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/// Represents any valid JSON value.
pub use json::JsonValue as Value;

use super::{Error, Pointer, ValueExt};

impl ValueExt for Value {
    fn pointer(&self, pointer: &Pointer<'_>) -> Option<&Self> {
        if pointer.is_root() {
            return Some(self);
        }

        pointer.tokenize().try_fold(self, |value, key| match value {
            Value::Object(object) => object.get(key.as_str()),
            Value::Array(array) => key.parse::<usize>().ok().and_then(move |i| array.get(i)),
            _ => None,
        })
    }

    fn pointer_mut(&mut self, pointer: &Pointer<'_>) -> Option<&mut Self> {
        if pointer.is_root() {
            return Some(self);
        }

        pointer.tokenize().try_fold(self, |value, key| match value {
            Value::Object(object) => object.get_mut(key.as_str()),
            Value::Array(array) => key.parse::<usize>().ok().and_then(move |i| array.get_mut(i)),
            _ => None,
        })
    }

    fn insert(&mut self, key: String, value: impl Into<Self>) -> Result<Option<Self>, Error> {
        match self {
            Value::Object(object) => {
                let key = key.as_str();
                let old_value = object.remove(key);

                object.insert(key, value.into());

                Ok(old_value)
            }
            _ => Err(Error::UnsupportedInsertion),
        }
    }
}

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

    use json::object;

    #[test]
    fn it_looks_up_values_by_json_pointer() -> Result<(), Box<dyn std::error::Error>> {
        let mut value = object! {"foo": "bar", "zoo": {"id": [1, 2, 3]}};
        let tests = [("", value.clone()), ("/foo", "bar".into()), ("/zoo/id/0", 1.into())];

        for (s, mut expected_value) in tests {
            let pointer = Pointer::new(s)?;

            let pointee_value = value.pointer(&pointer);
            assert_eq!(pointee_value, Some(&expected_value));

            let pointee_value = value.pointer_mut(&pointer);
            assert_eq!(pointee_value, Some(&mut expected_value));
        }

        Ok(())
    }

    #[test]
    fn it_inserts_value_at_pointee_json_value() -> Result<(), Box<dyn std::error::Error>> {
        let value = object! {"foo": {"bar": "zoo"}};

        let tests = [
            (object! {"foo": {"bar": "zoo", "test": 42}}, "/foo/test", 42),
            (object! {"foo": {"bar": "zoo"}, "test": 21}, "/test", 21),
        ];

        for (expected_value, s, new_value) in tests {
            let mut value = value.clone();
            let old_value = value.insert_at(&Pointer::new(s)?, new_value)?;

            assert_eq!(old_value, None);
            assert_eq!(value, expected_value);
        }

        Ok(())
    }

    #[test]
    fn it_inserts_value_at_root_json_value() -> Result<(), Box<dyn std::error::Error>> {
        let mut value = object! {"foo": {"bar": "zoo"}};
        let new_value = "test2";

        let expected_old_value = value.clone();
        let old_value = value.insert_at(&Pointer::root(), new_value)?;

        assert_eq!(old_value, Some(expected_old_value));
        assert_eq!(value, new_value);

        Ok(())
    }

    #[test]
    fn it_fails_to_insert_value_at_non_existing_pointee_json_value() -> Result<(), Box<dyn std::error::Error>> {
        let mut value = object! {"foo": {"bar": "zoo"}};
        let result = value.insert_at(&Pointer::new("/foo/not_existing/zoo")?, 42);

        assert_eq!(result, Err(Error::KeyNotFound));

        Ok(())
    }

    #[test]
    fn it_fails_to_insert_value_at_json_scalar_value() -> Result<(), Box<dyn std::error::Error>> {
        let mut value = object! {"foo": {"bar": "zoo", "array": [1, 2, 3]}};

        let tests = ["/foo/bar/zoo", "/foo/array/0"];

        for s in tests {
            let result = value.insert_at(&Pointer::new(s)?, 42);

            assert_eq!(result, Err(Error::UnsupportedInsertion));
        }

        Ok(())
    }
}