-- FIXME: Chests may appear at openings

local mg_name = minetest.get_mapgen_setting("mg_name")
local pr = PseudoRandom(os.time())

-- Get loot for dungeon chests
local get_loot = function()
	local loottable = {
	{
		stacks_min = 1,
		stacks_max = 3,
		items = {
			{ itemstring = "mcl_mobs:nametag", weight = 20 },
			{ itemstring = "mcl_mobitems:saddle", weight = 20 },
			{ itemstring = "mcl_jukebox:record_1", weight = 15 },
			{ itemstring = "mcl_jukebox:record_4", weight = 15 },
			{ itemstring = "mobs_mc:iron_horse_armor", weight = 15 },
			{ itemstring = "mcl_core:apple_gold", weight = 15 },
			-- TODO: Enchanted Book
			{ itemstring = "mcl_books:book", weight = 10 },
			{ itemstring = "mobs_mc:gold_horse_armor", weight = 10 },
			{ itemstring = "mobs_mc:diamond_horse_armor", weight = 5 },
			-- TODO: Enchanted Golden Apple
			{ itemstring = "mcl_core:apple_gold", weight = 2 },
		}
	},
	{
		stacks_min = 1,
		stacks_max = 4,
		items = {
			{ itemstring = "mcl_farming:wheat_item", weight = 20, amount_min = 1, amount_max = 4 },
			{ itemstring = "mcl_farming:bread", weight = 20 },
			{ itemstring = "mcl_core:coal_lump", weight = 15, amount_min = 1, amount_max = 4 },
			{ itemstring = "mesecons:redstone", weight = 15, amount_min = 1, amount_max = 4 },
			{ itemstring = "mcl_farming:beetroot_seeds", weight = 10, amount_min = 2, amount_max = 4 },
			{ itemstring = "mcl_farming:melon_seeds", weight = 10, amount_min = 2, amount_max = 4 },
			{ itemstring = "mcl_farming:pumpkin_seeds", weight = 10, amount_min = 2, amount_max = 4 },
			{ itemstring = "mcl_core:iron_ingot", weight = 10, amount_min = 1, amount_max = 4 },
			{ itemstring = "mcl_buckets:bucket_empty", weight = 10 },
			{ itemstring = "mcl_core:gold_ingot", weight = 5, amount_min = 1, amount_max = 4 },
		},
	},
	{
		stacks_min = 3,
		stacks_max = 3,
		items = {
			{ itemstring = "mcl_mobitems:bone", weight = 10, amount_min = 1, amount_max = 8 },
			{ itemstring = "mcl_mobitems:gunpowder", weight = 10, amount_min = 1, amount_max = 8 },
			{ itemstring = "mcl_mobitems:rotten_flesh", weight = 10, amount_min = 1, amount_max = 8 },
			{ itemstring = "mcl_mobitems:string", weight = 10, amount_min = 1, amount_max = 8 },
		},
	}
	}

	-- Bonus loot for v6 mapgen: Otherwise unobtainable saplings.
	if mg_name == "v6" then
		table.insert(loottable, {
			stacks_min = 1,
			stacks_max = 3,
			items = {
				{ itemstring = "mcl_core:birchsapling", weight = 1, amount_min = 1, amount_max = 2 },
				{ itemstring = "mcl_core:acaciasapling", weight = 1, amount_min = 1, amount_max = 2 },
				{ itemstring = "", weight = 6 },
			},
		})
	end
	local items = mcl_loot.get_multi_loot(loottable, pr)

	return items
end


-- Buffer for LuaVoxelManip
local lvm_buffer = {}

-- Below the bedrock, generate air/void
minetest.register_on_generated(function(minp, maxp)
	if maxp.y < mcl_vars.mg_overworld_min or minp.y > mcl_vars.mg_overworld_max then
		return
	end

