "fusion-reactor-equipment"})
                  p_armor.put({name = "exoskeleton-equipment"})
                  p_armor.put({name = "battery-mk2-equipment"})
                  p_armor.put({name = "battery-mk2-equipment"})
                  p_armor.put({name = "personal-roboport-mk2-equipment"})  
                  p_armor.put({name = "personal-roboport-mk2-equipment"})
                  p_armor.put({name = "personal-roboport-mk2-equipment"})
                  p_armor.put({name = "battery-mk2-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
                  p_armor.put({name = "solar-panel-equipment"})
            end
        player.insert{name="construction-robot", count = 100}
    end
end

-- Create area given point and radius-distance
function GetAreaFromPointAndDistance(point, dist)
    local area = {left_top=
                    {x=point.x-dist,
                     y=point.y-dist},
                  right_bottom=
                    {x=point.x+dist,
                     y=point.y+dist}}
    return area
end

-- Check if given position is in area bounding box
function CheckIfInArea(point, area)
    if ((point.x >= area.left_top.x) and (point.x < area.right_bottom.x)) then
        if ((point.y >= area.left_top.y) and (point.y < area.right_bottom.y)) then
            return true
        end
    end
    return false
end

-- Set all forces to ceasefire
function SetCeaseFireBetweenAllForces()
    for name,team in pairs(game.forces) do
        if name ~= "neutral" and name ~= "enemy" then
            for x,y in pairs(game.forces) do
                if x ~= "neutral" and x ~= "enemy" then
                    team.set_cease_fire(x,true)
                end
            end
        end
    end
end

-- Set all forces to friendly
function SetFriendlyBetweenAllForces()
    for name,team in pairs(game.forces) do
        if name ~= "neutral" and name ~= "enemy" then
            for x,y in pairs(game.forces) do
                if x ~= "neutral" and x ~= "enemy" then
                    team.set_friend(x,true)
                end
            end
        end
    end
end

-- For each other player force, share a chat msg.
function ShareChatBetweenForces(player, msg)
    for _,force in pairs(game.forces) do
        if (force ~= nil) then
            if ((force.name ~= enemy) and
                (force.name ~= neutral) and
                (force.name ~= player) and
                (force ~= player.force)) then
                force.print(player.name..": "..msg)
            end
        end
    end
end

-- Undecorator
function RemoveDecorationsArea(surface, area)
    surface.destroy_decoratives(area)
end

-- Remove fish
function RemoveFish(surface, area)
    for _, entity in pairs(surface.find_entities_filtered{area = area, type="fish"}) do
        entity.destroy()
    end
end

-- Apply a style option to a GUI
function ApplyStyle (guiIn, styleIn)
    for k,v in pairs(styleIn) do
        guiIn.style[k]=v
    end 
end

-- Get a random 1 or -1
function RandomNegPos()
    if (math.random(0,1) == 1) then
        return 1
    else
        return -1
    end
end

-- Create a random direction vector to look in
function GetRandomVector()
    local randVec = {x=0,y=0}   
    while ((randVec.x == 0) and (randVec.y == 0)) do
        randVec.x = math.random(-3,3)
        randVec.y = math.random(-3,3)
    end
    DebugPrint("direction: x=" .. randVec.x .. ", y=" .. randVec.y)
    return randVec
end

-- Check for ungenerated chunks around a specific chunk
-- +/- chunkDist in x and y directions
function IsChunkAreaUngenerated(chunkPos, chunkDist, surface)
    for x=-chunkDist, chunkDist do
        for y=-chunkDist, chunkDist do
            local checkPos = {x=chunkPos.x+x,
                             y=chunkPos.y+y}
            if (surface.is_chunk_generated(checkPos)) then
                return false
            end
        end
    end
    return true
end

-- Clear out enemies around an area with a certain distance
function ClearNearbyEnemies(player, safeDist)
    local safeArea = {left_top=
                    {x=player.position.x-safeDist,
                     y=player.position.y-safeDist},
                  right_bottom=
                    {x=player.position.x+safeDist,
                     y=player.position.y+safeDist}}

    for _, entity in pairs(player.surface.find_entities_filtered{area = safeArea, force = "enemy"}) do
        entity.destroy()
    end
end

-- Function to find coordinates of ungenerated map area in a given direction
-- starting from the center of the map
function FindMapEdge(directionVec, surface)
    local position = {x=0,y=0}
    local chunkPos = {x=0,y=0}

