//! Connection parameters
use std::error::Error;
use std::path::PathBuf;

use url::{self, Url};

/// Specifies the target server to connect to.
#[derive(Clone, Debug)]
pub enum ConnectTarget {
    /// Connect via TCP to the specified host.
    Tcp(String),
    /// Connect via a Unix domain socket in the specified directory.
    ///
    /// Unix sockets are only supported on Unixy platforms (i.e. not Windows).
    Unix(PathBuf),
}

/// Authentication information.
#[derive(Clone, Debug)]
pub struct UserInfo {
    /// The username.
    pub user: String,
    /// An optional password.
    pub password: Option<String>,
}

/// Information necessary to open a new connection to a Postgres server.
#[derive(Clone, Debug)]
pub struct ConnectParams {
    /// The target server.
    pub target: ConnectTarget,
    /// The target port.
    ///
    /// Defaults to 5432 if not specified.
    pub port: Option<u16>,
    /// The user to login as.
    ///
    /// `Connection::connect` requires a user but `cancel_query` does not.
    pub user: Option<UserInfo>,
    /// The database to connect to.
    ///
    /// Defaults the value of `user`.
    pub database: Option<String>,
    /// Runtime parameters to be passed to the Postgres backend.
    pub options: Vec<(String, String)>,
}

/// A trait implemented by types that can be converted into a `ConnectParams`.
pub trait IntoConnectParams {
    /// Converts the value of `self` into a `ConnectParams`.
    fn into_connect_params(self) -> Result<ConnectParams, Box<Error + Sync + Send>>;
}

impl IntoConnectParams for ConnectParams {
    fn into_connect_params(self) -> Result<ConnectParams, Box<Error + Sync + Send>> {
        Ok(self)
    }
}

impl<'a> IntoConnectParams for &'a str {
    fn into_connect_params(self) -> Result<ConnectParams, Box<Error + Sync + Send>> {
        match Url::parse(self) {
            Ok(url) => url.into_connect_params(),
            Err(err) => Err(err.into()),
        }
    }
}

impl IntoConnectParams for Url {
    fn into_connect_params(self) -> Result<ConnectParams, Box<Error + Sync + Send>> {
        let Url { host, port, user, path: url::Path { mut path, query: options, .. }, .. } = self;

        let maybe_path = try!(url::decode_component(&host));
        let target = if maybe_path.starts_with('/') {
            ConnectTarget::Unix(PathBuf::from(maybe_path))
        } else {
            ConnectTarget::Tcp(host)
        };

        let user = user.map(|url::UserInfo { user, pass }| {
            UserInfo {
                user: user,
                password: pass,
            }
        });

        let database = if path.is_empty() {
            None
        } else {
            // path contains the leading /
            path.remove(0);
            Some(path)
        };

        Ok(ConnectParams {
            target: target,
            port: port,
            user: user,
            database: database,
            options: options,
        })
    }
}