// standard
use std::collections::BTreeMap;
use std::convert::From;
use std::default::Default;
use std::net::{SocketAddr, TcpListener};
use std::option::Option;
use std::path::PathBuf;
use std::string::ToString;
use std::sync::{atomic, Arc};
use std::time::Duration;

// extern crates
use socks::Socks5Stream;

// internal crates
use crate::censorship_circumvention::*;
use crate::legacy_tor_control_stream::*;
use crate::legacy_tor_controller::*;
use crate::legacy_tor_process::*;
use crate::legacy_tor_version::*;
use crate::proxy::*;
use crate::tor_crypto::*;
use crate::tor_provider;
use crate::tor_provider::*;

/// [`LegacyTorClient`]-specific error type
#[derive(thiserror::Error, Debug)]
pub enum Error {
    #[error("failed to create LegacyTorProcess object")]
    LegacyTorProcessCreationFailed(#[source] crate::legacy_tor_process::Error),

    #[error("failed to create LegacyControlStream object")]
    LegacyControlStreamCreationFailed(#[source] crate::legacy_tor_control_stream::Error),

    #[error("failed to create LegacyTorController object")]
    LegacyTorControllerCreationFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to authenticate with the tor process")]
    LegacyTorProcessAuthenticationFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to determine the tor process version")]
    GetInfoVersionFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("tor process version to old; found {0} but must be at least {1}")]
    LegacyTorProcessTooOld(String, String),

    #[error("failed to register for STATUS_CLIENT and HS_DESC events")]
    SetEventsFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to delete unused onion service")]
    DelOnionFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed waiting for async events: {0}")]
    WaitAsyncEventsFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to begin bootstrap")]
    SetConfDisableNetwork0Failed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to setconf")]
    SetConfFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to add client auth for onion service")]
    OnionClientAuthAddFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to remove client auth from onion service")]
    OnionClientAuthRemoveFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("failed to get socks listener")]
    GetInfoNetListenersSocksFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("no socks listeners available to connect through")]
    NoSocksListenersFound(),

    #[error("invalid circuit token")]
    CircuitTokenInvalid(),

    #[error("unable to connect to socks listener")]
    Socks5ConnectionFailed(#[source] std::io::Error),

    #[error("unable to bind TCP listener")]
    TcpListenerBindFailed(#[source] std::io::Error),

    #[error("unable to get TCP listener's local address")]
    TcpListenerLocalAddrFailed(#[source] std::io::Error),

    #[error("failed to create onion service")]
    AddOnionFailed(#[source] crate::legacy_tor_controller::Error),

    #[error("tor not bootstrapped")]
    LegacyTorNotBootstrapped(),

    #[error("{0}")]
    PluggableTransportConfigDirectoryCreationFailed(#[source] std::io::Error),

    #[error("unable to create pluggable-transport directory because file with same name already exists: {0:?}")]
    PluggableTransportDirectoryNameCollision(PathBuf),

    #[error("{0}")]
    PluggableTransportSymlinkRemovalFailed(#[source] std::io::Error),

    #[error("{0}")]
    PluggableTransportSymlinkCreationFailed(#[source] std::io::Error),

    #[error("pluggable transport binary name not representable as utf8: {0:?}")]
    PluggableTransportBinaryNameNotUtf8Representnable(std::ffi::OsString),

    #[error("{0}")]
    PluggableTransportConfigError(#[source] crate::censorship_circumvention::PluggableTransportConfigError),

    #[error("pluggable transport multiply defines '{0}' bridge transport type")]
    BridgeTransportTypeMultiplyDefined(String),

    #[error("bridge transport '{0}' not supported by pluggable transport configuration")]
    BridgeTransportNotSupported(String),

    #[error("not implemented")]
    NotImplemented(),
}

impl From<Error> for crate::tor_provider::Error {
    fn from(error: Error) -> Self {
        crate::tor_provider::Error::Generic(error.to_string())
    }
}

//
// CircuitToken Implementation
//
struct LegacyCircuitToken {
    username: String,
    password: String,
}

impl LegacyCircuitToken {
    fn new() -> LegacyCircuitToken {
        const CIRCUIT_TOKEN_USERNAME_LENGTH: usize = 32usize;
        const CIRCUIT_TOKEN_PASSWORD_LENGTH: usize = 32usize;
        let username = generate_password(CIRCUIT_TOKEN_USERNAME_LENGTH);
        let password = generate_password(CIRCUIT_TOKEN_PASSWORD_LENGTH);