    -- Keep checking chunks in the direction of the vector
    while(true) do
            
        -- Set some absolute limits.
        if ((math.abs(chunkPos.x) > 1000) or (math.abs(chunkPos.y) > 1000)) then
            break
        
        -- If chunk is already generated, keep looking
        elseif (surface.is_chunk_generated(chunkPos)) then
            chunkPos.x = chunkPos.x + directionVec.x
            chunkPos.y = chunkPos.y + directionVec.y
        
        -- Found a possible ungenerated area
        else
            
            chunkPos.x = chunkPos.x + directionVec.x
            chunkPos.y = chunkPos.y + directionVec.y

            -- Check there are no generated chunks in a 10x10 area.
            if IsChunkAreaUngenerated(chunkPos, 10, surface) then
                position.x = (chunkPos.x*CHUNK_SIZE) + (CHUNK_SIZE/2)
                position.y = (chunkPos.y*CHUNK_SIZE) + (CHUNK_SIZE/2)
                break
            end
        end
    end

    -- DebugPrint("spawn: x=" .. position.x .. ", y=" .. position.y)
    return position
end

-- Find random coordinates within a given distance away
-- maxTries is the recursion limit basically.
function FindUngeneratedCoordinates(minDistChunks, maxDistChunks, surface)
    local position = {x=0,y=0}
    local chunkPos = {x=0,y=0}

    local maxTries = 100
    local tryCounter = 0

    local minDistSqr = minDistChunks^2
    local maxDistSqr = maxDistChunks^2

    while(true) do
        chunkPos.x = math.random(0,maxDistChunks) * RandomNegPos()
        chunkPos.y = math.random(0,maxDistChunks) * RandomNegPos()

        local distSqrd = chunkPos.x^2 + chunkPos.y^2

        -- Enforce a max number of tries
        tryCounter = tryCounter + 1
        if (tryCounter > maxTries) then
            DebugPrint("FindUngeneratedCoordinates - Max Tries Hit!")
            break
 
        -- Check that the distance is within the min,max specified
        elseif ((distSqrd < minDistSqr) or (distSqrd > maxDistSqr)) then
            -- Keep searching!
        
        -- Check there are no generated chunks in a 10x10 area.
        elseif IsChunkAreaUngenerated(chunkPos, CHECK_SPAWN_UNGENERATED_CHUNKS_RADIUS, surface) then
            position.x = (chunkPos.x*CHUNK_SIZE) + (CHUNK_SIZE/2)
            position.y = (chunkPos.y*CHUNK_SIZE) + (CHUNK_SIZE/2)
            break -- SUCCESS
        end       
    end

    DebugPrint("spawn: x=" .. position.x .. ", y=" .. position.y)
    return position
end

-- General purpose function for removing a particular recipe
function RemoveRecipe(force, recipeName)
    local recipes = force.recipes
    if recipes[recipeName] then
        recipes[recipeName].enabled = false
    end
end

-- General purpose function for adding a particular recipe
function AddRecipe(force, recipeName)
    local recipes = force.recipes
    if recipes[recipeName] then
        recipes[recipeName].enabled = true
    end
end

-- Get an area given a position and distance.
-- Square length = 2x distance
function GetAreaAroundPos(pos, dist)

    return {left_top=
                    {x=pos.x-dist,
                     y=pos.y-dist},
            right_bottom=
                    {x=pos.x+dist,
                     y=pos.y+dist}}
end

-- Removes the entity type from the area given
function RemoveInArea(surface, area, type)
    for key, entity in pairs(surface.find_entities_filtered({area=area, type= type})) do
        entity.destroy()
    end
end

-- Removes the entity type from the area given
-- Only if it is within given distance from given position.
function RemoveInCircle(surface, area, type, pos, dist)
    for key, entity in pairs(surface.find_entities_filtered({area=area, type= type})) do
        if ((pos.x - entity.position.x)^2 + (pos.y - entity.position.y)^2 < dist^2) then
            entity.destroy()
        end
    end
end

-- Convenient way to remove aliens, just provide an area
function RemoveAliensInArea(surface, area)
    for _, entity in pairs(surface.find_entities_filtered{area = area, force = "enemy"}) do
        entity.destroy()
    end
end

-- Make an area safer
-- Reduction factor divides the enemy spawns by that number. 2 = half, 3 = third, etc...
-- Also removes all big and huge worms in that area
function ReduceAliensInArea(surface, area, reductionFactor)
    for _, entity in pairs(surface.find_entities_filtered{area = area, force = "enemy"}) do
        if (math.random(0,reductionFactor) > 0) then
            entity.destroy()
        end
    end

