pub use types::*;
use {
    crate::{
        async_engine::{AsyncEngine, SpawnedFuture},
        dbus::{
            property::GetReply,
            types::{ObjectPath, Signature, Variant},
        },
        io_uring::{IoUring, IoUringError},
        utils::{
            bufio::{BufIo, BufIoError},
            clonecell::CloneCell,
            copyhashmap::CopyHashMap,
            numcell::NumCell,
            oserror::OsError,
            run_toplevel::RunToplevel,
            vecstorage::VecStorage,
            xrd::{xrd, XRD},
        },
    },
    ahash::AHashMap,
    std::{
        borrow::Cow,
        cell::{Cell, RefCell},
        fmt::{Debug, Display},
        future::Future,
        marker::PhantomData,
        mem,
        pin::Pin,
        rc::Rc,
        task::{Context, Poll, Waker},
    },
    thiserror::Error,
    uapi::OwnedFd,
};

mod auth;
mod dynamic_type;
mod formatter;
mod holder;
mod incoming;
mod outgoing;
mod parser;
mod property;
mod socket;
mod types;

#[derive(Debug)]
pub struct CallError {
    pub name: String,
    pub msg: Option<String>,
}

impl Display for CallError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        if let Some(msg) = &self.msg {
            write!(f, "{}: {}", self.name, msg)
        } else {
            write!(f, "{}", self.name)
        }
    }
}

#[derive(Debug, Error)]
pub enum DbusError {
    #[error("Encountered an unknown type in a signature")]
    UnknownType,
    #[error("Function call reply does not contain a reply serial")]
    NoReplySerial,
    #[error("Signal message contains no interface or member or path")]
    MissingSignalHeaders,
    #[error("Error has no error name")]
    NoErrorName,
    #[error("The socket was killed")]
    Killed,
    #[error("{0}")]
    CallError(CallError),
    #[error("FD index is out of bounds")]
    OobFds,
    #[error("Variant has an invalid type")]
    InvalidVariantType,
    #[error("Could not create a socket")]
    Socket(#[source] OsError),
    #[error("Could not connect")]
    Connect(#[source] OsError),
    #[error("Could not write to the dbus socket")]
    WriteError(#[source] OsError),
    #[error("Could not read from the dbus socket")]
    ReadError(#[source] OsError),
    #[error("timeout")]
    IoUringError(#[source] Box<IoUringError>),
    #[error("Server did not accept our authentication")]
    Auth,
    #[error("Array length is not a multiple of the element size")]
    PodArrayLength,
    #[error("Peer did not send enough fds")]
    TooFewFds,
    #[error("Variant signature is not a single type")]
    TrailingVariantSignature,
    #[error("Dict signature does not contain a terminating '}}'")]
    UnterminatedDict,
    #[error("Struct signature does not contain a terminating '}}'")]
    UnterminatedStruct,
    #[error("Dict signature contains trailing types")]
    DictTrailing,
    #[error("String does not contain valid UTF-8")]
    InvalidUtf8,
    #[error("Unexpected end of message")]
    UnexpectedEof,
    #[error("Boolean value was not 0 or 1")]
    InvalidBoolValue,
    #[error("Signature is empty")]
    EmptySignature,
    #[error("The session bus address is not set")]
    SessionBusAddressNotSet,
    #[error("Server does not support FD passing")]
    UnixFd,
    #[error("Server message has a different endianess than ourselves")]
    InvalidEndianess,
    #[error("Server speaks an unexpected protocol version")]
    InvalidProtocol,
    #[error("Signature contains an invalid type")]
    InvalidSignatureType,
    #[error("The signal already has a handler")]
    AlreadyHandled,
    #[error(transparent)]
    BufIoError(#[from] BufIoError),
    #[error(transparent)]
    DbusError(Rc<DbusError>),
}
efrom!(DbusError, IoUringError);

pub struct Dbus {
    eng: Rc<AsyncEngine>,
    ring: Rc<IoUring>,
    system: Rc<DbusHolder>,
    session: Rc<DbusHolder>,
    user_path: Option<String>,
}

