-- Some local constants to use for mapgen
local c_air     = minetest.CONTENT_AIR
local c_ignore  = minetest.CONTENT_IGNORE

local c_stone   = minetest.get_content_id("default:stone")
local c_water	= minetest.get_content_id("default:water_source")
local c_sand 	= minetest.get_content_id("default:sand")
local c_dirt 	= minetest.get_content_id("default:dirt")
local c_lawn 	= minetest.get_content_id("default:dirt_with_grass")

local stone_and_air_assoc = {[c_stone]=true,[c_air]=true} --associative array

--Makes a stratus of rocks
--name of the rock to generate
--c_wherein id of node to replace, for example minetest.get_content_id("default:stone")
--ca_ceilin associative array
--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(data, area, name, c_wherein, ca_ceilin, minp, maxp, seed, stratus_chance, radius, radius_y, deep, y_min, y_max)
	if maxp.y < y_min
	   or minp.y > y_max then
		return
	end

	local c_node = minetest.get_content_id(name)

	-- it will be only generate a stratus for every 100 m of area
	local stratus_per_volume=1
	local area_size = 45
	local y_min = math.max(minp.y, y_min)
	local y_max = math.min(maxp.y, y_max)
	local volume = ((maxp.x-minp.x+1)/area_size)*((y_max-y_min+1)/area_size)*((maxp.z-minp.z+1)/area_size)
	local pr = PseudoRandom(seed)
	local blocks = math.floor(stratus_per_volume*volume)
	minetest.log("info", "	<<"..name..">>");
	if blocks == 0 then
		blocks = 1
	end
	minetest.log("info", string.format("	blocks: %d in vol: %d (%d,%d,%d)",
									   blocks, volume, maxp.x-minp.x+1, y_max-y_min+1, maxp.z-minp.z+1))
	for i = 1,blocks do
		if pr:next(1,stratus_chance) == 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 n = data[area:index(x0, y0, z0)]
			local i = 0

			if ca_ceilin[n] then
				-- search for the node to replace
				--print("	Searching nodes to replace from "..dump(y0-1).." to "..dump(y_min))
				local vi = area:index(x0, y0-1, z0)
				for y1 = y0-1,y_min,-1 do
					if data[vi] == c_wherein then
						y0 = math.max(y1-deep, y_min)
						break
					end
					vi = vi - area.ystride
				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)..")")
				vi = area:index(x0, y0, z0)
				for x1=0,rx do
					local vi = vi + x1
					rz = math.max(rz + 3 - pr:next(1,6), 1)
					for z1=pr:next(1,3),rz do
						local vi = vi + z1 * area.zstride
						for y1 = pr:next(1,3), ry + pr:next(1,3) do
							local vi = vi + y1 * area.ystride
							if data[vi] == c_wherein then
								data[vi] = c_node
								i = i + 1
							end
						end
					end
				end
			end
			minetest.log("info", "	generated "..i.." blocks in ("..x0..","..y0..","..z0..")")
		end
	end
	--print("generate_ore done")
end

local function generate_claylike(data, varea, name, minp, maxp, seed, chance, minh, maxh, needs_dirt)
	if maxp.y >= maxh+1 and minp.y <= minh-1 then
		local c_ore = minetest.get_content_id(name)
		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 = data[varea:index(cx,yy,cz)]
						local down = data[varea:index(cx,yy-1,cz)]
						if ( up == c_water or up == c_air ) and ( down == c_sand or (needs_dirt and (down == c_dirt or down == c_lawn ))) then
							local num_water_around = 0
							if data[varea:index(cx-divlen*2,yy,cz)] == c_water then
								num_water_around = num_water_around + 1
							end
							if data[varea:index(cx+divlen*2,yy,cz)] == c_water then
								num_water_around = num_water_around + 1
							end
							if data[varea:index(cx,yy,cz-divlen*2)] == c_water then
								num_water_around = num_water_around + 1
							end
							if data[varea:index(cx,yy,cz+divlen*2)] == c_water then
								num_water_around = num_water_around + 1
							end
							if num_water_around < 3 then
								for x1=-divlen,divlen do
									for z1=-divlen,divlen do
										local i = varea:index(cx+x1,yy-1,cz+z1)
										local down = data[i]
										if down == c_sand or (needs_dirt and (down == c_dirt or down == c_lawn)) then
											data[i] = c_ore
										end
									end
								end
							end
						end
					end
				end
			end
		end
	end
end

local seed = minetest.get_mapgen_setting("seed")


