//! When serializing or deserializing DAG-CBOR goes wrong.

use core::fmt;
use core::num::TryFromIntError;

#[cfg(not(feature = "std"))]
use alloc::string::{String, ToString};

use serde::{de, ser};

/// An encoding error.
#[derive(Debug)]
pub enum EncodeError<E> {
    /// Custom error message.
    Msg(String),
    /// IO Error.
    Write(E),
}

impl<E> From<E> for EncodeError<E> {
    fn from(err: E) -> EncodeError<E> {
        EncodeError::Write(err)
    }
}

#[cfg(feature = "std")]
impl<E: std::error::Error + 'static> ser::Error for EncodeError<E> {
    fn custom<T: fmt::Display>(msg: T) -> Self {
        EncodeError::Msg(msg.to_string())
    }
}

#[cfg(not(feature = "std"))]
impl<E: fmt::Debug> ser::Error for EncodeError<E> {
    fn custom<T: fmt::Display>(msg: T) -> Self {
        EncodeError::Msg(msg.to_string())
    }
}

#[cfg(feature = "std")]
impl<E: std::error::Error + 'static> std::error::Error for EncodeError<E> {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            EncodeError::Msg(_) => None,
            EncodeError::Write(err) => Some(err),
        }
    }
}

#[cfg(not(feature = "std"))]
impl<E: fmt::Debug> ser::StdError for EncodeError<E> {}

impl<E: fmt::Debug> fmt::Display for EncodeError<E> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(self, f)
    }
}

impl<E: fmt::Debug> From<cbor4ii::EncodeError<E>> for EncodeError<E> {
    fn from(err: cbor4ii::EncodeError<E>) -> EncodeError<E> {
        match err {
            cbor4ii::EncodeError::Write(e) => EncodeError::Write(e),
            // Needed as `cbor4ii::EncodeError` is markes as non_exhaustive
            _ => EncodeError::Msg(err.to_string()),
        }
    }
}

/// A decoding error.
#[derive(Debug)]
pub enum DecodeError<E> {
    /// Custom error message.
    Msg(String),
    /// IO error.
    Read(E),
    /// End of file.
    Eof,
    /// Unexpected byte.
    Mismatch {
        /// Expected CBOR major type.
        expect_major: u8,
        /// Unexpected byte.
        byte: u8,
    },
    /// Unexpected type.
    TypeMismatch {
        /// Type name.
        name: &'static str,
        /// Type byte.
        byte: u8,
    },
    /// Too large integer.
    CastOverflow(TryFromIntError),
    /// Overflowing 128-bit integers.
    Overflow {
        /// Type of integer.
        name: &'static str,
    },
    /// Decoding bytes/strings might require a borrow.
    RequireBorrowed {
        /// Type name (e.g. "bytes", "str").
        name: &'static str,
    },
    /// Length wasn't large enough.
    RequireLength {
        /// Type name.
        name: &'static str,
        /// Required length.
        expect: usize,
        /// Given length.
        value: usize,
    },
    /// Invalid UTF-8.
    InvalidUtf8(core::str::Utf8Error),
    /// Unsupported byte.
    Unsupported {
        /// Unsupported bute.
        byte: u8,
    },
    /// Recursion limit reached.
    DepthLimit,
    /// Trailing data.
    TrailingData,
    /// Indefinite sized item was encountered.
    IndefiniteSize,
}

impl<E> From<E> for DecodeError<E> {
    fn from(err: E) -> DecodeError<E> {
        DecodeError::Read(err)
    }
}

#[cfg(feature = "std")]
impl<E: std::error::Error + 'static> de::Error for DecodeError<E> {
    fn custom<T: fmt::Display>(msg: T) -> Self {
        DecodeError::Msg(msg.to_string())
    }
}

#[cfg(not(feature = "std"))]
impl<E: fmt::Debug> de::Error for DecodeError<E> {
    fn custom<T: fmt::Display>(msg: T) -> Self {
        DecodeError::Msg(msg.to_string())
    }
}

#[cfg(feature = "std")]
impl<E: std::error::Error + 'static> std::error::Error for DecodeError<E> {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            DecodeError::Msg(_) => None,
            DecodeError::Read(err) => Some(err),
            _ => None,
        }
    }
}

#[cfg(not(feature = "std"))]
impl<E: fmt::Debug> ser::StdError for DecodeError<E> {}

impl<E: fmt::Debug> fmt::Display for DecodeError<E> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(self, f)
    }
}

impl<E: fmt::Debug> From<cbor4ii::DecodeError<E>> for DecodeError<E> {
    fn from(err: cbor4ii::DecodeError<E>) -> DecodeError<E> {
        match err {
            cbor4ii::DecodeError::Read(read) => DecodeError::Read(read),
            cbor4ii::DecodeError::Eof => DecodeError::Eof,
            cbor4ii::DecodeError::Mismatch { expect_major, byte } => {
                DecodeError::Mismatch { expect_major, byte }
            }
            cbor4ii::DecodeError::TypeMismatch { name, byte } => {
                DecodeError::TypeMismatch { name, byte }
            }
            cbor4ii::DecodeError::CastOverflow(overflow) => DecodeError::CastOverflow(overflow),
            cbor4ii::DecodeError::Overflow { name } => DecodeError::Overflow { name },
            cbor4ii::DecodeError::RequireBorrowed { name } => DecodeError::RequireBorrowed { name },
            cbor4ii::DecodeError::RequireLength {
                name,
                expect,
                value,
            } => DecodeError::RequireLength {
                name,
                expect,
                value,
            },
            cbor4ii::DecodeError::InvalidUtf8(invalid) => DecodeError::InvalidUtf8(invalid),
            cbor4ii::DecodeError::Unsupported { byte } => DecodeError::Unsupported { byte },
            cbor4ii::DecodeError::DepthLimit => DecodeError::DepthLimit,
            // Needed as `cbor4ii::EncodeError` is markes as non_exhaustive
            _ => DecodeError::Msg(err.to_string()),
        }
    }
}