/*!

This crate provides wrappers and convenience functions to make rust-url
and Serde work hand in hand.

The supported types are:

* `url::Url`

# How do I use a data type with a `Url` member with Serde?

Use the serde attributes `deserialize_with` and `serialize_with`.

```
#[derive(serde::Serialize, serde::Deserialize)]
struct MyStruct {
    #[serde(deserialize_with = "url_serde::deserialize",
    serialize_with = "url_serde::serialize")]
    url: Url,
}
```

# How do I encode a `Url` value with `serde_json::to_string`?

Use the `Ser` wrapper.

```
serde_json::to_string(&Ser::new(&url))
```

# How do I decode a `Url` value with `serde_json::parse`?

Use the `De` wrapper.

```
serde_json::from_str(r"http:://www.rust-lang.org").map(De::into_inner)
```

# How do I send `Url` values as part of an IPC channel?

Use the `Serde` wrapper. It implements `Deref` and `DerefMut` for convenience.

```
ipc::channel::<Serde<Url>>()
```
*/

#![deny(missing_docs)]
#![deny(unsafe_code)]

extern crate serde;
extern crate url;

use std::cmp::PartialEq;
use std::fmt;
use std::ops::{Deref, DerefMut};
use std::error::Error;
use serde::{Deserialize, Serialize, Serializer, Deserializer};
use url::{Url};


/// Serialises `value` with a given serializer.
///
/// This is useful to serialize `rust-url` types used in structure fields or
/// tuple members with `#[serde(serialize_with = "url_serde::serialize")]`.
pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
    where S: Serializer, for<'a> Ser<'a, T>: Serialize
{
    Ser::new(value).serialize(serializer)
}

/// A wrapper to serialize `rust-url` types.
///
/// This is useful with functions such as `serde_json::to_string`.
///
/// Values of this type can only be passed to the `serde::Serialize` trait.
#[derive(Debug)]
pub struct Ser<'a, T: 'a>(&'a T);

impl<'a, T> Ser<'a, T> where Ser<'a, T>: Serialize {
    /// Returns a new `Ser` wrapper.
    #[inline(always)]
    pub fn new(value: &'a T) -> Self {
        Ser(value)
    }
}


/// Serializes this URL into a `serde` stream.
impl<'a> Serialize for Ser<'a, Url> {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
        serializer.serialize_str(self.0.as_str())
    }
}


/// Deserialises a `T` value with a given deserializer.
///
/// This is useful to deserialize Url types used in structure fields or
/// tuple members with `#[serde(deserialize_with = "url_serde::deserialize")]`.
pub fn deserialize<T, D>(deserializer: D) -> Result<T, D::Error>
    where D: Deserializer, De<T>: Deserialize
{
    De::deserialize(deserializer).map(De::into_inner)
}


/// A wrapper to deserialize `rust-url` types.
///
/// This is useful with functions such as `serde_json::from_str`.
///
/// Values of this type can only be obtained through
/// the `serde::Deserialize` trait.
#[derive(Debug)]
pub struct De<T>(T);

impl<T> De<T> where De<T>: serde::Deserialize {
    /// Consumes this wrapper, returning the deserialized value.
    #[inline(always)]
    pub fn into_inner(self) -> T {
        self.0
    }
}


/// Deserializes this URL from a `serde` stream.
impl Deserialize for De<Url> {
    fn deserialize<D>(deserializer: D) -> Result<De<Url>, D::Error> where D: Deserializer {
        let string_representation: String = Deserialize::deserialize(deserializer)?;
        Url::parse(&string_representation).map(De).map_err(|err| {
            serde::de::Error::custom(err.description())
        })
    }
}


/// A convenience wrapper to be used as a type parameter, for example when
/// a `Vec<T>` need to be passed to serde.
#[derive(Clone, PartialEq)]
pub struct Serde<T>(pub T)
    where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize;

impl<T> Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    /// Consumes this wrapper, returning the inner value.
    #[inline(always)]
    pub fn into_inner(self) -> T {
        self.0
    }
}

impl<T> fmt::Debug for Serde<T>
where T: fmt::Debug, De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        self.0.fmt(formatter)
    }
}

impl<T> Deref for Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    type Target = T;

    fn deref(&self) -> &T {
        &self.0
    }
}

impl<T> DerefMut for Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    fn deref_mut(&mut self) -> &mut T {
        &mut self.0
    }
}

impl<T: PartialEq> PartialEq<T> for Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    fn eq(&self, other: &T) -> bool {
        self.0 == *other
    }
}

impl<T> Deserialize for Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where D: Deserializer
    {
        De::deserialize(deserializer).map(De::into_inner).map(Serde)
    }
}

impl<T> Serialize for Serde<T>
where De<T>: Deserialize, for<'a> Ser<'a, T>: Serialize
{
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where S: Serializer
    {
        Ser(&self.0).serialize(serializer)
    }
}


#[test]
fn test_ser_de_url() {
    extern crate serde_json;
    let url = Url::parse("http://www.test.com/foo/bar?$param=bazz").unwrap();
    let s = serde_json::to_string(&Ser::new(&url)).unwrap();
    let new_url: Url = serde_json::from_str(&s).map(De::into_inner).unwrap();
    assert_eq!(url, new_url);
}