-- Credit to the oarc folks, and jvmguy for getting an RSO version working in scenarios
-- To tie into this, maps must be generated with "NONE" for all resource ores
require("rso_config")
require("util")
require("rso_resource_config")
local Utils = require "utils.utils"
local Game = require 'utils.game'

local MB=require "metaball"
local drand = require 'drand'
local rng = drand.mwvc
if not deterministic then rng = drand.sys_rand end

if not scenario then scenario = {} end
if not scenario.config then scenario.config = {} end
if not scenario.config.mapsettings then scenario.config.mapsettings = {} end

scenario.config.mapSettings = {
   RSO_TERRAIN_SEGMENTATION = "very-low", -- Frequency of water
   RSO_WATER = "high", -- Size of water patches
   RSO_PEACEFUL = false, -- Peaceful mode for biters/aliens
   RSO_STARTING_AREA = "very-low"
}

-- math shortcuts
local floor = math.floor
local abs = math.abs
local cos = math.cos
local sin = math.sin
local pi = math.pi
local max = math.max

local function rso_debug(str)
   if rso_debug_enabled then
      if (type(str) == "table") then
         Game.get_player_by_index(1).print(serpent.dump(str))
      else
         Game.get_player_by_index(1).print(str)
      end
   end
end

-- constants
local CHUNK_SIZE = 32
local REGION_TILE_SIZE = CHUNK_SIZE*region_size
local MIN_BALL_DISTANCE = CHUNK_SIZE/6
local P_BALL_SIZE_FACTOR = 0.7
local N_BALL_SIZE_FACTOR = 0.95
local NEGATIVE_MODIFICATOR = 123456

local meta_shapes = nil

if use_donut_shapes then
   meta_shapes = {MB.MetaEllipse, MB.MetaSquare, MB.MetaDonut}
else
   meta_shapes = {MB.MetaEllipse, MB.MetaSquare}
end

-- local globals
local index_is_built = false
local max_allotment = 0
local rgen = nil
local distance = util.distance
local spawner_probability_edge = 0  -- below this value a biter spawner, above/equal this value a spitter spawner
local invalidResources = {}
local config = nil
local configIndexed = nil

-- map gen settings mapping

local startingAreaMultiplier =
{
   none = 0,
   ["very-low"] = 0.25,
   low = 0.5,
   normal = 1,
   high = 1.5,
   ["very-high"] = 2,
}

local frequencyAllotmentMultiplier =
{
   ["very-low"] = 0.5,
   low = 0.75,
   normal = 1,
   high = 1.5,
   ["very-high"] = 2,
}

local sizeMultiplier =
{
   none = 0,
   ["very-low"] = 0.5,
   low = 0.75,
   normal = 1,
   high = 1.25,
   ["very-high"] = 1.5,
}

local richnessMultiplier =
{
   ["very-low"] = 0.125,
   low = 0.25,
   normal = 1,
   high = 2,
   ["very-high"] = 4,
}

local entityFrequencyMultiplier =
{
   ["very-low"] = 0.25,
   low = 0.5,
   normal = 1,
   high = 2,
   ["very-high"] = 4,
}

local entitySizeMultiplier =
{
   none = 0,
   ["very-low"] = 0.5,
   low = 0.75,
   normal = 1,
   high = 2,
   ["very-high"] = 4,
}

--[[ HELPER METHODS ]]--

local function normalize(n) --keep numbers at (positive) 32 bits
   return floor(n) % 0x80000000
end

local function bearing(origin, dest)
   -- finds relative angle
   local xd = dest.x - origin.x
   local yd = dest.y - origin.y
   return math.atan2(xd, yd);
end

local function str2num(s)
   local num = 0
   for i=1,s:len() do
      num=num + (s:byte(i) - 33)*i
   end
   return num
end

local function mult_for_pos(pos)
   local num = 0
   local x = pos.x
   local y = pos.y

   if x == 0 then x = 0.5 end
   if y == 0 then y = 0.5 end
   if x < 0 then
      x = abs(x) + NEGATIVE_MODIFICATOR
   end
   if y < 0 then
      y = abs(y) + NEGATIVE_MODIFICATOR
   end

   return drand.lcg(y, 'mvc'):random(0)*drand.lcg(x, 'nr'):random(0)
end

local function rng_for_reg_pos(pos)
   local rgen = rng(normalize(global.seed*mult_for_pos(pos)))
   rgen:random()
   rgen:random()
   rgen:random()
   return rgen
end

local function rng_restricted_angle(restrictions)
   local rng = rgen:random()
   local x_scale, y_scale
   local deformX = rgen:random() * 2 - 1
   local deformY = rgen:random() * 2 - 1

   if restrictions=='xy' then
      y_scale=1.0 + deformY*0.5
      x_scale=1.0 + deformX*0.5
      angle = rng*pi*2
   elseif restrictions=='x' then
      y_scale=1.0 + deformY*0.6
      x_scale=1.0 + deformX*0.6
      angle = rng*pi/2 - pi/4
   elseif restrictions=='y' then
      y_scale=1.0 + deformY*0.6
      x_scale=1.0 + deformX*0.6
      angle = rng*pi/2 + pi/2
   else
      y_scale=1.0 + deformY*0.3
      x_scale=1.0 + deformX*0.3
      angle = rng*pi*2
   end

   return angle, x_scale, y_scale
end

local function vary_by_percentage(x, p)
   return x + (0.5 - rgen:random())*2*x*p
end