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

	local c_air = minetest.get_content_id("air")
	local c_cobble = minetest.get_content_id("mcl_core:cobble")
	local c_mossycobble = minetest.get_content_id("mcl_core:mossycobble")

	-- Remember spawner chest positions to set metadata later
	local chest_posses = {}
	local spawner_posses = {}

	-- Calculate the number of dungeon spawn attempts
	local sizevector = vector.subtract(maxp, minp)
	sizevector = vector.add(sizevector, 1)
	local chunksize = sizevector.x * sizevector.y * sizevector.z

	-- In Minecraft, there 8 dungeon spawn attempts Minecraft chunk (16*256*16 = 65536 blocks).
	-- Minetest chunks don't have this size, so scale the number accordingly.
	local attempts = math.ceil(chunksize / 65536 * 8)

	for a=1, attempts do
		local x, y, z
		local b = 7 -- buffer
		x = math.random(minp.x+b, maxp.x-b)

		local ymin = math.min(mcl_vars.mg_overworld_max, math.max(minp.y, mcl_vars.mg_bedrock_overworld_max) + 7)
		local ymax = math.min(mcl_vars.mg_overworld_max, math.max(maxp.y, mcl_vars.mg_bedrock_overworld_max) - 4)

		y = math.random(ymin, ymax)
		z = math.random(minp.z+b, maxp.z-b)

		local dungeonsizes = {
			{ x=5, y=4, z=5},
			{ x=5, y=4, z=7},
			{ x=7, y=4, z=5},
			{ x=7, y=4, z=7},
		}
		local dim = dungeonsizes[math.random(1, #dungeonsizes)]

		-- Check floor and ceiling: Must be *completely* solid
		local ceilingfloor_ok = true
		for tx = x, x+dim.x do
			for tz = z, z+dim.z do
				local floor = minetest.get_name_from_content_id(data[area:index(tx, y, tz)])
				local ceiling = minetest.get_name_from_content_id(data[area:index(tx, y+dim.y+1, tz)])
				if (not minetest.registered_nodes[floor].walkable) or (not minetest.registered_nodes[ceiling].walkable) then
					ceilingfloor_ok = false
					break
				end
			end
			if not ceilingfloor_ok then break end
		end

		-- Check for air openings (2 stacked air at ground level) in wall positions
		local openings_counter = 0
		-- Store positions of openings; walls will not be generated here
		local openings = {}
		-- Corners are stored because a corner-only opening needs to be increased,
		-- so entities can get through.
		local corners = {}
		if ceilingfloor_ok then

			local walls = {
				-- walls along x axis (contain corners)
				{ x, x+dim.x+1, "x", "z", z },
				{ x, x+dim.x+1, "x", "z", z+dim.z+1 },
				-- walls along z axis (exclude corners)
				{ z+1, z+dim.z, "z", "x", x },
				{ z+1, z+dim.z, "z", "x", x+dim.x+1 },
			}

			for w=1, #walls do
				local wall = walls[w]
				for iter = wall[1], wall[2] do
					local pos = {}
					pos[wall[3]] = iter
					pos[wall[4]] = wall[5]
					pos.y = y+1

					if openings[pos.x] == nil then openings[pos.x] = {} end

					local door1 = area:index(pos.x, pos.y, pos.z)
					pos.y = y+2
					local door2 = area:index(pos.x, pos.y, pos.z)
					local doorname1 = minetest.get_name_from_content_id(data[door1])
					local doorname2 = minetest.get_name_from_content_id(data[door2])
					if doorname1 == "air" and doorname2 == "air" then
						openings_counter = openings_counter + 1
						openings[pos.x][pos.z] = true

