shooter = {
	time = 0,
	objects = {},
	rounds = {},
	shots = {},
}

SHOOTER_ENABLE_PARTICLE_FX = true
SHOOTER_EXPLOSION_TEXTURE = "shooter_hit.png"
SHOOTER_ALLOW_NODES = true
SHOOTER_ALLOW_ENTITIES = false
SHOOTER_ALLOW_PLAYERS = true
SHOOTER_OBJECT_RELOAD_TIME = 1
SHOOTER_OBJECT_UPDATE_TIME = 0.25
SHOOTER_ROUNDS_UPDATE_TIME = 0.4
SHOOTER_PLAYER_OFFSET = {x=0, y=1, z=0}
SHOOTER_ENTITY_OFFSET = {x=0, y=0, z=0}
SHOOTER_ENTITIES = {
	"mobs:dirt_monster",
	"mobs:stone_monster",
	"mobs:sand_monster",
	"mobs:tree_monster",
	"mobs:sheep",
	"mobs:rat",
	"mobs:oerkki",
	"mobs:dungeon_master",
}

if minetest.is_singleplayer() == true then
	SHOOTER_ALLOW_ENTITIES = true
	SHOOTER_ALLOW_PLAYERS = false
end

local allowed_entities = {}
for _,v in ipairs(SHOOTER_ENTITIES) do
	allowed_entities[v] = 1
end

local modpath = minetest.get_modpath(minetest.get_current_modname())
local input = io.open(modpath.."/shooter.conf", "r")
if input then
	dofile(modpath.."/shooter.conf")
	input:close()
	input = nil
end

local rounds_update_time = 0
local object_update_time = 0
local object_reload_time = 0

local function get_dot_product(v1, v2)
	return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z
end

local function get_particle_pos(p, v, d)
	return vector.add(p, vector.multiply(v, {x=d, y=d, z=d}))
end

local function spawn_particles(pos, texture)
	if SHOOTER_ENABLE_PARTICLE_FX == true then
		if type(texture) ~= "string" then
			texture = SHOOTER_EXPLOSION_TEXTURE
		end
		local spread = {x=0.1, y=0.1, z=0.1}
		minetest.add_particlespawner(15, 0.3,
			vector.subtract(pos, spread), vector.add(pos, spread),
			{x=-1, y=1, z=-1}, {x=1, y=2, z=1},
			{x=-2, y=-2, z=-2}, {x=2, y=-2, z=2},
			0.1, 0.75, 1, 2, false, texture
		)
	end
end

local function is_valid_object(object)
	if object then
		if object:is_player() == true then
			return true
		end
		if SHOOTER_ALLOW_ENTITIES == true then
			local luaentity = object:get_luaentity()
			if luaentity then
				if luaentity.name then
					if allowed_entities[luaentity.name] then
						return true
					end
				end
			end
		end
	end
	return false
end

local function punch_node(pos, def)
	local node = minetest.get_node(pos)
	if not node then
		return
	end
	local item = minetest.registered_items[node.name]
	if not item then
		return
	end
	if item.groups then
		for k, v in pairs(def.groups) do
			local level = item.groups[k] or 0
			if level >= v then
				minetest.remove_node(pos)
				local sounds = item.sounds
				if item.sounds then
					local spec = item.sounds.dug
					if spec then
						spec.pos = pos
						minetest.sound_play(spec.name, spec)
					end
				end
				if item.tiles then
					return item.tiles[1]
				end
				break
			end
		end
	end
end

local function process_round(round)
	local target = {object=nil, distance=10000}
	local p1 = round.pos
	local v1 = round.ray
	for _,ref in ipairs(shooter.objects) do
		local p2 = vector.add(ref.pos, ref.offset)
		if p1 and p2 and ref.name ~= round.name then
			local d = vector.distance(p1, p2)
			if d < round.def.step then
				local n = vector.multiply(v1, {x=-1, y=0, z=-1})
				local v2 = vector.subtract(p1, p2)
				local r1 = get_dot_product(n, v2)
				local r2 = get_dot_product(n, v1)
				if r2 ~= 0 then
					local t = -(r1 / r2)
					local td = vector.multiply(v1, {x=t, y=t, z=t})
					local pt = vector.add(p1, td)
					local pd = vector.subtract(pt, p2)
					if math.abs(pd.x) < ref.collisionbox[4] and
							math.abs(pd.y) < ref.collisionbox[5] and
							math.abs(pd.z) < ref.collisionbox[6] then
						target.object = ref.object
						target.pos = pt
						target.distance = d
					end
				end
			end
		end
	end
	if target.object and target.pos then
		local success, pos = minetest.line_of_sight(p1, target.pos, 1)
		if success then
			local user = minetest.get_player_by_name(round.name)
			if user then
				target.object:punch(user, nil, round.def.tool_caps, v1)
				spawn_particles(target.pos, SHOOTER_EXPLOSION_TEXTURE)
			end
			return 1
		elseif pos and SHOOTER_ALLOW_NODES == true then
			local texture = punch_node(pos, round.def)
			if texture then
				local pp = get_particle_pos(p1, v1, vector.distance(p1, pos))
				spawn_particles(pp, texture)
			end
			return 1
		end
	elseif SHOOTER_ALLOW_NODES == true then
		local d = round.def.step
		local p2 = vector.add(p1, vector.multiply(v1, {x=d, y=d, z=d}))
		local success, pos = minetest.line_of_sight(p1, p2, 1)
		if pos then
			local texture = punch_node(pos, round.def)
			if texture then
				local pp = get_particle_pos(p1, v1, vector.distance(p1, pos))
				spawn_particles(pp, texture)
			end
			return 1
		end
	end
end