    -- Remove all big and huge worms
    for _, entity in pairs(surface.find_entities_filtered{area = area, name = "medium-worm-turret"}) do
            entity.destroy()
    end
    for _, entity in pairs(surface.find_entities_filtered{area = area, name = "big-worm-turret"}) do
            entity.destroy()
    end
end


-- Adjust alien params
function ConfigureAlienStartingParams()
    game.map_settings.enemy_evolution.time_factor=0
    game.map_settings.enemy_evolution.destroy_factor = game.map_settings.enemy_evolution.destroy_factor / ENEMY_DESTROY_FACTOR_DIVISOR
    game.map_settings.enemy_evolution.pollution_factor = game.map_settings.enemy_evolution.pollution_factor / ENEMY_POLLUTION_FACTOR_DIVISOR
    
    game.map_settings.enemy_expansion.enabled = ENEMY_EXPANSION

    game.map_settings.enemy_expansion.min_base_spacing = 10
    game.map_settings.enemy_expansion.max_expansion_distance = 10

    game.map_settings.enemy_expansion.settler_group_min_size = 5
    game.map_settings.enemy_expansion.settler_group_max_size = 20

    -- game.map_settings.enemy_expansion.friendly_base_influence_radius = 4
    -- game.map_settings.enemy_expansion.enemy_building_influence_radius = 4

    game.map_settings.enemy_expansion.min_expansion_cooldown = TICKS_PER_MINUTE*30
    game.map_settings.enemy_expansion.max_expansion_cooldown = TICKS_PER_MINUTE*120
end

-- Add Long Reach to Character
function GivePlayerLongReach(player)
    player.character.character_build_distance_bonus = BUILD_DIST_BONUS
    player.character.character_reach_distance_bonus = REACH_DIST_BONUS
    -- player.character.character_resource_reach_distance_bonus  = RESOURCE_DIST_BONUS
end

--------------------------------------------------------------------------------
-- Player List GUI - My own version
--------------------------------------------------------------------------------
function CreatePlayerListGui(event)
  local player = game.players[event.player_index]
  if player.gui.top.playerList == nil then
      player.gui.top.add{name="playerList", type="button", caption="Player List"}
  end   
end

local function ExpandPlayerListGui(player)
    local frame = player.gui.left["playerList-panel"]
    if (frame) then
        frame.destroy()
    else
        local frame = player.gui.left.add{type="frame",
                                            name="playerList-panel",
                                            caption="Online:"}
        local scrollFrame = frame.add{type="scroll-pane",
                                        name="playerList-panel",
                                        direction = "vertical"}
        ApplyStyle(scrollFrame, my_player_list_fixed_width_style)
        scrollFrame.horizontal_scroll_policy = "never"
        for _,player in pairs(game.connected_players) do
            local caption_str = player.name.." ["..player.force.name.."]".." ("..formattime_hours_mins(player.online_time)..")"
            local text = scrollFrame.add{type="label", caption=caption_str, name=player.name.."_plist"}
            if (player.admin) then
                ApplyStyle(text, my_player_list_admin_style)
            else
                ApplyStyle(text, my_player_list_style)
            end
        end
        local spacer = scrollFrame.add{type="label", caption="     ", name="plist_spacer_plist"}
        ApplyStyle(spacer, my_player_list_style_spacer)
    end
end

function PlayerListGuiClick(event) 
    if not (event and event.element and event.element.valid) then return end
    local player = game.players[event.element.player_index]
    local name = event.element.name

    if (name == "playerList") then
        ExpandPlayerListGui(player)        
    end
end

--------------------------------------------------------------------------------
-- Anti-griefing Stuff & Gravestone (My own version)
--------------------------------------------------------------------------------
function AntiGriefing(force)
    force.zoom_to_world_deconstruction_planner_enabled=false
    force.friendly_fire=false
end

--------------------------------------------------------------------------------
-- Gravestone soft mod. With my own modifications/improvements.
--------------------------------------------------------------------------------
-- Return steel chest entity (or nil)
function DropEmptySteelChest(player)
    local pos = player.surface.find_non_colliding_position("steel-chest", player.position, 15, 1)
    if not pos then
        return nil
    end
    local grave = player.surface.create_entity{name="steel-chest", position=pos, force="neutral"}
    return grave
end

function DropGravestoneChests(player)

    local grave
    local count = 0

    -- Make sure we save stuff we're holding in our hands.
    player.clean_cursor()

