-- pathv6alt 0.1.0 by paramat
-- For latest stable Minetest and back to 0.4.8
-- Depends default
-- License: code WTFPL

-- Parameters

-- 2D noise for base terrain

local np_base = {
	offset = -4,
	scale = 20,
	spread = {x=250, y=250, z=250},
	seed = 82341,
	octaves = 5,
	persist = 0.6
}

-- 2D noise for higher terrain

local np_higher = {
	offset = 20,
	scale = 16,
	spread = {x=500, y=500, z=500},
	seed = 85039,
	octaves = 5,
	persist = 0.6
}

-- 2D noise for height select

local np_hselect = {
	offset = 0.5,
	scale = 1,
	spread = {x=250, y=250, z=250},
	seed = 4213,
	octaves = 4, -- default - 1
	persist = 0.69
}

-- 2D noise for mud

local np_mud = {
	offset = 4,
	scale = 2,
	spread = {x=200, y=200, z=200},
	seed = 91013,
	octaves = 3,
	persist = 0.55
}

-- 2D noise for patha

local np_patha = {
	offset = 0,
	scale = 1,
	spread = {x=256, y=256, z=256},
	seed = 11,
	octaves = 4,
	persist = 0.33
}

-- 2D noise for pathb

local np_pathb = {
	offset = 0,
	scale = 1,
	spread = {x=256, y=256, z=256},
	seed = -80033,
	octaves = 4,
	persist = 0.33
}

-- Nodes

minetest.register_node("pathv6alt:wood", {
	description = "Path Planks",
	tiles = {"default_wood.png"},
	is_ground_content = false,
	groups = {choppy=2,oddly_breakable_by_hand=2,flammable=3,wood=1},
	drop = "default:wood",
	sounds = default.node_sound_wood_defaults(),
})

minetest.register_node("pathv6alt:path", {
	description = "Path",
	tiles = {"pathv6alt_path.png"},
	is_ground_content = false,
	groups = {crumbly=2},
	drop = "default:dirt",
	sounds = default.node_sound_dirt_defaults(),
})

minetest.register_node("pathv6alt:tree", {
	description = "Tree",
	tiles = {"default_tree_top.png", "default_tree_top.png", "default_tree.png"},
	paramtype2 = "facedir",
	is_ground_content = false,
	groups = {tree=1,choppy=2,oddly_breakable_by_hand=1,flammable=2},
	drop = "default:tree",
	sounds = default.node_sound_wood_defaults(),
	on_place = minetest.rotate_node
})

-- On generated function

minetest.register_on_generated(function(minp, maxp, seed)
	if minp.y ~= -32 then
		return
	end

	local t1 = os.clock()
	local x1 = maxp.x
	local y1 = maxp.y
	local z1 = maxp.z
	local x0 = minp.x
	local y0 = minp.y
	local z0 = minp.z
	
	print ("[pathv6alt] chunk minp ("..x0.." "..y0.." "..z0..")")
	
	local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
	local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
	local data = vm:get_data()
	
	local c_air = minetest.get_content_id("air")
	local c_tree = minetest.get_content_id("default:tree")
	local c_juntree = minetest.get_content_id("default:jungletree")
	local c_leaf = minetest.get_content_id("default:leaves")
	local c_apple = minetest.get_content_id("default:apple")
	local c_junleaf = minetest.get_content_id("default:jungleleaves")
	local c_sand = minetest.get_content_id("default:sand")
	local c_dirt = minetest.get_content_id("default:dirt")
	local c_grass = minetest.get_content_id("default:dirt_with_grass")
	local c_desand = minetest.get_content_id("default:desert_sand")
	local c_stone = minetest.get_content_id("default:stone")
	local c_destone = minetest.get_content_id("default:desert_stone")

	local c_wood = minetest.get_content_id("pathv6alt:wood")
	local c_path = minetest.get_content_id("pathv6alt:path")
	local c_column = minetest.get_content_id("pathv6alt:tree")
	
	local sidelen = x1 - x0 + 1
	local overlen = sidelen + 1
	local emerlen = sidelen + 32 -- voxelmanip emerged volume edge length for vvii
	local chulens = {x=overlen, y=overlen, z=sidelen} 
	local minpos = {x=x0-1, y=z0-1}