local function remove_trees(surface, x, y, x_size, y_size )
   local bb={{x - x_size, y - y_size}, {x + x_size, y + y_size}}
   for _, entity in pairs(surface.find_entities_filtered{area = bb, type="tree"}) do
      if entity.valid then
         entity.destroy()
      end
   end
end

local function find_intersection(surface, x, y)
   -- try to get position in between of valid chunks by probing map
   -- this may breaks determinism of generation, but so far it returned on first if
   local gt = surface.get_tile
   local restriction = ''
   if gt(x + CHUNK_SIZE*2, y + CHUNK_SIZE*2).valid and gt(x - CHUNK_SIZE*2, y - CHUNK_SIZE*2).valid and gt(x + CHUNK_SIZE*2, y - CHUNK_SIZE*2).valid and gt(x - CHUNK_SIZE*2, y + CHUNK_SIZE*2).valid then
      restriction = 'xy'
   elseif gt(x + CHUNK_SIZE*2, y + CHUNK_SIZE*2).valid and gt(x + CHUNK_SIZE*2, y).valid and gt(x, y + CHUNK_SIZE*2).valid then
      x=x + CHUNK_SIZE/2
      y=y + CHUNK_SIZE/2
      restriction = 'xy'
   elseif gt(x + CHUNK_SIZE*2, y - CHUNK_SIZE*2).valid and gt(x + CHUNK_SIZE*2, y).valid and gt(x, y - CHUNK_SIZE*2).valid then
      x=x + CHUNK_SIZE/2
      y=y - CHUNK_SIZE/2
      restriction = 'xy'
   elseif gt(x - CHUNK_SIZE*2, y + CHUNK_SIZE*2).valid and gt(x - CHUNK_SIZE*2, y).valid and gt(x, y + CHUNK_SIZE*2).valid then
      x=x - CHUNK_SIZE/2
      y=y + CHUNK_SIZE/2
      restriction = 'xy'
   elseif gt(x - CHUNK_SIZE*2, y - CHUNK_SIZE*2).valid and gt(x - CHUNK_SIZE*2, y).valid and gt(x, y - CHUNK_SIZE*2).valid then
      x=x - CHUNK_SIZE/2
      y=y - CHUNK_SIZE/2
      restriction = 'xy'
   elseif gt(x + CHUNK_SIZE*2, y).valid then
      x=x + CHUNK_SIZE/2
      restriction = 'x'
   elseif gt(x - CHUNK_SIZE*2, y).valid then
      x=x - CHUNK_SIZE/2
      restriction = 'x'
   elseif gt(x, y + CHUNK_SIZE*2).valid then
      y=y + CHUNK_SIZE/2
      restriction = 'y'
   elseif gt(x, y - CHUNK_SIZE*2).valid then
      y=y - CHUNK_SIZE/2
      restriction = 'y'
   end
   return x, y, restriction
end

local function find_random_chunk(r_x, r_y)
   local offset_x=rgen:random(region_size)-1
   local offset_y=rgen:random(region_size)-1
   local c_x=r_x*REGION_TILE_SIZE + offset_x*CHUNK_SIZE
   local c_y=r_y*REGION_TILE_SIZE + offset_y*CHUNK_SIZE
   return c_x, c_y
end

local function is_same_region(c_x1, c_y1, c_x2, c_y2)
   if not floor(c_x1/REGION_TILE_SIZE) == floor(c_x2/REGION_TILE_SIZE) then
      return false
   end
   if not floor(c_y1/REGION_TILE_SIZE) == floor(c_y2/REGION_TILE_SIZE) then
      return false
   end
   return true
end

local function find_random_neighbour_chunk(ocx, ocy)
   -- somewhat bruteforce and unoptimized
   local x_dir = rgen:random(-1,1)
   local y_dir = rgen:random(-1,1)
   local ncx = ocx + x_dir*CHUNK_SIZE
   local ncy = ocy + y_dir*CHUNK_SIZE
   if is_same_region(ncx, ncy, ocx, ocy) then
      return ncx, ncy
   end

   ncx = ocx - x_dir*CHUNK_SIZE
   ncy = ocy - y_dir*CHUNK_SIZE
   if is_same_region(ncx, ncy, ocx, ocy) then
      return ncx, ncy
   end

   ncx = ocx - x_dir*CHUNK_SIZE
   if is_same_region(ncx, ocy, ocx, ocy) then
      return ncx, ocy
   end

   ncy = ocy - y_dir*CHUNK_SIZE
   if is_same_region(ocx, ncy, ocx, ocy) then
      return ocx, ncy
   end

   return ocx, ocy
end

local function isInStartingArea( regionX, regionY )
   for idx, pos in pairs( global.startingAreas ) do

      local adjustedX = regionX - pos.x / REGION_TILE_SIZE
      local adjustedY = regionY - pos.y / REGION_TILE_SIZE
      if ((adjustedX * adjustedX + adjustedY * adjustedY) <= starting_area_size * starting_area_size) then
         return true
      end
   end

   return false
end

-- modifies the resource size - only used in endless_resource_mode
local function modify_resource_size(resourceName, resourceSize, startingArea)

   if not startingArea then
      resourceSize = math.ceil(resourceSize * global_size_mult)
   end

   resourceEntity = game.entity_prototypes[resourceName]
   return resourceSize
end

--[[ SPAWN METHODS ]]--

local locationOrder =
{
   { x = 0, y = 0 },
   { x = -1, y = 0 },
   { x = 1, y = 0 },
   { x = 0, y = -1 },
   { x = 0, y = 1 },
   { x = -1, y = -1 },
   { x = 1, y = -1 },
   { x = -1, y = 1 },
   { x = 1, y = 1 }
}

