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/// A helper enum that is passed to the `Client::new` function in
/// order to avoid errors on unsupported connection schemes.
pub enum Scheme {
    Http,
    Https,
}

impl Scheme {
    fn as_str(&self) -> &str {
        match self {
            Scheme::Http => "http",
            Scheme::Https => "https",
        }
    }
}

/// A client used to execute queries. It uses a `reqwest::Client` internally
/// that manages connections for us.
pub struct Client {
    pub(crate) client: reqwest::Client,
    pub(crate) base_url: String,
}

impl Default for Client {
    /// Create a Client that connects to a local Prometheus instance at port 9090.
    ///
    /// ```rust
    /// use prometheus_http_query::Client;
    ///
    /// let client: Client = Default::default();
    /// ```
    fn default() -> Self {
        Client {
            client: reqwest::Client::new(),
            base_url: String::from("http://127.0.0.1:9090/api/v1"),
        }
    }
}

impl Client {
    /// Create a Client that connects to a Prometheus instance at the
    /// given FQDN/domain and port, using either HTTP or HTTPS.
    ///
    /// Note that possible errors regarding domain name resolution or
    /// connection establishment will only be propagated from the underlying
    /// `reqwest::Client` when a query is executed.
    ///
    /// ```rust
    /// use prometheus_http_query::{Client, Scheme};
    ///
    /// let client = Client::new(Scheme::Http, "localhost", 9090);
    /// ```
    pub fn new(scheme: Scheme, host: &str, port: u16) -> Self {
        Client {
            base_url: format!("{}://{}:{}/api/v1", scheme.as_str(), host, port),
            ..Default::default()
        }
    }
}