//! Server support for the [varlink protocol](http://varlink.org)
//!
//! To create a varlink server in rust, place your varlink interface definition file in src/.
//! E.g. `src/org.example.ping.varlink`:
//!
//! ```varlink
//! ## Example service
//! interface org.example.ping
//!
//! ## Returns the same string
//! method Ping(ping: string) -> (pong: string)
//! ```
//!
//! Then create a `build.rs` file in your project directory:
//!
//! ```rust,no_run
//! extern crate varlink;
//!
//! fn main() {
//!     varlink::generator::cargo_build("src/org.example.ping.varlink");
//! }
//! ```
//!
//! Add to your `Cargo.toml`:
//!
//! ```toml
//! [package]
//! build = "build.rs"
//! ```
//!
//! In your `main.rs` you can then use:
//!
//! ```rust,ignore
//! mod org_example_ping {
//!     include!(concat!(env!("OUT_DIR"), "/org.example.ping.rs"));
//! }
//!
//! use org_example_ping::*;
//!
//! struct MyOrgExamplePing;
//!
//! impl org_example_ping::VarlinkInterface for MyOrgExamplePing {
//!     fn ping(&self, call: &mut _CallPing, ping: Option<String>) -> io::Result<()> {
//!         return call.reply(ping);
//!     }
//! }
//! ```
//! to implement the interface methods.
//!
//! If your varlink method is called `TestMethod`, the rust method to be implemented is called
//! `test_method`. The first parameter is of type `_CallTestMethod`, which has the method `reply()`.
//!
//! ```rust,ignore
//!    fn test_method(&self, call: &mut _CallTestMethod, /* more arguments */) -> io::Result<()> {
//!        /* ... */
//!        return call.reply( /* more arguments */ );
//!    }
//! ```
//!
//! A typical server creates a `VarlinkService` and starts a server via `varlink::listen()`
//!
//! ```rust,ignore
//! let myorgexampleping = MyOrgExamplePing;
//! let myorgexampleping_interface = org_example_ping::new(Box::new(myorgexampleping));
//!
//! let service = VarlinkService::new(
//!     "org.varlink",
//!     "test service",
//!     "0.1",
//!     "http://varlink.org",
//!     vec![
//!         Box::new(myorgexampleping_interface),
//!         /* more interfaces ...*/
//!     ],
//! );
//!
//! varlink::listen(service, &args[1], 10, 0)
//! ```
//!
//! where args[1] would follow the varlink
//! [address specification](https://github.com/varlink/documentation/wiki#address).
//!
//! Currently supported address URIs are:
//!
//! - TCP `tcp:127.0.0.1:12345` hostname/IP address and port
//! - UNIX socket `unix:/run/org.example.ftl` optional access `;mode=0666` parameter
//! - UNIX abstract namespace socket `unix:@org.example.ftl` (on Linux only)
//! - executed binary `exec:/usr/bin/org.example.ftl` via
//!   [socket activation](https://github.com/varlink/documentation/wiki#activation)
//!   (on Linux only)

extern crate bytes;
extern crate itertools;

extern crate libc;
extern crate serde;
#[macro_use]
extern crate serde_derive;
#[macro_use]
extern crate serde_json;
extern crate unix_socket;

extern crate varlink_parser;

pub mod generator;
mod server;

use serde_json::Value;
use serde::ser::Serialize;

use std::convert::From;
use std::collections::HashMap;
use std::borrow::Cow;
use std::io::{self, BufRead, BufReader, Error, ErrorKind, Read, Write};

/// This trait has to be implemented by any varlink interface implementor.
/// All methods are generated by the varlink-rust-generator, so you don't have to care
/// about them.
pub trait Interface {
    fn get_description(&self) -> &'static str;
    fn get_name(&self) -> &'static str;
    fn call(&self, &mut Call) -> io::Result<()>;
    fn call_upgraded(&self, &mut Call) -> io::Result<()>;
}

/// The structure of a varlink request. Used to serialize json into it.
///
/// There should be no need to use this directly.
#[derive(Serialize, Deserialize, Debug, Default)]
pub struct Request {
    pub more: Option<bool>,
    pub oneshot: Option<bool>,
    pub upgrade: Option<bool>,
    pub method: Cow<'static, str>,
    pub parameters: Option<Value>,
}

/// Marker trait for the rust code generated by the varlink-rust-generator
///
/// There should be no need to use this directly.
pub trait VarlinkReply {}

