-- Directory where the map data will be stored
tutorial.map_directory = minetest.get_modpath("tutorial").."/mapdata/"

-- entity management functions

function save_entities()
	local entities = {}
	local count = 0;

	for id,entity in pairs(minetest.luaentities) do
		local entry = {
			pos = entity.object:getpos(),
			name = entity.name,
			staticdata = entity.object:get_luaentity().get_staticdata(entity.object)
		}
		if entry.name == "__builtin:item" then
			entry.itemstring = entity.itemstring
		end
		table.insert(entities, entry)
		count = count+1
		minetest.log("action", "[tutorial] entity FOUND to be saved: "..(entry.itemstring or entry.name).." at " ..entry.pos.x..","..entry.pos.y..","..entry.pos.z)
	end

	-- Because the entities can easily be unloaded, we won't override the
	-- entities save file. Instead, we will try to deduce as best as we can to try
	-- to include as well the already saved entities without creating duplicates.
	local saved_entities = get_saved_entities()

	for k,ent in pairs(saved_entities) do
		local already_added=false

		for k,e in pairs(entities) do
			if math.abs(ent.pos.x-e.pos.x) + math.abs(ent.pos.y - e.pos.y) + math.abs(ent.pos.z -e.pos.z) < 1 then
				already_added=true
				break
			end
		end
		if not already_added then
			table.insert(entities,ent)
			count = count + 1
			minetest.log("action", "[tutorial] entity to CONTINUE saved: "..(ent.itemstring or ent.name).." at " ..ent.pos.x..","..ent.pos.y..","..ent.pos.z)
		end
	end

	local str = minetest.serialize(entities)

	local filename = tutorial.map_directory .. "entities"
	local file, err = io.open(filename, "wb")
	if err ~= nil then
		error("Couldn't write to \"" .. filename .. "\"")
	end
	file:write(minetest.compress(str))
	file:flush()
	file:close()
	minetest.log("action","[tutorial] " .. filename .. ": " .. count .. " entities saved")
	return count
end

function get_saved_entities()
	local filename = tutorial.map_directory .. "entities"
	local f, err = io.open(filename, "rb")
	if not f then
		minetest.log("action", "[tutorial] Could not open file '" .. filename .. "': " .. err)
		return {}
	end
	local entities = minetest.deserialize(minetest.decompress(f:read("*a")))
	f:close()
	return entities
end

function load_entities()
	local entities = get_saved_entities()

	local count = 0
	for k,entity in pairs(entities) do
		if entity.name == "__builtin:item" then
			minetest.add_item(entity.pos, entity.itemstring)
		else
			local luaentity = minetest.add_entity(entity.pos, entity.name)
			luaentity.on_activate(luaentity, entity.staticdata)
		end
		count = count + 1
	end
	minetest.log("action", "[tutorial] " .. count .. " entities loaded")
end

function load_entities_area(minp, maxp)

	if not tutorial.entities_cache then
		tutorial.entities_cache = get_saved_entities()
	end

	local count = 0
	for k,entity in pairs(tutorial.entities_cache) do

		-- Only load it if not out of the generating range
		if not ((maxp.x < entity.pos.x) or (minp.x > entity.pos.x)
			or (maxp.y < entity.pos.y) or (minp.y > entity.pos.y)
			or (maxp.z < entity.pos.z) or (minp.z > entity.pos.z))
		then
			if entity.name == "__builtin:item" then
				minetest.add_item(entity.pos, entity.itemstring)
			else
				local luaentity = minetest.add_entity(entity.pos, entity.name)
				luaentity.on_activate(luaentity, entity.staticdata)
			end
			count = count + 1
		end
	end
	minetest.log("action", "[tutorial] " .. count .. " entities loaded")
end

---

-- Sectors of the map to save/load
-- Each element of the array will contain the coordinate where the sector starts
-- along with a "l" property indicating its length in each direction.
tutorial.map_sector = {}