--[[ entity-field ]]--
local function spawn_resource_ore(surface, rname, pos, size, richness, startingArea, restrictions)
   -- blob generator, centered at pos, size controls blob diameter
   restrictions = restrictions or ''
   rso_debug("Entering spawn_resource_ore "..rname.." at:"..pos.x..","..pos.y.." size:"..size.." richness:"..richness.." isStart:"..tostring(startingArea).." restrictions:"..restrictions)

   size = modify_resource_size(rname, size, startingArea)
   local radius = size / 2 -- to radius

   local p_balls={}
   local n_balls={}
   local MIN_BALL_DISTANCE = math.min(MIN_BALL_DISTANCE, radius/2)

   local maxPradius = 0
   local outside = { xmin = 1e10, xmax = -1e10, ymin = 1e10, ymax = -1e10 }
   local inside = { xmin = 1e10, xmax = -1e10, ymin = 1e10, ymax = -1e10 }

   local function adjustRadius(radius, scaleX, scaleY, up)
      return radius
   end

   local function updateRect(rect, x, y, radius)
      rect.xmin = math.min(rect.xmin, x - radius)
      rect.xmax = math.max(rect.xmax, x + radius)
      rect.ymin = math.min(rect.ymin, y - radius)
      rect.ymax = math.max(rect.ymax, y + radius)
   end

   local function updateRects(x, y, radius, scaleX, scaleY)
      local adjustedRadius = adjustRadius(radius, scaleX, scaleY, true)
      local radiusMax = adjustedRadius * 3 -- arbitrary multiplier - needs to be big enough to not cut any metaballs
      updateRect(outside, x, y, radiusMax)
      updateRect(inside, x, y, adjustedRadius)
   end

   local function generate_p_ball()
      local angle, x_scale, y_scale, x, y, b_radius, shape
      angle, x_scale, y_scale=rng_restricted_angle(restrictions)
      local dev = radius / 2 + rgen:random() * radius / 4--math.min(CHUNK_SIZE/3, radius*1.5)
      local dev_x, dev_y = pos.x, pos.y
      x = rgen:random(-dev, dev)+dev_x
      y = rgen:random(-dev, dev)+dev_y
      if p_balls[#p_balls] and Utils.distance(p_balls[#p_balls], {x=x, y=y}) < MIN_BALL_DISTANCE then
         local new_angle = bearing(p_balls[#p_balls], {x=x, y=y})
         rso_debug("Move ball old xy @ "..x..","..y)
         x=(cos(new_angle)*MIN_BALL_DISTANCE) + x
         y=(sin(new_angle)*MIN_BALL_DISTANCE) + y
         rso_debug("Move ball new xy @ "..x..","..y)
      end

      if #p_balls == 0 then
         b_radius = ( 3 * radius / 4 + rgen:random() * radius / 4) -- * (P_BALL_SIZE_FACTOR^#p_balls)
      else
         b_radius = ( radius / 4 + rgen:random() * radius / 2) -- * (P_BALL_SIZE_FACTOR^#p_balls)
      end


      if #p_balls > 0 then
         local tempRect = table.deepcopy(inside)
         updateRect(tempRect, x, y, adjustRadius(b_radius, x_scale, y_scale))
         local rectSize = math.max(tempRect.xmax - tempRect.xmin, tempRect.ymax - tempRect.ymin)
         local targetSize = size * 1.25
         rso_debug("Rect size "..rectSize.." targetSize "..targetSize)
         if rectSize > targetSize then
            local widthLeft = (targetSize - (inside.xmax - inside.xmin))
            local heightLeft = (targetSize - (inside.ymax - inside.ymin))
            local widthMod = math.min(x - inside.xmin, inside.xmax - x)
            local heightMod = math.min(y - inside.ymin, inside.ymax - y)
            local radiusBackup = b_radius
            b_radius = math.min(widthLeft + widthMod, heightLeft + heightMod)
            b_radius = adjustRadius(b_radius, x_scale, y_scale, false)
            rso_debug("Reduced ball radius from "..radiusBackup.." to "..b_radius.." widthLeft:"..widthLeft.." heightLeft:"..heightLeft.." widthMod:"..widthMod.." heightMod:"..heightMod)
         end
      end

      if b_radius < 2 and #p_balls == 0 then
         b_radius = 2
      end

      if b_radius > 0 then

         maxPradius = math.max(maxPradius, b_radius)
         shape = meta_shapes[rgen:random(1,#meta_shapes)]
         local radiusText = ""
         if shape.type == "MetaDonut" then
            local inRadius = b_radius / 4 + b_radius / 2 * rgen:random()
            radiusText = " inRadius:"..inRadius
            p_balls[#p_balls+1] = shape:new(x, y, b_radius, inRadius, angle, x_scale, y_scale, 1.1)
         else
            p_balls[#p_balls+1] = shape:new(x, y, b_radius, angle, x_scale, y_scale, 1.1)
         end
         updateRects(x, y, b_radius, x_scale, y_scale)