    -- Loop through a players different inventories
    -- Put it all into a chest.
    -- If the chest is full, create a new chest.
    for i, id in ipairs{
        defines.inventory.player_armor,
        defines.inventory.player_main,
        defines.inventory.player_quickbar,
        defines.inventory.player_guns,
        defines.inventory.player_ammo,
        defines.inventory.player_tools,
        defines.inventory.player_trash} do
        
        local inv = player.get_inventory(id)
        
        if (not inv.is_empty()) then
            for j = 1, #inv do
                if inv[j].valid_for_read then
                    
                    -- Create a chest when counter is reset
                    if (count == 0) then
                        grave = DropEmptySteelChest(player)
                        if (grave == nil) then
                            -- player.print("Not able to place a chest nearby! Some items lost!")
                            return
                        end
                        grave_inv = grave.get_inventory(defines.inventory.chest)
                    end
                    count = count + 1

                    -- Copy the item stack into a chest slot.
                    grave_inv[count].set_stack(inv[j])

                    -- Reset counter when chest is full
                    if (count == #grave_inv) then
                        count = 0
                    end
                end
            end
        end

        -- Clear the player inventory so we don't have duplicate items lying around.
        inv.clear()
    end

    if (grave ~= nil) then
        player.print("Successfully dropped your items into a chest! Go get them quick!")
    end
end

--------------------------------------------------------------------------------
-- Frontier style rocket silo stuff
--------------------------------------------------------------------------------

-- This creates a random silo position, stored to global.siloPosition
-- It uses the config setting SILO_CHUNK_DISTANCE and spawns the silo somewhere
-- on a circle edge with radius using that distance.
function SetRandomSiloPosition()
    if (global.siloPosition == nil) then
        -- Get an X,Y on a circle far away.
        local distX = math.random(0,SILO_CHUNK_DISTANCE_X)
        local distY = RandomNegPos() * math.floor(math.sqrt(SILO_CHUNK_DISTANCE_X^2 - distX^2))
        local distX = RandomNegPos() * distX

        -- Set those values.
        local siloX = distX*CHUNK_SIZE + CHUNK_SIZE/2
        local siloY = distY*CHUNK_SIZE + CHUNK_SIZE/2
        global.siloPosition = {x = siloX, y = siloY}
    end
end

-- Sets the global.siloPosition var to the set in the config file
function SetFixedSiloPosition()
    if (global.siloPosition == nil) then
        global.siloPosition = SILO_POSITION
    end
end

--------------------------------------------------------------------------------
-- Autofill Stuff
--------------------------------------------------------------------------------

-- Transfer Items Between Inventory
-- Returns the number of items that were successfully transferred.
-- Returns -1 if item not available.
-- Returns -2 if can't place item into destInv (ERROR)
function TransferItems(srcInv, destEntity, itemStack)
    -- Check if item is in srcInv
    if (srcInv.get_item_count(itemStack.name) == 0) then
        return -1
    end

    -- Check if can insert into destInv
    if (not destEntity.can_insert(itemStack)) then
        return -2
    end
    
    -- Insert items
    local itemsRemoved = srcInv.remove(itemStack)
    itemStack.count = itemsRemoved
    return destEntity.insert(itemStack)
end

-- Attempts to transfer at least some of one type of item from an array of items.
-- Use this to try transferring several items in order
-- It returns once it successfully inserts at least some of one type.
function TransferItemMultipleTypes(srcInv, destEntity, itemNameArray, itemCount)
    local ret = 0
    for _,itemName in pairs(itemNameArray) do
        ret = TransferItems(srcInv, destEntity, {name=itemName, count=itemCount})
        if (ret > 0) then
            return ret -- Return the value succesfully transferred
        end
    end
    return ret -- Return the last error code
end

-- Autofills a turret with ammo
function AutofillTurret(player, turret)
    local mainInv = player.get_inventory(defines.inventory.player_main)

    -- Attempt to transfer some ammo
    local ret = TransferItemMultipleTypes(mainInv, turret, {"uranium-rounds-magazine", "piercing-rounds-magazine", "firearm-magazine"}, AUTOFILL_TURRET_AMMO_QUANTITY)

