stamina = {}

local stamina_players = {}

STAMINA_TICK = 800		-- time in seconds after that 1 stamina point is taken
STAMINA_TICK_MIN = 4		-- stamina ticks won't reduce stamina below this level
STAMINA_HEALTH_TICK = 4		-- time in seconds after player gets healed/damaged
STAMINA_MOVE_TICK = 0.5		-- time in seconds after the movement is checked

STAMINA_EXHAUST_DIG = 3		-- exhaustion increased this value after digged node
STAMINA_EXHAUST_PLACE = 1	-- .. after placing node
STAMINA_EXHAUST_MOVE = 1.5	-- .. if player movement detected
STAMINA_EXHAUST_JUMP = 5	-- .. if jumping
STAMINA_EXHAUST_CRAFT = 10	-- .. if player crafts (was 20)
STAMINA_EXHAUST_PUNCH = 20	-- .. if player punches another player (was 40)
STAMINA_EXHAUST_LVL = 160	-- at what exhaustion player saturation gets lowered

STAMINA_HEAL = 1		-- number of HP player gets healed after STAMINA_HEALTH_TICK
STAMINA_HEAL_LVL = 5		-- lower level of saturation needed to get healed
STAMINA_STARVE = 1		-- number of HP player gets damaged by stamina after STAMINA_HEALTH_TICK
STAMINA_STARVE_LVL = 3		-- level of staturation that causes starving

STAMINA_VISUAL_MAX = 20		-- hud bar extends only to 20

SPRINT_SPEED = 0.8 		-- how much faster player can run if satiated
SPRINT_JUMP = 0.1 		-- how much higher player can jump if satiated
SPRINT_DRAIN = 0.35 		-- how fast to drain satation while sprinting (0-1)

local function stamina_read(player)
	local inv = player:get_inventory()
	if not inv then
		return nil
	end

	-- itemstack storage is offest by 1 to make the math work
	local v = inv:get_stack("stamina", 1):get_count()
	if v == 0 then
		v = 21
		inv:set_stack("stamina", 1, ItemStack({name = ":", count = v}))
	end

	return v - 1
end

local function stamina_save(player)
	local inv = player:get_inventory()
	if not inv then
		return nil
	end
	local name = player:get_player_name()
	local level = stamina_players[name].level

	level = math.max(level, 0)

	inv:set_stack("stamina", 1, ItemStack({name = ":", count = level + 1}))
	return true
end

local function stamina_update(player, level)
	local name = player:get_player_name()
	if not name then
		return false
	end
	local old = stamina_players[name].level
	if level == old then
		return
	end
	stamina_players[name].level = level

	player:hud_change(stamina_players[name].hud_id, "number", math.min(STAMINA_VISUAL_MAX, level))
	stamina_save(player)
end

stamina.change = function(player, change)
	local name = player:get_player_name()
	if not name or not change or change == 0 then
		return false
	end
	local level = stamina_players[name].level
	level = level + change
	if level < 0 then level = 0 end
	if level > STAMINA_VISUAL_MAX then level = STAMINA_VISUAL_MAX end
	stamina_update(player, level)
end

local function exhaust_player(player, v)
	if not player or not player:is_player() then
		return
	end

	local name = player:get_player_name()
	if not name then
		return
	end

	local s = stamina_players[name]
	if not s then
		return
	end

	local e = s.exhaust
	if not e then
		s.exhaust = 0
	end

	e = e + v

	if e > STAMINA_EXHAUST_LVL then
		e = 0
		local h = tonumber(stamina_players[name].level)
		if h > 0 then
			stamina_update(player, h - 1)
		end
	end

	s.exhaust = e
end

-- Sprint settings and function
local enable_sprint = minetest.setting_getbool("sprint") ~= false
local enable_sprint_particles = minetest.setting_getbool("sprint_particles") ~= false
local armor_mod = minetest.get_modpath("3d_armor")

function set_sprinting(name, sprinting)

	if stamina_players[name] then

		local player = minetest.get_player_by_name(name)
		local def = {}

		if armor_mod and armor and armor.def then
			-- get player physics from armor
			def.speed = armor.def[name].speed
			def.jump = armor.def[name].jump
			def.gravity = armor.def[name].gravity
		end

		def.speed = def.speed or 1
		def.jump = def.jump or 1
		def.gravity = def.gravity or 1

		if sprinting == true then

			def.speed = def.speed + SPRINT_SPEED
			def.jump = def.jump + SPRINT_JUMP

		end

		player:set_physics_override({
			speed = def.speed,
			jump = def.jump,
			gravity = def.gravity
		})

