use thiserror::Error;

/// Represents errors that can occur during application configuration.
///
/// These errors typically happen during application startup when loading
/// and validating configuration from environment variables and files.
#[derive(Debug, Error)]
pub enum ConfigError {
    /// Error when a required environment variable is not set.
    ///
    /// This error occurs when the application starts up and a required
    /// environment variable is missing from the execution environment.
    #[error("error-smokesignal-config-1 {0} must be set")]
    EnvVarRequired(String),

    /// Error when no valid signing keys are found.
    ///
    /// This error occurs when the OAuth client credentials key is empty
    /// or cannot be identified as a valid key.
    #[error("error-smokesignal-config-4 OAuth client credentials key must be a valid key")]
    EmptySigningKeys,

    /// Error when the PORT environment variable cannot be parsed.
    ///
    /// This error occurs when the PORT environment variable contains a value
    /// that cannot be parsed as a valid u16 integer.
    #[error("error-smokesignal-config-7 Parsing PORT into u16 failed: {0:?}")]
    PortParsingFailed(std::num::ParseIntError),

    /// Error when the HTTP_COOKIE_KEY cannot be decoded.
    ///
    /// This error occurs when the HTTP_COOKIE_KEY environment variable
    /// contains a value that is not valid base64-encoded data.
    #[error("error-smokesignal-config-8 Unable to base64 decode HTTP_COOKIE_KEY: {0:?}")]
    CookieKeyDecodeFailed(base64::DecodeSliceError),

    /// Error when the decoded HTTP_COOKIE_KEY cannot be processed.
    ///
    /// This error occurs when the decoded HTTP_COOKIE_KEY has an invalid
    /// format or length that prevents it from being used.
    #[error("error-smokesignal-config-9 Unable to process decoded HTTP_COOKIE_KEY")]
    CookieKeyProcessFailed,

    /// Error when version information is not available.
    ///
    /// This error occurs when neither GIT_HASH nor CARGO_PKG_VERSION
    /// environment variables are set, preventing version identification.
    #[error("error-smokesignal-config-10 One of GIT_HASH or CARGO_PKG_VERSION must be set")]
    VersionNotSet,

    /// Error when a DNS nameserver IP cannot be parsed.
    ///
    /// This error occurs when the DNS_NAMESERVERS environment variable contains
    /// an IP address that cannot be parsed as a valid IpAddr.
    #[error("error-smokesignal-config-12 Unable to parse nameserver IP '{0}': {1}")]
    NameserverParsingFailed(String, std::net::AddrParseError),

    /// Error when the EMAIL_SECRET_KEY cannot be decoded.
    ///
    /// This error occurs when the EMAIL_SECRET_KEY environment variable
    /// contains a value that is not valid hex-encoded data.
    #[error("error-smokesignal-config-21 Unable to hex decode EMAIL_SECRET_KEY: {0:?}")]
    EmailSecretKeyDecodeFailed(hex::FromHexError),

    /// Error when the EMAIL_SECRET_KEY is too short.
    ///
    /// This error occurs when the decoded EMAIL_SECRET_KEY is less than
    /// 32 bytes (256 bits), which is the minimum required for security.
    #[error(
        "error-smokesignal-config-22 EMAIL_SECRET_KEY must be at least 32 bytes, got {0} bytes"
    )]
    EmailSecretKeyTooShort(usize),
}