-- Fun_Caves deco.lua
-- Copyright Duane Robertson (duane@duanerobertson.com), 2017
-- Distributed under the LGPLv2.1 (https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html)


dofile(fun_caves_mod.path .. "/nodes.lua")
dofile(fun_caves_mod.path .. "/fungal_tree.lua")


local deco_depth = -5  -- place cave stuff this far beneath the surface
local water_level = 1
local fluid_compression = -22000  -- the depth to start planting lava/water
local max_depth = -27960

local csize
local node_match_cache = {}


local biome_noise = {offset = 0.0, scale = 1.0, spread = {x = 400, y = 400, z = 400}, seed = 903, octaves = 3, persist = 0.5, lacunarity = 2.0}


-- Air needs to be placed prior to decorations.
fun_caves_mod.decogen = function(minp, maxp, data, area, node, heightmap)
	if not (minp and maxp and data and area and node and type(data) == 'table' and fun_caves_mod.cave_biomes and fun_caves_mod.make_fungal_tree) then
		return
	end
    local temp_y = (minp.y+maxp.y)/2
    if temp_y > -28000 or temp_y < -30999 then return end

	csize = vector.add(vector.subtract(maxp, minp), 1)

	local map_max = {x = csize.x, y = csize.y + 2, z = csize.z}
	local map_min = {x = minp.x, y = minp.y - 1, z = minp.z}

	local biome_n = minetest.get_perlin_map(biome_noise, map_max):get3dMap_flat(map_min)

	local write
	local index = 0
	local index3d = 0
	local math_max = math.max
	local math_min = math.min
	local math_log = math.log
  local math_random = math.random

	for z = minp.z, maxp.z do
		for x = minp.x, maxp.x do
			index = index + 1
			index3d = (z - minp.z) * (csize.y + 2) * csize.x + (x - minp.x) + 1
			local ivm = area:index(x, minp.y, z)
			local height = heightmap[index]

			for y = minp.y-1, maxp.y+1 do
				if y <= height + deco_depth and (height < max_depth or y < 0) then
					for deco_non_loop = 1, 1 do
						if not (data[ivm] == node["air"] or data[ivm] == node["default:stone"]) then
							break
						end

						local biome
            local biome_val = biome_n[index3d]

            -- Compress biomes at the surface to avoid fluids.
            if y > fluid_compression then
              biome_val = biome_val / math_max(1, math_log(y - fluid_compression))
            end

            for _, bi in pairs(fun_caves_mod.cave_biomes) do
              if biome_val >= bi.biome_val_low and biome_val < bi.biome_val_high then
                biome = bi
              end
            end
            --biome = fun_caves_mod.cave_biomes['salt']

            if not biome then
              print(("* Fun Caves: Error in biome selection: %s"):format(biome_val))
              biome = fun_caves_mod.cave_biomes['algae']
            end


						local node_below
						if y > minp.y then
							node_below = data[ivm - area.ystride]
						end
						local node_above = data[ivm + area.ystride]

						if data[ivm] == node["default:stone"] then
							if node_above == node["air"] and biome and biome.dirt and math_random(biome.dirt_chance) == 1 then
								data[ivm] = node[biome.dirt]
								write = true
								break
							end

							local air_above = false
							for i = 1, biome.stone_depth do
								if data[ivm + area.ystride * i] == node["air"] then
									air_above = true
								end
							end

							if air_above then
								if biome and biome.deco and math_random(biome.deco_chance) == 1 then
									data[ivm] = node[biome.deco]
									write = true
									break
								else
									data[ivm] = node[biome.floor_node]
									write = true
									break
								end
							end

							local air_below = false
							for i = 1, biome.stone_depth do
								if data[ivm - area.ystride * i] == node["air"] then
									air_below = true
								end
							end

              -- Prevent server-crashing sandslides.
							if not air_above and biome.floor_node == "default:sand" then
								data[ivm] = node["default:sandstone"]
								write = true
								break
							end

							if air_below then
								if biome and biome.deco and math_random(biome.deco_chance) == 1 then
									data[ivm] = node[biome.deco]
									write = true
									break
								else
									data[ivm] = node[biome.ceiling_node]
									write = true
									break
								end
							end
						end

						if data[ivm] == node["air"] and y < maxp.y then
							-- hanging down
							--  stone hasn't yet been changed
							if biome and biome.stalactite and node_above == node["default:stone"] and math_random(biome.stalactite_chance) == 1 then
								data[ivm] = node[biome.stalactite]
								write = true
								break
							end

							-- fluids
							if y > minp.y and biome and biome.fluid and node_below == node[biome.floor_node] and math_random(biome.fluid_chance) == 1 then
								data[ivm] = node[biome.fluid]
								write = true
								break

								-- standing up
							elseif node_below == node[biome.floor_node] and biome and biome.stalagmite and math_random(biome.stalagmite_chance) == 1 then
								if type(biome.stalagmite) == 'table' then
									data[ivm] = node[biome.stalagmite[math_random(#biome.stalagmite)]]
								else
									data[ivm] = node[biome.stalagmite]
								end
								write = true
								break

								-- vegetation
							elseif node_below == node["default:dirt"] and biome and biome.fungi then
								if math_random(10) == 1 then
									data[ivm] = node["flowers:mushroom_red"]
									write = true
									break
								elseif math_random(10) == 1 then
									data[ivm] = node["flowers:mushroom_brown"]
									write = true
									break
								elseif node_above == node["air"] and math_random(10) == 1 then
									data[ivm] = node["fun_caves:giant_mushroom_stem"]
									write = true
									break
								elseif math_random(30) == 1 then
									local air_count = 0
									local j
									for i = 1, 12 do
										j = ivm + area.ystride * i
										if j <= #data and data[j] == node["air"] then
											air_count = air_count + 1
										end
									end
									if air_count > 5 then
										fun_caves_mod.make_fungal_tree(data, area, ivm, math_random(2, math_min(air_count, 12)))
									end
								end
							elseif node_below == node["fun_caves:giant_mushroom_stem"] and data[ivm - area.ystride * 2] == node["fun_caves:giant_mushroom_stem"] then
								data[ivm] = node["fun_caves:giant_mushroom_cap"]
								write = true
								break
							elseif node_below == node["fun_caves:giant_mushroom_stem"] then
								if node_above == node["air"] and math_random(3) == 1 then
									data[ivm] = node["fun_caves:giant_mushroom_stem"]
									write = true
									break
								else
									data[ivm] = node["fun_caves:huge_mushroom_cap"]
									write = true
									break
								end
							end
						end
					end
				elseif y < height and data[ivm] == node["air"] and (data[ivm - area.ystride] == node['default:stone'] or data[ivm - area.ystride] == node['default:sandstone']) then
					-- This just places non-abm dirt inside caves.
					-- Its value is questionable.
						data[ivm - area.ystride] = node["fun_caves:dirt"]
						write = true
				end

				ivm = ivm + area.ystride
				index3d = index3d + csize.x
			end
		end
	end

	return write
end