    -- Check the result and print the right text to inform the user what happened.
    if (ret > 0) then
        -- Inserted ammo successfully
        -- FlyingText("Inserted ammo x" .. ret, turret.position, my_color_red, player.surface)
    elseif (ret == -1) then
        FlyingText("Out of ammo!", turret.position, my_color_red, player.surface) 
    elseif (ret == -2) then
        FlyingText("Autofill ERROR! - Report this bug!", turret.position, my_color_red, player.surface)
    end
end

-- Autofills a vehicle with fuel, bullets and shells where applicable
function AutoFillVehicle(player, vehicle)
    local mainInv = player.get_inventory(defines.inventory.player_main)

    -- Attempt to transfer some fuel
    if ((vehicle.name == "car") or (vehicle.name == "tank") or (vehicle.name == "locomotive")) then
        TransferItemMultipleTypes(mainInv, vehicle, {"rocket-fuel", "solid-fuel", "coal", "raw-wood"}, 50)
    end

    -- Attempt to transfer some ammo
    if ((vehicle.name == "car") or (vehicle.name == "tank")) then
        TransferItemMultipleTypes(mainInv, vehicle, {"uranium-rounds-magazine", "piercing-rounds-magazine", "firearm-magazine"}, 100)
    end

    -- Attempt to transfer some tank shells
    if (vehicle.name == "tank") then
        TransferItemMultipleTypes(mainInv, vehicle, {"explosive-uranium-cannon-shell", "uranium-cannon-shell", "explosive-cannon-shell", "cannon-shell"}, 100)
    end
end

--------------------------------------------------------------------------------
-- Resource patch and starting area generation
--------------------------------------------------------------------------------

-- Enforce a circle of land, also adds trees in a ring around the area.
function CreateCropCircle(surface, centerPos, chunkArea, tileRadius)

    local tileRadSqr = tileRadius^2

    local dirtTiles = {}
    for i=chunkArea.left_top.x,chunkArea.right_bottom.x,1 do
        for j=chunkArea.left_top.y,chunkArea.right_bottom.y,1 do

            -- This ( X^2 + Y^2 ) is used to calculate if something
            -- is inside a circle area.
            local distVar = math.floor((centerPos.x - i)^2 + (centerPos.y - j)^2)

            -- Fill in all unexpected water in a circle
            if (distVar < tileRadSqr) then
                if (surface.get_tile(i,j).collides_with("water-tile") or ENABLE_SPAWN_FORCE_GRASS) then
                    table.insert(dirtTiles, {name = "grass", position ={i,j}})
                end
            end

            -- Create a circle of trees around the spawn point.
            if ((distVar < tileRadSqr-200) and 
                (distVar > tileRadSqr-300)) then
                surface.create_entity({name="tree-01", amount=1, position={i, j}})
            end
        end
    end

    surface.set_tiles(dirtTiles)
end

-- COPIED FROM jvmguy!
-- Enforce a square of land, with a tree border
-- this is equivalent to the CreateCropCircle code
function CreateCropOctagon(surface, centerPos, chunkArea, tileRadius)

    local dirtTiles = {}
    for i=chunkArea.left_top.x,chunkArea.right_bottom.x,1 do
        for j=chunkArea.left_top.y,chunkArea.right_bottom.y,1 do

            local distVar1 = math.floor(math.max(math.abs(centerPos.x - i), math.abs(centerPos.y - j)))
            local distVar2 = math.floor(math.abs(centerPos.x - i) + math.abs(centerPos.y - j))
            local distVar = math.max(distVar1, distVar2 * 0.707);

            -- Fill in all unexpected water in a circle
            if (distVar < tileRadius+2) then
                if (surface.get_tile(i,j).collides_with("water-tile") or ENABLE_SPAWN_FORCE_GRASS) then
                    table.insert(dirtTiles, {name = "grass", position ={i,j}})
                end
            end

            -- Create a tree ring
            if ((distVar < tileRadius) and 
                (distVar > tileRadius-2)) then
                surface.create_entity({name="tree-01", amount=1, position={i, j}})
            end
        end
    end    
    surface.set_tiles(dirtTiles)
end

-- Add a circle of water
function CreateMoat(surface, centerPos, chunkArea, tileRadius)

    local tileRadSqr = tileRadius^2

    local waterTiles = {}
    for i=chunkArea.left_top.x,chunkArea.right_bottom.x,1 do
        for j=chunkArea.left_top.y,chunkArea.right_bottom.y,1 do

            -- This ( X^2 + Y^2 ) is used to calculate if something
            -- is inside a circle area.
            local distVar = math.floor((centerPos.x - i)^2 + (centerPos.y - j)^2)

