//! CBOR codec marker and optional [`minicbor`] integration.
//!
//! The [`Cbor`] marker type is always available and can be used in type
//! signatures without any feature flags. Enable the `minicbor` feature to get
//! [`Encode`](super::Encode)/[`Decode`](super::Decode) implementations via
//! [`minicbor`].

/// CBOR codec marker type.
///
/// This type is always available regardless of feature flags, so you can
/// reference it in type signatures from `no_std` crates. Enable the
/// `minicbor` feature for [`Encode`](super::Encode)/[`Decode`](super::Decode)
/// implementations.
///
/// This codec does **not** implement [`Canonical`](super::Canonical) because
/// minicbor does not explicitly guarantee deterministic encoding per RFC 8949 §4.2.
/// If you need canonical CBOR, define your own codec type and audit the encoding.
///
/// # Example
///
/// ```
/// # #[cfg(all(feature = "minicbor", feature = "sha2"))]
/// # {
/// use evidence::digest::{Digest, sha2::Sha256};
/// use evidence::codec::cbor::Cbor;
/// use minicbor::{Encode, Decode};
///
/// #[derive(Encode, Decode)]
/// struct MyData {
///     #[n(0)] id: u32,
///     #[n(1)] name: String,
/// }
///
/// let data = MyData { id: 42, name: "test".into() };
/// let digest: Digest<MyData, Sha256, Cbor> = Digest::hash(&data);
/// # }
/// ```
#[derive(Debug, Clone, Copy)]
pub enum Cbor {}

/// Error returned when CBOR encoding fails.
#[cfg(feature = "minicbor")]
#[derive(Debug, Clone)]
pub struct CborEncodeError(alloc::string::String);

#[cfg(feature = "minicbor")]
impl core::fmt::Display for CborEncodeError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        write!(f, "CBOR encode error: {}", self.0)
    }
}

#[cfg(feature = "minicbor")]
impl<T: minicbor::Encode<()>> super::Encode<T> for Cbor {
    type Error = CborEncodeError;

    fn encode(value: &T) -> Result<alloc::vec::Vec<u8>, Self::Error> {
        minicbor::to_vec(value).map_err(|e| CborEncodeError(alloc::string::ToString::to_string(&e)))
    }
}

/// Error returned when CBOR decoding fails.
#[cfg(feature = "minicbor")]
#[derive(Debug, Clone)]
pub struct CborDecodeError(alloc::string::String);

#[cfg(feature = "minicbor")]
impl core::fmt::Display for CborDecodeError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        write!(f, "CBOR decode error: {}", self.0)
    }
}

#[cfg(feature = "minicbor")]
impl<T: for<'a> minicbor::Decode<'a, ()>> super::Decode<T> for Cbor {
    type Error = CborDecodeError;

    fn decode(bytes: &[u8]) -> Result<T, Self::Error> {
        minicbor::decode(bytes).map_err(|e| CborDecodeError(alloc::string::ToString::to_string(&e)))
    }
}