//! See what can go wrong when creating graphical backends.

/// An error that occurred while creating an application's graphical context.
#[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
pub enum Error {
    /// The requested backend version is not supported.
    #[error("the requested backend version is not supported")]
    VersionNotSupported,

    /// Failed to find any pixel format that matches the criteria.
    #[error("failed to find any pixel format that matches the criteria")]
    NoAvailablePixelFormat,

    /// A suitable graphics adapter or device could not be found.
    #[error("a suitable graphics adapter or device could not be found")]
    GraphicsAdapterNotFound {
        /// The name of the backend where the error happened
        backend: &'static str,
        /// The reason why this backend could not be used
        reason: Reason,
    },

    /// An error occurred in the context's internal backend
    #[error("an error occurred in the context's internal backend")]
    BackendError(String),

    /// Multiple errors occurred
    #[error("multiple errors occurred: {0:?}")]
    List(Vec<Self>),
}

/// The reason why a graphics adapter could not be found
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Reason {
    /// The backend did not match the preference
    DidNotMatch {
        /// The preferred backend
        preferred_backend: String,
    },
    /// The request to create the backend failed
    RequestFailed(String),
}