use std::sync::Arc;

use pyo3::{exceptions::PyException, prelude::*};
use snafu::{ResultExt, Snafu};

#[derive(Debug, Clone, derive_more::Display)]
pub struct UnexpectedState(pub Arc<str>);

#[derive(Debug, Snafu)]
pub enum ExtractUnexpectedStateError {
    /// couldn't extract the object as a string
    ExtractStringError { source: PyErr },
}

impl From<ExtractUnexpectedStateError> for PyErr {
    fn from(error: ExtractUnexpectedStateError) -> Self {
        match &error {
            ExtractUnexpectedStateError::ExtractStringError { .. } => {
                PyException::new_err(error.to_string())
            }
        }
    }
}

// TODO: replace with a derive(PyFromStr) (analogous to serde_with::DeserializeFromStr) once I make one
impl<'a, 'py> FromPyObject<'a, 'py> for UnexpectedState {
    type Error = ExtractUnexpectedStateError;

    fn extract(ob: Borrowed<'a, 'py, PyAny>) -> Result<Self, Self::Error> {
        let s = ob.extract::<String>().context(ExtractStringSnafu)?;
        let s = s.into();

        Ok(UnexpectedState(s))
    }
}