function watershed_appletree(x, y, z, area, data)
	local c_tree = minetest.get_content_id("default:tree")
	local c_apple = minetest.get_content_id("default:apple")
	local c_wsappleaf = minetest.get_content_id("watershed:appleleaf")
	for j = -2, 4 do
		if j == 3 or j == 4 then
			for i = -2, 2 do
			for k = -2, 2 do
				local vil = area:index(x + i, y + j, z + k)
				if math.random(64) == 2 then
					data[vil] = c_apple
				elseif math.random(5) ~= 2 then
					data[vil] = c_wsappleaf
				end
			end
			end
		elseif j == 2 then
			for i = -1, 1 do
			for k = -1, 1 do
				if math.abs(i) + math.abs(k) == 2 then
					local vit = area:index(x + i, y + j, z + k)
					data[vit] = c_tree
				end
			end
			end
		else
			local vit = area:index(x, y + j, z)
			data[vit] = c_tree
		end
	end
end

function watershed_pinetree(x, y, z, area, data)
	local c_wspitree = minetest.get_content_id("watershed:pinetree")
	local c_wsneedles = minetest.get_content_id("watershed:needles")
	local c_snowblock = minetest.get_content_id("default:snowblock")
	for j = -4, 14 do
		if j == 3 or j == 6 or j == 9 or j == 12 then
			for i = -2, 2 do
			for k = -2, 2 do
				if math.abs(i) == 2 or math.abs(k) == 2 then
					if math.random(7) ~= 2 then
						local vil = area:index(x + i, y + j, z + k)
						data[vil] = c_wsneedles
						local vila = area:index(x + i, y + j + 1, z + k)
						data[vila] = c_snowblock
					end
				end
			end
			end
		elseif j == 4 or j == 7 or j == 10 then
			for i = -1, 1 do
			for k = -1, 1 do
				if not (i == 0 and j == 0) then
					if math.random(11) ~= 2 then
						local vil = area:index(x + i, y + j, z + k)
						data[vil] = c_wsneedles
						local vila = area:index(x + i, y + j + 1, z + k)
						data[vila] = c_snowblock
					end
				end
			end
			end
		elseif j == 13 then
			for i = -1, 1 do
			for k = -1, 1 do
				if not (i == 0 and j == 0) then
					local vil = area:index(x + i, y + j, z + k)
					data[vil] = c_wsneedles
					local vila = area:index(x + i, y + j + 1, z + k)
					data[vila] = c_wsneedles
					local vilaa = area:index(x + i, y + j + 2, z + k)
					data[vilaa] = c_snowblock
				end
			end
			end
		end
		local vit = area:index(x, y + j, z)
		data[vit] = c_wspitree
	end
	local vil = area:index(x, y + 15, z)
	local vila = area:index(x, y + 16, z)
	local vilaa = area:index(x, y + 17, z)
	data[vil] = c_wsneedles
	data[vila] = c_wsneedles
	data[vilaa] = c_snowblock
end

function watershed_jungletree(x, y, z, area, data)
	local c_juntree = minetest.get_content_id("default:jungletree")
	local c_wsjunleaf = minetest.get_content_id("watershed:jungleleaf")
	local c_vine = minetest.get_content_id("watershed:vine")
	local top = math.random(17,23)
	local branch = math.floor(top * 0.6)
	for j = -5, top do
		if j == top or j == top - 1 or j == branch + 1 or j == branch + 2 then
			for i = -2, 2 do -- leaves
			for k = -2, 2 do
				local vi = area:index(x + i, y + j, z + k)
				if math.random(5) ~= 2 then
					data[vi] = c_wsjunleaf
				end
			end
			end
		elseif j == top - 2 or j == branch then -- branches
			for i = -1, 1 do
			for k = -1, 1 do
				if math.abs(i) + math.abs(k) == 2 then
					local vi = area:index(x + i, y + j, z + k)
					data[vi] = c_juntree
				end
			end
			end
		end
		if j >= 0 and j <= top - 3 then -- climbable nodes
			for i = -1, 1 do
			for k = -1, 1 do
				if math.abs(i) + math.abs(k) == 1 then
					local vi = area:index(x + i, y + j, z + k)
					data[vi] = c_vine
				end
			end
			end
		end
		if j <= top - 3 then -- trunk
			local vi = area:index(x, y + j, z)
			data[vi] = c_juntree
		end
	end
end

