#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]

#[path = "../example_common.rs"]
mod example_common;

use core::mem;

use defmt::{info, *};
use embassy_executor::Spawner;
use nrf_softdevice::ble::gatt_server::builder::ServiceBuilder;
use nrf_softdevice::ble::gatt_server::characteristic::{Attribute, Metadata, Properties};
use nrf_softdevice::ble::gatt_server::{CharacteristicHandles, RegisterError};
use nrf_softdevice::ble::{gatt_server, peripheral, Connection, Uuid};
use nrf_softdevice::{raw, Softdevice};

const DEVICE_INFORMATION: Uuid = Uuid::new_16(0x180a);
const BATTERY_SERVICE: Uuid = Uuid::new_16(0x180f);

const BATTERY_LEVEL: Uuid = Uuid::new_16(0x2a19);
const MODEL_NUMBER: Uuid = Uuid::new_16(0x2a24);
const SERIAL_NUMBER: Uuid = Uuid::new_16(0x2a25);
const FIRMWARE_REVISION: Uuid = Uuid::new_16(0x2a26);
const HARDWARE_REVISION: Uuid = Uuid::new_16(0x2a27);
const SOFTWARE_REVISION: Uuid = Uuid::new_16(0x2a28);
const MANUFACTURER_NAME: Uuid = Uuid::new_16(0x2a29);
const PNP_ID: Uuid = Uuid::new_16(0x2a50);

#[embassy_executor::task]
async fn softdevice_task(sd: &'static Softdevice) -> ! {
    sd.run().await
}

#[repr(u8)]
#[derive(Clone, Copy)]
pub enum VidSource {
    BluetoothSIG = 1,
    UsbIF = 2,
}

#[repr(C, packed)]
#[derive(Clone, Copy)]
pub struct PnPID {
    pub vid_source: VidSource,
    pub vendor_id: u16,
    pub product_id: u16,
    pub product_version: u16,
}

#[derive(Debug, Default, defmt::Format)]
pub struct DeviceInformation {
    pub manufacturer_name: Option<&'static str>,
    pub model_number: Option<&'static str>,
    pub serial_number: Option<&'static str>,
    pub hw_rev: Option<&'static str>,
    pub fw_rev: Option<&'static str>,
    pub sw_rev: Option<&'static str>,
}

pub struct DeviceInformationService {}

impl DeviceInformationService {
    pub fn new(sd: &mut Softdevice, pnp_id: &PnPID, info: DeviceInformation) -> Result<Self, RegisterError> {
        let mut sb = ServiceBuilder::new(sd, DEVICE_INFORMATION)?;

        Self::add_pnp_characteristic(&mut sb, pnp_id)?;
        Self::add_opt_str_characteristic(&mut sb, MANUFACTURER_NAME, info.manufacturer_name)?;
        Self::add_opt_str_characteristic(&mut sb, MODEL_NUMBER, info.model_number)?;
        Self::add_opt_str_characteristic(&mut sb, SERIAL_NUMBER, info.serial_number)?;
        Self::add_opt_str_characteristic(&mut sb, HARDWARE_REVISION, info.hw_rev)?;
        Self::add_opt_str_characteristic(&mut sb, FIRMWARE_REVISION, info.fw_rev)?;
        Self::add_opt_str_characteristic(&mut sb, SOFTWARE_REVISION, info.sw_rev)?;

        let _service_handle = sb.build();

        Ok(DeviceInformationService {})
    }

    fn add_opt_str_characteristic(
        sb: &mut ServiceBuilder,
        uuid: Uuid,
        val: Option<&'static str>,
    ) -> Result<Option<CharacteristicHandles>, RegisterError> {
        if let Some(val) = val {
            let attr = Attribute::new(val);
            let md = Metadata::new(Properties::new().read());
            Ok(Some(sb.add_characteristic(uuid, attr, md)?.build()))
        } else {
            Ok(None)
        }
    }

    fn add_pnp_characteristic(sb: &mut ServiceBuilder, pnp_id: &PnPID) -> Result<CharacteristicHandles, RegisterError> {
        // SAFETY: `PnPID` is `repr(C, packed)` so viewing it as an immutable slice of bytes is safe.
        let val =
            unsafe { core::slice::from_raw_parts(pnp_id as *const _ as *const u8, core::mem::size_of::<PnPID>()) };

        let attr = Attribute::new(val);
        let md = Metadata::new(Properties::new().read());
        Ok(sb.add_characteristic(PNP_ID, attr, md)?.build())
    }
}

pub struct BatteryService {
    value_handle: u16,
    cccd_handle: u16,
}

impl BatteryService {
    pub fn new(sd: &mut Softdevice) -> Result<Self, RegisterError> {
        let mut service_builder = ServiceBuilder::new(sd, BATTERY_SERVICE)?;

        let attr = Attribute::new(&[0u8]);
        let metadata = Metadata::new(Properties::new().read().notify());
        let characteristic_builder = service_builder.add_characteristic(BATTERY_LEVEL, attr, metadata)?;
        let characteristic_handles = characteristic_builder.build();

        let _service_handle = service_builder.build();

