reqlang-expr 0.5.0

use std::fmt::{Debug, Display};

use crate::value::Value;

#[derive(Clone, PartialEq)]
pub enum Type {
    Value,
    String,
    Fn {
        args: Vec<Type>,
        variadic_arg: Option<Box<Type>>,
        returns: Box<Type>,
    },
    Bool,
}

impl Type {
    pub fn name(&self) -> String {
        match self {
            Type::Value => "Value".to_string(),
            Type::String => "String".to_string(),
            Type::Fn {
                args,
                variadic_arg,
                returns,
            } => {
                let mut args: Vec<String> = args.iter().map(|arg| arg.name()).collect();

                if let Some(varg) = variadic_arg {
                    args.push(format!("...{}", varg.name()));
                }

                let args = args.join(", ");

                let returns = returns.name();

                format!("Fn({args}) -> {returns}")
            }
            Type::Bool => "Bool".to_string(),
        }
    }
}

impl Display for Type {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.name())
    }
}

impl Debug for Type {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.name())
    }
}

impl From<Value> for Type {
    fn from(value: Value) -> Self {
        match value {
            Value::String(_) => Type::String,
            Value::Fn(builtin_fn) => {
                let mut args: Vec<Type> =
                    builtin_fn.args.iter().map(|arg| arg.ty.clone()).collect();

                let variadic_arg = builtin_fn
                    .args
                    .last()
                    .filter(|arg| arg.variadic)
                    .map(|arg| Box::new(arg.ty.clone()));

                if variadic_arg.is_some() {
                    args.pop();
                }

                Type::Fn {
                    args,
                    variadic_arg,
                    returns: Box::new(builtin_fn.return_type.clone()),
                }
            }
            Value::Bool(_) => Type::Bool,
        }
    }
}

#[cfg(test)]
mod from_tests {
    use std::rc::Rc;

    use crate::prelude::{BuiltinFn, FnArg};

    use super::*;

    #[test]
    fn test_from_string_value() {
        let string_value = Value::String("test".to_string());
        let ty: Type = string_value.into();
        assert_eq!(Type::String, ty);
    }

    #[test]
    fn test_get_type_string_value() {
        let string_value = Value::String("test".to_string());
        let ty: Type = string_value.get_type();
        assert_eq!(Type::String, ty);
    }

    #[test]
    fn test_from_bool_value() {
        let bool_value = Value::Bool(true);
        let ty: Type = bool_value.into();
        assert_eq!(Type::Bool, ty);
    }

    #[test]
    fn test_get_type_bool_value() {
        let bool_value = Value::Bool(true);
        let ty: Type = bool_value.get_type();
        assert_eq!(Type::Bool, ty);
    }

    #[test]
    fn test_from_fn_value() {
        let builtin_fn = Value::Fn(Rc::new(BuiltinFn {
            name: "test".to_string(),
            args: vec![FnArg::new("a", Type::Value)],
            return_type: Type::String,
            func: Rc::new(|_| Value::String("".to_string())),
        }));

        let ty: Type = builtin_fn.into();

        assert_eq!(
            Type::Fn {
                args: vec![Type::Value],
                variadic_arg: None,
                returns: Box::new(Type::String),
            },
            ty
        );
    }

    #[test]
    fn test_get_type_fn_value() {
        let builtin_fn = Value::Fn(Rc::new(BuiltinFn {
            name: "test".to_string(),
            args: vec![FnArg::new("a", Type::Value)],
            return_type: Type::String,
            func: Rc::new(|_| Value::String("".to_string())),
        }));

        let ty: Type = builtin_fn.get_type();

        assert_eq!(
            Type::Fn {
                args: vec![Type::Value],
                variadic_arg: None,
                returns: Box::new(Type::String),
            },
            ty
        );
    }
}

#[cfg(test)]
mod name_and_display_tests {
    use super::*;

    #[test]
    fn test_name_value() {
        assert_eq!("Value", Type::Value.name());
    }

    #[test]
    fn test_name_string() {
        assert_eq!("String", Type::String.name());
    }

    #[test]
    fn test_name_fn_0_args() {
        assert_eq!(
            "Fn() -> String",
            Type::Fn {
                args: vec![],
                variadic_arg: None,
                returns: Type::String.into(),
            }
            .name()
        );
    }

    #[test]
    fn test_name_fn_0_args_and_varadic() {
        assert_eq!(
            "Fn(...Value) -> String",
            Type::Fn {
                args: vec![],
                variadic_arg: Some(Type::Value.into()),
                returns: Type::String.into(),
            }
            .name()
        );
    }

    #[test]
    fn test_name_fn_1_args() {
        assert_eq!(
            "Fn(Value) -> String",
            Type::Fn {
                args: vec![Type::Value],
                variadic_arg: None,
                returns: Type::String.into(),
            }
            .name()
        );
    }

    #[test]
    fn test_name_fn_2_args() {
        assert_eq!(
            "Fn(Value, String) -> String",
            Type::Fn {
                args: vec![Type::Value, Type::String],
                variadic_arg: None,
                returns: Type::String.into(),
            }
            .name()
        );
    }

    #[test]
    fn test_name_fn_2_args_and_varadic() {
        assert_eq!(
            "Fn(Value, String, ...Value) -> String",
            Type::Fn {
                args: vec![Type::Value, Type::String],
                variadic_arg: Some(Type::Value.into()),
                returns: Type::String.into(),
            }
            .name()
        );
    }

    #[test]
    fn test_name_bool() {
        assert_eq!("Bool", Type::Bool.name());
    }
}