         rso_debug("P+Ball "..shape.type.." @ "..x..","..y.." radius: "..b_radius..radiusText.." angle: "..math.deg(angle).." scale: "..x_scale..", "..y_scale)
      end
   end

   local function generate_n_ball(i)
      local angle, x_scale, y_scale, x, y, b_radius, shape
      angle, x_scale, y_scale=rng_restricted_angle('xy')
      if p_balls[i] then
         local new_angle = p_balls[i].angle + pi*rgen:random(0,1) + (rgen:random()-0.5)*pi/2
         local dist = p_balls[i].radius
         x=(cos(new_angle)*dist) + p_balls[i].x
         y=(sin(new_angle)*dist) + p_balls[i].y
         angle = p_balls[i].angle + pi/2 + (rgen:random()-0.5)*pi*2/3
      else
         x = rgen:random(-radius, radius)+pos.x
         y = rgen:random(-radius, radius)+pos.y
      end

      if p_balls[i] then
         b_radius = (p_balls[i].radius / 4 + rgen:random() * p_balls[i].radius / 2) -- * (N_BALL_SIZE_FACTOR^#n_balls)
      else
         b_radius = (radius / 4 + rgen:random() * radius / 2) -- * (N_BALL_SIZE_FACTOR^#n_balls)
      end

      if b_radius < 1 then
         b_radius = 1
      end

      shape = meta_shapes[rgen:random(1,#meta_shapes)]
      local radiusText = ""
      if shape.type == "MetaDonut" then
         local inRadius = b_radius / 4 + b_radius / 2 * rgen:random()
         radiusText = " inRadius:"..inRadius
         n_balls[#n_balls+1] = shape:new(x, y, b_radius, inRadius, angle, x_scale, y_scale, 1.15)
      else
         n_balls[#n_balls+1] = shape:new(x, y, b_radius, angle, x_scale, y_scale, 1.15)
      end
      -- updateRects(x, y, b_radius, x_scale, y_scale) -- should not be needed here - only positive ball can generate ore
      rso_debug("N-Ball "..shape.type.." @ "..x..","..y.." radius: "..b_radius..radiusText.." angle: "..math.deg(angle).." scale: "..x_scale..", "..y_scale)
   end

   local function calculate_force(x,y)
      local p_force = 0
      local n_force = 0
      for _,ball in ipairs(p_balls) do
         p_force = p_force + ball:force(x,y)
      end
      for _,ball in ipairs(n_balls) do
         n_force = n_force + ball:force(x,y)
      end
      local totalForce = 0
      if p_force > n_force then
         totalForce = 1 - 1/(p_force - n_force)
      end
      --rso_debug("Force at "..x..","..y.." p:"..p_force.." n:"..n_force.." result:"..totalForce)
      --return (1 - 1/p_force) - n_force
      return totalForce
   end

   local max_p_balls = 2
   local min_amount = config[rname].min_amount or min_amount
   if restrictions == 'xy' then
      max_p_balls = 3
   end

   radius = math.min(radius, 2*CHUNK_SIZE)

   local force
   -- generate blobs
   for i=1,max_p_balls do
      generate_p_ball()
   end

   for i=1,rgen:random(1, #p_balls) do
      generate_n_ball(i)
   end


   local _total = 0
   local oreLocations = {}
   local forceTotal = 0

   -- fill the map
   for y=outside.ymin, outside.ymax do

      for x=outside.xmin, outside.xmax do
         force = calculate_force(x, y)
         if force > 0 then
            oreLocations[#oreLocations + 1] = {x = x, y = y, force = force, valid = false}
            forceTotal = forceTotal + force
         end
      end
   end

   local validCount, resOffsetX, resOffsetY, ratio

   for _,locationOffset in ipairs(locationOrder) do
      validCount = 0
      resOffsetX = locationOffset.x * CHUNK_SIZE
      resOffsetY = locationOffset.y * CHUNK_SIZE

      for _, location in ipairs(oreLocations) do

         local newX = location.x + resOffsetX
         local newY = location.y + resOffsetY
         location.valid = false
         if surface.can_place_entity{name = rname, position = {x = newX,y = newY}} then
            location.valid = true
            validCount = validCount + 1
         end
      end

      ratio = 0

      if validCount > 0 then
         ratio = validCount / #oreLocations
      end

      rso_debug("Valid ratio ".. ratio)

      if not useResourceCollisionDetection then
         break
      end

      if ratio > resourceCollisionDetectionRatio then
         break
      elseif resourceCollisionFieldSkip then -- in case no valid ratio was found we skip the field completely
         validCount = 0
      end
   end

   if validCount > 0 then
      local rectSize = ((inside.xmax - inside.xmin) + (inside.ymax - inside.ymin)) / 2

      local sizeMultiplier = rectSize ^ 0.6
      local minSize = richness * 5 * sizeMultiplier
      local maxSize = richness * 10 * sizeMultiplier
      local approxDepositSize = rgen:random(minSize, maxSize)

      approxDepositSize = approxDepositSize - validCount * min_amount

      if approxDepositSize < 0 then
         approxDepositSize = 100 * validCount
      end

      local forceFactor = approxDepositSize / forceTotal

      -- don't create very dense resources in starting area - another field will be generated
      if startingArea and forceFactor > 4000 then
         forceFactor = rgen:random(3000, 4000)
      end

      rso_debug( "Force total:"..forceTotal.." sizeMin:"..minSize.." sizeMax:"..maxSize.." factor:"..forceFactor.." location#:"..validCount.." rectSize:"..rectSize.." sizeMultiplier:"..sizeMultiplier)
      local richnessMultiplier = global_richness_mult

      if startingArea then
         richnessMultiplier = starting_richness_mult
      end