impl Dbus {
    pub fn new(eng: &Rc<AsyncEngine>, ring: &Rc<IoUring>, run_toplevel: &Rc<RunToplevel>) -> Self {
        let user_path = match xrd() {
            Some(path) => Some(format!("{}/bus", path)),
            _ => {
                log::warn!("{} is not set", XRD);
                None
            }
        };
        log::info!("dbus path = {:?}", user_path);
        Self {
            eng: eng.clone(),
            ring: ring.clone(),
            system: Rc::new(DbusHolder::new(run_toplevel)),
            session: Rc::new(DbusHolder::new(run_toplevel)),
            user_path,
        }
    }

    pub fn clear(&self) {
        self.system.clear();
        self.session.clear();
    }

    pub fn system(&self) -> Result<Rc<DbusSocket>, DbusError> {
        self.system.get(
            &self.eng,
            &self.ring,
            "/var/run/dbus/system_bus_socket",
            "System bus",
        )
    }

    pub fn session(&self) -> Result<Rc<DbusSocket>, DbusError> {
        let sba = match self.user_path.as_deref() {
            None => return Err(DbusError::SessionBusAddressNotSet),
            Some(sba) => sba,
        };
        self.session.get(&self.eng, &self.ring, sba, "Session bus")
    }
}

unsafe trait ReplyHandler {
    fn signature(&self) -> &str;
    fn handle_error(self: Box<Self>, socket: &Rc<DbusSocket>, error: DbusError);
    fn handle(
        self: Box<Self>,
        socket: &Rc<DbusSocket>,
        headers: &Headers,
        parser: &mut Parser,
        buf: Vec<u8>,
    ) -> Result<(), DbusError>;
}

pub struct DbusSocket {
    bus_name: &'static str,
    fd: Rc<OwnedFd>,
    ring: Rc<IoUring>,
    bufio: Rc<BufIo>,
    eng: Rc<AsyncEngine>,
    next_serial: NumCell<u32>,
    unique_name: CloneCell<Rc<String>>,
    reply_handlers: CopyHashMap<u32, Box<dyn ReplyHandler>>,
    incoming: Cell<Option<SpawnedFuture<()>>>,
    outgoing_: Cell<Option<SpawnedFuture<()>>>,
    auth: Cell<Option<SpawnedFuture<()>>>,
    dead: Cell<bool>,
    headers: RefCell<VecStorage<(u8, Variant<'static>)>>,
    run_toplevel: Rc<RunToplevel>,
    signal_handlers: RefCell<AHashMap<(&'static str, &'static str), InterfaceSignalHandlers>>,
}

const TY_BYTE: u8 = b'y';
const TY_BOOLEAN: u8 = b'b';
const TY_INT16: u8 = b'n';
const TY_UINT16: u8 = b'q';
const TY_INT32: u8 = b'i';
const TY_UINT32: u8 = b'u';
const TY_INT64: u8 = b'x';
const TY_UINT64: u8 = b't';
const TY_DOUBLE: u8 = b'd';
const TY_STRING: u8 = b's';
const TY_OBJECT_PATH: u8 = b'o';
const TY_SIGNATURE: u8 = b'g';
const TY_ARRAY: u8 = b'a';
const TY_VARIANT: u8 = b'v';
const TY_UNIX_FD: u8 = b'h';

const HDR_PATH: u8 = 1;
const HDR_INTERFACE: u8 = 2;
const HDR_MEMBER: u8 = 3;
const HDR_ERROR_NAME: u8 = 4;
const HDR_REPLY_SERIAL: u8 = 5;
const HDR_DESTINATION: u8 = 6;
const HDR_SENDER: u8 = 7;
const HDR_SIGNATURE: u8 = 8;
const HDR_UNIX_FDS: u8 = 9;

const MSG_METHOD_CALL: u8 = 1;
const MSG_METHOD_RETURN: u8 = 2;
const MSG_ERROR: u8 = 3;
const MSG_SIGNAL: u8 = 4;

const NO_REPLY_EXPECTED: u8 = 0x1;
#[allow(dead_code)]
const NO_AUTO_START: u8 = 0x2;
#[allow(dead_code)]
const ALLOW_INTERACTIVE_AUTHORIZATION: u8 = 0x4;

pub const BUS_DEST: &str = "org.freedesktop.DBus";
pub const BUS_PATH: &str = "/org/freedesktop/DBus";