function watershed_acaciatree(x, y, z, area, data)
	local c_wsactree = minetest.get_content_id("watershed:acaciatree")
	local c_wsacleaf = minetest.get_content_id("watershed:acacialeaf")
	for j = -3, 6 do
		if j == 6 then
			for i = -4, 4 do
			for k = -4, 4 do
				if not (i == 0 or k == 0) then
					if math.random(7) ~= 2 then
						local vil = area:index(x + i, y + j, z + k)
						data[vil] = c_wsacleaf
					end
				end
			end
			end
		elseif j == 5 then
			for i = -2, 2, 4 do
			for k = -2, 2, 4 do
				local vit = area:index(x + i, y + j, z + k)
				data[vit] = c_wsactree
			end
			end
		elseif j == 4 then
			for i = -1, 1 do
			for k = -1, 1 do
				if math.abs(i) + math.abs(k) == 2 then
					local vit = area:index(x + i, y + j, z + k)
					data[vit] = c_wsactree
				end
			end
			end
		else
			local vit = area:index(x, y + j, z)
			data[vit] = c_wsactree
		end
	end
end

function watershed_flower(data, vi, noise)
	local c_danwhi = minetest.get_content_id("flowers:dandelion_white")
	local c_danyel = minetest.get_content_id("flowers:dandelion_yellow")
	local c_rose = minetest.get_content_id("flowers:rose")
	local c_tulip = minetest.get_content_id("flowers:tulip")
	local c_geranium = minetest.get_content_id("flowers:geranium")
	local c_viola = minetest.get_content_id("flowers:viola")
	if noise > 0.8 then
		data[vi] = c_danwhi
	elseif noise > 0.4 then
		data[vi] = c_rose
	elseif noise > 0 then
		data[vi] = c_tulip
	elseif noise > -0.4 then
		data[vi] = c_danyel
	elseif noise > -0.8 then
		data[vi] = c_geranium
	else
		data[vi] = c_viola
	end
end

function watershed_cactus(x, y, z, area, data)
	local c_wscactus = minetest.get_content_id("watershed:cactus")
	for j = -2, 4 do
	for i = -2, 2 do
		if i == 0 or j == 2 or (j == 3 and math.abs(i) == 2) then
			local vic = area:index(x + i, y + j, z)
			data[vic] = c_wscactus
		end
	end
	end
end

function watershed_papyrus(x, y, z, area, data)
	local c_papyrus = minetest.get_content_id("default:papyrus")
	local ph = math.random(1, 4)
	for j = 0, ph do
		local vip = area:index(x, y + j, z)
		data[vip] = c_papyrus
	end
end

-- Singlenode option

local SINGLENODE = true

if SINGLENODE then
	-- Set mapgen parameters

	minetest.set_mapgen_params({mgname = "singlenode", flags = "nolight"})

	-- Spawn player function. Requires chunksize = 80 nodes (the default)

	function spawnplayer(player)
		local TERCEN = -128
		local TERSCA = 512
		local XLSAMP = 0.1
		local BASAMP = 0.3
		local MIDAMP = 0.1
		local CANAMP = 0.4
		local ATANAMP = 1.1
		local BLENEXP = 2
		local xsp
		local ysp
		local zsp

		local np_terrain = {
			offset = 0,
			scale = 1,
			spread = {x=384, y=192, z=384},
			seed = 593,
			octaves = 5,
			persist = 0.67
		}
		local np_mid = {
			offset = 0,
			scale = 1,
			spread = {x=768, y=768, z=1},
			seed = 85546,
			octaves = 5,
			persist = 0.5
		}
		local np_base = {
			offset = 0,
			scale = 1,
			spread = {x=4096, y=4096, z=1},
			seed = 8890,
			octaves = 3,
			persist = 0.33
		}
		local np_xlscale = {
			offset = 0,
			scale = 1,
			spread = {x=8192, y=8192, z=1},
			seed = -72,
			octaves = 3,
			persist = 0.33
		}

		local nobj_terrain = nil
		local nobj_mid     = nil
		local nobj_base    = nil
		local nobj_xlscale = nil

		for chunk = 1, 64 do
			print ("[watershed] searching for spawn "..chunk)
			local x0 = 80 * math.random(-32, 32) - 32
			local z0 = 80 * math.random(-32, 32) - 32
			local y0 = -32
			local x1 = x0 + 79
			local z1 = z0 + 79
			local y1 = 47
			local sidelen = 80
			local chulensxyz = {x = sidelen, y = sidelen + 2, z = sidelen}
			local chulensxz = {x = sidelen, y = sidelen, z = 1}
			local minposxyz = {x = x0, y = y0 - 1, z = z0}
			local minposxz = {x = x0, y = z0}

			nobj_terrain = nobj_terrain or minetest.get_perlin_map(np_terrain, chulensxyz)
			nobj_mid     = nobj_mid     or minetest.get_perlin_map(np_mid, chulensxz)
			nobj_base    = nobj_base    or minetest.get_perlin_map(np_base, chulensxz)
			nobj_xlscale = nobj_xlscale or minetest.get_perlin_map(np_xlscale, chulensxz)

			local nvals_terrain = nobj_terrain:get3dMap_flat(minposxyz)
			local nvals_mid     = nobj_mid:get2dMap_flat(minposxz)
			local nvals_base    = nobj_base:get2dMap_flat(minposxz)
			local nvals_xlscale = nobj_xlscale:get2dMap_flat(minposxz)