						-- Record corners
						if wall[3] == "x" and (iter == wall[1] or iter == wall[2]) then
							table.insert(corners, {x=pos.x, z=pos.z})
						end
					end
				end
			end

		end

		-- If all openings are only at corners, the dungeon can't be accessed yet.
		-- This code extends the openings of corners so they can be entered.
		if openings_counter >= 1 and openings_counter == #corners then
			for c=1, #corners do
				-- Prevent creating too many openings because this would lead to dungeon rejection
				if openings_counter >= 5 then
					break
				end
				-- A corner is widened by adding openings to both neighbors
				local cx, cz = corners[c].x, corners[c].z
				local cxn, czn = cx, cz
				if x == cx then
					cxn = cxn + 1
				else
					cxn = cxn - 1
				end
				if z == cz then
					czn = czn + 1
				else
					czn = czn - 1
				end
				openings[cx][czn] = true
				openings_counter = openings_counter + 1
				if openings_counter < 5 then
					openings[cxn][cz] = true
					openings_counter = openings_counter + 1
				end
			end
		end

		-- Check conditions. If okay, start generating
		if ceilingfloor_ok and openings_counter >= 1 and openings_counter <= 5 then
			-- Okay! Spawning starts!

			-- First prepare random chest positions.
			-- Chests spawn at wall

			-- We assign each position at the wall a number and each chest gets one of these numbers randomly
			local totalChests = 2 -- this code strongly relies on this number being 2
			local totalChestSlots = (dim.x-1) * (dim.z-1)
			local chestSlots = {}
			-- There is a small chance that both chests have the same slot.
			-- In that case, we give a 2nd chance for the 2nd chest to get spawned.
			-- If it failed again, tough luck! We stick with only 1 chest spawned.
			local lastRandom
			local secondChance = true -- second chance is still available
			for i=1, totalChests do
				local r = math.random(1, totalChestSlots)
				if r == lastRandom and secondChance then
					-- Oops! Same slot selected. Try again.
					r = math.random(1, totalChestSlots)
					secondChance = false
				end
				lastRandom = r
				table.insert(chestSlots, r)
			end
			table.sort(chestSlots)
			local currentChest = 1

			-- Calculate the mob spawner position, to be re-used for later
			local spawner_pos = {x = x + math.ceil(dim.x/2), y = y+1, z = z + math.ceil(dim.z/2)}
			table.insert(spawner_posses, spawner_pos)

			-- Generate walls and floor
			local maxx, maxy, maxz = x+dim.x+1, y+dim.y, z+dim.z+1
			local chestSlotCounter = 1
			for tx = x, maxx do
				for tz = z, maxz do
					for ty = y, maxy do
						local p_pos = area:index(tx, ty, tz)

						-- Do not overwrite nodes with is_ground_content == false (e.g. bedrock)
						-- Exceptions: cobblestone and mossy cobblestone so neighborings dungeons nicely connect to each other
						local name = minetest.get_name_from_content_id(data[p_pos])
						if name == "mcl_core:cobble" or name == "mcl_core:mossycobble" or minetest.registered_nodes[name].is_ground_content then
							-- Floor
							if ty == y then
								if math.random(1,4) == 1 then
									data[p_pos] = c_cobble
								else
									data[p_pos] = c_mossycobble
								end

							-- Generate walls
							--[[ Note: No additional cobblestone ceiling is generated. This is intentional.
							The solid blocks above the dungeon are considered as the “ceiling”.
							It is possible (but rare) for a dungeon to generate below sand or gravel. ]]

							elseif ty > y and (tx == x or tx == maxx or (tz == z or tz == maxz)) then
								-- Check if it's an opening first
								if (not openings[tx][tz]) or ty == maxy then
									-- Place wall or ceiling
									data[p_pos] = c_cobble
								elseif ty < maxy - 1 then
									-- Normally the openings are already clear, but not if it is a corner
									-- widening. Make sure to clear at least the bottom 2 nodes of an opening.
									data[p_pos] = c_air
								elseif ty == maxy - 1 and data[p_pos] ~= c_air then
									-- This allows for variation between 2-node and 3-node high openings.
									data[p_pos] = c_cobble
								end
								-- If it was an opening, the lower 3 blocks are not touched at all