#[derive(Default, Debug)]
struct Headers<'a> {
    path: Option<ObjectPath<'a>>,
    interface: Option<Cow<'a, str>>,
    member: Option<Cow<'a, str>>,
    error_name: Option<Cow<'a, str>>,
    reply_serial: Option<u32>,
    destination: Option<Cow<'a, str>>,
    sender: Option<Cow<'a, str>>,
    signature: Option<Signature<'a>>,
    unix_fds: Option<u32>,
}

struct DbusHolder {
    socket: CloneCell<Option<Rc<DbusSocket>>>,
    run_toplevel: Rc<RunToplevel>,
}

impl DbusHolder {
    pub fn new(run_toplevel: &Rc<RunToplevel>) -> Self {
        Self {
            socket: Default::default(),
            run_toplevel: run_toplevel.clone(),
        }
    }

    pub fn clear(&self) {
        if let Some(socket) = self.socket.take() {
            socket.clear();
        }
    }
}

impl Drop for DbusHolder {
    fn drop(&mut self) {
        if let Some(socket) = self.socket.take() {
            socket.auth.take();
            socket.outgoing_.take();
            socket.incoming.take();
        }
    }
}

#[derive(Clone, Debug)]
pub enum DynamicType {
    U8,
    Bool,
    I16,
    U16,
    I32,
    U32,
    I64,
    U64,
    F64,
    String,
    ObjectPath,
    Signature,
    Variant,
    Fd,
    Array(Box<DynamicType>),
    DictEntry(Box<DynamicType>, Box<DynamicType>),
    Struct(Vec<DynamicType>),
}

pub struct Parser<'a> {
    buf: &'a [u8],
    pos: usize,
    fds: &'a [Rc<OwnedFd>],
}

pub struct Formatter<'a> {
    fds: &'a mut Vec<Rc<OwnedFd>>,
    buf: &'a mut Vec<u8>,
}

pub unsafe trait Message<'a>: Sized + 'a {
    const SIGNATURE: &'static str;
    const INTERFACE: &'static str;
    const MEMBER: &'static str;
    type Generic<'b>: Message<'b>;

    fn marshal(&self, w: &mut Formatter);
    fn unmarshal(p: &mut Parser<'a>) -> Result<Self, DbusError>;
    fn num_fds(&self) -> u32;
}

pub trait Property {
    const INTERFACE: &'static str;
    const PROPERTY: &'static str;
    type Type: DbusType<'static>;
}

pub trait Signal<'a>: Message<'a> {}

pub trait MethodCall<'a>: Message<'a> {
    type Reply: Message<'static>;
}

pub unsafe trait DbusType<'a>: Clone + 'a {
    const ALIGNMENT: usize;
    const IS_POD: bool;
    type Generic<'b>: DbusType<'b> + 'b;

    fn consume_signature(s: &mut &[u8]) -> Result<(), DbusError>;
    fn write_signature(w: &mut Vec<u8>);
    fn marshal(&self, fmt: &mut Formatter);
    fn unmarshal(parser: &mut Parser<'a>) -> Result<Self, DbusError>;

    fn num_fds(&self) -> u32 {
        0
    }
}

pub struct Reply<T: Message<'static>> {
    socket: Rc<DbusSocket>,
    buf: Vec<u8>,
    t: T::Generic<'static>,
}

pub struct PropertyValue<T: Property> {
    reply: Reply<GetReply<'static, T::Type>>,
}

impl<T: Property> Debug for PropertyValue<T>
where
    for<'a> <T::Type as DbusType<'static>>::Generic<'a>: Debug,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.get().fmt(f)
    }
}