        LegacyCircuitToken { username, password }
    }
}

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

//
// LegacyTorClientConfig
//

#[derive(Clone, Debug)]
pub enum LegacyTorClientConfig {
    BundledTor {
        tor_bin_path: PathBuf,
        data_directory: PathBuf,
        proxy_settings: Option<ProxyConfig>,
        allowed_ports: Option<Vec<u16>>,
        pluggable_transports: Option<Vec<PluggableTransportConfig>>,
        bridge_lines: Option<Vec<BridgeLine>>,
    },
    SystemTor {
        tor_socks_addr: SocketAddr,
        tor_control_addr: SocketAddr,
        tor_control_passwd: String,
    },
}

//
// LegacyTorClient
//

/// A `LegacyTorClient` implements the [`TorProvider`] trait using a legacy c-tor daemon backend.
///
/// The tor process can either be launched and owned by `LegacyTorClient`, or it can use an already running tor-daemon. When using an already runnng tor-daemon, the [`TorProvider::bootstrap()`] automatically succeeds, presuming the connected tor-daemon has successfully bootstrapped.
///
/// The minimum supported c-tor is version 0.4.6.1.
pub struct LegacyTorClient {
    daemon: Option<LegacyTorProcess>,
    version: LegacyTorVersion,
    controller: LegacyTorController,
    bootstrapped: bool,
    socks_listener: Option<SocketAddr>,
    // list of open onion services and their is_active flag
    onion_services: Vec<(V3OnionServiceId, Arc<atomic::AtomicBool>)>,
    // our list of circuit tokens for the tor daemon
    circuit_token_counter: usize,
    circuit_tokens: BTreeMap<CircuitToken, LegacyCircuitToken>,
}

impl LegacyTorClient {
    /// Construct a new `LegacyTorClient` from a [`LegacyTorClientConfig`].
    pub fn new(config: LegacyTorClientConfig) -> Result<LegacyTorClient, Error> {
        let (daemon, mut controller, password, socks_listener) = match &config {
            LegacyTorClientConfig::BundledTor {
                tor_bin_path,
                data_directory,
                ..
            } => {
                // launch tor
                let daemon =
                    LegacyTorProcess::new(tor_bin_path.as_path(), data_directory.as_path())
                        .map_err(Error::LegacyTorProcessCreationFailed)?;
                // open a control stream
                let control_stream =
                    LegacyControlStream::new(daemon.get_control_addr(), Duration::from_millis(16))
                        .map_err(Error::LegacyControlStreamCreationFailed)?;

                // create a controler
                let controller = LegacyTorController::new(control_stream)
                    .map_err(Error::LegacyTorControllerCreationFailed)?;

                let password = daemon.get_password().to_string();
                (Some(daemon), controller, password, None)
            }
            LegacyTorClientConfig::SystemTor {
                tor_socks_addr,
                tor_control_addr,
                tor_control_passwd,
            } => {
                // open a control stream
                let control_stream =
                    LegacyControlStream::new(&tor_control_addr, Duration::from_millis(16))
                        .map_err(Error::LegacyControlStreamCreationFailed)?;

                // create a controler
                let controller = LegacyTorController::new(control_stream)
                    .map_err(Error::LegacyTorControllerCreationFailed)?;

                (
                    None,
                    controller,
                    tor_control_passwd.clone(),
                    Some(tor_socks_addr.clone()),
                )
            }
        };

        // authenticate
        controller
            .authenticate(&password)
            .map_err(Error::LegacyTorProcessAuthenticationFailed)?;

        // min required version for v3 client auth (see control-spec.txt)
        let min_required_version = LegacyTorVersion {
            major: 0u32,
            minor: 4u32,
            micro: 6u32,
            patch_level: 1u32,
            status_tag: None,
        };

        // verify version is recent enough
        let version = controller
            .getinfo_version()
            .map_err(Error::GetInfoVersionFailed)?;

        if version < min_required_version {
            return Err(Error::LegacyTorProcessTooOld(
                version.to_string(),
                min_required_version.to_string(),
            ));
        }