-- Generate desert stone with iron in derset.
minetest.register_ore({
	ore_type       = "scatter",
	ore            = "darkage:desert_stone_with_iron",
	wherein        = "default:desert_stone",
	clust_scarcity = 12 * 12 * 12,
	clust_num_ores = 3,
	clust_size     = 2,
	y_min          = -1,
	y_max          = 200,
})

-- Generate chalk inside mountains
minetest.register_ore({
	ore_type        	= "sheet",
	ore             	= "darkage:chalk",
	wherein         	= {"default:stone"},
	column_height_max = 30,
	column_height_min = 20,
	y_min            = -20,
	y_max            = 50,
	noise_threshold = 0.45,
	noise_params     = {
		offset = 0.35,
		scale = 0.2,
		spread = {x = 30, y = 30, z = 30},
		octaves = 1,
		persistence = 0.6
	},
})

minetest.register_ore({
	ore_type        	= "sheet",
	ore             	= "darkage:tuff",
	wherein         	= {"default:stone", "default:dirt", "default:gravel", "default:stone_with_coal"},
	column_height_max = 20,
	column_height_min = 15,
	y_min            = -200,
	y_max            = 200,
	noise_threshold = 0.5,
	noise_params     = {
		offset = 0.35,
		scale = 0.19,
		seed = seed+12,
		spread = {x = 45, y = 45, z = 45},
		octaves = 1,
		persistence = 0.6
	},
})

minetest.register_ore({
	ore_type        	= "sheet",
	ore             	= "darkage:rhyolitic_tuff",
	wherein         	= {"default:stone", "default:dirt", "default:gravel", "default:stone_with_coal"},
	column_height_max = 20,
	column_height_min = 15,
	y_min            = -2000,
	y_max            = 200,
	noise_threshold = 0.53,
	noise_params     = {
		offset = 0.35,
		scale = 0.2,
		seed = seed+13,
		spread = {x = 100, y = 100, z = 100},
		octaves = 1,
		persistence = 0.6
	},
})

--old red sandstone
minetest.register_ore({
	ore_type        	= "sheet",
	ore             	= "darkage:ors",
	wherein         	= {"default:stone", "default:dirt", "default:gravel", "default:stone_with_coal"},
	column_height_max = 8,
	column_height_min = 6,
	y_min            = -200,
	y_max            = 500,
	noise_threshold = 0.49,
	noise_params     = {
		offset = 0.28,
		scale = 0.3,
		seed = seed+4,
		spread = {x = 10, y = 10, z = 10},
		octaves = 1,
		persistence = 0.6
	},
})


-- Generate strati
local dbuf = {} --for mapgen
local function generate_strati(minp, maxp, seed)

	local t1 = os.clock()

	local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
	local area = VoxelArea:new({MinEdge = emin, MaxEdge = emax})
	local data = vm:get_data(dbuf)


	generate_claylike(data, area, "darkage:mud", minp, maxp, seed+1, 4, 0, 2, false)
	generate_claylike(data, area, "darkage:silt", minp, maxp, seed+2, 4, -1, 1, true)

	-- TODO: Maybe realize the following stuff with register ore. somehow.
	generate_stratus(data, area, "darkage:shale",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+5, 4, 23, 7, 50, -50,  20)

	generate_stratus(data, area, "darkage:slate",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+6, 6, 23, 5, 50, -500, 0)

	generate_stratus(data, area, "darkage:schist",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+7, 6, 19, 6, 50, -31000, -10)

	generate_stratus(data, area, "darkage:basalt",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+8, 5, 20, 5, 20, -31000, -50)

	generate_stratus(data, area, "darkage:marble",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+9, 4, 25, 6, 50, -31000,  -75)

	generate_stratus(data, area, "darkage:serpentine",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+10, 4, 28, 8, 50, -31000,  -350)

	generate_stratus(data, area, "darkage:gneiss",
					c_stone,
					stone_and_air_assoc,
					minp, maxp, seed+11, 4, 15, 5, 50, -31000, -250)

	vm:set_data(data)
	vm:write_to_map()

	minetest.log("info", string.format("[darkage] Generated Strati after %.2fs.", os.clock() - t1))
end

minetest.register_on_generated(generate_strati)