-- lib_mount by Blert2112 (edited by TenPlus1)

local enable_crash = true
local crash_threshold = 6.5 -- ignored if enable_crash=false

------------------------------------------------------------------------------

--
-- Helper functions
--

local function node_is(pos)

	local node = minetest.get_node(pos)

	if node.name == "air" then
		return "air"
	end

	if minetest.get_item_group(node.name, "lava") ~= 0 then
		return "lava"
	end

	if minetest.get_item_group(node.name, "liquid") ~= 0 then
		return "liquid"
	end

	if minetest.get_item_group(node.name, "walkable") ~= 0 then
		return "walkable"
	end

	return "other"
end


local function get_sign(i)

	i = i or 0

	if i == 0 then
		return 0
	else
		return i / math.abs(i)
	end
end


local function get_velocity(v, yaw, y)

	local x = -math.sin(yaw) * v
	local z =  math.cos(yaw) * v

	return {x = x, y = y, z = z}
end


local function get_v(v)
	return math.sqrt(v.x * v.x + v.z * v.z)
end


local function force_detach(player)

	local attached_to = player:get_attach()

	if not attached_to then
		return
	end

	local entity = attached_to:get_luaentity()

	if entity.driver
	and entity.driver == player then

		entity.driver = nil
	end

	player:set_detach()
	default.player_attached[player:get_player_name()] = false
	player:set_eye_offset({x = 0, y = 0, z = 0}, {x = 0, y = 0, z = 0})
	default.player_set_animation(player, "stand" , 30)

end

-------------------------------------------------------------------------------


minetest.register_on_leaveplayer(function(player)
	force_detach(player)
end)

minetest.register_on_shutdown(function()
	local players = minetest.get_connected_players()
	for i = 1, #players do
		force_detach(players[i])
	end
end)

minetest.register_on_dieplayer(function(player)
	force_detach(player)
	return true
end)

-------------------------------------------------------------------------------

function mobs.attach(entity, player)

	local attach_at, eye_offset = {}, {}

	if not entity.player_rotation then
		entity.player_rotation = {x = 0, y = 0, z = 0}
	end

	local rot_view = 0

	if entity.player_rotation.y == 90 then
		rot_view = math.pi/2
	end

	if not entity.driver_attach_at then
		entity.driver_attach_at = {x = 0, y = 0, z = 0}
	end

	if not entity.driver_eye_offset then
		entity.driver_eye_offset = {x = 0, y = 0, z = 0}
	end

	attach_at = entity.driver_attach_at
	eye_offset = entity.driver_eye_offset
	entity.driver = player

	force_detach(player)

	player:set_attach(entity.object, "", attach_at, entity.player_rotation)
	default.player_attached[player:get_player_name()] = true
	player:set_eye_offset(eye_offset, {x = 0, y = 0, z = 0})
	player:set_properties({visual_size = {x=1, y=1}})

	minetest.after(0.2, function()
		default.player_set_animation(player, "sit" , 30)
	end)

	player:set_look_yaw(entity.object:getyaw() - rot_view)
end


function mobs.detach(player, offset)

	force_detach(player)
	default.player_set_animation(player, "stand" , 30)

	local pos = player:getpos()

	pos = {x = pos.x + offset.x, y = pos.y + 0.2 + offset.y, z = pos.z + offset.z}

	minetest.after(0.1, function()
		player:setpos(pos)
	end)
end


function mobs.drive(entity, moving_anim, stand_anim, can_fly, dtime)

	local rot_steer, rot_view = math.pi/2, 0

	if entity.player_rotation.y == 90 then
		rot_steer, rot_view = 0, math.pi/2
	end

	local acce_y = 0
	local velo = entity.object:getvelocity()

	entity.v = get_v(velo) * get_sign(entity.v)

	-- process controls
	if entity.driver then

--print ("---velo", get_v(velo))

		local ctrl = entity.driver:get_player_control()