            -- Create a circle of water
            if ((distVar < tileRadSqr+400) and 
                (distVar > tileRadSqr-500)) then
                table.insert(waterTiles, {name = "water", position ={i,j}})
            end

            -- Enforce land inside the edges of the circle to make sure it's
            -- a clean transition
            if ((distVar < tileRadSqr-500) and 
                (distVar > tileRadSqr-1000)) then
                table.insert(waterTiles, {name = "grass", position ={i,j}})
            end
        end
    end

    surface.set_tiles(waterTiles)
end

-- Create a horizontal line of water
function CreateWaterStrip(surface, leftPos, length)
    local waterTiles = {}
    for i=0,length,1 do
        table.insert(waterTiles, {name = "water", position={leftPos.x+i,leftPos.y}})
    end
    surface.set_tiles(waterTiles)
end 

-- Function to generate a resource patch, of a certain size/amount at a pos.
function GenerateResourcePatch(surface, resourceName, diameter, pos, amount)
    local midPoint = math.floor(diameter/2)
    for y=0, diameter do
        for x=0, diameter do
            if (not ENABLE_RESOURCE_SHAPE_CIRCLE or ((x-midPoint)^2 + (y-midPoint)^2 < midPoint^2)) then
                surface.create_entity({name=resourceName, amount=amount,
                    position={pos.x+x, pos.y+y}})
            end
        end
    end
end



-- Generate the basic starter resource around a given location.
function GenerateStartingResources(surface, pos)
    -- Generate stone
    local stonePos = {x=pos.x+START_RESOURCE_STONE_POS_X,
                  y=pos.y+START_RESOURCE_STONE_POS_Y}

    -- Generate coal
    local coalPos = {x=pos.x+START_RESOURCE_COAL_POS_X,
                  y=pos.y+START_RESOURCE_COAL_POS_Y}

    -- Generate copper ore
    local copperOrePos = {x=pos.x+START_RESOURCE_COPPER_POS_X,
                  y=pos.y+START_RESOURCE_COPPER_POS_Y}
                  
    -- Generate iron ore
    local ironOrePos = {x=pos.x+START_RESOURCE_IRON_POS_X,
                  y=pos.y+START_RESOURCE_IRON_POS_Y}

    -- Generate uranium
    local uraniumOrePos = {x=pos.x+START_RESOURCE_URANIUM_POS_X,
                  y=pos.y+START_RESOURCE_URANIUM_POS_Y}

    -- Tree generation is taken care of in chunk generation

    -- Generate 2 oil patches
    surface.create_entity({name="crude-oil", amount=START_OIL_AMOUNT,
                    position={pos.x+START_RESOURCE_OIL_A_POS_X, pos.y+START_RESOURCE_OIL_A_POS_Y}})
    surface.create_entity({name="crude-oil", amount=START_OIL_AMOUNT,
                    position={pos.x+START_RESOURCE_OIL_B_POS_X, pos.y+START_RESOURCE_OIL_B_POS_Y}})

    -- Generate Stone
    GenerateResourcePatch(surface, "stone", START_RESOURCE_STONE_SIZE, stonePos, START_STONE_AMOUNT)

    -- Generate Coal
    GenerateResourcePatch(surface, "coal", START_RESOURCE_COAL_SIZE, coalPos, START_COAL_AMOUNT)

    -- Generate Copper
    GenerateResourcePatch(surface, "copper-ore", START_RESOURCE_COPPER_SIZE, copperOrePos, START_COPPER_AMOUNT)

    -- Generate Iron
    GenerateResourcePatch(surface, "iron-ore", START_RESOURCE_IRON_SIZE, ironOrePos, START_IRON_AMOUNT)

    -- Generate Uranium
    GenerateResourcePatch(surface, "uranium-ore", START_RESOURCE_URANIUM_SIZE, uraniumOrePos, START_URANIUM_AMOUNT)
end



-- Create the spawn areas.
-- This should be run inside the chunk generate event and be given a list of all
-- unique spawn points.
-- This clears enemies in the immediate area, creates a slightly safe area around it,
-- And spawns the basic resources as well
function CreateSpawnAreas(surface, chunkArea, spawnPointTable)
    for name,spawn in pairs(spawnPointTable) do

