//! Why a preview was not produced. Every reason is non-fatal: the caller keeps
//! the original and serves it instead.

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum PreviewSkip {
    /// The declared content type is not one of the supported raster formats.
    UnsupportedFormat,
    /// The payload had no bytes.
    Empty,
    /// The source exceeds the byte or pixel ceiling for previews.
    SourceTooLarge,
    /// The source could not be decoded (corrupt, truncated, or a decoder limit).
    Decode(String),
    /// The decoded image could not be encoded back into a preview.
    Encode(String),
}

impl std::fmt::Display for PreviewSkip {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::UnsupportedFormat => write!(f, "unsupported format"),
            Self::Empty => write!(f, "empty payload"),
            Self::SourceTooLarge => write!(f, "source too large"),
            Self::Decode(reason) => write!(f, "decode failed: {reason}"),
            Self::Encode(reason) => write!(f, "encode failed: {reason}"),
        }
    }
}

impl std::error::Error for PreviewSkip {}