local mod_name = minetest.get_current_modname()
local mod_path = minetest.get_modpath(mod_name)

me = {
    lift = 4,
    speed = 4,
    fuel_time = 10,
    speed_mult = 4,
    i = {},
}

local ship = {
    physical = true,
    pointable = true,
    collisionbox = {-0.9, -0.0, -0.9, 0.9, 0.9, 0.9},
    selectionbox = {-0.7, -0.0, -0.7, 0.7, 0.9, 0.7},
    hp_max = 3,
    visual = "mesh",
    backface_culling = true,
    mesh = "sum_airship.b3d",
    textures = {"sum_airship_texture.png"},
    _animations = {
        idle = {x=  10, y= 90},
        fly = {x=  91, y= 170},
        boost = {x=  91, y= 170},
    },
    _driver = nil,
    _removed = false,
    _flags = {},
    _itemstring = "sum_airship:boat",
    _passenger = nil,
    _vel = 0,
    _regen_timer = 0,
    _fuel = 0,
}

local sounds = {
    engine_idle = {
        sound_name = "sum_airship_lip_trill",
        gain = 1.4,
        max_hear_distance = 10,
        loop = false,
        pitch = 0.75,
    },
    engine_stop = {
        sound_name = "sum_airship_lip_trill_end",
        gain = 2.2,
        max_hear_distance = 10,
        loop = false,
        pitch = 1,
    },
    engine_boost = {
        sound_name = "sum_airship_lip_trill",
        gain = 40,
        max_hear_distance = 10,
        loop = false,
        pitch = 1,
    },
}

function me.sound_play(self, sound_obj, sound_instance)
    sound_instance.handle = minetest.sound_play(sound_obj.sound_name, {
        gain = sound_obj.gain,
        max_hear_distance = sound_obj.max_hear_distance,
        loop = sound_obj.loop,
        pitch = sound_obj.pitch,
        object = self.object,
    })
    sound_instance.playing = true
    sound_instance.time_elapsed = 0
end

function me.sound_stop(sound_instance)
    if sound_instance.handle then
        minetest.sound_stop(sound_instance.handle)
    end
    sound_instance.playing = false
    sound_instance.time_elapsed = 0
    sound_instance.handle = nil
end

function me.sound_countdown(self, dtime)
    for _, sound in pairs(self._sounds) do
        if sound.playing then
            sound.time_elapsed = sound.time_elapsed + dtime
        end
    end
end

function me.update_sound(self, dtime, forward)
    me.sound_countdown(self, dtime)

    local is_thrust = (forward ~= 0) and self._driver

    if self._sounds.engine.time_elapsed > 2.1
    and self._sounds.engine.handle
    and self._sounds.engine.playing then
        me.sound_stop(self._sounds.engine)
    end
    if not self._sounds.engine.playing then
        if self._fuel > 1 then
            me.sound_play(self, sounds.engine_boost, self._sounds.engine)
        elseif is_thrust then
            me.sound_play(self, sounds.engine_idle, self._sounds.engine)
        end
        if self._fuel > 1 and self._sounds.engine_stop.playing then
            me.sound_stop(self._sounds.engine_stop)
        end
    end

    if self._fuel <= 1 and self._sounds.engine.playing then
        if self._fuel > 0 and not self._sounds.engine_stop.playing
        and self._sounds.engine_stop.time_elapsed == 0 then
            me.sound_play(self, sounds.engine_stop, self._sounds.engine_stop)
        end
        if not is_thrust
        or (self._sounds.engine_stop.time_elapsed == 0
        and self._sounds.engine_stop.playing) then
            me.sound_stop(self._sounds.engine)
        end
    end
end


function ship.on_activate(self, staticdata, dtime_s)
    local data = minetest.deserialize(staticdata)
    if type(data) == "table" then
        self._vel = data.v
        self._itemstring = data.itemstring
        self._fuel = data.fuel
        if data._driver then
            self._driver = minetest.get_player_by_name((data._driver))
        else
            self._driver = nil
        end
        self._flags = data._flags
        if self._driver then me.detach(self) end
    end
    self.object:set_armor_groups({
        pierce=100,
        slash=100,
        blunt=100,
        magic=100,
        poison=100,
        fleshy=100,
    })
    self.object:set_animation(ship._animations.idle, 24)
    self._sounds = { -- workaround for copy vs reference issue
        engine = {
            handle = nil,
            gain = 0.1,
            playing = false,
            time_elapsed = 0,
        },
        engine_stop = {
            handle = nil,
            gain = 0.1,
            playing = false,
            time_elapsed = 0,
        },
    }
end

function ship.get_staticdata(self)
    return minetest.serialize({
        itemstring = self._itemstring,
        _driver = ((self._driver and self._driver:is_player())
            and self._driver:get_player_name()) or nil,
        _flags = self._flags,
        v = self._vel,
        fuel = self._fuel,
    })
end

