--Makes a stratus of rocks
--name of the rock to generate
--wherein kind of node to replace, for example default:stone
--minp, maxp the corners of the map to be generated
--seed random seed
--stratus_chance inverse probability in a given radius 1:2, 1:3 etc
--radius horizontal radius of the stratus
--radius_y vertical radius of the stratus
--deep how deep can be from the ground
local function generate_stratus(name, wherein, ceilin, ceil, minp, maxp, seed, stratus_chance, radius, radius_y, deep, height_min, height_max)
  if maxp.y < height_min or minp.y > height_max then
    return
  end
  -- it will be only generate a stratus for every 100 m of area
  local stratus_per_volume=1
  local area=45
  local y_min = math.max(minp.y, height_min)
  local y_max = math.min(maxp.y, height_max)
  local volume = ((maxp.x-minp.x+1)/area)*((y_max-y_min+1)/area)*((maxp.z-minp.z+1)/area)
  local pr = PseudoRandom(seed)
  local blocks = math.floor(stratus_per_volume*volume)
  print("  <<"..dump(name)..">>");
  if blocks == 0 then
    blocks = 1
  end
  print("    blocks: "..dump(blocks).." in vol: "..dump(volume).." ("..dump(maxp.x-minp.x+1)..","..dump(y_max-y_min+1)..","..dump(maxp.z-minp.z+1)..")")
  for i=1,blocks do
    local x = pr:next(1,stratus_chance)
    if x == 1 then
      -- TODO deep
      local y0=y_max-radius_y+1
      if y0 < y_min then
        y0=y_min
      else
        y0=pr:next(y_min, y0)
      end
      local x0 = maxp.x-radius+1
      if x0 < minp.x then
        x0 = minp.x
      else
        x0 = pr:next(minp.x, x0)
      end
      local z0 = maxp.z-radius+1
      if z0 < minp.z then
        x0 = minp.z
      else
        z0 = pr:next(minp.z, z0)
      end
      local p0 = {x=x0, y=y0, z=z0}
      local n = minetest.env:get_node(p0).name
      local i = 0
      --print("    upper node "..n)
      x = 0
      for k, v in ipairs(ceilin) do
        if n == v then
          x = 1
          break
        end
      end
      if x == 1 then
        -- search for the node to replace
        --print("    Searching nodes to replace from "..dump(y0-1).." to "..dump(y_min))
        for y1=y0-1,y_min,-1 do
          p0.y=y1
          n = minetest.env:get_node(p0).name
          x = 0
          for k, v in ipairs(wherein) do
            if n == v then
              x = 1
              break
            end
          end
          if x == 1 then
            y0=y1-deep
            if y0 < y_min then
              y0 = y_min
            end
            break
          end
        end
        local rx=pr:next(radius/2,radius)+1
        local rz=pr:next(radius/2,radius)+1
        local ry=pr:next(radius_y/2,radius_y)+1
        --print("    area of generation ("..dump(rx)..","..dump(rz)..","..dump(ry)..")")
        for x1=0,rx do
          rz = rz + 3 - pr:next(1,6)
          if rz < 1 then 
            rz = 1
          end
          for z1=pr:next(1,3),rz do
            local ry0=ry+ pr:next(1,3)
            for y1=pr:next(1,3),ry0 do
              local x2 = x0+x1
              local y2 = y0+y1
              local z2 = z0+z1
              local p2 = {x=x2, y=y2, z=z2}
              n = minetest.env:get_node(p2).name
              x = 0
              for k, v in ipairs(wherein) do
                if n == v then
                  x = 1
                  break
                end
              end
              if x == 1 then
                if ceil == nil then
                  minetest.env:set_node(p2, {name=name})
                  i = i +1
                else
                  local p3 = {p2.x,p2.y+1,p2}
                  if minetest.env:get_node(p3).name == ceil then
                     minetest.env:set_node(p2, {name=name})
                     i = i +1
                  end
                end
              end
            end
          end
        end
        print("    generated "..dump(i).." blocks in ("..dump(x0)..","..dump(y0)..","..dump(z0)..")")
      end

