use crate::parser::Pos;
use crate::{registry, ContextSelectionSet, OutputValueType, Result, ScalarType, Type, Value};
use async_graphql_derive::Scalar;
use std::borrow::Cow;

const STRING_DESC: &str = "The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.";

#[Scalar(internal)]
impl ScalarType for String {
    fn type_name() -> &'static str {
        "String"
    }

    fn description() -> Option<&'static str> {
        Some(STRING_DESC)
    }

    fn parse(value: &Value) -> Option<Self> {
        match value {
            Value::String(s) => Some(s.clone()),
            _ => None,
        }
    }

    fn is_valid(value: &Value) -> bool {
        match value {
            Value::String(_) => true,
            _ => false,
        }
    }

    fn to_json(&self) -> Result<serde_json::Value> {
        Ok(self.clone().into())
    }
}

impl<'a> Type for &'a str {
    fn type_name() -> Cow<'static, str> {
        Cow::Borrowed("String")
    }

    fn create_type_info(registry: &mut registry::Registry) -> String {
        registry.create_type::<Self, _>(|_| registry::Type::Scalar {
            name: Self::type_name().to_string(),
            description: Some(STRING_DESC),
            is_valid: |value| match value {
                Value::String(_) => true,
                _ => false,
            },
        })
    }
}

#[async_trait::async_trait]
impl<'a> OutputValueType for &'a str {
    async fn resolve(&self, _: &ContextSelectionSet<'_>, _pos: Pos) -> Result<serde_json::Value> {
        Ok((*self).into())
    }
}