function me.attach(self, player)
    if not (player and player:is_player()) then
        return false
    end
    self._driver = player
    self._driver:set_attach(self.object, "",
        {x = 0, y = -2.0, z = -2}, {x = 0, y = 0, z = 0})
    self._driver:set_look_horizontal(self.object:get_yaw())
end

function me.detach(self)
    if not self._driver then return false end
    self._driver:set_detach()
    self._driver = nil
    return true
end


function ship.on_death(self, killer)
    if killer and killer:is_player()
    and not minetest.is_creative_enabled(killer:get_player_name()) then
        local inv = killer:get_inventory()
        inv:add_item("main", self._itemstring)
    else
        minetest.add_item(self.object:get_pos(), self._itemstring)
    end
    me.detach(self)
    self._driver = nil
end

function ship.on_rightclick(self, clicker)
    local item = clicker:get_wielded_item()
    local item_name = item:get_name()
    if clicker and (item and item_name)
    and (string.find(item_name, ":coal")
    or string.find(item_name, ":charcoal")) then
        if not minetest.is_creative_enabled(clicker:get_player_name()) then
            item:take_item()
            clicker:set_wielded_item(item)
        end
        self._fuel = self._fuel + me.fuel_time
        me.sound_stop(self._sounds.engine)
        minetest.sound_play("sum_airship_fire", {
            gain = 1,
            object = self.object,
        })
    else
        me.attach(self, clicker)
    end
end


-- 10, 5, 5
-- this system ensures collision kind of works with balloons.
-- does not include entity to entity collisions
local balloon = {}
balloon.offset = 6
balloon.length = 3.5
balloon.height = 2.5
local balloon_nodes = {}
balloon_nodes[0] = { -- top
    p = vector.new(0, balloon.offset + balloon.height, 0),
    dir = vector.new(0, -5, 0),}
balloon_nodes[1] = { -- front
    p = vector.new(0, balloon.offset, balloon.length),
    dir = vector.new(0, -0.5, -1),}
balloon_nodes[2] = { -- back
    p = vector.new(0, balloon.offset, -balloon.length),
    dir = vector.new(0, 0, 1),}
balloon_nodes[3] = { -- left or right
    p = vector.new(balloon.length, balloon.offset, 0),
    dir = vector.new(-1, 0, 0),}
balloon_nodes[4] = { -- left or right
    p = vector.new(-balloon.length, balloon.offset, 0),
    dir = vector.new(1, 0, 0),}
-- diagonals
local vdiag = 0.7
balloon_nodes[5] = {
    p = vector.new(-balloon.length*vdiag, balloon.offset, -balloon.length*vdiag),
    dir = vector.new(vdiag, 0, vdiag),}
balloon_nodes[6] = {
    p = vector.new(balloon.length*vdiag, balloon.offset, -balloon.length*vdiag),
    dir = vector.new(-vdiag, 0, vdiag),}
balloon_nodes[7] = {
    p = vector.new(-balloon.length*vdiag, balloon.offset, balloon.length*vdiag),
    dir = vector.new(vdiag, 0, -vdiag),}
balloon_nodes[8] = {
    p = vector.new(balloon.length*vdiag, balloon.offset, balloon.length*vdiag),
    dir = vector.new(-vdiag, 0, -vdiag),}

function me.get_balloon_collide(self)
    local force = vector.new()
    local o = self.object:get_pos()
    for _, check in pairs(balloon_nodes) do
        local n = minetest.get_node(vector.add(check.p, o))
        if n and minetest.registered_nodes[n.name]
        and minetest.registered_nodes[n.name].walkable then
            force = vector.add(force, check.dir)
        end
    end
    return force
end

me.chimney_dist = -0.8
me.chimney_yaw = 0.13
me.chimney_height = 1.5
function me.get_chimney_pos(self)
    local p = self.object:get_pos()
    local yaw = self.object:get_yaw()
    local ret = {
    x = p.x + (me.chimney_dist * math.sin(-yaw + me.chimney_yaw)),
    y = p.y + me.chimney_height,
    z = p.z + (me.chimney_dist * math.cos(-yaw + me.chimney_yaw))}
    return ret
end

function ship.on_step(self, dtime, moveresult)
    local exit = false
    local pi = nil
    -- allow to exit
    if self._driver and self._driver:is_player() then
        local name = self._driver:get_player_name()
        pi = self._driver:get_player_control()
        exit = pi.sneak
    end
    if exit then
        me.detach(self)
        return false
    end