	local nvals_base = minetest.get_perlin_map(np_base, chulens):get2dMap_flat({x=x0+124, y=z0+124}) -- offsets - 1
	local nvals_higher = minetest.get_perlin_map(np_higher, chulens):get2dMap_flat({x=x0+249, y=z0+249})
	local nvals_hselect = minetest.get_perlin_map(np_hselect, chulens):get2dMap_flat({x=x0+124, y=z0+124})
	local nvals_mud = minetest.get_perlin_map(np_mud, chulens):get2dMap_flat({x=x0+99, y=z0+99})

	local nvals_patha = minetest.get_perlin_map(np_patha, chulens):get2dMap_flat(minpos)
	local nvals_pathb = minetest.get_perlin_map(np_pathb, chulens):get2dMap_flat(minpos)
	
	local ni = 1
	local stable = {}
	for z = z0 - 1, z1 do
		local n_xprepatha = false
		local n_xprepathb = false
		for x = x0 - 1, x1 do
			local chunk = x >= x0 and z >= z0

			local n_patha = nvals_patha[ni]
			local n_zprepatha = nvals_patha[(ni - overlen)]

			local n_pathb = nvals_pathb[ni]
			local n_zprepathb = nvals_pathb[(ni - overlen)]
			
			if chunk then
				local base = nvals_base[ni]
				local higher = nvals_higher[ni]
				local hselect = nvals_hselect[ni]
				local mudadd = nvals_mud[ni] / 2 + 0.5
				if higher < base then
					higher = base
				end
				local tblend = 0.5 + 0.5 * (hselect - 0.5) -- 0.2
				tblend = math.min(math.max(tblend, 0), 1)
				local tlevel = base * (1 - tblend) + higher * tblend + mudadd
				local pathy = math.floor(math.max(tlevel, 4))

				if (n_patha >= 0 and n_xprepatha < 0) or (n_patha < 0 and n_xprepatha >= 0) -- patha
				or (n_patha >= 0 and n_zprepatha < 0) or (n_patha < 0 and n_zprepatha >= 0)
				or (n_pathb >= 0 and n_xprepathb < 0) or (n_pathb < 0 and n_xprepathb >= 0) -- pathb
				or (n_pathb >= 0 and n_zprepathb < 0) or (n_pathb < 0 and n_zprepathb >= 0) then
					local wood = true
					for k = -1, 1 do
						local vi = area:index(x-1, pathy, z+k)
						for i = -1, 1 do
							local nodid = data[vi]
							if nodid == c_sand
							or nodid == c_desand
							or nodid == c_dirt
							or nodid == c_grass
							or nodid == c_stone
							or nodid == c_destone then
								wood = false
							end
							vi = vi + 1
						end
					end

					local excatop
					local vi = area:index(x, pathy + 4, z) -- tunnel roof
					local nodid = data[vi]
					if nodid == c_stone
					or nodid == c_destone then
						excatop = pathy + 3 -- tunnel
					else
						excatop = y1 -- excavate to chunk top
					end

					for y = pathy, excatop do
						for k = -1, 1 do
							local vi = area:index(x-1, y, z+k)
							for i = -1, 1 do
								local nodid = data[vi]
								if y == pathy then
									if wood then
										data[vi] = c_wood
									else
										data[vi] = c_path
									end
								elseif nodid ~= c_wood and nodid ~= c_path then
									data[vi] = c_air
								end
								vi = vi + 1
							end
						end
					end

					if wood and math.random() < 0.2 then
						local vi = area:index(x, pathy - 1, z)
						for y = pathy - 1, y0, -1 do
							local nodid = data[vi]
							if nodid == c_stone
							or nodid == c_destone then
								break
							else
								data[vi] = c_column
							end
							vi = vi - emerlen
						end
					end
				end
			end

			n_xprepatha = n_patha
			n_xprepathb = n_pathb
			ni = ni + 1
		end
	end
	
	vm:set_data(data)
	vm:set_lighting({day=0, night=0})
	vm:calc_lighting()
	vm:write_to_map(data)

	local chugent = math.ceil((os.clock() - t1) * 1000)
	print ("[pathv6alt] "..chugent.." ms")
end)