      -- infinite ore handling for Angels Ores mod
      local spawnName = rname

      for _,location in pairs(oreLocations) do
         if location.valid then

            local amount = floor(( forceFactor * location.force + min_amount ) * richnessMultiplier)

            if amount > 1e9 then
               amount = 1e9
            end

            _total = _total + amount

            spawnName = rname

            if amount > 0 then
               surface.create_entity{name = spawnName,
               position = {location.x + resOffsetX,location.y + resOffsetY},
               force = game.forces.neutral,
               amount = amount}
               if removeTrees then
						remove_trees(surface, location.x + resOffsetX, location.y + resOffsetY, 1, 1)
					end
            end
         end
      end

   end

   if rso_debug_enabled then
      rso_debug("Total amount: ".._total)
      rso_debug("Leaving spawn_resource_ore")
   end
   return _total
end

--[[ entity-liquid ]]--
local function spawn_resource_liquid(surface, rname, pos, size, richness, startingArea, restrictions)
   restrictions = restrictions or ''
   rso_debug("Entering spawn_resource_liquid "..rname.." "..pos.x..","..pos.y.." "..size.." "..richness.." "..tostring(startingArea).." "..restrictions)
   local _total = 0
   local max_radius = rgen:random()*CHUNK_SIZE/2 + CHUNK_SIZE

   richness = ( 0.75 + rgen:random() / 2 ) * richness * size

   resourceEntity = game.entity_prototypes[rname]


   local total_share = 0
   local avg_share = 1/size
   local angle = rgen:random()*pi*2
   local saved = 0
   while total_share < 1 do
      local new_share = vary_by_percentage(avg_share, 0.25)
      if new_share + total_share > 1 then
         new_share = 1 - total_share
      end

      total_share = new_share + total_share
      if new_share < avg_share/10 then
         -- too small
         break
      end
      local amount = floor(richness*new_share) + saved

      local richnessMultiplier = global_richness_mult

      if startingArea then
         richnessMultiplier = starting_richness_mult
      end

      --if amount >= game.entity_prototypes[rname].minimum then
      if amount >= config[rname].minimum_amount then
         saved = 0
         for try=1,5 do
            local dist = rgen:random()*(max_radius - max_radius*0.1)
            angle = angle + pi/4 + rgen:random()*pi/2
            local x, y = pos.x + cos(angle)*dist, pos.y + sin(angle)*dist
            if surface.can_place_entity{name = rname, position = {x,y}} then
               rso_debug("@ "..x..","..y.." amount: "..amount.." new_share: "..new_share.." try: "..try)
               amount = floor(amount * richnessMultiplier)

               if amount > 1e9 then
                  amount = 1e9
               end

               _total = _total + amount

               if amount > 0 then
                  surface.create_entity{name = rname,
                  position = {x,y},
                  force = game.forces.neutral,
                  amount = amount,
                  direction = rgen:random(4)}
               end
               break
            elseif not startingArea then -- we don't want to make ultra rich nodes in starting area - failing to make them will add second spawn in different location
               entities = surface.find_entities_filtered{area = {{x-2.75, y-2.75}, {x+2.75, y+2.75}}, name=rname}
               if entities and #entities > 0 then
                  _total = _total + amount
                  for k, ent in pairs(entities) do
                     ent.amount = ent.amount + floor(amount/#entities)
                  end
                  break
               end
            end
         end
      else
         saved = amount
      end
   end
   rso_debug("Total amount: ".._total)
   rso_debug("Leaving spawn_resource_liquid")
   return _total
end

--[[ EVENT/INIT METHODS ]]--

local function spawn_starting_resources( surface, index )

   if global.startingAreas[index].spawned then return end
   if surface.map_gen_settings.starting_area == "none" and not ignoreMapGenSettings then return end -- starting area disabled by map gen
   if starting_area_size < 0.1 then return end -- skip spawning if starting area is to small

   local position = global.startingAreas[index]

   rso_debug(position)
   rgen = rng_for_reg_pos( position )
   local status = true
   rso_debug(configIndexed)

   for index,v in ipairs(configIndexed) do
      if v.starting then
         local prob = rgen:random() -- probability that this resource is spawned
         rso_debug("starting resource probability rolled "..prob)
         if v.starting.probability > 0 and prob <= v.starting.probability then
            local total = 0
            local radius = 25
            local min_threshold = 0

            if v.type == "resource-ore" then
               min_threshold = v.starting.richness * rgen:random(5, 10) -- lets make sure that there is at least 10-15 times starting richness ore at start
            elseif v.type == "resource-liquid" then
               min_threshold = v.starting.richness * 0.5 * v.starting.size
            end
            rso_debug("Starting threshold: " .. min_threshold)

            while (radius < 200) and (total < min_threshold) do
               local angle = rgen:random() * pi * 2
               local dist = rgen:random() * 30 + radius * 2
               local pos = { x = floor(cos(angle) * dist) + position.x, y = floor(sin(angle) * dist) + position.y }
               if v.type == "resource-ore" then
                  total = total + spawn_resource_ore(surface, v.name, pos, v.starting.size, v.starting.richness, true)
               elseif v.type == "resource-liquid" then
                  total = total + spawn_resource_liquid(surface, v.name, pos, v.starting.size, v.starting.richness, true)
               end
               radius = radius + 10
            end
            if total < min_threshold then
               status = false
            end
         end
      end
   end