    local climb = 0
    local right = 0
    local forward = 0
    local v = self.object:get_velocity()
    local p = self.object:get_pos()
    local node_below = minetest.get_node(vector.offset(p, 0, -0.8, 0)).name
    local is_on_floor = minetest.registered_nodes[node_below].walkable
    local in_water = minetest.get_item_group(minetest.get_node(p).name, "liquid") ~= 0
    local on_water = (minetest.get_item_group(minetest.get_node(vector.offset(p, 0, -0.2, 0)).name, "liquid") ~= 0 and not in_water)

    local speedboost = 1
    if self._fuel > 0 then
        self._fuel = self._fuel - dtime
        speedboost = 3
    end

    if pi then
        if pi.up then forward = 1
        elseif pi.down then forward = -1 end
        if pi.jump then climb = 1
        elseif pi.aux1 then climb = -1 end
        if pi.right then right = 1
        elseif pi.left then right = -1 end

        local yaw = self.object:get_yaw()
        local dir = minetest.yaw_to_dir(yaw)
        self.object:set_yaw(yaw - right * dtime)
        local added_vel = vector.multiply(dir, forward * dtime * me.speed * speedboost)
        added_vel.y = added_vel.y + (climb * dtime * me.lift)
        v = vector.add(v, added_vel)
    end

    if self._driver then
        local collide_force = me.get_balloon_collide(self)
        if collide_force ~= vector.new() then
            collide_force = vector.multiply(collide_force, 0.1)
            v = vector.multiply(v, 0.95)
        end
        v = vector.add(v, collide_force)
    end

    if not self._driver then
        v.y = v.y - dtime
    end

    if minetest.get_modpath("sum_air_currents") then
        if self._driver or not is_on_floor then
            local wind_vel = sum_air_currents.get_wind(p)
            wind_vel = vector.multiply(wind_vel, dtime)
            v = vector.add(wind_vel, v)
        end
    end
    if in_water then
        v.y = 1
    elseif on_water and not self._driver then
        v.y = 0
    end

    if (not self._driver) and is_on_floor then
        v.x = v.x * 0.8
        v.y = v.y * 0.95
        v.z = v.z * 0.8
    else
        v.x = v.x * (0.98)
        v.y = v.y * (0.98)
        v.z = v.z * (0.98)
    end

    local wind_vel = vector.new(0,0,0)
    if minetest.get_modpath("sum_air_currents") ~= nil then
        wind_vel = sum_air_currents.get_wind(p)
        if self._driver or not is_on_floor then
            v = vector.add(wind_vel, v)
        end
    end


    self.object:set_velocity(v)

    me.update_sound(self, dtime, forward)


    local is_thrust = self._driver and forward ~= 0

    local chimney_pos = me.get_chimney_pos(self)

    local spread = 0.06
    if self._fuel > 0 or (math.random(0,100) > 80 and is_thrust) or math.random(0,100) > 95 then
        minetest.add_particle({
            pos = vector.offset(chimney_pos, math.random(-1, 1)*spread, 0, math.random(-1, 1)*spread),
            velocity = vector.add(wind_vel, {x=0, y=math.random(0.2*100,0.7*100)/100, z=0}),
            expirationtime = math.random(0.5, 2),
            size = math.random(0.1, 4),
            collisiondetection = false,
            vertical = false,
            texture = "sum_airship_smoke.png",
        })
    end
    -- animations
    if self._fuel > 0 then
        self.object:set_animation(self._animations.boost, 25)
    elseif is_thrust then
        self.object:set_animation(self._animations.fly, 25)
    else
        self.object:set_animation(self._animations.idle, 25)
    end
end


minetest.register_entity("sum_airship:boat", ship)

minetest.register_craftitem("sum_airship:boat", {
    description = "Airship",
    inventory_image = "sum_airship.png",
    groups = { vehicle = 1, airship = 1, transport = 1},
    on_place = function(itemstack, placer, pointed_thing)
        if pointed_thing.type ~= "node" then
            return itemstack
        end
        local node = minetest.get_node(pointed_thing.under)
        if placer and not placer:get_player_control().sneak then
            if minetest.registered_nodes[node.name] and minetest.registered_nodes[node.name].on_rightclick then
                return minetest.registered_nodes[node.name].on_rightclick(pointed_thing.under, node, placer, itemstack) or itemstack
            end
        end
        local pos = vector.offset(pointed_thing.above, 0, 0.5, 0)
        local self = minetest.add_entity(pos, "sum_airship:boat"):get_luaentity()
        if not minetest.is_creative_enabled(placer:get_player_name()) then
            itemstack:take_item()
        end
        return itemstack
    end,
})


-- Support SilverSandstone's subtitles mod:
if minetest.get_modpath("subtitles") then
    subtitles.register_description('sum_airship_lip_trill',     'Engine purring');
    subtitles.register_description('sum_airship_lip_trill_end', 'Engine sputtering');
    subtitles.register_description('sum_airship_fire',          'Engine stoked');
end
