use bluer::gatt::remote::Characteristic;
use bluer::{Adapter, AdapterEvent, Address, Device, Result, Uuid};
use futures::{pin_mut, StreamExt};
use std::collections::HashSet;
use std::time::Duration;
use tokio::sync::mpsc;

// const CONNECT_RETRIES: u8 = 3;
// const SERVICE_UUID: bluer::Uuid = bluer::Uuid::from_u128(0xadaf0900c33242a893bd25e905756cb8);
// const PIXEL_DATA_UUID: bluer::Uuid = bluer::Uuid::from_u128(0xadaf0903c33242a893bd25e905756cb8);

pub(crate) async fn create_session() -> Result<Adapter> {
    let session = bluer::Session::new().await?;
    let adapter_names = session.adapter_names().await?;
    let adapter_name = adapter_names.first().expect("no Bluetooth adapter found");
    let adapter = session.adapter(adapter_name)?;

    adapter.set_powered(true).await?;
    Ok(adapter)
}

async fn has_service(device: &Device, uuid: &Uuid) -> Result<bool> {
    let uuids = device.uuids().await?.unwrap_or_default();
    if uuids.contains(uuid) {
        return Ok(true);
    }
    Ok(false)
}

async fn bluetooth_scan(tx: mpsc::Sender<Device>, adapter: Adapter, uuid: Uuid) -> Result<()> {
    println!("start bluetooth scan");
    let discover = adapter.discover_devices().await?;
    let mut already_scanned: HashSet<Address> = HashSet::new();
    pin_mut!(discover);
    while let Some(evt) = discover.next().await {
        match evt {
            AdapterEvent::DeviceAdded(addr) => {
                if already_scanned.contains(&addr) {
                    continue;
                }
                already_scanned.insert(addr);
                let device = adapter.device(addr)?;
                match has_service(&device, &uuid).await {
                    Ok(service_found) => {
                        if service_found {
                            tx.send(device).await.unwrap();
                            println!("found service in device {}", addr);
                        }
                    }
                    Err(_) => continue,
                }
            }
            _ => {}
        }
    }
    Ok(())
}

pub(crate) async fn scan_devices(adapter: Adapter, uuid: Uuid) -> Vec<Device> {
    let (tx, mut rx) = mpsc::channel(4);

    let timeout = tokio::time::timeout(Duration::from_secs(30), bluetooth_scan(tx, adapter, uuid));
    let scan = tokio::spawn(timeout);
    let mut devices: Vec<Device> = Vec::new();
    while let Some(device) = rx.recv().await {
        devices.push(device);
        if devices.len() >= 2 {
            drop(scan);
            break;
        }
    }

    devices
}

pub async fn connect(device: &Device, retries: u8) -> bluer::Result<()> {
    if device.is_connected().await? {
        return Ok(());
    }
    for i in 0..retries {
        match device.connect().await {
            Ok(()) => return Ok(()),
            Err(_) => {
                println!("connection error ({}), retry…", i);
            }
        }
    }

    Err(bluer::Error {
        kind: bluer::ErrorKind::ConnectionAttemptFailed,
        message: "all attempts fail".parse().unwrap(),
    })
}

pub async fn get_char(
    device: &Device,
    service_uuid: Uuid,
    char_uuid: Uuid,
) -> Result<Option<Characteristic>> {
    for service in device.services().await? {
        if service_uuid == service.uuid().await? {
            for char in service.characteristics().await? {
                if char_uuid == char.uuid().await? {
                    return Ok(Some(char));
                }
            }
        }
    }
    Ok(None)
}