        Ok(BatteryService {
            value_handle: characteristic_handles.value_handle,
            cccd_handle: characteristic_handles.cccd_handle,
        })
    }

    pub fn battery_level_get(&self, sd: &Softdevice) -> Result<u8, gatt_server::GetValueError> {
        let buf = &mut [0u8];
        gatt_server::get_value(sd, self.value_handle, buf)?;
        Ok(buf[0])
    }

    pub fn battery_level_set(&self, sd: &Softdevice, val: u8) -> Result<(), gatt_server::SetValueError> {
        gatt_server::set_value(sd, self.value_handle, &[val])
    }
    pub fn battery_level_notify(&self, conn: &Connection, val: u8) -> Result<(), gatt_server::NotifyValueError> {
        gatt_server::notify_value(conn, self.value_handle, &[val])
    }

    pub fn on_write(&self, handle: u16, data: &[u8]) {
        if handle == self.cccd_handle && !data.is_empty() {
            info!("battery notifications: {}", (data[0] & 0x01) != 0);
        }
    }
}

struct Server {
    _dis: DeviceInformationService,
    bas: BatteryService,
}

impl Server {
    pub fn new(sd: &mut Softdevice, serial_number: &'static str) -> Result<Self, RegisterError> {
        let dis = DeviceInformationService::new(
            sd,
            &PnPID {
                vid_source: VidSource::UsbIF,
                vendor_id: 0xDEAD,
                product_id: 0xBEEF,
                product_version: 0x0000,
            },
            DeviceInformation {
                manufacturer_name: Some("Embassy"),
                model_number: Some("M1234"),
                serial_number: Some(serial_number),
                ..Default::default()
            },
        )?;

        let bas = BatteryService::new(sd)?;

        Ok(Self { _dis: dis, bas })
    }
}

impl gatt_server::Server for Server {
    type Event = ();

    fn on_write(&self, handle: u16, data: &[u8]) -> Option<Self::Event> {
        self.bas.on_write(handle, data);
        None
    }
}

#[embassy_executor::main]
async fn main(spawner: Spawner) {
    info!("Hello World!");

    let config = nrf_softdevice::Config {
        clock: Some(raw::nrf_clock_lf_cfg_t {
            source: raw::NRF_CLOCK_LF_SRC_RC as u8,
            rc_ctiv: 4,
            rc_temp_ctiv: 2,
            accuracy: 7,
        }),
        conn_gap: Some(raw::ble_gap_conn_cfg_t {
            conn_count: 6,
            event_length: 24,
        }),
        conn_gatt: Some(raw::ble_gatt_conn_cfg_t { att_mtu: 256 }),
        gatts_attr_tab_size: Some(raw::ble_gatts_cfg_attr_tab_size_t { attr_tab_size: 32768 }),
        gap_role_count: Some(raw::ble_gap_cfg_role_count_t {
            adv_set_count: 1,
            periph_role_count: 3,
            central_role_count: 3,
            central_sec_count: 0,
            _bitfield_1: raw::ble_gap_cfg_role_count_t::new_bitfield_1(0),
        }),
        gap_device_name: Some(raw::ble_gap_cfg_device_name_t {
            p_value: b"HelloRust" as *const u8 as _,
            current_len: 9,
            max_len: 9,
            write_perm: unsafe { mem::zeroed() },
            _bitfield_1: raw::ble_gap_cfg_device_name_t::new_bitfield_1(raw::BLE_GATTS_VLOC_STACK as u8),
        }),
        ..Default::default()
    };

    let sd = Softdevice::enable(&config);
    let server = unwrap!(Server::new(sd, "12345678"));
    unwrap!(spawner.spawn(softdevice_task(sd)));

    #[rustfmt::skip]
    let adv_data = &[
        0x02, 0x01, raw::BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE as u8,
        0x03, 0x03, 0x09, 0x18,
        0x0a, 0x09, b'H', b'e', b'l', b'l', b'o', b'R', b'u', b's', b't',
    ];
    #[rustfmt::skip]
    let scan_data = &[
        0x03, 0x03, 0x09, 0x18,
    ];

    loop {
        let config = peripheral::Config::default();
        let adv = peripheral::ConnectableAdvertisement::ScannableUndirected { adv_data, scan_data };
        let conn = unwrap!(peripheral::advertise_connectable(sd, adv, &config).await);

        info!("advertising done!");

        // Run the GATT server on the connection. This returns when the connection gets disconnected.
        let res = gatt_server::run(&conn, &server, |_| {}).await;

        if let Err(e) = res {
            info!("gatt_server run exited with error: {:?}", e);
        }
    }
}