		-- move forwards
		if ctrl.up then

			entity.v = entity.v + entity.accel / 10

		-- move backwards
		elseif ctrl.down then

			if entity.max_speed_reverse == 0 and entity.v == 0 then
				return
			end

			entity.v = entity.v - entity.accel / 10
		end

		--entity.object:setyaw(entity.driver:get_look_yaw() - rot_steer)
		entity.object:setyaw(entity.driver:get_look_horizontal())-- - rot_steer)

		if can_fly then

			-- fly up
			if ctrl.jump then
				velo.y = velo.y + 1
				if velo.y > entity.accel then velo.y = entity.accel end

			elseif velo.y > 0 then
				velo.y = velo.y - 0.1
				if velo.y < 0 then velo.y = 0 end
			end

			-- fly down
			if ctrl.sneak then
				velo.y = velo.y - 1
				if velo.y < -entity.accel then velo.y = -entity.accel end

			elseif velo.y < 0 then
				velo.y = velo.y + 0.1
				if velo.y > 0 then velo.y = 0 end
			end

		else

			-- jump
			if ctrl.jump then

				if velo.y == 0 then
					velo.y = velo.y + entity.jump_height
					acce_y = acce_y + (acce_y * 3) + 1
				end
			end

		end
	end

	-- if not moving then set animation and return
	if entity.v == 0 and velo.x == 0 and velo.y == 0 and velo.z == 0 then

		if stand_anim then
			set_animation(entity, stand_anim)
		end

		return
	end
	
	-- set moving animation
	if moving_anim then
		set_animation(entity, moving_anim)
	end

	-- Stop!
	local s = get_sign(entity.v)

	entity.v = entity.v - 0.02 * s

	if s ~= get_sign(entity.v) then

		entity.object:setvelocity({x = 0, y = 0, z = 0})
		entity.v = 0
		return
	end

	-- enforce speed limit forward and reverse
	local max_spd = entity.max_speed_reverse

	if get_sign(entity.v) >= 0 then
		max_spd = entity.max_speed_forward
	end

	if math.abs(entity.v) > max_spd then
		entity.v = entity.v - get_sign(entity.v)
	end

	-- Set position, velocity and acceleration
	local p = entity.object:getpos()
	local new_velo = {x = 0, y = 0, z = 0}
	local new_acce = {x = 0, y = -9.8, z = 0}

	p.y = p.y - 0.5

	local ni = node_is(p)
	local v = entity.v

	if ni == "air" then

		if can_fly == true then
			new_acce.y = 0
		end

	elseif ni == "liquid" or ni == "lava" then

		if ni == "lava" and entity.lava_damage ~= 0 then

			entity.lava_counter = (entity.lava_counter or 0) + dtime

			if entity.lava_counter > 1 then

				minetest.sound_play("default_punch", {
					object = entity.object,
					max_hear_distance = 5
				})

				entity.object:punch(entity.object, 1.0, {
					full_punch_interval = 1.0,
					damage_groups = {fleshy = entity.lava_damage}
				}, nil)

				entity.lava_counter = 0
			end
		end

		if entity.terrain_type == 2
		or entity.terrain_type == 3 then

			new_acce.y = 0
			p.y = p.y + 1

			if node_is(p) == "liquid" then

				if velo.y >= 5 then
					velo.y = 5
				elseif velo.y < 0 then
					new_acce.y = 20
				else
					new_acce.y = 5
				end
			else
				if math.abs(velo.y) < 1 then
					local pos = entity.object:getpos()
					pos.y = math.floor(pos.y) + 0.5
					entity.object:setpos(pos)
					velo.y = 0
				end
			end
		else
			v = v * 0.25
		end
--	elseif ni == "walkable" then
--		v = 0
--		new_acce.y = 1
	end

	new_velo = get_velocity(v, entity.object:getyaw() - rot_view, velo.y)
	new_acce.y = new_acce.y + acce_y

	entity.object:setvelocity(new_velo)
	entity.object:setacceleration(new_acce)

	-- CRASH!
	if enable_crash then

		local intensity = entity.v2 - v

		if intensity >= crash_threshold then

--print("----------- crash", intensity)

			entity.object:punch(entity.object, 1.0, {
				full_punch_interval = 1.0,
				damage_groups = {fleshy = intensity}
			}, nil)

		end
	end

	entity.v2 = v
end