        -- Create a bunch of useful area and position variables
        local landArea = GetAreaAroundPos(spawn.pos, ENFORCE_LAND_AREA_TILE_DIST+CHUNK_SIZE)
        local safeArea = GetAreaAroundPos(spawn.pos, SAFE_AREA_TILE_DIST)
        local warningArea = GetAreaAroundPos(spawn.pos, WARNING_AREA_TILE_DIST)
        local chunkAreaCenter = {x=chunkArea.left_top.x+(CHUNK_SIZE/2),
                                         y=chunkArea.left_top.y+(CHUNK_SIZE/2)}
        local spawnPosOffset = {x=spawn.pos.x+ENFORCE_LAND_AREA_TILE_DIST,
                                         y=spawn.pos.y+ENFORCE_LAND_AREA_TILE_DIST}

        -- Make chunks near a spawn safe by removing enemies
        if CheckIfInArea(chunkAreaCenter,safeArea) then
            RemoveAliensInArea(surface, chunkArea)
        
        -- Create a warning area with reduced enemies
        elseif CheckIfInArea(chunkAreaCenter,warningArea) then
            ReduceAliensInArea(surface, chunkArea, WARN_AREA_REDUCTION_RATIO)
        end

        -- If the chunk is within the main land area, then clear trees/resources
        -- and create the land spawn areas (guaranteed land with a circle of trees)
        if CheckIfInArea(chunkAreaCenter,landArea) then

            -- Remove trees/resources inside the spawn area
            RemoveInCircle(surface, chunkArea, "tree", spawn.pos, ENFORCE_LAND_AREA_TILE_DIST+5)
            RemoveInCircle(surface, chunkArea, "resource", spawn.pos, ENFORCE_LAND_AREA_TILE_DIST+5)

            if (SPAWN_TREE_CIRCLE_ENABLED) then
                CreateCropCircle(surface, spawn.pos, chunkArea, ENFORCE_LAND_AREA_TILE_DIST)
            end
            if (SPAWN_TREE_OCTAGON_ENABLED) then
                CreateCropOctagon(surface, spawn.pos, chunkArea, ENFORCE_LAND_AREA_TILE_DIST)
            end
            if (SPAWN_MOAT_CHOICE_ENABLED) then
                if (spawn.moat) then
                    CreateMoat(surface, spawn.pos, chunkArea, ENFORCE_LAND_AREA_TILE_DIST+10)
                end
            end
        end

        -- Provide starting resources
        -- This is run on the bottom, right chunk of the spawn area which should be
        -- generated last, so it should work everytime.
        if CheckIfInArea(spawnPosOffset,chunkArea) then
            CreateWaterStrip(surface,
                            {x=spawn.pos.x+WATER_SPAWN_OFFSET_X, y=spawn.pos.y+WATER_SPAWN_OFFSET_Y},
                            WATER_SPAWN_LENGTH)
            GenerateStartingResources(surface, spawn.pos)
        end
    end
end

--------------------------------------------------------------------------------
-- Surface Generation Functions
--------------------------------------------------------------------------------
-- To use RSO resources, we have to disable vanilla ore generation
local surface_autoplace_none = {
    ["coal"]={
        size="none"
    },
    ["copper-ore"]={
        size="none"
    },
    ["iron-ore"]={
        size="none"
    },
    ["stone"]={
        size="none"
    },
    ["uranium-ore"]={
        size="none"
    },
    ["crude-oil"]={
        size="none"
    },
    ["enemy-base"]={
        size="none"
    }
}

RSO_MODE = 1
VANILLA_MODE = 2

function CreateLobbySurface()
    local surface = game.create_surface("Lobby",{width = 1, height = 1})
    surface.set_tiles({{name = "out-of-map",position = {1,1}}})
end              