		--print ("Speed:", def.speed, "Jump:", def.jump, "Gravity:", def.gravity)

		return true
	end

	return false
end

-- Time based stamina functions
local stamina_timer = 0
local health_timer = 0
local action_timer = 0

local function stamina_globaltimer(dtime)
	stamina_timer = stamina_timer + dtime
	health_timer = health_timer + dtime
	action_timer = action_timer + dtime

	if action_timer > STAMINA_MOVE_TICK then
		for _,player in pairs(minetest.get_connected_players()) do
			local controls = player:get_player_control()
			-- Determine if the player is walking
			if controls.jump then
				exhaust_player(player, STAMINA_EXHAUST_JUMP)
			elseif controls.up or controls.down or controls.left or controls.right then
				exhaust_player(player, STAMINA_EXHAUST_MOVE)
			end

			--- START sprint
			if enable_sprint then

				local name = player:get_player_name()

				-- check if player can sprint (stamina must be over 6 points)
				if controls.aux1 and controls.up
				and not minetest.check_player_privs(player, {fast = true})
				and stamina_players[name].level > 6 then

					set_sprinting(name, true)

					-- create particles behind player when sprinting
					if enable_sprint_particles then

						local pos = player:getpos()
--						local node = minetest.get_node({
--							x = pos.x,
--							y = pos.y - 1,
--							z = pos.z
--						})

--						if node.name ~= "air" then

						minetest.add_particlespawner({
							amount = 5,
							time = 0.01,
							minpos = {x = pos.x - 0.25, y = pos.y + 0.1, z = pos.z - 0.25},
							maxpos = {x = pos.x + 0.25, y = pos.y + 0.1, z = pos.z + 0.25},
							minvel = {x = -0.5, y = 1, z = -0.5},
							maxvel = {x = 0.5, y = 2, z = 0.5},
							minacc = {x = 0, y = -5, z = 0},
							maxacc = {x = 0, y = -12, z = 0},
							minexptime = 0.25,
							maxexptime = 0.5,
							minsize = 0.5,
							maxsize = 1.0,
							vertical = false,
							collisiondetection = false,
							texture = "default_dirt.png",
						})

--						end
					end

					-- Lower the player's stamina when sprinting
					local level = tonumber(stamina_players[name].level)
					stamina_update(player, level - (SPRINT_DRAIN * STAMINA_MOVE_TICK))
				else
					set_sprinting(name, false)
				end
			end
			-- END sprint

		end
		action_timer = 0
	end

	-- lower saturation by 1 point after STAMINA_TICK second(s)
	if stamina_timer > STAMINA_TICK then
		for _,player in pairs(minetest.get_connected_players()) do
			local name = player:get_player_name()
			local tab = stamina_players[name]
			if tab then
				local h = tab.level
				if h > STAMINA_TICK_MIN then
					stamina_update(player, h - 1)
				end
			end
		end
		stamina_timer = 0
	end

	-- heal or damage player, depending on saturation
	if health_timer > STAMINA_HEALTH_TICK then
		for _,player in pairs(minetest.get_connected_players()) do
			local name = player:get_player_name()
			local tab = stamina_players[name]
			if tab then
				local air = player:get_breath() or 0
				local hp = player:get_hp()

				-- don't heal if drowning, dead or poisoned
				local h = tonumber(tab.level)
				if h >= STAMINA_HEAL_LVL and h >= hp and hp > 0 and air > 0
				and tab.poison == false then
					player:set_hp(hp + STAMINA_HEAL)
					stamina_update(player, h - 1)
				end