   global.startingAreas[index].spawned = true
end

local function modifyMinMax(value, mod)
   value.min = math.round( value.min * mod )
   value.max = math.round( value.max * mod )
end

local function prebuild_config_data(surface)
   if index_is_built then return false end

   local mapGenSettings = nil

   if not ignoreMapGenSettings then
      mapGenSettings = surface.map_gen_settings
   end
   local autoPlaceSettings = nil
   if mapGenSettings then
      autoPlaceSettings = mapGenSettings.autoplace_controls
   end

   configIndexed = {}
   -- build additional indexed array to the associative array
   for res_name, res_conf in pairs(config) do
      if res_conf.valid then -- only add valid resources
         res_conf.name = res_name

         local settingsForResource = nil
         local isEntity = (res_conf.type == "entity")
         local addResource = true

         local autoplaceName = res_name

         if res_conf.autoplace_name then
            autoplaceName = res_conf.autoplace_name
         end

         if autoPlaceSettings then
            settingsForResource = autoPlaceSettings[autoplaceName]
         end

         if settingsForResource then
            local allotmentMod = nil
            local sizeMod = nil
            if isEntity then
               allotmentMod = entityFrequencyMultiplier[settingsForResource.frequency]
               sizeMod = entitySizeMultiplier[settingsForResource.size]
            else
               allotmentMod =frequencyAllotmentMultiplier[settingsForResource.frequency]
               sizeMod = sizeMultiplier[settingsForResource.size]
            end

            local richnessMod = richnessMultiplier[settingsForResource.richness]

            rso_debug(res_name .. " allotment mod " .. allotmentMod .. " size mod " .. sizeMod .. " richness mod " .. richnessMod )

            if allotmentMod then
               if isEntity then
                  res_conf.absolute_probability = res_conf.absolute_probability * allotmentMod
                  rso_debug("Entity chance modified to "..res_conf.absolute_probability)
               else
                  res_conf.allotment = math.round( res_conf.allotment * allotmentMod )
               end
            end

            if sizeMod ~= nil and sizeMod == 0 then
               addResource = false
            end

            if sizeMod then
               modifyMinMax(res_conf.size, sizeMod)

               if res_conf.starting then
                  res_conf.starting.size = math.round( res_conf.starting.size * sizeMod )
               end

               if isEntity then
                  if res_conf.sub_spawn_size then
                     modifyMinMax(res_conf.sub_spawn_size, sizeMod)
                  end
                  modifyMinMax(res_conf.spawns_per_region, sizeMod)
               end
            end

            if richnessMod then
               if type == "resource-ore" then
                  res_conf.richness = math.round( res_conf.richness * richnessMod )
               elseif type == "resource-liquid" then
                  modifyMinMax(res_conf.richness, richnessMod)
               end

               if res_conf.starting then
                  res_conf.starting.richness = math.round( res_conf.starting.richness * richnessMod )
               end
            end
         end

         if addResource then
            configIndexed[#configIndexed + 1] = res_conf
            if res_conf.multi_resource and multi_resource_active then
               local new_list = {}
               for sub_res_name, allotment in pairs(res_conf.multi_resource) do
                  if config[sub_res_name] and config[sub_res_name].valid then
                     new_list[#new_list+1] = {name = sub_res_name, allotment = allotment}
                  end
               end
               table.sort(new_list, function(a, b) return a.name < b.name end)
               res_conf.multi_resource = new_list
            else
               res_conf.multi_resource_chance = nil
            end
         end
      end
   end

   table.sort(configIndexed, function(a, b) return a.name < b.name end)

   local pr=0
   for index,v in pairs(config) do
      if v.along_resource_probability then
         v.along_resource_probability_range={min=pr, max=pr+v.along_resource_probability}
         pr=pr+v.along_resource_probability
      end
      if v.allotment and v.allotment > 0 then
         v.allotment_range={min=max_allotment, max=max_allotment+v.allotment}
         max_allotment=max_allotment+v.allotment
      end
   end

   if mapGenSettings and mapGenSettings.starting_area then
      local multiplier = startingAreaMultiplier[mapGenSettings.starting_area]
      if multiplier ~= nil then
         starting_area_size = starting_area_size * multiplier
         rso_debug("Starting area "..starting_area_size)
      end
   end

   index_is_built = true
end


local function checkConfigForInvalidResources()
   --make sure that every resource in the config is actually available.
   --call this function, before the auxiliary config is prebuilt!
   if index_is_built then return end

   local prototypes = game.entity_prototypes

   for resourceName, resourceConfig in pairs(config) do
      if prototypes[resourceName] or resourceConfig.type == "entity" then
         resourceConfig.valid = true
      else
         -- resource was in config, but it doesn't exist in game files anymore - mark it invalid
         resourceConfig.valid = false

         table.insert(invalidResources, "Resource not available: " .. resourceName)
         rso_debug("Resource not available: " .. resourceName)
      end

      if resourceConfig.valid and resourceConfig.type ~= "entity" then
         if prototypes[resourceName].autoplace_specification == nil then
            resourceConfig.valid = false
            rso_debug("Resource "..resourceName.." invalidated - autoplace not present")
         end
      end
   end
end

