--[[
	This is an example treasure spawning mod (TSM) for the default mod.
	It needs the mods “treasurer” and “default” to work.
	For an example, it is kinda advanced.

	A TSM’s task is to somehow bring treasures (which are ItemStacks) into the world.
	This is also called “spawning treasures”.
	How it does this task is completely free to the programmer of the TSM.

	This TSM spawns the treasures by placing chests (tsm_chests:chest) between 20 and 200 node lengths below the water surface. This cau
	The chests are provided by the default mod, therefore this TSM depends on the default mod.
	The treasures are requested from the treasurer mod. The TSM asks the treasurer mod for some treasures.

	However, the treasurer mod comes itself with no treasures whatsoever. You need another mod which tells the treasurer what treasures to add. These mods are called “treasure registration mods” (TRMs).
	For this, there is another example mod, called “trm_default_example”, which registers a bunch of items of the default mod, like default:gold_ingot.
]]


local chest_formspec =
	"size[8,9]" ..
	default.gui_bg ..
	default.gui_bg_img ..
	default.gui_slots ..
	"list[current_name;main;0,0.3;8,4;]" ..
	"list[current_player;main;0,4.85;8,1;]" ..
	"list[current_player;main;0,6.08;8,3;8]" ..
	"listring[current_name;main]" ..
	"listring[current_player;main]" ..
	default.get_hotbar_bg(0,4.85)

minetest.register_node("tsm_chests:chest", {
	description = "Chest",
	tiles = {"default_chest_top.png", "default_chest_top.png", "default_chest_side.png",
		"default_chest_side.png", "default_chest_side.png", "default_chest_front.png"},
	paramtype2 = "facedir",
	groups = {choppy = 2, oddly_breakable_by_hand = 2},
	legacy_facedir_simple = true,
	is_ground_content = false,
	sounds = default.node_sound_wood_defaults(),
	allow_metadata_inventory_put = function(pos, listname, index, stack, player)
		if player then
			minetest.chat_send_player(player:get_player_name(),
				"You're not allowed to put things in treasure chests!")
			return 0
		end
	end,
	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
		meta:set_string("formspec", chest_formspec)
		meta:set_string("infotext", "Chest")
		local inv = meta:get_inventory()
		inv:set_size("main", 8*4)
	end,
	can_dig = function(pos,player)
		local meta = minetest.get_meta(pos);
		local inv = meta:get_inventory()
		return inv:is_empty("main")
	end,
	on_metadata_inventory_move = function(pos, from_list, from_index,
			to_list, to_index, count, player)
		minetest.log("action", player:get_player_name() ..
			" moves stuff in chest at " .. minetest.pos_to_string(pos))
	end,
    on_metadata_inventory_put = function(pos, listname, index, stack, player)
		minetest.log("action", player:get_player_name() ..
			" moves stuff to chest at " .. minetest.pos_to_string(pos))
	end,
    on_metadata_inventory_take = function(pos, listname, index, stack, player)
		minetest.log("action", player:get_player_name() ..
			" takes stuff from chest at " .. minetest.pos_to_string(pos))
		local inv = minetest.get_inventory({type = "node", pos=pos})
		if not inv or inv:is_empty("main") then
			minetest.set_node(pos, {name="air"})
			minetest.show_formspec(player:get_player_name(), "", player:get_inventory_formspec())
		end
	end,
})

--[[ here are some configuration variables ]]

local chests_per_chunk = 13	-- number of chests per chunk. 15 is a bit high, an actual mod might have a lower number
local h_min = -65  		-- minimum chest spawning height, relative to water_level
local h_max = 40		-- maximum chest spawning height, relative to water_level
local t_min = 3			-- minimum amount of treasures found in a chest
local t_max = 6			-- maximum amount of treasures found in a chest

local r_max = tonumber(minetest.setting_get("barrier"))
local water_level = tonumber(minetest.setting_get("water_level"))
local get_node = minetest.get_node
local env = minetest.env

local function findGroundLevel(pos, y_min, y_max)
	local ground = nil
	local top    = y_max
	for y = y_max, y_min, -1 do
		local p = {x=pos.x,y=y,z=pos.z}
		local name = get_node(p).name
		if name == "air" or name == "default:water_source" or name == "default:lava_source" then
			top = y
			break
		end
	end
	for y=top,y_min,-1 do
		local p = {x=pos.x,y=y,z=pos.z}
					local name = get_node(p).name
		if name ~= "air" and name ~= "default:water_source" and name ~= "default:lava_source" then
			ground = y
			break
		end
	end
	return ground
end

local function getFacedirs(pos, ground)
	-- secondly: rotate the chest
	-- find possible faces
	local xp, xm, zp, zm
	xp = minetest.get_node({x=pos.x+1, y=ground+1, z=pos.z})
	xm = minetest.get_node({x=pos.x-1, y=ground+1, z=pos.z})
	zp = minetest.get_node({x=pos.x, y=ground+1, z=pos.z+1})
	zm = minetest.get_node({x=pos.x, y=ground+1, z=pos.z-1})