-- Array with the minimum and the maximum positions of the cube that contains the
-- entire Tutorial World, it's best if the start matches the start of a mapchunk
tutorial.limits = {
	{ x = -32, y = -32, z = -32 },
	{ x = 224, y = 48, z = 144 },
}

-- size of the sectors to form divisions of the map.
-- This needs to be a multiple of 16, since it will also determine the
-- chunksize
tutorial.sector_size = 80

-- perform the divisions using the given sector size within the limits provided
for x = tutorial.limits[1].x, tutorial.limits[2].x, tutorial.sector_size do
	for y = tutorial.limits[1].y, tutorial.limits[2].y, tutorial.sector_size do
		for z = tutorial.limits[1].z, tutorial.limits[2].z, tutorial.sector_size do
			table.insert(tutorial.map_sector, {x=x,y=y,z=z,l=(tutorial.sector_size - 1)})
		end
	end
end
--]]

function save_schematic()
	local success = true
	for k,sector in pairs(tutorial.map_sector) do
		local filename = tutorial.map_directory .. "sector_"..k
		local minp = sector
		local maxp = {
			x = sector.x + sector.l,
			y = sector.y + sector.l,
			z = sector.z + sector.l
		}
		if not save_region(minp, maxp, nil, filename) then
			minetest.log("error", "[tutorial] error loading Tutorial World sector " .. minetest.pos_to_string(sector))
			success = false
		end
	end
	return success
end

function load_schematic()
	local success = true
	for k,sector in pairs(tutorial.map_sector) do
		local filename = tutorial.map_directory .. "sector_"..k
		minetest.log("action", "loading sector " .. minetest.pos_to_string(sector))
		sector.maxp = vector.add(sector, {x=sector.l, y=sector.l, z=sector.l})

		-- Load the area above the schematic to guarantee we have blue sky above
		-- and prevent lighting glitches
		--minetest.emerge_area(vector.add(sector, {x=0, y=sector.l, z=0}), vector.add(sector.maxp, {x=0,y=32,z=0}))

		local vmanip = VoxelManip(sector, sector.maxp)
		if not load_region(sector, filename, vmanip, nil, nil, true) then
			minetest.log("error", "[tutorial] error loading Tutorial World sector " .. minetest.pos_to_string(sector))
			success = false
		end
		vmanip:calc_lighting()
		vmanip:write_to_map()
		vmanip:update_map()
	end
	return success
end


-- Saves schematic in the Minetest Schematic (and metadata) to disk.
-- Takes the same arguments as minetest.create_schematic
-- @param minp Lowest position (in all 3 coordinates) of the area to save
-- @param maxp Highest position (in all 3 coordinates) of the area to save
-- @param probability_list = {{pos={x=,y=,z=},prob=}, ...} list of probabilities for the nodes to be loaded (if nil, always load)
-- @param filename (without externsion) with the path to save the shcematic and metadata to
-- @param slice_prob_list = {{ypos=,prob=}, ...} list of probabilities for the slices to be loaded (if nil, always load)
-- @return The number of nodes with metadata.
function save_region(minp, maxp, probability_list, filename, slice_prob_list)

	local success = minetest.create_schematic(minp, maxp, probability_list, filename .. ".mts", slice_prob_list)
	if not success then
		minetest.log("error", "[tutorial] problem creating schematic on ".. minetest.pos_to_string(minp) .. ": " .. filename)
		return false
	end

	local manip = minetest.get_voxel_manip()
	manip:read_from_map(minp, maxp)
	local pos = {x=minp.x, y=0, z=0}
	local count = 0
	local nodes = {}
	local get_node, get_meta = minetest.get_node, minetest.get_meta
	while pos.x <= maxp.x do
		pos.y = minp.y
		while pos.y <= maxp.y do
			pos.z = minp.z
			while pos.z <= maxp.z do
				local node = get_node(pos)
				if node.name ~= "air" and node.name ~= "ignore" then
					local meta = get_meta(pos):to_table()