				-- or damage player by 1 hp if saturation is < 2 (of 30)
				if tonumber(tab.level) < STAMINA_STARVE_LVL then
					player:set_hp(hp - STAMINA_STARVE)
				end
			end
		end

		health_timer = 0
	end
end

local function poison_player(ticks, time, elapsed, user)
	local name = user:get_player_name()
	if elapsed <= ticks then
		minetest.after(time, poison_player, ticks, time, elapsed + 1, user)
		stamina_players[name].poison = true
	else
		user:hud_change(stamina_players[name].hud_id, "text", "stamina_hud_fg.png")
		stamina_players[name].poison = false
	end
	local hp = user:get_hp() -1 or 0
	if hp > 0 then
		user:set_hp(hp)
	end
end

-- override core.do_item_eat() so we can redirect hp_change to stamina
core.do_item_eat = function(hp_change, replace_with_item, itemstack, user, pointed_thing)
	local old_itemstack = itemstack
	itemstack = stamina.eat(hp_change, replace_with_item, itemstack, user, pointed_thing)
	for _, callback in pairs(core.registered_on_item_eats) do
		local result = callback(hp_change, replace_with_item, itemstack, user, pointed_thing, old_itemstack)
		if result then
			return result
		end
	end
	return itemstack
end

-- not local since it's called from within core context
function stamina.eat(hp_change, replace_with_item, itemstack, user, pointed_thing)
	if not itemstack then
		return itemstack
	end

	if not user then
		return itemstack
	end

	local name = user:get_player_name()
	if not stamina_players[name] then
		return itemstack
	end

	local level = tonumber(stamina_players[name].level or 0)
	if level >= STAMINA_VISUAL_MAX then
		return itemstack
	end

	if hp_change > 0 then
		level = level + hp_change
		stamina_update(user, level)
	else
		-- assume hp_change < 0.
		user:hud_change(stamina_players[name].hud_id, "text", "stamina_hud_poison.png")
		poison_player(2.0, -hp_change, 0, user)
	end

	minetest.sound_play("stamina_eat", {to_player = name, gain = 0.7, max_hear_distance = 5})

	itemstack:take_item()

	if replace_with_item then
		if itemstack:is_empty() then
			itemstack:add_item(replace_with_item)
		else
			local inv = user:get_inventory()
			if inv:room_for_item("main", {name=replace_with_item}) then
				inv:add_item("main", replace_with_item)
			else
				local pos = user:getpos()
				pos.y = math.floor(pos.y + 0.5)
				core.add_item(pos, replace_with_item)
			end
		end
	end

	return itemstack
end

-- stamina is disabled if damage is disabled
if minetest.setting_getbool("enable_damage") and minetest.is_yes(minetest.setting_get("enable_stamina") or "1") then
	minetest.register_on_joinplayer(function(player)
		local inv = player:get_inventory()
		inv:set_size("stamina", 1)

		local name = player:get_player_name()
		stamina_players[name] = {}
		stamina_players[name].level = stamina_read(player)
		stamina_players[name].exhaust = 0
		stamina_players[name].poison = false
		local level = math.min(stamina_players[name].level, STAMINA_VISUAL_MAX)
		local id = player:hud_add({
			name = "stamina",
			hud_elem_type = "statbar",
			position = {x = 0.5, y = 1},
			size = {x = 24, y = 24},
			text = "stamina_hud_fg.png",
			number = level,
			alignment = {x = -1, y = -1},
			offset = {x = -266, y = -110},
			max = 0,
		})
		stamina_players[name].hud_id = id
	end)

	minetest.register_globalstep(stamina_globaltimer)

	minetest.register_on_placenode(function(pos, oldnode, player, ext)
		exhaust_player(player, STAMINA_EXHAUST_PLACE)
	end)
	minetest.register_on_dignode(function(pos, oldnode, player, ext)
		exhaust_player(player, STAMINA_EXHAUST_DIG)
	end)
	minetest.register_on_craft(function(itemstack, player, old_craft_grid, craft_inv)
		exhaust_player(player, STAMINA_EXHAUST_CRAFT)
	end)
	minetest.register_on_punchplayer(function(player, hitter, time_from_last_punch, tool_capabilities, dir, damage)
		exhaust_player(hitter, STAMINA_EXHAUST_PUNCH)
	end)

	minetest.register_on_respawnplayer(function(player)
		stamina_update(player, STAMINA_VISUAL_MAX)
	end)
end