-- lib_mount by Blert2112 (edited by TenPlus1)

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

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

--
-- Helper functions
--

local function adj_yaw (entity)
    return (entity.object:get_yaw() or 0) + entity.rotate
end

local node_ok = function(pos, fallback)

    fallback = fallback or mobs.fallback_node

    local node = minetest.get_node_or_nil(pos)

    if node and minetest.registered_nodes[node.name] then
        return node
    end

    return {name = fallback}
end


local function node_is(pos)

    local node = node_ok(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.registered_nodes[node.name].walkable == true 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)
    if v == nil then
        ocutil.log ("debug nil: 0077: v == nil") -- @@@
        return 0
    end
    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)
    player:set_properties ({visual_size = {x = 1, y = 1} })
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 = {}, {}

    entity.player_rotation   = entity.player_rotation
        or { x = 0, y = 0, z = 0 }
    entity.driver_attach_at  = entity.driver_attach_at
        or { x = 0, y = 0, z = 0 }
    entity.driver_eye_offset = entity.driver_eye_offset
        or { x = 0, y = 0, z = 0 }
    entity.driver_scale = entity.driver_scale
        or { x = 1, y = 1 }

    local rot_view = 0

    if (entity.player_rotation.y == 90) and
        (entity.rotate == 0) then
        rot_view = math.pi/2
    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 = entity.driver_scale.x ,
            y = entity.driver_scale.y ,
        }
    })

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

    player:set_look_horizontal (adj_yaw (entity) - rot_view)
end

function mobs.detach (player, offset)
    force_detach (player)
    default.player_set_animation (player, "stand" , 30)

    local pos = player:get_pos()

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

    minetest.after (0.1, function()
        player:set_pos (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) and
        (entity.rotate == 0) then
        rot_steer, rot_view = 0, math.pi/2
    end

    local s    = get_sign (entity.v)
    local velo = entity.object:get_velocity()

    if entity.v == nil or s == nil or velo == nil or s ~= s then
        ocutil.log ("debug mount: fixing nil velo")
        entity.object:set_velocity ({ x = 0, y = 0, z = 0 })
        entity.v = 0
    end

    velo = entity.object:get_velocity()

    if velo == nil then
        ocutil.log ("debug mount: error: still nil")
        if  entity.driver then
            mobs.detach (entity.driver, { x=1, y=0, z=1 })
        end
        entity.object:remove()
        return
    end

    entity.v = get_v (velo) * get_sign (entity.v)
    local acce_y = 0

    -- process controls
    if entity.driver then

        local ctrl = entity.driver:get_player_control()
        if  entity.accel == nil then
            entity.accel = 2
        end

        local adj_rotate = 0

        -- 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

        elseif ctrl.left then
            adj_rotate =  0.2
        elseif ctrl.right then
            adj_rotate = -0.2
        end

        -- fix mob rotation
        local d = entity.driver

        if  d                       ~= nil and
            d:get_look_horizontal() ~= nil then
            local g = d:get_look_horizontal() + adj_rotate
            if adj_rotate ~= 0 then
                d:set_look_horizontal (g)
            end
            entity.object:set_yaw (g - entity.rotate)
        end

        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
            mobs:set_animation (entity, stand_anim)
        end
        return
    end

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

    if ocutil.get_sopos (entity) == nil then
        if  entity.driver then
            mobs.detach (entity.driver, { x=1, y=0, z=1 })
        end
        return
    end

    -- Stop!
    local s  = get_sign (entity.v)
    entity.v = entity.v - 0.02 * s

    if s ~= get_sign (entity.v) then
        entity.object:set_velocity ({ 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 max_spd == nil then max_spd = 3 end

    if get_sign(entity.v) >= 0 then
        max_spd = entity.max_speed_forward
        if max_spd == nil then max_spd = 5 end
    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:get_pos()
    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:get_pos()
                    pos.y = math.floor(pos.y) + 0.5
                    entity.object:set_pos(pos)
                    velo.y = 0
                end
            end
        else
            v = v * 0.25
        end
    end

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

    entity.object:set_velocity(new_velo)
    entity.object:set_acceleration(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

-- directional flying routine by D00Med (edited by TenPlus1)

function mobs.fly (entity, dtime, speed, shoots, arrow, moving_anim, stand_anim)

    local ctrl = entity.driver:get_player_control()
    local velo = entity.object:get_velocity()
    local dir = entity.driver:get_look_dir()
    local yaw = entity.driver:get_look_horizontal() + 1.57 -- offset fix between old and new commands
    local rot_steer, rot_view = math.pi / 2, 0

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

    local adj_rotate = 0

    if ctrl.up then
        entity.object:set_velocity({
            x = dir.x * speed,
            y = dir.y * speed + 2,
            z = dir.z * speed
        })

    elseif ctrl.down then
        entity.object:set_velocity({
            x = -dir.x * speed,
            y = dir.y * speed + 2,
            z = -dir.z * speed
        })

    elseif ctrl.left then
        adj_rotate =  0.5
    elseif ctrl.right then
        adj_rotate = -0.5

    elseif not ctrl.down or ctrl.up or ctrl.jump then
        entity.object:set_velocity({x = 0, y = -2, z = 0})
    end

    yaw = yaw + adj_rotate

    entity.object:set_yaw (yaw + math.pi + math.pi / 2 - entity.rotate)

    -- firing arrows
    if ctrl.LMB and ctrl.sneak and shoots then

        local pos = entity.object:get_pos()
        local obj = minetest.add_entity({
            x = pos.x + 0 + dir.x * 2.5,
            y = pos.y + 1.5 + dir.y,
            z = pos.z + 0 + dir.z * 2.5}, arrow)

        local ent = obj:get_luaentity()
        if ent then
            ent.switch = 1 -- for mob specific arrows
            ent.owner_id = tostring(entity.object) -- so arrows dont hurt entity you are riding
            local vec = {x = dir.x * 6, y = dir.y * 6, z = dir.z * 6}
            local yaw = entity.driver:get_look_horizontal()
            obj:set_yaw(yaw + math.pi / 2)
            obj:set_velocity(vec)
        else
            obj:remove()
        end
    end

    -- change animation if stopped
    if velo.x == 0 and velo.y == 0 and velo.z == 0 then

        mobs:set_animation(entity, stand_anim)
    else
        -- moving animation
        mobs:set_animation(entity, moving_anim)
    end
end