//! BT snoop logger

use crate::internal::RawHal;
use bt_common::sys_prop;
use bt_packets::hci::{AclPacket, CommandPacket, EventPacket, IsoPacket, Packet};
use bytes::{BufMut, Bytes, BytesMut};
use gddi::{module, part_out, provides, Stoppable};
use log::error;
use std::convert::TryFrom;
use std::sync::Arc;
use std::time::SystemTime;
use tokio::fs::{remove_file, rename, File};
use tokio::io::AsyncWriteExt;
use tokio::runtime::Runtime;
use tokio::select;
use tokio::sync::mpsc::{channel, Receiver, Sender, UnboundedReceiver};
use tokio::sync::Mutex;

#[part_out]
#[derive(Clone, Stoppable)]
struct Hal {
    control: ControlHal,
    acl: AclHal,
    iso: IsoHal,
}

/// Command & event tx/rx
#[derive(Clone, Stoppable)]
pub struct ControlHal {
    /// Transmit end
    pub tx: Sender<CommandPacket>,
    /// Receive end
    pub rx: Arc<Mutex<Receiver<EventPacket>>>,
}

/// Acl tx/rx
#[derive(Clone, Stoppable)]
pub struct AclHal {
    /// Transmit end
    pub tx: Sender<AclPacket>,
    /// Receive end
    pub rx: Arc<Mutex<Receiver<AclPacket>>>,
}

/// Iso tx/rx
#[derive(Clone, Stoppable)]
pub struct IsoHal {
    /// Transmit end
    pub tx: Sender<IsoPacket>,
    /// Receive end
    pub rx: Arc<Mutex<Receiver<IsoPacket>>>,
}

/// The different modes snoop logging can be in
#[derive(Clone)]
pub enum SnoopMode {
    /// All logs disabled
    Disabled,
    /// Only sanitized logs
    Filtered,
    /// Log everything
    Full,
}

/// There was an error parsing the mode from a string
pub struct SnoopModeParseError;

impl std::str::FromStr for SnoopMode {
    type Err = SnoopModeParseError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "disabled" => Ok(SnoopMode::Disabled),
            "filtered" => Ok(SnoopMode::Filtered),
            "full" => Ok(SnoopMode::Full),
            _ => Err(SnoopModeParseError),
        }
    }
}

/// All snoop logging config
#[derive(Clone, Stoppable)]
pub struct SnoopConfig {
    path: String,
    max_packets_per_file: u32,
    mode: SnoopMode,
}

impl SnoopConfig {
    /// Constructs a new snoop config
    pub fn new() -> Self {
        Self {
            path: "/data/misc/bluetooth/logs/btsnoop_hci.log".to_string(),
            max_packets_per_file: sys_prop::get_u32("persist.bluetooth.btsnoopsize")
                .unwrap_or(0xFFFF),
            mode: get_configured_snoop_mode().parse().unwrap_or(SnoopMode::Disabled),
        }
    }

    /// Overwrites the laoded log path with the provided one
    pub fn set_path(&mut self, value: String) {
        self.path = value;
    }

    /// Overwrites the loaded mode with the provided one
    pub fn set_mode(&mut self, value: SnoopMode) {
        self.mode = value;
    }
}

impl Default for SnoopConfig {
    fn default() -> Self {
        Self::new()
    }
}

fn get_configured_snoop_mode() -> String {
    sys_prop::get("persist.bluetooth.btsnooplogmode").unwrap_or(if sys_prop::get_debuggable() {
        sys_prop::get("persist.bluetooth.btsnoopdefaultmode").unwrap_or_default()
    } else {
        String::default()
    })
}

module! {
    snoop_module,
    providers {
        parts Hal => provide_snooped_hal,
    },
}

#[provides]
async fn provide_snooped_hal(config: SnoopConfig, raw_hal: RawHal, rt: Arc<Runtime>) -> Hal {
    let (cmd_down_tx, mut cmd_down_rx) = channel::<CommandPacket>(10);
    let (evt_up_tx, evt_up_rx) = channel::<EventPacket>(10);
    let (acl_down_tx, mut acl_down_rx) = channel::<AclPacket>(10);
    let (acl_up_tx, acl_up_rx) = channel::<AclPacket>(10);
    let (iso_down_tx, mut iso_down_rx) = channel::<IsoPacket>(10);
    let (iso_up_tx, iso_up_rx) = channel::<IsoPacket>(10);