impl<T: Property> PropertyValue<T> {
    pub fn get<'a>(&'a self) -> &'a <T::Type as DbusType<'static>>::Generic<'a> {
        &self.reply.get().value
    }
}

impl<T: Message<'static>> Debug for Reply<T>
where
    for<'a> T::Generic<'a>: Debug,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.get().fmt(f)
    }
}

impl<T: Message<'static>> Reply<T> {
    pub fn get<'a>(&'a self) -> &'a T::Generic<'a> {
        unsafe { mem::transmute(&self.t) }
    }
}

impl<T: Message<'static>> Drop for Reply<T> {
    fn drop(&mut self) {
        self.socket.bufio.add_buf(mem::take(&mut self.buf));
    }
}

struct AsyncReplySlot<T: Message<'static>> {
    data: Cell<Option<Result<Reply<T>, DbusError>>>,
    waker: Cell<Option<Waker>>,
}

pub struct AsyncReply<T: Message<'static>> {
    socket: Rc<DbusSocket>,
    serial: u32,
    slot: Rc<AsyncReplySlot<T>>,
}

#[pin_project::pin_project]
pub struct AsyncProperty<T: Property> {
    #[pin]
    reply: AsyncReply<GetReply<'static, T::Type>>,
}

impl<T: Message<'static>> Drop for AsyncReply<T> {
    fn drop(&mut self) {
        self.socket.reply_handlers.remove(&self.serial);
    }
}

impl<T: Message<'static>> Future for AsyncReply<T> {
    type Output = Result<Reply<T>, DbusError>;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        if let Some(d) = self.slot.data.take() {
            Poll::Ready(d)
        } else {
            self.slot.waker.set(Some(cx.waker().clone()));
            Poll::Pending
        }
    }
}

impl<T: Property> Future for AsyncProperty<T> {
    type Output = Result<PropertyValue<T>, DbusError>;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        AsyncProperty::project(self)
            .reply
            .poll(cx)
            .map(|r| r.map(|v| PropertyValue { reply: v }))
    }
}

struct SignalHandlerData<T, F> {
    path: Option<String>,
    rule: String,
    handler: F,
    _phantom: PhantomData<T>,
}

trait SignalHandlerApi {
    fn interface(&self) -> &'static str;
    fn member(&self) -> &'static str;
    fn signature(&self) -> &'static str;
    fn path(&self) -> Option<&str>;
    fn rule(&self) -> &str;
    fn handle(&self, parser: &mut Parser) -> Result<(), DbusError>;
}

impl<T, F> SignalHandlerApi for SignalHandlerData<T, F>
where
    T: Signal<'static>,
    F: for<'a> Fn(T::Generic<'a>),
{
    fn interface(&self) -> &'static str {
        T::INTERFACE
    }

    fn member(&self) -> &'static str {
        T::MEMBER
    }

    fn signature(&self) -> &'static str {
        T::SIGNATURE
    }

    fn path(&self) -> Option<&str> {
        self.path.as_deref()
    }

    fn rule(&self) -> &str {
        &self.rule
    }

    fn handle<'a>(&self, parser: &mut Parser<'a>) -> Result<(), DbusError> {
        (self.handler)(T::Generic::<'a>::unmarshal(parser)?);
        Ok(())
    }
}

#[must_use]
pub struct SignalHandler {
    socket: Rc<DbusSocket>,
    data: Rc<dyn SignalHandlerApi>,
}

impl Drop for SignalHandler {
    fn drop(&mut self) {
        self.socket.remove_signal_handler(&*self.data);
    }
}

struct InterfaceSignalHandlers {
    unconditional: Option<Rc<dyn SignalHandlerApi>>,
    conditional: AHashMap<String, Rc<dyn SignalHandlerApi>>,
}

pub mod prelude {
    pub use {
        super::{
            types::{Bool, DictEntry, ObjectPath, Signature, Variant},
            DbusError, DbusType, Formatter, Message, MethodCall, Parser, Property, Signal,
        },
        std::{borrow::Cow, rc::Rc},
        uapi::OwnedFd,
    };
}