tracing-formatters 0.0.1

use crate::value::Value;
use core::fmt;
use core::fmt::Display;
use std::collections::BTreeMap;
use std::ops;

pub trait Index: private::Sealed {
    /// Return None if the key is not already in the array or object.
    #[doc(hidden)]
    fn index_into<'v>(&self, v: &'v Value) -> Option<&'v Value>;

    /// Return None if the key is not already in the array or object.
    #[doc(hidden)]
    fn index_into_mut<'v>(&self, v: &'v mut Value) -> Option<&'v mut Value>;

    /// Panic if array index out of bounds. If key is not already in the object,
    /// insert it with a value of null. Panic if Value is a type that cannot be
    /// indexed into, except if Value is null then it can be treated as an empty
    /// object.
    #[doc(hidden)]
    fn index_or_insert<'v>(&self, v: &'v mut Value) -> &'v mut Value;
}

impl Index for usize {
    fn index_into<'v>(&self, v: &'v Value) -> Option<&'v Value> {
        match v {
            Value::Array(vec) => vec.get(*self),
            _ => None,
        }
    }
    fn index_into_mut<'v>(&self, v: &'v mut Value) -> Option<&'v mut Value> {
        match v {
            Value::Array(vec) => vec.get_mut(*self),
            _ => None,
        }
    }
    fn index_or_insert<'v>(&self, v: &'v mut Value) -> &'v mut Value {
        match v {
            Value::Array(vec) => {
                let len = vec.len();
                vec.get_mut(*self).unwrap_or_else(|| {
                    panic!(
                        "cannot access index {} of JSON array of length {}",
                        self, len
                    )
                })
            }
            _ => panic!("cannot access index {} of JSON {}", self, Type(v)),
        }
    }
}

impl Index for str {
    fn index_into<'v>(&self, v: &'v Value) -> Option<&'v Value> {
        match v {
            Value::Map(map) => map.get(self),
            _ => None,
        }
    }
    fn index_into_mut<'v>(&self, v: &'v mut Value) -> Option<&'v mut Value> {
        match v {
            Value::Map(map) => map.get_mut(self),
            _ => None,
        }
    }
    fn index_or_insert<'v>(&self, v: &'v mut Value) -> &'v mut Value {
        if let Value::Null = v {
            *v = Value::Map(BTreeMap::new());
        }
        match v {
            Value::Map(map) => map.entry(self.to_owned()).or_insert(Value::Null),
            _ => panic!("cannot access key {:?} in JSON {}", self, Type(v)),
        }
    }
}

impl Index for String {
    fn index_into<'v>(&self, v: &'v Value) -> Option<&'v Value> {
        self[..].index_into(v)
    }
    fn index_into_mut<'v>(&self, v: &'v mut Value) -> Option<&'v mut Value> {
        self[..].index_into_mut(v)
    }
    fn index_or_insert<'v>(&self, v: &'v mut Value) -> &'v mut Value {
        self[..].index_or_insert(v)
    }
}

impl<'a, T> Index for &'a T
where
    T: ?Sized + Index,
{
    fn index_into<'v>(&self, v: &'v Value) -> Option<&'v Value> {
        (**self).index_into(v)
    }
    fn index_into_mut<'v>(&self, v: &'v mut Value) -> Option<&'v mut Value> {
        (**self).index_into_mut(v)
    }
    fn index_or_insert<'v>(&self, v: &'v mut Value) -> &'v mut Value {
        (**self).index_or_insert(v)
    }
}

// Prevent users from implementing the Index trait.
mod private {
    pub trait Sealed {}
    impl Sealed for usize {}
    impl Sealed for str {}
    impl Sealed for alloc::string::String {}
    impl<'a, T> Sealed for &'a T where T: ?Sized + Sealed {}
}

/// Used in panic messages.
struct Type<'a>(&'a Value);

impl<'a> Display for Type<'a> {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        match *self.0 {
            Value::Null => formatter.write_str("null"),
            Value::Bool(_) => formatter.write_str("boolean"),
            Value::Int(_) => formatter.write_str("integer"),
            Value::UInt(_) => formatter.write_str("uinteger"),
            Value::Float(_) => formatter.write_str("float"),
            Value::String(_) => formatter.write_str("string"),
            Value::Array(_) => formatter.write_str("array"),
            Value::Map(_) => formatter.write_str("object"),
        }
    }
}

impl<I> ops::Index<I> for Value
where
    I: Index,
{
    type Output = Value;

    fn index(&self, index: I) -> &Value {
        static NULL: Value = Value::Null;
        index.index_into(self).unwrap_or(&NULL)
    }
}

impl<I> ops::IndexMut<I> for Value
where
    I: Index,
{
    fn index_mut(&mut self, index: I) -> &mut Value {
        index.index_or_insert(self)
    }
}