function shooter:register_weapon(name, def)
	local shots = def.shots or 1
	local wear = math.ceil(65534 / def.rounds)
	local max_wear = (def.rounds - 1) * wear
	minetest.register_tool(name, {
		description = def.description,
		inventory_image = def.inventory_image,
		on_use = function(itemstack, user, pointed_thing)
			if itemstack:get_wear() < max_wear then
				def.spec.name = user:get_player_name()
				if shots > 1 then
					local step = def.spec.tool_caps.full_punch_interval
					for i = 0, step * (shots), step do
						minetest.after(i, function()
							shooter:fire_weapon(user, pointed_thing, def.spec)
						end)
					end
				else
					shooter:fire_weapon(user, pointed_thing, def.spec)
				end
				itemstack:add_wear(wear)
			else
				local inv = user:get_inventory()
				if inv then
					local stack = "shooter:ammo 1"
					if inv:contains_item("main", stack) then
						minetest.sound_play("shooter_reload", {object=user})
						inv:remove_item("main", stack)
						itemstack:replace(name.." 1 1")
					else
						minetest.sound_play("shooter_click", {object=user})
					end
				end
			end
			return itemstack
		end,
	})
end

function shooter:fire_weapon(user, pointed_thing, def)
	if shooter.shots[def.name] then
		if shooter.time < shooter.shots[def.name] then
			return
		end
	end
	shooter.shots[def.name] = shooter.time + def.tool_caps.full_punch_interval
	minetest.sound_play(def.sound, {object=user})
	local v1 = user:get_look_dir()
	local p1 = user:getpos()
	if not v1 or not p1 then
		return
	end
	minetest.add_particle({x=p1.x, y=p1.y + 1.6, z=p1.z},
		vector.multiply(v1, {x=30, y=30, z=30}),
		{x=0, y=0, z=0}, 0.5, 0.25,
		false, def.particle
	)
	if pointed_thing.type == "node" and SHOOTER_ALLOW_NODES == true then
		local pos = minetest.get_pointed_thing_position(pointed_thing, false)
		local texture = punch_node(pos, def)
		if texture then
			local pp = get_particle_pos(p1, v1, vector.distance(p1, pos))
			pp.y = pp.y + 1.75
			spawn_particles(pp, texture)
		end
	elseif pointed_thing.type == "object" then
		local object = pointed_thing.ref
		if is_valid_object(object) == true then
			object:punch(user, nil, def.tool_caps, v1)
			local p2 = object:getpos()
			local pp = get_particle_pos(p1, v1, vector.distance(p1, p2))
			pp.y = pp.y + 1.75
			spawn_particles(pp, SHOOTER_EXPLOSION_TEXTURE)
		end
	else
		shooter:update_objects()
		table.insert(shooter.rounds, {
			name = def.name,
			pos = vector.add(p1, {x=0, y=1.75, z=0}),
			ray = v1,
			dist = 0,
			def = def,
		})
	end
end

function shooter:load_objects()
	local objects = {}
	if SHOOTER_ALLOW_PLAYERS == true then
		local players = minetest.get_connected_players()
		for _,player in ipairs(players) do
			local pos = player:getpos()
			local name = player:get_player_name()
			local hp = player:get_hp() or 0
			if pos and name and hp > 0 then
				table.insert(objects, {
					name = name,
					object = player,
					pos = pos,
					collisionbox = {-0.25,-1.0,-0.25, 0.25, 0.8, 0.25},
					offset = SHOOTER_PLAYER_OFFSET,
				})
			end
		end
	end
	if SHOOTER_ALLOW_ENTITIES == true then
		for _,ref in pairs(minetest.luaentities) do
			if ref.object and ref.name then
				if allowed_entities[ref.name] then
					local pos = ref.object:getpos()
					local hp = ref.object:get_hp() or 0
					if pos and hp > 0 then
						local def = minetest.registered_entities[ref.name]
						table.insert(objects, {
							name = ref.name,
							object = ref.object,
							pos = pos,
							collisionbox = def.collisionbox,
							offset = SHOOTER_ENTITY_OFFSET,
						})
					end
				end
			end
		end
	end
	object_reload_time = shooter.time
	object_update_time = shooter.time
	shooter.objects = {}
	for _,v in ipairs(objects) do
		table.insert(shooter.objects, v)
	end
end

function shooter:update_objects()
	if shooter.time - object_reload_time > SHOOTER_OBJECT_RELOAD_TIME then
		shooter:load_objects()
	elseif shooter.time - object_update_time > SHOOTER_OBJECT_UPDATE_TIME then
		for i, ref in ipairs(shooter.objects) do
			if ref.object then
				local pos = ref.object:getpos()
				if pos then
					shooter.objects[i].pos = pos
				end
			else
				table.remove(shooter.objects, i)
			end
		end
		object_update_time = shooter.time
	end
end

minetest.register_on_joinplayer(function(player)
	player:hud_set_flags({crosshair = true})
end)

minetest.register_globalstep(function(dtime)
	shooter.time = shooter.time + dtime
	if shooter.time - rounds_update_time > SHOOTER_ROUNDS_UPDATE_TIME then
		for i, round in ipairs(shooter.rounds) do
			if process_round(round) or round.dist > round.def.range then
				table.remove(shooter.rounds, i)
			else
				local v = vector.multiply(round.ray, round.def.step)
				shooter.rounds[i].pos = vector.add(round.pos, v)
				shooter.rounds[i].dist = round.dist + round.def.step
			end
		end
		rounds_update_time = shooter.time
	end
	if shooter.time > 100000 then
		shooter.shots = {}
		rounds_update_time = 0
		object_reload_time = 0
		object_update_time = 0
		shooter.time = 0
	end
end)