use std::{
    clone::Clone,
    fmt::{self, Debug, Formatter},
    marker::PhantomData,
};

use serde::{
    de::{Deserialize, DeserializeOwned, Deserializer},
    ser::{Serialize, Serializer},
};
use serde_json::value::RawValue;

/// A wrapper around `Box<RawValue>`, to be used in place of any type in the Matrix endpoint
/// definition to allow request and response types to contain that said type represented by
/// the generic argument `Ev`.
///
/// Ruma offers the `Raw` wrapper to enable passing around JSON text that is only partially
/// validated. This is useful when a client receives events that do not follow the spec perfectly
/// or a server needs to generate reference hashes with the original canonical JSON string.
/// All event structs and enums implement `Serialize` / `Deserialize`, `Raw` should be used
/// to pass around events in a lossless way.
///
/// ```ignore
/// let json = r#"{ "type": "imagine a full event", "content": {...} }"#;
///
/// let deser = serde_json::from_str::<Raw<AnyRoomEvent>>(json)
///     .unwrap() // the first Result from serde_json::from_str, will not fail
///     .deserialize() // deserialize to the inner type
///     .unwrap(); // finally get to the AnyRoomEvent
/// ```
pub struct Raw<T> {
    json: Box<RawValue>,
    _ev: PhantomData<T>,
}

impl<T> Raw<T> {
    fn new(json: Box<RawValue>) -> Self {
        Self { json, _ev: PhantomData }
    }

    /// Create a `Raw` from a boxed `RawValue`.
    pub fn from_json(raw: Box<RawValue>) -> Self {
        Self::new(raw)
    }

    /// Access the underlying json value.
    pub fn json(&self) -> &RawValue {
        &self.json
    }

    /// Convert `self` into the underlying json value.
    pub fn into_json(self) -> Box<RawValue> {
        self.json
    }
}

impl<T> Raw<T>
where
    T: DeserializeOwned,
{
    /// Try to deserialize the JSON into the expected type.
    pub fn deserialize(&self) -> Result<T, serde_json::Error> {
        serde_json::from_str(self.json.get())
    }
}

impl<T: Serialize> From<&T> for Raw<T> {
    fn from(val: &T) -> Self {
        Self::new(serde_json::value::to_raw_value(val).unwrap())
    }
}

// With specialization a fast path from impl for `impl<T> From<Box<RawValue...`
// could be used. Until then there is a special constructor `from_json` for this.
impl<T: Serialize> From<T> for Raw<T> {
    fn from(val: T) -> Self {
        Self::from(&val)
    }
}

impl<T> Clone for Raw<T> {
    fn clone(&self) -> Self {
        Self::new(self.json.clone())
    }
}

impl<T> Debug for Raw<T> {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        use std::any::type_name;
        f.debug_struct(&format!("Raw::<{}>", type_name::<T>())).field("json", &self.json).finish()
    }
}

impl<'de, T> Deserialize<'de> for Raw<T> {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        Box::<RawValue>::deserialize(deserializer).map(Self::new)
    }
}

impl<T> Serialize for Raw<T> {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        self.json.serialize(serializer)
    }
}