    end
  end
  --print("generate_ore done")
end

local function generate_claylike(name, minp, maxp, seed, chance, minh, maxh, dirt)
	if maxp.y >= maxh+1 and minp.y <= minh-1 then
    local pr = PseudoRandom(seed)
    local divlen = 4
    local divs = (maxp.x-minp.x)/divlen+1;
    for yy=minh,maxh do
      local x = pr:next(1,chance)
      if x == 1 then
		    for divx=0+1,divs-1-1 do
		      for divz=0+1,divs-1-1 do
			      local cx = minp.x + math.floor((divx+0.5)*divlen)
			      local cz = minp.z + math.floor((divz+0.5)*divlen)
            local up = minetest.env:get_node({x=cx,y=yy,z=cz}).name
            local down = minetest.env:get_node({x=cx,y=yy-1,z=cz}).name
			      if ( up == "default:water_source" or up == "air" ) and
				       ( down == "default:sand" or (dirt == 1 and (down == "default:dirt" or down == "default:dirt_with_grass" ))) then
				      local is_shallow = true
				      local num_water_around = 0
				      if minetest.env:get_node({x=cx-divlen*2,y=yy,z=cz}).name == "default:water_source" then
					      num_water_around = num_water_around + 1 end
				      if minetest.env:get_node({x=cx+divlen*2,y=yy,z=cz}).name == "default:water_source" then
					      num_water_around = num_water_around + 1 end
				      if minetest.env:get_node({x=cx,y=yy,z=cz-divlen*2}).name == "default:water_source" then
					      num_water_around = num_water_around + 1 end
				      if minetest.env:get_node({x=cx,y=yy,z=cz+divlen*2}).name == "default:water_source" then
					      num_water_around = num_water_around + 1 end
				      if num_water_around >= 3 then
					      is_shallow = false
				      end	
				      if is_shallow then
					      for x1=-divlen,divlen do
					        for z1=-divlen,divlen do
                    local p={x=cx+x1,y=yy-1,z=cz+z1}
                    down = minetest.env:get_node(p).name
						        if down == "default:sand" or (dirt == 1 and (down == "default:dirt" or down == "default:dirt_with_grass")) then
							        minetest.env:set_node(p, {name=name})
						        end
					        end
					      end
				      end
			      end
		      end
        end
      end
    end
  end
end

local function generate_ore(name, wherein, minp, maxp, seed, chunks_per_volume, chunk_size, ore_per_chunk, height_min, height_max)
	if maxp.y < height_min or minp.y > height_max then
		return
	end
	local y_min = math.max(minp.y, height_min)
	local y_max = math.min(maxp.y, height_max)
	local volume = (maxp.x-minp.x+1)*(y_max-y_min+1)*(maxp.z-minp.z+1)
	local pr = PseudoRandom(seed)
	local num_chunks = math.floor(chunks_per_volume * volume)
	local inverse_chance = math.floor(chunk_size*chunk_size*chunk_size / ore_per_chunk)
	--print("generate_ore num_chunks: "..dump(num_chunks))
	for i=1,num_chunks do
		local y0 = pr:next(y_min, y_max-chunk_size+1)
		if y0 >= height_min and y0 <= height_max then
			local x0 = pr:next(minp.x, maxp.x-chunk_size+1)
			local z0 = pr:next(minp.z, maxp.z-chunk_size+1)
			local p0 = {x=x0, y=y0, z=z0}
			for x1=0,chunk_size-1 do
			for y1=0,chunk_size-1 do
			for z1=0,chunk_size-1 do
				if pr:next(1,inverse_chance) == 1 then
					local x2 = x0+x1
					local y2 = y0+y1
					local z2 = z0+z1
					local p2 = {x=x2, y=y2, z=z2}
					if minetest.env:get_node(p2).name == wherein then
						minetest.env:set_node(p2, {name=name})
					end
				end
			end
			end
			end
		end
	end
	--print("generate_ore done")
end

minetest.register_on_generated(function(minp, maxp, seed)
  -- Generate stratus
  print("DARKAGE: Generate stratus");
  generate_ore("darkage:desert_stone_with_iron", "default:desert_stone", minp, maxp, seed+0, 1/7/7/7, 3, 5, -15, 40)
  generate_claylike("darkage:mud", minp, maxp, seed+1, 4, 0, 2, 0)
  generate_claylike("darkage:silt", minp, maxp, seed+2, 4, -1, 1, 1)
  generate_stratus("darkage:chalk", 
                   {"default:stone"},
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+3, 4, 25, 8, 0, -20,  50)
  generate_stratus("darkage:ors", 
                   {"default:stone"},
                   {"default:stone","air","default:water_source"}, nil,
                   minp, maxp, seed+4, 4, 25, 7, 50, -200,  500)
  generate_stratus("darkage:shale", 
                   {"default:stone"}, 
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+5, 4, 23, 7, 50, -50,  20)
  generate_stratus("darkage:slate", 
                   {"default:stone"}, 
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+6, 6, 23, 5, 50, -500, 0)
  generate_stratus("darkage:schist", 
                   {"default:stone"}, 
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+7, 6, 19, 6, 50, -31000, -10)
  generate_stratus("darkage:basalt", 
                   {"default:stone"}, 
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+8, 5, 20, 5, 20, -31000, -50)
  generate_stratus("darkage:marble", 
                   {"default:stone"},
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+9, 4, 25, 6, 50, -31000,  -75)
  generate_stratus("darkage:serpentine", 
                   {"default:stone"},
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+10, 4, 28, 8, 50, -31000,  -350)
  generate_stratus("darkage:gneiss", 
                   {"default:stone"}, 
                   {"default:stone","air"}, nil,
                   minp, maxp, seed+11, 4, 15, 5, 50, -31000, -250)
end)