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use std::fmt::{Debug, Error, Formatter};
use std::ops::Deref;
use std::mem;

use traits;
use traits::Stream as StreamT;
use unique_stream::Stream as UniqueStream;
use iter::IterAsync;
use serde::{Serialize, Serializer, Deserialize, Deserializer};
use parameter::Parameter;

#[must_use = "droping a property unsubscribes it and all the chain until the origin sender"]
pub struct UniqueProperty<'a, T: Clone + Debug + 'static>{
    parent: Option<Box<UniqueStream<'a,T>>>,
    value: T,
}

impl<'a,T: Clone + Debug + 'a> UniqueProperty<'a,T>{
    pub fn new(initial: T) -> UniqueProperty<'a,T>{
        UniqueProperty{
            parent: None,
            value: initial,
        }
    }

    // pub fn from_parent<S: Into<UniqueStream<'a,T>>>(stream: S, initial: T) -> UniqueProperty<'a,T>{
    //     UniqueProperty{
    //         parent: Some(Box::new(stream.into())),
    //         value: initial,
    //     }
    // }

    pub fn connect_stream<'b,'c, S: Into<UniqueStream<'b,T>>>(&'c mut self, stream: S) where 'c: 'b, 'a: 'b{
        let value: &mut T = &mut self.value;
        let stream = stream.into();
        let next_parent = match self.parent{
            Some(ref mut parent) => {
                let prev_parent = mem::replace(parent, unsafe{ mem::uninitialized() });
                prev_parent.merge(stream.on_value(move |v| *value = v))
            }
            None => {
                stream.on_value(move |v| *value = v)
            }
        };
        let next_parent: Box<UniqueStream<T>> = Box::new(next_parent);
        let next_parent: Box<UniqueStream<T>> = unsafe{ mem::transmute(next_parent) };
        let _drop_previous = mem::replace(&mut self.parent, Some(next_parent));
    }

    pub fn value(&self) -> &T{
        &self.value
    }

    pub fn to_value(&self) -> T{
        self.value.clone()
    }

    pub fn into_value(self) -> T{
        self.value
    }

    pub fn set(&mut self, t: T){
        if let Some(ref p) = self.parent{
            p.send(t);
        }else{
            self.value = t;
        }
    }

    pub fn stream(self) -> UniqueStream<'a, T>{
        self.parent.map(|st| *st).unwrap_or_else(|| UniqueStream::never())
    }
}

// impl<'a,'b> UniqueProperty<'a,bool>{
//     pub fn switch<T: 'a + Clone + Debug>(self, then: Stream<'b,T>, else_: Stream<'b,T>) -> Stream<'b,T> where 'a: 'b{
//         let initial = self.to_value();
//         let cpy = self.stream().to_property(initial);
//         let then = then.filter_by(cpy.clone());
//         let else_ = else_.filter_by(!cpy);
//         then.merge(else_)
//     }
// }

impl<'a,'b,T: Clone + Debug> UniqueProperty<'a,Vec<T>>{
    pub fn push(&mut self, t: T){
        let mut current = (**self).clone();
        current.push(t);
        self.set(current);
    }
}

impl<'a,'b,T: Clone + Debug + 'a> Deref for UniqueProperty<'a,T>{
    type Target = T;
    fn deref(&self) -> &T{
        self.value()
    }
}

// impl<'a,'b,T:Clone + Debug + 'a> traits::Property<'b,T> for &'b UniqueProperty<'a,T>{
//     fn iter_async<'c>(self) -> IterAsync<'c,T> where 'b: 'c{
//         let v = self.value.clone();
//         let stream = self.parent.as_ref().map(|st| st.rc())
//             .unwrap_or_else(|| Stream::never());
//         IterAsync::new_initial(stream, v)
//     }
// }

impl<'a,T:Clone + Debug + 'a> traits::Property<'a,T> for UniqueProperty<'a,T>{
    fn iter_async<'b>(self) -> IterAsync<'b,T> where 'a: 'b{
        let initial = self.to_value();
        IterAsync::new_initial(self.stream(), initial)
    }

    fn to_parameter<'b>(self) -> Parameter<'b,T> where 'a: 'b{
        let initial = self.to_value();
        Parameter::from_parent(self.iter_async(), initial)
    }
}

impl<'a,'b,T: Clone + Debug> AsRef<T> for UniqueProperty<'a,T>{
    fn as_ref(&self) -> &T{
        self
    }
}


impl<'a,'b,T: Clone + Debug + 'a> Debug for UniqueProperty<'a,T>{
    fn fmt(&self, f: &mut Formatter) -> Result<(), Error>{
        f.write_str(&format!("Property{{ value: {:?} }}", self.value))
    }
}

impl<'a,'b,T: Clone + Debug + Serialize + 'a> Serialize for UniqueProperty<'a,T>{
    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error>{
        self.value.serialize(serializer)
    }
}

impl<'a,'b, 'de, T: Clone + Debug + Deserialize<'de> + 'a> Deserialize<'de> for UniqueProperty<'a,T>{
    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<UniqueProperty<'a,T>, D::Error>{
        T::deserialize(deserializer).map(|t| UniqueProperty::new(t))
    }
}

impl<'a,'b,T: Clone + Debug + Default> Default for UniqueProperty<'a,T>{
    fn default() -> UniqueProperty<'a,T>{
        UniqueProperty::new(T::default())
    }
}