    rt.spawn(async move {
        let mut logger = SnoopLogger::new(config).await;
        loop {
            select! {
                Some(evt) = consume(&raw_hal.evt_rx) => {
                    if let Err(e) = evt_up_tx.send(evt.clone()).await {
                        error!("evt channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Evt, Direction::Up, evt.to_bytes()).await;
                },
                Some(cmd) = cmd_down_rx.recv() => {
                    if let Err(e) = raw_hal.cmd_tx.send(cmd.clone())  {
                        error!("cmd channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Cmd, Direction::Down, cmd.to_bytes()).await;
                },
                Some(acl) = acl_down_rx.recv() => {
                    if let Err(e) = raw_hal.acl_tx.send(acl.clone()) {
                        error!("acl down channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Acl, Direction::Down, acl.to_bytes()).await;
                },
                Some(acl) = consume(&raw_hal.acl_rx) => {
                    if let Err(e) = acl_up_tx.send(acl.clone()).await {
                        error!("acl up channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Acl, Direction::Up, acl.to_bytes()).await;
                },
                Some(iso) = iso_down_rx.recv() => {
                    if let Err(e) = raw_hal.iso_tx.send(iso.clone()) {
                        error!("iso down channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Iso, Direction::Down, iso.to_bytes()).await;
                },
                Some(iso) = consume(&raw_hal.iso_rx) => {
                    if let Err(e) = iso_up_tx.send(iso.clone()).await {
                        error!("iso up channel closed {:?}", e);
                        break;
                    }
                    logger.log(Type::Iso, Direction::Up, iso.to_bytes()).await;
                },
                else => break,
            }
        }
    });

    Hal {
        control: ControlHal { tx: cmd_down_tx, rx: Arc::new(Mutex::new(evt_up_rx)) },
        acl: AclHal { tx: acl_down_tx, rx: Arc::new(Mutex::new(acl_up_rx)) },
        iso: IsoHal { tx: iso_down_tx, rx: Arc::new(Mutex::new(iso_up_rx)) },
    }
}

async fn consume<T>(rx: &Arc<Mutex<UnboundedReceiver<T>>>) -> Option<T> {
    rx.lock().await.recv().await
}

#[allow(unused)]
enum Type {
    Cmd = 1,
    Acl,
    Sco,
    Evt,
    Iso,
}

enum Direction {
    Up,
    Down,
}

struct SnoopLogger {
    config: SnoopConfig,
    file: Option<File>,
    packets: u32,
}

// micros since 0000-01-01
const SNOOP_EPOCH_DELTA: u64 = 0x00dcddb30f2f8000;

impl SnoopLogger {
    async fn new(mut config: SnoopConfig) -> Self {
        // filtered snoop is not available at this time
        if let SnoopMode::Filtered = config.mode {
            config.mode = SnoopMode::Disabled;
        }

        remove_file(&config.path).await.ok();
        remove_file(config.path.clone() + ".last").await.ok();
        if let SnoopMode::Disabled = config.mode {
            remove_file(config.path.clone() + ".filtered").await.ok();
            remove_file(config.path.clone() + ".filtered.last").await.ok();
        }

        let mut ret = Self { config, file: None, packets: 0 };
        ret.open_next_file().await;

        ret
    }

    async fn log(&mut self, t: Type, dir: Direction, bytes: Bytes) {
        if let SnoopMode::Disabled = self.config.mode {
            return;
        }

        let mut flags = 0;
        if let Direction::Up = dir {
            flags |= 0b01;
        }
        if let Type::Cmd | Type::Evt = t {
            flags |= 0b10;
        }

        let timestamp: u64 = u64::try_from(
            SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_micros(),
        )
        .unwrap()
            + SNOOP_EPOCH_DELTA;

        // Add one for the type byte
        let length = u32::try_from(bytes.len()).unwrap() + 1;

        let mut buffer = BytesMut::new();
        buffer.put_u32(length); // original length
        buffer.put_u32(length); // captured length
        buffer.put_u32(flags); // flags
        buffer.put_u32(0); // dropped packets
        buffer.put_u64(timestamp); // timestamp
        buffer.put_u8(t as u8); // type
        buffer.put(bytes);

        self.packets += 1;
        if self.packets > self.config.max_packets_per_file {
            self.open_next_file().await;
        }

        if let Some(file) = &mut self.file {
            if file.write_all(&buffer).await.is_err() {
                error!("Failed to write");
            }
            if file.flush().await.is_err() {
                error!("Failed to flush");
            }
        } else {
            panic!("Logging without a backing file");
        }
    }

    async fn close_file(&mut self) {
        if let Some(file) = &mut self.file {
            file.flush().await.ok();
            self.file = None;
        }
        self.packets = 0;
    }

    async fn open_next_file(&mut self) {
        self.close_file().await;

        rename(&self.config.path, self.config.path.clone() + ".last").await.ok();
        let mut file = File::create(&self.config.path).await.expect("could not open snoop log");
        file.write_all(b"btsnoop\x00\x00\x00\x00\x01\x00\x00\x03\xea")
            .await
            .expect("could not write snoop header");
        if file.flush().await.is_err() {
            error!("Failed to flush");
        }
        self.file = Some(file);
    }
}