/// The structure of a varlink reply. Used to deserialize it into json.
///
/// There should be no need to use this directly.
#[derive(Serialize, Deserialize)]
pub struct Reply {
    pub continues: Option<bool>,
    pub upgraded: Option<bool>,
    pub error: Option<Cow<'static, str>>,
    pub parameters: Option<Value>,
}

impl Reply {
    pub fn parameters(parameters: Option<Value>) -> Self {
        Reply {
            continues: None,
            upgraded: None,
            error: None,
            parameters: parameters,
        }
    }

    pub fn error(name: Cow<'static, str>, parameters: Option<Value>) -> Self {
        Reply {
            continues: None,
            upgraded: None,
            error: Some(name),
            parameters,
        }
    }
}

impl<T> From<T> for Reply
where
    T: VarlinkReply + Serialize,
{
    fn from(a: T) -> Self {
        Reply::parameters(Some(serde_json::to_value(a).unwrap()))
    }
}

/// Call is a struct, which is passed as the first argument to the interface methods in a derived form.
pub struct Call<'a> {
    writer: &'a mut Write,
    pub request: Option<&'a Request>,
    continues: bool,
    upgraded: bool,
}

/// CallTrait provides convenience methods for the `Call` struct, which is passed as
/// the first argument to the interface methods.
///
/// E.g. for not yet implemented methods:
///
/// ```rust,ignore
///    fn test_method_not_implemented(
///        &self,
///        call: &mut _CallTestMethodNotImplemented,
///    ) -> io::Result<()> {
///        return call.reply_method_not_implemented(Some("TestMethodNotImplemented".into()));
///    }
/// ```
pub trait CallTrait {
    /// Don't use this directly. Rather use the standard `reply()` method.
    fn reply_struct(&mut self, Reply) -> io::Result<()>;

    /// Set this to `true` to indicate, that more replies are following.
    ///
    /// ```rust,ignore
    ///    fn test_method(
    ///        &self,
    ///        call: &mut _CallTestMethod,
    ///    ) -> io::Result<()> {
    ///        call.set_continue(true);
    ///        call.reply( /* more args*/ )?;
    ///        call.reply( /* more args*/ )?;
    ///        call.reply( /* more args*/ )?;
    ///        call.set_continue(false);
    ///        return call.reply( /* more args*/ );
    ///    }
    /// ```
    fn set_continues(&mut self, cont: bool);

    /// reply with the standard varlink `org.varlink.service.MethodNotFound` error
    fn reply_method_not_found(&mut self, method_name: Option<String>) -> io::Result<()> {
        self.reply_struct(Reply::error(
            "org.varlink.service.MethodNotFound".into(),
            match method_name {
                Some(a) => {
                    let s = format!("{{  \"method\" : \"{}\" }}", a);
                    Some(serde_json::from_str(s.as_ref()).unwrap())
                }
                None => None,
            },
        ))
    }

    /// reply with the standard varlink `org.varlink.service.MethodNotImplemented` error
    fn reply_method_not_implemented(&mut self, method_name: Option<String>) -> io::Result<()> {
        self.reply_struct(Reply::error(
            "org.varlink.service.MethodNotImplemented".into(),
            match method_name {
                Some(a) => {
                    let s = format!("{{  \"method\" : \"{}\" }}", a);
                    Some(serde_json::from_str(s.as_ref()).unwrap())
                }
                None => None,
            },
        ))
    }

    /// reply with the standard varlink `org.varlink.service.InvalidParameter` error
    fn reply_invalid_parameter(&mut self, parameter_name: Option<String>) -> io::Result<()> {
        self.reply_struct(Reply::error(
            "org.varlink.service.InvalidParameter".into(),
            match parameter_name {
                Some(a) => {
                    let s = format!("{{  \"parameter\" : \"{}\" }}", a);
                    Some(serde_json::from_str(s.as_ref()).unwrap())
                }
                None => None,
            },
        ))
    }
}

impl<'a> CallTrait for Call<'a> {
    fn reply_struct(&mut self, mut reply: Reply) -> io::Result<()> {
        if self.continues && !self.wants_more() {
            return Err(Error::new(
                ErrorKind::Other,
                "Call::reply() called with continues, but without more in the request",
            ));
        }
        if self.continues {
            reply.continues = Some(true);
        }
        serde_json::to_writer(&mut *self.writer, &reply)?;
        self.writer.write_all(b"\0")?;
        self.writer.flush()?;
        Ok(())
    }
    fn set_continues(&mut self, cont: bool) {
        self.continues = cont;
    }
}

impl<'a> Call<'a> {
    fn new(writer: &'a mut Write, request: &'a Request) -> Self {
        Call {
            writer,
            request: Some(request),
            continues: false,
            upgraded: false,
        }
    }
    fn new_upgraded(writer: &'a mut Write) -> Self {
        Call {
            writer,
            request: None,
            continues: false,
            upgraded: false,
        }
    }