			local nixz = 1
			local nixyz = 1
			for z = z0, z1 do
				for y = y0, y1 do
					for x = x0, x1 do
						local n_absterrain = math.abs(nvals_terrain[nixyz])
						local n_absmid = math.abs(nvals_mid[nixz])
						local n_absbase = math.abs(nvals_base[nixz])
						local n_xlscale = nvals_xlscale[nixz]
						
						local n_invbase = (1 - n_absbase)
						local terblen = (math.max(n_invbase, 0)) ^ BLENEXP
						local grad = math.atan((TERCEN - y) / TERSCA) * ATANAMP
						local densitybase = n_invbase * BASAMP + n_xlscale * XLSAMP + grad
						local densitymid = n_absmid * MIDAMP + densitybase
						local canexp = 0.5 + terblen * 0.5
						local canamp = terblen * CANAMP
						local density = n_absterrain ^ canexp * canamp * n_absmid + densitymid
						
						if y >= 1 and density > -0.005 and density < 0 then
							ysp = y + 1
							xsp = x
							zsp = z
							break
						end
						nixz = nixz + 1
						nixyz = nixyz + 1
					end
					if ysp then
						break
					end
					nixz = nixz - 80
				end
				if ysp then
					break
				end
				nixz = nixz + 80
			end
			if ysp then
				break
			end
		end
		print ("[watershed] spawn player (" .. xsp .. " " .. ysp .. " " .. zsp .. ")")
		player:setpos({x = xsp, y = ysp, z = zsp})
	end

	minetest.register_on_newplayer(function(player)
		spawnplayer(player)
	end)

	minetest.register_on_respawnplayer(function(player)
		spawnplayer(player)
		return true
	end)
end

-- ABM

-- Lava-water cooling

minetest.register_abm({
	nodenames = {"group:lava"},
	neighbors = {"group:water"},
	interval = 11,
	chance = 64,
	action = function(pos)
		minetest.add_node(pos, {name = "default:obsidian"})
		minetest.sound_play("default_cool_lava", {pos = pos, gain = 0.25})
	end,
})

-- Appletree sapling

minetest.register_abm({
	nodenames = {"watershed:appling"},
	interval = 57,
	chance = 3,
	action = function(pos, node)
		local x = pos.x
		local y = pos.y
		local z = pos.z
		local vm = minetest.get_voxel_manip()
		local pos1 = {x = x - 2, y = y - 2, z = z - 2}
		local pos2 = {x = x + 2, y = y + 4, z = z + 2}
		local emin, emax = vm:read_from_map(pos1, pos2)
		local area = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
		local data = vm:get_data()
		watershed_appletree(x, y, z, area, data)
		vm:set_data(data)
		vm:write_to_map()
		vm:update_map()
	end,
})

-- Pine sapling

minetest.register_abm({
	nodenames = {"watershed:pineling"},
	interval = 59,
	chance = 3,
	action = function(pos)
		local x = pos.x
		local y = pos.y
		local z = pos.z
		local vm = minetest.get_voxel_manip()
		local pos1 = {x = x - 2, y = y - 4, z = z - 2}
		local pos2 = {x = x + 2, y = y + 17, z = z + 2}
		local emin, emax = vm:read_from_map(pos1, pos2)
		local area = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
		local data = vm:get_data()
		watershed_pinetree(x, y, z, area, data)
		vm:set_data(data)
		vm:write_to_map()
		vm:update_map()
	end,
})

-- Acacia sapling

minetest.register_abm({
	nodenames = {"watershed:acacialing"},
	interval = 61,
	chance = 3,
	action = function(pos)
		local x = pos.x
		local y = pos.y
		local z = pos.z
		local vm = minetest.get_voxel_manip()
		local pos1 = {x = x - 4, y = y - 3, z = z - 4}
		local pos2 = {x = x + 4, y = y + 6, z = z + 4}
		local emin, emax = vm:read_from_map(pos1, pos2)
		local area = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
		local data = vm:get_data()
		watershed_acaciatree(x, y, z, area, data)
		vm:set_data(data)
		vm:write_to_map()
		vm:update_map()
	end,
})

-- Jungletree sapling

minetest.register_abm({
	nodenames = {"watershed:jungling"},
	interval = 63,
	chance = 3,
	action = function(pos)
		local x = pos.x
		local y = pos.y
		local z = pos.z
		local vm = minetest.get_voxel_manip()
		local pos1 = {x = x - 2, y = y - 5, z = z - 2}
		local pos2 = {x = x + 2, y = y + 23, z = z + 2}
		local emin, emax = vm:read_from_map(pos1, pos2)
		local area = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
		local data = vm:get_data()
		watershed_jungletree(x, y, z, area, data)
		vm:set_data(data)
		vm:write_to_map()
		vm:update_map()
	end,
})