local function roll_region(c_x, c_y)
   --in what region is this chunk?
   local r_x=floor(c_x/REGION_TILE_SIZE)
   local r_y=floor(c_y/REGION_TILE_SIZE)
   local r_data = nil
   rso_debug("Region rolling...")
   --don't spawn stuff in starting area
   if isInStartingArea( c_x/REGION_TILE_SIZE, c_y/REGION_TILE_SIZE ) then
      return false
   end

   if global.regions[r_x] and global.regions[r_x][r_y] then
      r_data = global.regions[r_x][r_y]
   else
      --if this chunk is the first in its region to be generated
      if not global.regions[r_x] then global.regions[r_x] = {} end
      global.regions[r_x][r_y]={}
      r_data = global.regions[r_x][r_y]
      rgen = rng_for_reg_pos{x=r_x,y=r_y}

      local rollCount = math.ceil(#configIndexed / 10) - 1 -- 0 based counter is more convenient here
      rollCount = math.min(rollCount, 3)

      for rollNumber = 0,rollCount do

         local resourceChance = absolute_resource_chance - rollNumber * 0.1
         --absolute chance to spawn resource
         local abct = rgen:random()
         rso_debug("Rolling resource "..abct.." against "..resourceChance.." roll "..rollNumber)
         if abct <= resourceChance then
            local res_type=rgen:random(1, max_allotment)
            for index,v in ipairs(configIndexed) do
               if v.allotment_range and ((res_type >= v.allotment_range.min) and (res_type <= v.allotment_range.max)) then
                  rso_debug("Rolled primary resource "..v.name.." with res_type="..res_type.." @ "..r_x..","..r_y)
                  local num_spawns=rgen:random(v.spawns_per_region.min, v.spawns_per_region.max)
                  local last_spawn_coords = {}
                  local along_
                  for i=1,num_spawns do
                     local c_x, c_y = find_random_chunk(r_x, r_y)
                     if not r_data[c_x] then r_data[c_x] = {} end
                     if not r_data[c_x][c_y] then r_data[c_x][c_y] = {} end
                     local c_data = r_data[c_x][c_y]
                     c_data[#c_data+1]={v.name, rollNumber}
                     last_spawn_coords[#last_spawn_coords+1] = {c_x, c_y}
                     rso_debug("Rolled primary chunk "..v.name.." @ "..c_x.."."..c_y.." reg: "..r_x..","..r_y)
                     -- Along resource spawn, only once
                     if i == 1 then
                        local am_roll = rgen:random()
                        for index,vv in ipairs(configIndexed) do
                           if vv.along_resource_probability_range and am_roll >= vv.along_resource_probability_range.min and am_roll <= vv.along_resource_probability_range.max then
                              c_data = r_data[c_x][c_y]
                              c_data[#c_data+1]={vv.name, rollNumber}
                              rso_debug("Rolled along "..vv.name.." @ "..c_x.."."..c_y.." reg: "..r_x..","..r_y)
                           end
                        end
                     end
                  end
                  -- roll multiple resources in same region
                  local deep=0
                  while v.multi_resource_chance and rgen:random() <= v.multi_resource_chance*(multi_resource_chance_diminish^deep) do
                     deep = deep + 1
                     local max_allotment = 0
                     for index,sub_res in pairs(v.multi_resource) do max_allotment=max_allotment+sub_res.allotment end

                     local res_type=rgen:random(1, max_allotment)
                     local min=0
                     for _, sub_res in pairs(v.multi_resource) do
                        if (res_type >= min) and (res_type <= sub_res.allotment + min) then
                           local last_coords = last_spawn_coords[rgen:random(1, #last_spawn_coords)]
                           local c_x, c_y = find_random_neighbour_chunk(last_coords[1], last_coords[2]) -- in same as primary resource chunk
                           if not r_data[c_x] then r_data[c_x] = {} end
                           if not r_data[c_x][c_y] then r_data[c_x][c_y] = {} end
                           local c_data = r_data[c_x][c_y]
                           c_data[#c_data+1]={sub_res.name, deep}
                           rso_debug("Rolled multiple "..sub_res.name..":"..deep.." with res_type="..res_type.." @ "..c_x.."."..c_y.." reg: "..r_x.."."..r_y)
                           break
                        else
                           min = min + sub_res.allotment
                        end
                     end
                  end
                  break
               end
            end

         end
      end
      -- roll for absolute_probability - this rolls the enemies

      for index,v in ipairs(configIndexed) do
         if v.absolute_probability then
            local prob_factor = 1
            if v.probability_distance_factor then
               prob_factor = math.min(v.max_probability_distance_factor, v.probability_distance_factor^Utils.distance({x=0,y=0},{x=r_x,y=r_y}))
            end
            local abs_roll = rgen:random()
            if abs_roll<v.absolute_probability*prob_factor then
               local num_spawns=rgen:random(v.spawns_per_region.min, v.spawns_per_region.max)
               for i=1,num_spawns do
                  local c_x, c_y = find_random_chunk(r_x, r_y)
                  if not r_data[c_x] then r_data[c_x] = {} end
                  if not r_data[c_x][c_y] then r_data[c_x][c_y] = {} end
                  c_data = r_data[c_x][c_y]
                  c_data[#c_data+1] = {v.name, 1}
                  rso_debug("Rolled absolute "..v.name.." with rt="..abs_roll.." @ "..c_x..","..c_y.." reg: "..r_x..","..r_y)
               end
            end
         end
      end
   end
end

local function roll_chunk(surface, c_x, c_y)
   --handle spawn in chunks
   local r_x=floor(c_x/REGION_TILE_SIZE)
   local r_y=floor(c_y/REGION_TILE_SIZE)
   local r_data = nil

