serde-path 0.1.0

use std::fmt;

// this wrapper type is used as the deserializer error to hide the `serde::de::Error` impl which
// would otherwise be public if we used `ErrorKind` as the error directly
#[derive(Debug)]
pub struct PathDeserializationError {
    pub(crate) kind: ErrorKind,
}

impl PathDeserializationError {
    pub(crate) fn new(kind: ErrorKind) -> Self {
        Self { kind }
    }

    pub(crate) fn wrong_number_of_parameters() -> WrongNumberOfParameters<()> {
        WrongNumberOfParameters { got: () }
    }

    #[track_caller]
    pub(crate) fn unsupported_type(name: &'static str) -> Self {
        Self::new(ErrorKind::UnsupportedType { name })
    }
}

pub(crate) struct WrongNumberOfParameters<G> {
    got: G,
}

impl<G> WrongNumberOfParameters<G> {
    #[allow(clippy::unused_self)]
    pub(crate) fn got<G2>(self, got: G2) -> WrongNumberOfParameters<G2> {
        WrongNumberOfParameters { got }
    }
}

impl WrongNumberOfParameters<usize> {
    pub(crate) fn expected(self, expected: usize) -> PathDeserializationError {
        PathDeserializationError::new(ErrorKind::WrongNumberOfParameters {
            got: self.got,
            expected,
        })
    }
}

impl serde::de::Error for PathDeserializationError {
    #[inline]
    fn custom<T>(msg: T) -> Self
    where
        T: fmt::Display,
    {
        Self {
            kind: ErrorKind::Message(msg.to_string()),
        }
    }
}

impl fmt::Display for PathDeserializationError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.kind.fmt(f)
    }
}

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

/// The kinds of errors that can happen we deserializing into a [`Path`].
///
/// This type is obtained through [`FailedToDeserializePathParams::kind`] or
/// [`FailedToDeserializePathParams::into_kind`] and is useful for building
/// more precise error messages.
#[derive(Debug, PartialEq, Eq)]
#[non_exhaustive]
pub enum ErrorKind {
    /// The URI contained the wrong number of parameters.
    WrongNumberOfParameters {
        /// The number of actual parameters in the URI.
        got: usize,
        /// The number of expected parameters.
        expected: usize,
    },

    /// Failed to parse the value at a specific key into the expected type.
    ///
    /// This variant is used when deserializing into types that have named fields, such as structs.
    ParseErrorAtKey {
        /// The key at which the value was located.
        key: String,
        /// The value from the URI.
        value: String,
        /// The expected type of the value.
        expected_type: &'static str,
    },

    /// Failed to parse the value at a specific index into the expected type.
    ///
    /// This variant is used when deserializing into sequence types, such as tuples.
    ParseErrorAtIndex {
        /// The index at which the value was located.
        index: usize,
        /// The value from the URI.
        value: String,
        /// The expected type of the value.
        expected_type: &'static str,
    },

    /// Failed to parse a value into the expected type.
    ///
    /// This variant is used when deserializing into a primitive type (such as `String` and `u32`).
    ParseError {
        /// The value from the URI.
        value: String,
        /// The expected type of the value.
        expected_type: &'static str,
    },

    /// A parameter contained text that, once percent decoded, wasn't valid UTF-8.
    InvalidUtf8InPathParam {
        /// The key at which the invalid value was located.
        key: String,
    },

    /// Tried to serialize into an unsupported type such as nested maps.
    ///
    /// This error kind is caused by programmer errors and thus gets converted into a `500 Internal
    /// Server Error` response.
    UnsupportedType {
        /// The name of the unsupported type.
        name: &'static str,
    },

    /// Catch-all variant for errors that don't fit any other variant.
    Message(String),
}

impl fmt::Display for ErrorKind {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ErrorKind::Message(error) => error.fmt(f),
            ErrorKind::InvalidUtf8InPathParam { key } => write!(f, "Invalid UTF-8 in `{key}`"),
            ErrorKind::WrongNumberOfParameters { got, expected } => {
                write!(
                    f,
                    "Wrong number of path arguments for `Path`. Expected {expected} but got {got}"
                )?;

                if *expected == 1 {
                    write!(f, ". Note that multiple parameters must be extracted with a tuple `Path<(_, _)>` or a struct `Path<YourParams>`")?;
                }

                Ok(())
            }
            ErrorKind::UnsupportedType { name } => write!(f, "Unsupported type `{name}`"),
            ErrorKind::ParseErrorAtKey {
                key,
                value,
                expected_type,
            } => write!(
                f,
                "Cannot parse `{key}` with value `{value:?}` to a `{expected_type}`"
            ),
            ErrorKind::ParseError {
                value,
                expected_type,
            } => write!(f, "Cannot parse `{value:?}` to a `{expected_type}`"),
            ErrorKind::ParseErrorAtIndex {
                index,
                value,
                expected_type,
            } => write!(
                f,
                "Cannot parse value at index {index} with value `{value:?}` to a `{expected_type}`"
            ),
        }
    }
}