        // configure tor client
        if let LegacyTorClientConfig::BundledTor {
            data_directory,
            proxy_settings,
            allowed_ports,
            pluggable_transports,
            bridge_lines,
            ..
        } = config
        {
            // configure proxy
            match proxy_settings {
                Some(ProxyConfig::Socks4(Socks4ProxyConfig { address })) => {
                    controller
                        .setconf(&[("Socks4Proxy", address.to_string())])
                        .map_err(Error::SetConfFailed)?;
                }
                Some(ProxyConfig::Socks5(Socks5ProxyConfig {
                    address,
                    username,
                    password,
                })) => {
                    controller
                        .setconf(&[("Socks5Proxy", address.to_string())])
                        .map_err(Error::SetConfFailed)?;
                    let username = username.unwrap_or("".to_string());
                    if !username.is_empty() {
                        controller
                            .setconf(&[("Socks5ProxyUsername", username.to_string())])
                            .map_err(Error::SetConfFailed)?;
                    }
                    let password = password.unwrap_or("".to_string());
                    if !password.is_empty() {
                        controller
                            .setconf(&[("Socks5ProxyPassword", password.to_string())])
                            .map_err(Error::SetConfFailed)?;
                    }
                }
                Some(ProxyConfig::Https(HttpsProxyConfig {
                    address,
                    username,
                    password,
                })) => {
                    controller
                        .setconf(&[("HTTPSProxy", address.to_string())])
                        .map_err(Error::SetConfFailed)?;
                    let username = username.unwrap_or("".to_string());
                    let password = password.unwrap_or("".to_string());
                    if !username.is_empty() || !password.is_empty() {
                        let authenticator = format!("{}:{}", username, password);
                        controller
                            .setconf(&[("HTTPSProxyAuthenticator", authenticator)])
                            .map_err(Error::SetConfFailed)?;
                    }
                }
                None => (),
            }
            // configure firewall
            if let Some(allowed_ports) = allowed_ports {
                let allowed_addresses: Vec<String> = allowed_ports
                    .iter()
                    .map(|port| format!("*{{}}:{port}"))
                    .collect();
                let allowed_addresses = allowed_addresses.join(", ");
                controller
                    .setconf(&[("ReachableAddresses", allowed_addresses)])
                    .map_err(Error::SetConfFailed)?;
            }
            // configure pluggable transports
            let mut supported_transports: std::collections::BTreeSet<String> = Default::default();
            if let Some(pluggable_transports) = pluggable_transports {
                // Legacy tor daemon cannot be configured to use pluggable-transports which
                // exist in paths containing spaces. To work around this, we create a known, safe
                // path in the tor daemon's working directory, and soft-link the provided
                // binary path to this safe location. Finally, we configure tor to use the soft-linked
                // binary in the ClientTransportPlugin setconf call.

                // create pluggable-transport directory
                let mut pt_directory = data_directory.clone();
                pt_directory.push("pluggable-transports");
                if !std::path::Path::exists(&pt_directory) {
                    // path does not exist so create it
                    std::fs::create_dir(&pt_directory)
                        .map_err(Error::PluggableTransportConfigDirectoryCreationFailed)?;
                } else if !std::path::Path::is_dir(&pt_directory) {
                    // path exists but it is not a directory
                    return Err(Error::PluggableTransportDirectoryNameCollision(
                        pt_directory,
                    ));
                }

                // symlink all our pts and configure tor
                let mut conf: Vec<(&str, String)> = Default::default();
                for pt_settings in &pluggable_transports {
                    // symlink absolute path of pt binary to pt_directory in tor's working
                    // directory
                    let path_to_binary = pt_settings.path_to_binary();
                    let binary_name = path_to_binary
                        .file_name()
                        .expect("file_name should be absolute path");
                    let mut pt_symlink = pt_directory.clone();
                    pt_symlink.push(binary_name);
                    let binary_name = if let Some(binary_name) = binary_name.to_str() {
                        binary_name
                    } else {
                        return Err(Error::PluggableTransportBinaryNameNotUtf8Representnable(
                            binary_name.to_os_string(),
                        ));
                    };

                    // remove any file that may exist with the same name
                    if std::path::Path::exists(&pt_symlink) {
                        std::fs::remove_file(&pt_symlink)
                            .map_err(Error::PluggableTransportSymlinkRemovalFailed)?;
                    }

                    // create new symlink
                    #[cfg(windows)]
                    std::os::windows::fs::symlink_file(path_to_binary, &pt_symlink)
                        .map_err(Error::PluggableTransportSymlinkCreationFailed)?;
                    #[cfg(unix)]
                    std::os::unix::fs::symlink(path_to_binary, &pt_symlink)
                        .map_err(Error::PluggableTransportSymlinkCreationFailed)?;

                    // verify a bridge-type support has not been defined for multiple pluggable-transports
                    for transport in pt_settings.transports() {
                        if supported_transports.contains(transport) {
                            return Err(Error::BridgeTransportTypeMultiplyDefined(
                                transport.to_string(),
                            ));
                        }
                        supported_transports.insert(transport.to_string());
                    }