   --don't spawn stuff in starting area (RSO version of starting areas)
   if isInStartingArea( c_x/REGION_TILE_SIZE, c_y/REGION_TILE_SIZE ) then
      return false
   end

   local c_center_x=c_x + CHUNK_SIZE/2
   local c_center_y=c_y + CHUNK_SIZE/2

   if not (global.regions[r_x] and global.regions[r_x][r_y]) then
      return
   end

   r_data = global.regions[r_x][r_y]
   if not (r_data[c_x] and r_data[c_x][c_y]) then
      return
   end
   if r_data[c_x] and r_data[c_x][c_y] then
      rgen = rng_for_reg_pos{x=c_center_x,y=c_center_y}

      rso_debug("Stumbled upon "..c_x..","..c_y.." reg: "..r_x.."."..r_y)
      local resource_list = r_data[c_x][c_y]
      --for resource, deep in pairs(r_data[c_x][c_y]) do
      --  resource_list[#resource_list+1] = {resource, deep}
      --end
      table.sort(resource_list, function(res1, res2) return res1[2] < res2[2] end)

      for _, res_con in ipairs(resource_list) do
         local resource = res_con[1]
         local deep = res_con[2]
         local r_config = config[resource]
         if r_config and r_config.valid then
            local dist = Utils.distance({x=0,y=0},{x=r_x,y=r_y})
            local sizeFactor = dist^size_distance_factor
            if r_config.type=="resource-ore" then
               local richFactor = dist^richness_distance_factor
               rso_debug("Resource "..resource.." distance "..dist.." factors (size, richness) "..sizeFactor..","..richFactor)
               local size=rgen:random(r_config.size.min, r_config.size.max) * (multi_resource_size_factor^deep) * sizeFactor
               local richness = r_config.richness * richFactor * (multi_resource_richness_factor^deep)
               local restriction = ''
               rso_debug("Center @ "..c_center_x..","..c_center_y)
               c_center_x, c_center_y, restriction = find_intersection(surface, c_center_x, c_center_y)
               rso_debug("New Center @ "..c_center_x..","..c_center_y)
               spawn_resource_ore(surface, resource, {x=c_center_x,y=c_center_y}, size, richness, false, restriction)
            elseif r_config.type=="resource-liquid" then
               local richFactor = dist^fluid_richness_distance_factor
               rso_debug("Resource "..resource.." distance "..dist.." factors (size, richness) "..sizeFactor..","..richFactor)
               local size=rgen:random(r_config.size.min, r_config.size.max)  * (multi_resource_size_factor^deep) * sizeFactor
               local richness=rgen:random(r_config.richness.min, r_config.richness.max) * richFactor * (multi_resource_richness_factor^deep)
               local restriction = ''
               c_center_x, c_center_y, restriction = find_intersection(surface, c_center_x, c_center_y)
               spawn_resource_liquid(surface, resource, {x=c_center_x,y=c_center_y}, size, richness, false, restriction)
            elseif r_config.type=="entity" then
               if (not isNearSpawn) then
                  spawn_entity(surface, resource, r_config, c_center_x, c_center_y)
               end
            end
         else
            rso_debug("Resource access failed for " .. resource)
         end
      end
      r_data[c_x][c_y]=nil
   end
end

function RSO_init()
   if not initDone then

      local surface = game.surfaces["nauvis"]

      if not global.regions then
         global.regions = {}
      end

      if not config then
         config = loadResourceConfig()
         checkConfigForInvalidResources()
         prebuild_config_data(surface)
      end

      global.seed = surface.map_gen_settings.seed

      if not global.startingAreas then
         global.startingAreas = {}
         table.insert( global.startingAreas, { x = 0, y = 0, spawned = false } )

         if global.start_resources_spawned or game.tick > 10 then
            global.startingAreas[1].spawned = true
         end
      end

      rso_debug("Starting resources...")
      spawn_starting_resources(surface, 1 )

      initDone = true

      if surface.map_gen_settings.autoplace_controls["iron-ore"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA iron-ore GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["copper-ore"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA copper-ore GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["uranium-ore"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA uranium-ore GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["crude-oil"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA crude-oil GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["enemy-base"].size ~= "none" then
         -- Not a problem, as this  RSO does not gen biters
--         Game.get_player_by_index(1).print("RSO WARNING - VANILLA enemy-base GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["stone"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA stone GEN IS NOT DISABLED!")
      end
      if surface.map_gen_settings.autoplace_controls["coal"].size ~= "none" then
         Game.get_player_by_index(1).print("RSO WARNING - VANILLA coal GEN IS NOT DISABLED!")
      end
   end

end

local Event = require 'utils.event'

local function run_ores_module(event) -- AKA RSO_ChunkGenerated(event)
      local c_x = event.area.left_top.x
      local c_y = event.area.left_top.y
  
      RSO_init()
  
      roll_region(c_x, c_y)
      roll_chunk(event.surface, c_x, c_y)
  end
  
Event.add(defines.events.on_chunk_generated, run_ores_module)