use thiserror::Error;

/// Errors that can occur while generating or verifying an Altcha PoW CAPTCHA.
#[derive(Debug, Error)]
pub enum PowError {
    /// The HMAC secret is not configured. Challenges cannot be signed or
    /// verified without one.
    #[error("pow hmac secret is not configured")]
    MissingSecret,
    /// The configured algorithm is not supported by the underlying library.
    #[error("unsupported pow algorithm: {0}")]
    UnsupportedAlgorithm(String),
    /// The challenge has expired.
    #[error("pow challenge expired")]
    Expired,
    /// The challenge signature is missing or invalid.
    #[error("invalid pow challenge signature")]
    InvalidSignature,
    /// The submitted solution does not satisfy the challenge.
    #[error("invalid pow solution")]
    InvalidSolution,
    /// The challenge was not issued by the server (or was already consumed).
    #[error("pow challenge was not issued or already used")]
    NotIssued,
    /// The challenge is bound to a different client than the caller.
    #[error("pow challenge was issued for a different client")]
    ClientMismatch,
    /// The one-time challenge store reported an error.
    #[error("pow store error: {0}")]
    Storage(String),
    /// The underlying altcha library reported an error.
    #[error("pow error: {0}")]
    Altcha(#[from] altcha::Error),
}