							-- Room interiour
							else
								local forChest = ty==y+1 and (tx==x+1 or tx==maxx-1 or tz==z+1 or tz==maxz-1)

								-- Place next chest at the wall (if it was its chosen wall slot)
								if forChest and (currentChest < totalChests + 1) and (chestSlots[currentChest] == chestSlotCounter) then
									table.insert(chest_posses, {x=tx, y=ty, z=tz})
									currentChest = currentChest + 1
								else
									data[p_pos] = c_air
								end
								if forChest then
									chestSlotCounter = chestSlotCounter + 1
								end
							end
						end

					end
				end
			end
		end

		lvm_used = true
	end

	if lvm_used then
		local chest_param2 = {}
		-- Determine correct chest rotation (must pointi outwards)
		for c=1, #chest_posses do
			local cpos = chest_posses[c]

			-- Check surroundings of chest to determine correct rotation
			local surround_vectors = {
				{ x=-1, y=0, z=0 },
				{ x=1, y=0, z=0 },
				{ x=0, y=0, z=-1 },
				{ x=0, y=0, z=1 },
			}
			local surroundings = {}

			for s=1, #surround_vectors do
				-- Detect the 4 horizontal neighbors
				local spos = vector.add(cpos, surround_vectors[s])
				local wpos = vector.subtract(cpos, surround_vectors[s])
				local p_pos = area:index(spos.x, spos.y, spos.z)
				local p_pos2 = area:index(wpos.x, wpos.y, wpos.z)

				local nodename = minetest.get_name_from_content_id(data[p_pos])
				local nodename2 = minetest.get_name_from_content_id(data[p_pos2])
				local nodedef = minetest.registered_nodes[nodename]
				local nodedef2 = minetest.registered_nodes[nodename2]
				-- The chest needs an open space in front of it and a walkable node (except chest) behind it
				if nodedef and nodedef.walkable == false and nodedef2 and nodedef2.walkable == true and nodename2 ~= "mcl_chests:chest" then
					table.insert(surroundings, spos)
				end
			end
			-- Set param2 (=facedir) of this chest
			local facedir
			if #surroundings <= 0 then
				-- Fallback if chest ended up in the middle of a room for some reason
				facedir = math.random(0, 0)
			else
				-- 1 or multiple possible open directions: Choose random facedir
				local face_to = surroundings[math.random(1, #surroundings)]
				facedir = minetest.dir_to_facedir(vector.subtract(cpos, face_to))
			end
			chest_param2[c] = facedir
		end

		-- Finally generate the dungeons all at once (except the chests and the spawners)
		vm:set_data(data)
		vm:calc_lighting()
		vm:update_liquids()
		vm:write_to_map()

		-- Chests are placed seperately
		for c=1, #chest_posses do
			local cpos = chest_posses[c]
			minetest.set_node(cpos, {name="mcl_chests:chest", param2=chest_param2[c]})
			local meta = minetest.get_meta(cpos)
			local inv = meta:get_inventory()
			local items = get_loot()
			mcl_loot.fill_inventory(inv, "main", items)
		end

		-- Mob spawners are placed seperately, too
		-- We don't want to destroy non-ground nodes
		for s=1, #spawner_posses do
			local sp = spawner_posses[s]
			local n = minetest.get_name_from_content_id(data[area:index(sp.x,sp.y,sp.z)])
			if minetest.registered_nodes[n].is_ground_content then

				-- ... and place it and select a random mob
				minetest.set_node(sp, {name = "mcl_mobspawners:spawner"})
				local mobs = {
					"mobs_mc:zombie",
					"mobs_mc:zombie",
					"mobs_mc:spider",
					"mobs_mc:skeleton",
				}
				local spawner_mob = mobs[math.random(1, #mobs)]

				mcl_mobspawners.setup_spawner(sp, spawner_mob, 0, 7)
			end
		end

	end

end)