	-- Set Facedirs
	local facedirs = {}
	if xp.name=="air" or xp.name=="default:water_source" then
		table.insert(facedirs, minetest.dir_to_facedir({x=-1,y=0,z=0}))
	end
	if xm.name=="air" or xm.name=="default:water_source" then
		table.insert(facedirs, minetest.dir_to_facedir({x=1,y=0,z=0}))
	end
	if zp.name=="air" or zp.name=="default:water_source" then
		table.insert(facedirs, minetest.dir_to_facedir({x=0,y=0,z=-1}))
	end
	if zm.name=="air" or zm.name=="default:water_source" then
		table.insert(facedirs, minetest.dir_to_facedir({x=0,y=0,z=1}))
	end

	return facedirs
end

local function placeChest(pos, chest_pos, ground, nn)
	local chest = {name = "tsm_chests:chest"}
	local facedirs = getFacedirs(pos, ground)

	-- choose a random face (if possible)
	if #facedirs == 0 then
		minetest.set_node({x=pos.x,y=ground+1, z=pos.z+1}, {name=nn})
		chest.param2 = minetest.dir_to_facedir({x=0,y=0,z=1})
	else
		chest.param2 = facedirs[math.floor(math.random(#facedirs))]
	end

	-- Lastly: place the chest
	minetest.set_node(chest_pos, chest)

	-- Get treasure
	local treasure_amount = math.ceil(math.random(t_min, t_max))
	local height = math.abs(h_min) - math.abs(h_max)
	local y_norm = (ground+1) - h_min
	local scale = 1 - (y_norm/height)
	local minp = 0 --scale*4		-- minimal preciousness:   0..4
	local maxp = 10 --scale*4+2.1	-- maximum preciousness: 2.1..6.1
	local treasures = treasurer.select_random_treasures(treasure_amount, minp, maxp)

	-- Add Treasure to Chst
	local meta = minetest.get_meta(chest_pos)
	local inv = meta:get_inventory()
	for i=1, #treasures do
		inv:set_stack("main", i, treasures[i])
	end
end

--[[ here comes the generation code
	the interesting part which involes treasurer comes way below
]]
function place_chests(minp, maxp, seed)
	minp = {x=minp.x, y=minp.y, z=minp.z}
	maxp = {x=maxp.x, y=maxp.y, z=maxp.z}

	if minp.x <= -r_max then
		minp.x = -r_max + 1
	end
	if minp.z <= -r_max then
		minp.z = -r_max + 1
	end
	if minp.x >= r_max then
		minp.x = r_max - 1
	end
	if minp.z >= r_max then
		minp.z = r_max - 1
	end

	-- chests minimum and maximum spawn height
	local height_min = water_level + h_min
	local height_max = water_level + h_max

	if(maxp.y < height_min or minp.y > height_max) then
		return
	end
	local y_min = math.max(minp.y, height_min)
	local y_max = math.min(maxp.y, height_max)
	local attempts = 0
	local chests_placed = 0
	while chests_placed < chests_per_chunk and attempts < chests_per_chunk + 6 do
		attempts = attempts + 1
		local pos = {
			x = math.random(minp.x, maxp.x),
			y = minp.y,
			z = math.random(minp.z, maxp.z)
		}

		-- Find ground level
		local ground = findGroundLevel(pos, y_min, y_max)
		if ground ~= nil then
			local chest_pos = {x = pos.x, y = ground + 1, z = pos.z}

			-- Don't spawn at barrier
			if chest_pos.z == 0 then
				chest_pos.z = -1
			end

			local nn = minetest.get_node(chest_pos).name	-- chest node name (before it becomes a chest)
			if nn == "air" or nn == "default:water_source" then
				placeChest(pos, chest_pos, ground, nn)

				chests_placed = chests_placed + 1
			end
		end
	end

	print("Spawned " .. chests_placed .. " chests after " .. attempts .. " attempts!")
end