					local meta_empty = true
					-- Convert metadata item stacks to item strings
					for name, inventory in pairs(meta.inventory) do
						for index, stack in ipairs(inventory) do
							meta_empty = false
							inventory[index] = stack.to_string and stack:to_string() or stack
						end
					end
					if meta.fields and next(meta.fields) ~= nil then
						meta_empty = false
					end

					if not meta_empty then
						count = count + 1
						nodes[count] = {
							x = pos.x - minp.x,
							y = pos.y - minp.y,
							z = pos.z - minp.z,
							meta = meta,
						}
					end
				end
				pos.z = pos.z + 1
			end
			pos.y = pos.y + 1
		end
		pos.x = pos.x + 1
	end
	if count > 0 then

		local result = {
			size = {
				x = maxp.x - minp.x,
				y = maxp.y - minp.y,
				z = maxp.z - minp.z,
			},
			nodes = nodes,
		}

		-- Serialize entries
		result = minetest.serialize(result)

		local file, err = io.open(filename..".meta", "wb")
		if err ~= nil then
			error("Couldn't write to \"" .. filename .. "\"")
		end
		file:write(minetest.compress(result))
		file:flush()
		file:close()
		minetest.log("action", "[tutorial] schematic + metadata saved: " .. filename)
	else
	   minetest.log("action", "[tutorial] schematic (no metadata) saved: " .. filename)
	end
	return success, count
end



-- Places the schematic specified in the given position.
-- @param minp Lowest position (in all 3 coordinates) of the area to load
-- @param filename without extension, but with path of the file to load
-- @param vmanip voxelmanip object to use to place the schematic in
-- @param rotation can be 0, 90, 180, 270, or "random".
-- @param replacements = {["old_name"] = "convert_to", ...}
-- @param force_placement is a boolean indicating whether nodes other than air and ignore are replaced by the schematic
-- @return boolean indicating success or failure
function load_region(minp, filename, vmanip, rotation, replacements, force_placement)

	if rotation == "random" then
		rotation = {nil, 90, 180, 270}
		rotation = rotation[math.random(1,4)]
	end

	local success
	if vmanip and minetest.place_schematic_on_vmanip then
		success = minetest.place_schematic_on_vmanip(vmanip, minp, filename .. ".mts", tostring(rotation), replacements, force_placement)
	else
		success = minetest.place_schematic(minp, filename .. ".mts", tostring(rotation), replacements, force_placement)
	end

	if success == false then
		minetest.log("action", "[tutorial] schematic partionally loaded on ".. minetest.pos_to_string(minp))
	elseif not success then
		minetest.log("error", "[tutorial] problem placing schematic on ".. minetest.pos_to_string(minp) .. ": " .. filename)
		return nil
	end

	local f, err = io.open(filename..".meta", "rb")
	if not f then
		minetest.log("action", "[tutorial] schematic loaded  on ".. minetest.pos_to_string(minp))
		return true
	end
	local data = minetest.deserialize(minetest.decompress(f:read("*a")))
	f:close()
	if not data then return end

	local get_meta = minetest.get_meta

	if not rotation or rotation == 0 then
		for i, entry in ipairs(data.nodes) do
			entry.x, entry.y, entry.z = minp.x + entry.x, minp.y + entry.y, minp.z + entry.z
			if entry.meta then get_meta(entry):from_table(entry.meta) end
		end
	else
		local maxp_x, maxp_z = minp.x + data.size.x, minp.z + data.size.z
		if rotation == 90 then
		for i, entry in ipairs(data.nodes) do
			entry.x, entry.y, entry.z = minp.x + entry.z, minp.y + entry.y, maxp_z - entry.x
			if entry.meta then get_meta(entry):from_table(entry.meta) end
		end
		elseif rotation == 180 then
			for i, entry in ipairs(data.nodes) do
				entry.x, entry.y, entry.z = maxp_x - entry.x, minp.y + entry.y, maxp_z - entry.z
				if entry.meta then get_meta(entry):from_table(entry.meta) end
			end
		elseif rotation == 270 then
			for i, entry in ipairs(data.nodes) do
				entry.x, entry.y, entry.z = maxp_x - entry.z, minp.y + entry.y, minp.z + entry.x
				if entry.meta then get_meta(entry):from_table(entry.meta) end
			end
		else
			minetest.log("error", "[tutorial] unsupported rotation angle: " ..  (rotation or "nil"))
			return false
		end
	end
	minetest.log("action", "[tutorial] schematic + metadata loaded  on ".. minetest.pos_to_string(minp))
	return true
end