    /// True, if this request does not want a reply.
    pub fn is_oneshot(&self) -> bool {
        match self.request {
            Some(req) => {
                if let Some(val) = req.oneshot {
                    val
                } else {
                    false
                }
            }
            None => false,
        }
    }

    /// True, if this request accepts more than one reply.
    pub fn wants_more(&self) -> bool {
        match self.request {
            Some(req) => if let Some(val) = req.more {
                val
            } else {
                false
            },
            None => false,
        }
    }

    fn reply_interface_not_found(&mut self, arg: Option<String>) -> io::Result<()> {
        self.reply_struct(Reply::error(
            "org.varlink.service.InterfaceNotFound".into(),
            match arg {
                Some(a) => {
                    let s = format!("{{  \"interface\" : \"{}\" }}", a);
                    Some(serde_json::from_str(s.as_ref()).unwrap())
                }
                None => None,
            },
        ))
    }

    fn reply_parameters(&mut self, parameters: Value) -> io::Result<()> {
        let reply = Reply::parameters(Some(parameters));
        serde_json::to_writer(&mut *self.writer, &reply)?;
        self.writer.write_all(b"\0")?;
        self.writer.flush()?;
        Ok(())
    }
}

#[derive(Deserialize)]
struct GetInterfaceArgs {
    interface: Cow<'static, str>,
}

#[derive(Serialize, Deserialize)]
struct ServiceInfo {
    vendor: Cow<'static, str>,
    product: Cow<'static, str>,
    version: Cow<'static, str>,
    url: Cow<'static, str>,
    interfaces: Vec<Cow<'static, str>>,
}

/// VarlinkService handles all the I/O and dispatches method calls to the registered interfaces.
pub struct VarlinkService {
    info: ServiceInfo,
    ifaces: HashMap<Cow<'static, str>, Box<Interface + Send + Sync>>,
}

impl Interface for VarlinkService {
    fn get_description(&self) -> &'static str {
        r#"
# The Varlink Service Interface is provided by every varlink service. It
# describes the service and the interfaces it implements.
interface org.varlink.service

# Get a list of all the interfaces a service provides and information
# about the implementation.
method GetInfo() -> (
  vendor: string,
  product: string,
  version: string,
  url: string,
  interfaces: string[]
)

# Get the description of an interface that is implemented by this service.
method GetInterfaceDescription(interface: string) -> (description: string)

# The requested interface was not found.
error InterfaceNotFound (interface: string)

# The requested method was not found
error MethodNotFound (method: string)

# The interface defines the requested method, but the service does not
# implement it.
error MethodNotImplemented (method: string)

# One of the passed parameters is invalid.
error InvalidParameter (parameter: string)
	"#
    }

    fn get_name(&self) -> &'static str {
        "org.varlink.service"
    }

    fn call(&self, call: &mut Call) -> io::Result<()> {
        let req = call.request.unwrap();
        match req.method.as_ref() {
            "org.varlink.service.GetInfo" => {
                return call.reply_parameters(serde_json::to_value(&self.info)?);
            }
            "org.varlink.service.GetInterfaceDescription" => {
                if req.parameters == None {
                    return call.reply_invalid_parameter(None);
                }
                if let Some(val) = req.parameters.clone() {
                    let args: GetInterfaceArgs = serde_json::from_value(val)?;
                    match args.interface.as_ref() {
                        "org.varlink.service" => {
                            return call.reply_parameters(
                                json!({"description": self.get_description()}),
                            );
                        }
                        key => {
                            if self.ifaces.contains_key(key) {
                                return call.reply_parameters(
                                    json!({"description": self.ifaces[key].get_description()}),
                                );
                            } else {
                                return call.reply_invalid_parameter(Some("interface".into()));
                            }
                        }
                    }
                } else {
                    return call.reply_invalid_parameter(Some("interface".into()));
                }
            }
            _ => {
                let method: String = req.method.clone().into();
                let n: usize = match method.rfind('.') {
                    None => 0,
                    Some(x) => x + 1,
                };
                let m = String::from(&method[n..]);
                return call.reply_method_not_found(Some(m.into()));
            }
        }
    }
    fn call_upgraded(&self, call: &mut Call) -> io::Result<()> {
        call.upgraded = false;
        Ok(())
    }
}