                    // finally construct our setconf value
                    let transports = pt_settings.transports().join(",");
                    use std::path::MAIN_SEPARATOR;
                    let path_to_binary =
                        format!("pluggable-transports{MAIN_SEPARATOR}{binary_name}");
                    let options = pt_settings.options().join(" ");

                    let value = format!("{transports} exec {path_to_binary} {options}");
                    conf.push(("ClientTransportPlugin", value));
                }
                controller
                    .setconf(conf.as_slice())
                    .map_err(Error::SetConfFailed)?;
            }
            // configure bridge lines
            if let Some(bridge_lines) = bridge_lines {
                let mut conf: Vec<(&str, String)> = Default::default();
                for bridge_line in &bridge_lines {
                    if !supported_transports.contains(bridge_line.transport()) {
                        return Err(Error::BridgeTransportNotSupported(
                            bridge_line.transport().to_string(),
                        ));
                    }
                    let value = bridge_line.as_legacy_tor_setconf_value();
                    conf.push(("Bridge", value));
                }
                conf.push(("UseBridges", "1".to_string()));
                controller
                    .setconf(conf.as_slice())
                    .map_err(Error::SetConfFailed)?;
            }
        }

        // register for STATUS_CLIENT async events
        controller
            .setevents(&["STATUS_CLIENT", "HS_DESC"])
            .map_err(Error::SetEventsFailed)?;

        Ok(LegacyTorClient {
            daemon,
            version,
            controller,
            bootstrapped: false,
            socks_listener,
            onion_services: Default::default(),
            circuit_token_counter: 0usize,
            circuit_tokens: Default::default(),
        })
    }

    /// Get the version of the connected c-tor daemon.
    pub fn version(&mut self) -> LegacyTorVersion {
        self.version.clone()
    }
}

impl TorProvider for LegacyTorClient {
    fn update(&mut self) -> Result<Vec<TorEvent>, tor_provider::Error> {
        let mut i = 0;
        while i < self.onion_services.len() {
            // remove onion services with no active listeners
            if !self.onion_services[i].1.load(atomic::Ordering::Relaxed) {
                let entry = self.onion_services.swap_remove(i);
                let service_id = entry.0;

                self.controller
                    .del_onion(&service_id)
                    .map_err(Error::DelOnionFailed)?;
            } else {
                i += 1;
            }
        }

        let mut events: Vec<TorEvent> = Default::default();
        for async_event in self
            .controller
            .wait_async_events()
            .map_err(Error::WaitAsyncEventsFailed)?
            .iter()
        {
            match async_event {
                AsyncEvent::StatusClient {
                    severity,
                    action,
                    arguments,
                } => {
                    if severity == "NOTICE" && action == "BOOTSTRAP" {
                        let mut progress: u32 = 0;
                        let mut tag: String = Default::default();
                        let mut summary: String = Default::default();
                        for (key, val) in arguments.iter() {
                            match key.as_str() {
                                "PROGRESS" => progress = val.parse().unwrap_or(0u32),
                                "TAG" => tag = val.to_string(),
                                "SUMMARY" => summary = val.to_string(),
                                _ => {} // ignore unexpected arguments
                            }
                        }
                        events.push(TorEvent::BootstrapStatus {
                            progress,
                            tag,
                            summary,
                        });
                        if progress == 100u32 {
                            events.push(TorEvent::BootstrapComplete);
                            self.bootstrapped = true;
                        }
                    }
                }
                AsyncEvent::HsDesc { action, hs_address } => {
                    if action == "UPLOADED" {
                        events.push(TorEvent::OnionServicePublished {
                            service_id: hs_address.clone(),
                        });
                    }
                }
                AsyncEvent::Unknown { lines } => {
                    println!("Received Unknown Event:");
                    for line in lines.iter() {
                        println!(" {}", line);
                    }
                }
            }
        }

        if let Some(daemon) = &mut self.daemon {
            // bundled tor gives us log-lines
            for log_line in daemon.wait_log_lines().iter_mut() {
                events.push(TorEvent::LogReceived {
                    line: std::mem::take(log_line),
                });
            }
        } else if !self.bootstrapped {
            // system tor needs to send a bootstrap complete event *once*
            events.push(TorEvent::BootstrapComplete);
            self.bootstrapped = true;
        }