------ Commands

minetest.register_privilege("tutorialmap", "Can use commands to manage the tutorial map")
minetest.register_chatcommand("treset", {
	params = "",
	description = "Resets the tutorial map",
	privs = {tutorialmap=true},
	func = function(name, param)
		if load_schematic() then
			minetest.chat_send_player(name, "Tutorial World schematic loaded")
		else
			minetest.chat_send_player(name, "An error occurred while loading Tutorial World schematic")
		end

		-- TODO: right now there's no clear way we can properly remove all entities
		--remove_entities()
		--load_entities()
	end,
})

minetest.register_chatcommand("tsave", {
	params = "",
	description = "Saves the tutorial map",
	privs = {tutorialmap=true},
	func = function(name, param)
		if save_schematic() then
			minetest.chat_send_player(name, "Tutorial World schematic saved")
		else
			minetest.chat_send_player(name, "An error occurred while saving Tutorial World schematic")
		end
	end,
})

minetest.register_chatcommand("tsave_entities", {
	params = "",
	description = "Saves the tutorial map",
	privs = {tutorialmap=true},
	func = function(name, param)
		for k,s in pairs(tutorial.map_sector) do
			minetest.forceload_block(s)
		end
		local count = save_entities()
		minetest.chat_send_player(name, count .. " entities saved")
	end,
})

------ Map Generation

tutorial.state = tutorial.state or {}
tutorial.state.loaded = tutorial.state.loaded or {}
minetest.register_on_generated(function(minp, maxp, seed)
	local state_changed = false
	local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")

	for k,sector in pairs(tutorial.map_sector) do
		if not tutorial.state.loaded[k] then

			if sector.maxp == nil then
				sector.maxp = {
					x = sector.x + sector.l,
					y = sector.y + sector.l,
					z = sector.z + sector.l,
				}
			end

			-- Only load it if not out of the generating range
			if not ((maxp.x < sector.x) or (minp.x > sector.maxp.x)
				or (maxp.y < sector.y) or (minp.y > sector.maxp.y)
				or (maxp.z < sector.z) or (minp.z > sector.maxp.z))
			then

				local filename = tutorial.map_directory .. "sector_" .. k
				local loaded = load_region(sector, filename, vm)
				if loaded then
					-- Load entities in the area as well, and mark it as loaded
					load_entities_area(sector, sector.maxp)
					tutorial.state.loaded[k] = true
				end
				state_changed = true
			end
		end
	end

	if(state_changed) then
		vm:calc_lighting(nil, nil, false)
		vm:write_to_map()
		tutorial.save_state()
		-- Update the lgihting of the sector below as well
		minp.y = minp.y - tutorial.sector_size
		local vm = minetest.get_voxel_manip(minp, maxp)
		vm:calc_lighting(nil, nil, false)
		vm:write_to_map()
		vm:update_map()
	end
end)

minetest.register_on_mapgen_init(function(mgparams)
	minetest.set_mapgen_params({mgname="singlenode", water_level=-31000, chunksize=(tutorial.sector_size/16)})
end)

-- coordinates for the first time the player spawns
tutorial.first_spawn = { pos={x=42,y=0.5,z=28}, yaw=(math.pi * 0.5) }