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use proc_macro2::TokenStream;
use pyo3::FromPyObject;
use quote::quote;
use serde::{Deserialize, Serialize};

use crate::{CodeGen, CodeGenContext, ExprType, PythonOptions, SymbolTableScopes};

/// A keyword argument, gnerally used in function calls.
#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
pub struct NamedExpr {
    left: Box<ExprType>,
    right: Box<ExprType>,
}

impl<'a> FromPyObject<'a> for NamedExpr {
    fn extract(ob: &pyo3::PyAny) -> pyo3::PyResult<Self> {
        let left = ob.getattr("left")?.extract::<ExprType>()?;
        let right = ob.getattr("right")?.extract::<ExprType>()?;
        Ok(NamedExpr {
            left: Box::new(left),
            right: Box::new(right),
        })
    }
}

impl CodeGen for NamedExpr {
    type Context = CodeGenContext;
    type Options = PythonOptions;
    type SymbolTable = SymbolTableScopes;

    fn to_rust(
        self,
        ctx: Self::Context,
        options: Self::Options,
        symbols: Self::SymbolTable,
    ) -> Result<TokenStream, Box<dyn std::error::Error>> {
        let left = self
            .left
            .clone()
            .to_rust(ctx.clone(), options.clone(), symbols.clone())
            .expect(format!("parsing left side of named expression {:?}", self.left).as_str());
        let right =
            self.right.clone().to_rust(ctx, options, symbols).expect(
                format!("parsing right side of named expression {:?}", self.right).as_str(),
            );
        Ok(quote!(#left = #right))
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::{Constant, ExprType, Name};
    use litrs::*;

    #[test]
    fn test_named_expression() {
        let named_expression = NamedExpr {
            left: Box::new(ExprType::Name(Name {
                id: "a".to_string(),
            })),
            right: Box::new(ExprType::Constant(Constant(Some(Literal::Integer(
                IntegerLit::parse("1".to_string()).unwrap(),
            ))))),
        };
        let rust = named_expression
            .to_rust(
                CodeGenContext::Module("test".to_string()),
                PythonOptions::default(),
                SymbolTableScopes::new(),
            )
            .unwrap();
        assert_eq!(rust.to_string(), "a = 1");
    }
}