        Ok(events)
    }

    fn bootstrap(&mut self) -> Result<(), tor_provider::Error> {
        if !self.bootstrapped {
            self.controller
                .setconf(&[("DisableNetwork", "0".to_string())])
                .map_err(Error::SetConfDisableNetwork0Failed)?;
        }
        Ok(())
    }

    fn add_client_auth(
        &mut self,
        service_id: &V3OnionServiceId,
        client_auth: &X25519PrivateKey,
    ) -> Result<(), tor_provider::Error> {
        Ok(self
            .controller
            .onion_client_auth_add(service_id, client_auth, None, &Default::default())
            .map_err(Error::OnionClientAuthAddFailed)?)
    }

    fn remove_client_auth(
        &mut self,
        service_id: &V3OnionServiceId,
    ) -> Result<(), tor_provider::Error> {
        Ok(self
            .controller
            .onion_client_auth_remove(service_id)
            .map_err(Error::OnionClientAuthRemoveFailed)?)
    }

    // connect to an onion service and returns OnionStream
    fn connect(
        &mut self,
        target: TargetAddr,
        circuit: Option<CircuitToken>,
    ) -> Result<OnionStream, tor_provider::Error> {
        if !self.bootstrapped {
            return Err(Error::LegacyTorNotBootstrapped().into());
        }

        if self.socks_listener.is_none() {
            let mut listeners = self
                .controller
                .getinfo_net_listeners_socks()
                .map_err(Error::GetInfoNetListenersSocksFailed)?;
            if listeners.is_empty() {
                return Err(Error::NoSocksListenersFound())?;
            }
            self.socks_listener = Some(listeners.swap_remove(0));
        }

        let socks_listener = match self.socks_listener {
            Some(socks_listener) => socks_listener,
            None => unreachable!(),
        };

        // our target
        let socks_target = match target.clone() {
            TargetAddr::Socket(socket_addr) => socks::TargetAddr::Ip(socket_addr),
            TargetAddr::Domain(domain_addr) => {
                socks::TargetAddr::Domain(domain_addr.domain().to_string(), domain_addr.port())
            }
            TargetAddr::OnionService(OnionAddr::V3(OnionAddrV3 {
                service_id,
                virt_port,
            })) => socks::TargetAddr::Domain(format!("{}.onion", service_id), virt_port),
        };

        // readwrite stream
        let stream = match &circuit {
            None => Socks5Stream::connect(socks_listener, socks_target),
            Some(circuit) => {
                if let Some(circuit) = self.circuit_tokens.get(circuit) {
                    Socks5Stream::connect_with_password(
                        socks_listener,
                        socks_target,
                        &circuit.username,
                        &circuit.password,
                    )
                } else {
                    return Err(Error::CircuitTokenInvalid())?;
                }
            }
        }
        .map_err(Error::Socks5ConnectionFailed)?;

        Ok(OnionStream {
            stream: stream.into_inner(),
            local_addr: None,
            peer_addr: Some(target),
        })
    }

    // stand up an onion service and return an LegacyOnionListener
    fn listener(
        &mut self,
        private_key: &Ed25519PrivateKey,
        virt_port: u16,
        authorized_clients: Option<&[X25519PublicKey]>,
    ) -> Result<OnionListener, tor_provider::Error> {
        if !self.bootstrapped {
            return Err(Error::LegacyTorNotBootstrapped().into());
        }

        // try to bind to a local address, let OS pick our port
        let socket_addr = SocketAddr::from(([127, 0, 0, 1], 0u16));
        let listener = TcpListener::bind(socket_addr).map_err(Error::TcpListenerBindFailed)?;
        let socket_addr = listener
            .local_addr()
            .map_err(Error::TcpListenerLocalAddrFailed)?;

        let mut flags = AddOnionFlags {
            discard_pk: true,
            ..Default::default()
        };
        if authorized_clients.is_some() {
            flags.v3_auth = true;
        }

        let onion_addr = OnionAddr::V3(OnionAddrV3::new(
            V3OnionServiceId::from_private_key(private_key),
            virt_port,
        ));

        // start onion service
        let (_, service_id) = self
            .controller
            .add_onion(
                Some(private_key),
                &flags,
                None,
                virt_port,
                Some(socket_addr),
                authorized_clients,
            )
            .map_err(Error::AddOnionFailed)?;

        let is_active = Arc::new(atomic::AtomicBool::new(true));
        self.onion_services
            .push((service_id, Arc::clone(&is_active)));

        Ok(OnionListener::new(listener, onion_addr, is_active, |is_active| {
            is_active.store(false, atomic::Ordering::Relaxed);
        }))
    }

    fn generate_token(&mut self) -> CircuitToken {
        let new_token = self.circuit_token_counter;
        self.circuit_token_counter += 1;
        self.circuit_tokens
            .insert(new_token, LegacyCircuitToken::new());
        new_token
    }

    fn release_token(&mut self, circuit_token: CircuitToken) {
        self.circuit_tokens.remove(&circuit_token);
    }
}