impl VarlinkService {
    /// Create a new `VarlinkService`.
    ///
    /// See the [Service](https://github.com/varlink/documentation/wiki/Service) section of the
    /// varlink wiki about the `vendor`, `product`, `version` and `url`.
    ///
    /// The `interfaces` vector is an array of varlink `Interfaces` this service provides.
    ///
    /// ```rust,ignore
    ///     let service = VarlinkService::new(
    ///         "org.varlink",
    ///         "test service",
    ///         "0.1",
    ///         "http://varlink.org",
    ///         vec![
    ///             Box::new(interface_foo),
    ///             Box::new(interface_bar),
    ///             Box::new(interface_baz),
    ///         ],
    ///     );
    ///
    ///     varlink::listen(service, &args[1], 10, 0)
    /// ```
    pub fn new(
        vendor: &str,
        product: &str,
        version: &str,
        url: &str,
        interfaces: Vec<Box<Interface + Send + Sync>>,
    ) -> Self {
        let mut ifhashmap = HashMap::<Cow<'static, str>, Box<Interface + Send + Sync>>::new();
        for i in interfaces {
            ifhashmap.insert(i.get_name().into(), i);
        }
        let mut ifnames: Vec<Cow<'static, str>> = Vec::new();
        ifnames.push("org.varlink.service".into());
        ifnames.extend(
            ifhashmap
                .keys()
                .map(|i| Cow::<'static, str>::from(i.clone())),
        );
        VarlinkService {
            info: ServiceInfo {
                vendor: String::from(vendor).into(),
                product: String::from(product).into(),
                version: String::from(version).into(),
                url: String::from(url).into(),
                interfaces: ifnames,
            },
            ifaces: ifhashmap,
        }
    }

    fn call(&self, iface: String, call: &mut Call) -> io::Result<()> {
        match iface.as_ref() {
            "org.varlink.service" => return self::Interface::call(self, call),
            key => {
                if self.ifaces.contains_key(key) {
                    return self.ifaces[key].call(call);
                } else {
                    return call.reply_interface_not_found(Some(iface.clone().into()));
                }
            }
        }
    }

    fn call_upgraded(&self, iface: String, call: &mut Call) -> io::Result<()> {
        match iface.as_ref() {
            "org.varlink.service" => return self::Interface::call_upgraded(self, call),
            key => {
                if self.ifaces.contains_key(key) {
                    return self.ifaces[key].call_upgraded(call);
                } else {
                    return call.reply_interface_not_found(Some(iface.clone().into()));
                }
            }
        }
    }

    /// Handles incoming varlink messages from `reader` and sends the reply on `writer`.
    ///
    /// This method can be used to implement your own server.
    pub fn handle(&self, reader: &mut Read, writer: &mut Write) -> io::Result<()> {
        let mut bufreader = BufReader::new(reader);
        let mut upgraded = false;
        let mut last_iface = String::from("");
        loop {
            if !upgraded {
                let mut buf = Vec::new();
                let read_bytes = bufreader.read_until(b'\0', &mut buf)?;
                if read_bytes > 0 {
                    buf.pop();
                    let req: Request = serde_json::from_slice(&buf)?;
                    let mut call = Call::new(writer, &req);

                    let n: usize = match req.method.rfind('.') {
                        None => {
                            let method = req.method.clone();
                            return call.reply_interface_not_found(Some(method.into()));
                        }
                        Some(x) => x,
                    };

                    let iface = String::from(&req.method[..n]);

                    self.call(iface.clone(), &mut call)?;
                    upgraded = call.upgraded;
                    if upgraded {
                        last_iface = iface;
                    }
                } else {
                    break;
                }
            } else {
                let mut call = Call::new_upgraded(writer);
                self.call_upgraded(last_iface.clone(), &mut call)?;
                upgraded = call.upgraded;
            }
        }
        Ok(())
    }
}

/// `listen` creates a server, with `num_worker` threads listening on `varlink_uri`.
///
/// If an `accept_timeout` != 0 is specified, this function returns after the specified
/// amount of seconds, if no new connection is made in that time frame. It still waits for
/// all pending connections to finish.
///
/// ```
///    let service = varlink::VarlinkService::new(
///        "org.varlink",
///        "test service",
///        "0.1",
///        "http://varlink.org",
///        vec![/* Your varlink interfaces go here */],
///    );
///
///    if let Err(e) = varlink::listen(service, "unix:/tmp/test_listen_timeout", 10, 1) {
///        panic!("Error listen: {}", e);
///    }
/// ```
/// You don't have to use this simple server. With the `VarlinkService::handle()` method you
/// can implement your own server model using whatever framework you prefer.
pub fn listen(
    service: VarlinkService,
    varlink_uri: &str,
    num_worker: usize,
    accept_timeout: u64,
) -> io::Result<()> {
    match server::do_listen(service, varlink_uri, num_worker, accept_timeout) {
        Err(e) => match e {
            server::ServerError::IoError(e) => Err(e),
            server::ServerError::AcceptTimeout => Ok(()),
        },
        Ok(_) => Ok(()),
    }
}