function CreateGameSurface(mode)
    local mapSettings =  game.surfaces["nauvis"].map_gen_settings
    if (mode == RSO_MODE) then
        mapSettings.terrain_segmentation=MAP_SETTINGS_RSO_TERRAIN_SEGMENTATION
        mapSettings.water=MAP_SETTINGS_RSO_WATER
        mapSettings.starting_area=MAP_SETTINGS_RSO_STARTING_AREA
        mapSettings.peaceful_mode=MAP_SETTINGS_RSO_PEACEFUL
        mapSettings.seed=math.random(999999999);
        mapSettings.autoplace_controls = {
            ["coal"]={ size="none" },
            ["copper-ore"]={ size="none" },
            ["iron-ore"]={ size="none" },
            ["stone"]={ size="none" },
            ["uranium-ore"]={ size="none" },
            ["crude-oil"]={ size="none" },
            ["enemy-base"]={ size="none" }
        }
    else
        mapSettings.terrain_segmentation="normal"
        mapSettings.water="normal"
        mapSettings.starting_area="normal"
        mapSettings.peaceful_mode=false
        mapSettings.seed=math.random(999999999);
        mapSettings.autoplace_controls = {
            ["coal"]={frequency="very-low", size= "normal", richness= "very-high"},
            ["copper-ore"]={frequency= "very-low", size= "normal", richness= "very-high"},
            ["crude-oil"]={frequency= "very-low", size= "normal", richness= "very-high"},
            ["enemy-base"]={frequency= "very-low", size= "very-low", richness= "very-low"},
            ["iron-ore"]={frequency= "very-low", size= "normal", richness= "very-high"},
            ["stone"]={frequency= "very-low", size= "normal", richness= "very-high"},
            ["uranium-ore"]={frequency= "very-low", size= "normal", richness= "very-high"}
        }
    end

    local surface = game.create_surface(GAME_SURFACE_NAME,mapSettings)
    surface.set_tiles({{name = "out-of-map",position = {1,1}}})
end


--------------------------------------------------------------------------------
-- Holding pen for new players joining the map
--------------------------------------------------------------------------------
function CreateWall(surface, pos)
    local wall = surface.create_entity({name="stone-wall", position=pos, force=MAIN_TEAM})
    if wall then
        wall.destructible = false
        wall.minable = false
    end
end

function CreateHoldingPen(surface, chunkArea)
    if (((chunkArea.left_top.x == -32) or (chunkArea.left_top.x == 0)) and
        ((chunkArea.left_top.y == -32) or (chunkArea.left_top.y == 0))) then

        -- Remove stuff
        RemoveAliensInArea(surface, chunkArea)
        RemoveInArea(surface, chunkArea, "tree")
        RemoveInArea(surface, chunkArea, "resource")

        -- This loop runs through each tile
        local grassTiles = {}
        local waterTiles = {}
        for i=chunkArea.left_top.x,chunkArea.right_bottom.x,1 do
            for j=chunkArea.left_top.y,chunkArea.right_bottom.y,1 do

                -- Fill all area with grass only
                table.insert(grassTiles, {name = "grass", position ={i,j}})

                -- Create the spawn box walls
                if (j<15 and j>-16) then

                    -- Create horizontal sides of center spawn box
                    if (((j>-16 and j<-12) or (j<15 and j>11)) and (i<15 and i>-16)) then
                        -- CreateWall(surface, {i,j})
                        table.insert(waterTiles, {name = "water", position ={i,j}})
                    end

                    -- Create vertical sides of center spawn box
                    if ((i>-16 and i<-12) or (i<15 and i>11)) then
                        -- CreateWall(surface, {i,j})
                        table.insert(waterTiles, {name = "water", position ={i,j}})
                    end

                end
                
            end
        end
        surface.set_tiles(grassTiles)
        surface.set_tiles(waterTiles)
    end
end

function CreateHoldingPenGenerateChunk(event)
    CreateHoldingPen(event.surface, event.area)
end

--------------------------------------------------------------------------------
-- EVENT SPECIFIC FUNCTIONS
--------------------------------------------------------------------------------

-- Display messages to a user everytime they join
function PlayerJoinedMessages(event)
    local player = game.players[event.player_index]
    player.print(global.welcome_msg)
    player.print(GAME_MODE_MSG)
    player.print(MODULES_ENABLED)
end

-- Remove decor to save on file size
function UndecorateOnChunkGenerate(event)
    local surface = event.surface
    local chunkArea = event.area
    RemoveDecorationsArea(surface, chunkArea)
    RemoveFish(surface, chunkArea)
end

-- Give player items on respawn
-- Intended to be the default behavior when not using separate spawns
function PlayerRespawnItems(event)
    GivePlayerItems(game.players[event.player_index])
end

function PlayerSpawnItems(event)
    GivePlayerStarterItems(game.players[event.player_index])
end

-- Autofill softmod
function Autofill(event)
    local player = game.players[event.player_index]
    local eventEntity = event.created_entity

    if (eventEntity.name == "gun-turret") then
        AutofillTurret(player, eventEntity)
    end

    if ((eventEntity.name == "car") or (eventEntity.name == "tank") or (eventEntity.name == "locomotive")) then
        AutoFillVehicle(player, eventEntity)
    end
end