use std::any::{Any, TypeId};
use std::fmt;

use fxhash::FxHashMap;

#[derive(Default)]
/// A type map of request extensions.
pub struct Extensions {
    map: FxHashMap<TypeId, Box<dyn Any>>,
}

impl Extensions {
    /// Create an empty `Extensions`.
    #[inline]
    pub fn new() -> Extensions {
        Extensions {
            map: FxHashMap::default(),
        }
    }

    /// Insert a type into this `Extensions`.
    ///
    /// If a extension of this type already existed, it will
    /// be returned.
    pub fn insert<T: 'static>(&mut self, val: T) {
        self.map.insert(TypeId::of::<T>(), Box::new(val));
    }

    /// Check if container contains entry
    pub fn contains<T: 'static>(&self) -> bool {
        self.map.contains_key(&TypeId::of::<T>())
    }

    /// Get a reference to a type previously inserted on this `Extensions`.
    pub fn get<T: 'static>(&self) -> Option<&T> {
        self.map
            .get(&TypeId::of::<T>())
            .and_then(|boxed| boxed.downcast_ref())
    }

    /// Get a mutable reference to a type previously inserted on this `Extensions`.
    pub fn get_mut<T: 'static>(&mut self) -> Option<&mut T> {
        self.map
            .get_mut(&TypeId::of::<T>())
            .and_then(|boxed| boxed.downcast_mut())
    }

    /// Remove a type from this `Extensions`.
    ///
    /// If a extension of this type existed, it will be returned.
    pub fn remove<T: 'static>(&mut self) -> Option<T> {
        self.map
            .remove(&TypeId::of::<T>())
            .and_then(|boxed| boxed.downcast().ok().map(|boxed| *boxed))
    }

    /// Clear the `Extensions` of all inserted extensions.
    #[inline]
    pub fn clear(&mut self) {
        self.map.clear();
    }
}

impl fmt::Debug for Extensions {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Extensions").finish()
    }
}

#[test]
fn test_remove() {
    let mut map = Extensions::new();

    map.insert::<i8>(123);
    assert!(map.get::<i8>().is_some());

    map.remove::<i8>();
    assert!(map.get::<i8>().is_none());
}

#[test]
fn test_clear() {
    let mut map = Extensions::new();

    map.insert::<i8>(8);
    map.insert::<i16>(16);
    map.insert::<i32>(32);

    assert!(map.contains::<i8>());
    assert!(map.contains::<i16>());
    assert!(map.contains::<i32>());

    map.clear();

    assert!(!map.contains::<i8>());
    assert!(!map.contains::<i16>());
    assert!(!map.contains::<i32>());

    map.insert::<i8>(10);
    assert_eq!(*map.get::<i8>().unwrap(), 10);
}

#[test]
fn test_integers() {
    let mut map = Extensions::new();

    map.insert::<i8>(8);
    map.insert::<i16>(16);
    map.insert::<i32>(32);
    map.insert::<i64>(64);
    map.insert::<i128>(128);
    map.insert::<u8>(8);
    map.insert::<u16>(16);
    map.insert::<u32>(32);
    map.insert::<u64>(64);
    map.insert::<u128>(128);
    assert!(map.get::<i8>().is_some());
    assert!(map.get::<i16>().is_some());
    assert!(map.get::<i32>().is_some());
    assert!(map.get::<i64>().is_some());
    assert!(map.get::<i128>().is_some());
    assert!(map.get::<u8>().is_some());
    assert!(map.get::<u16>().is_some());
    assert!(map.get::<u32>().is_some());
    assert!(map.get::<u64>().is_some());
    assert!(map.get::<u128>().is_some());
}

#[test]
fn test_composition() {
    struct Magi<T>(T);

    struct Madoka {
        god: bool,
    }

    struct Homura {
        attempts: usize,
    }

    struct Mami {
        guns: usize,
    }

    let mut map = Extensions::new();

    map.insert(Magi(Madoka { god: false }));
    map.insert(Magi(Homura { attempts: 0 }));
    map.insert(Magi(Mami { guns: 999 }));

    assert!(!map.get::<Magi<Madoka>>().unwrap().0.god);
    assert_eq!(0, map.get::<Magi<Homura>>().unwrap().0.attempts);
    assert_eq!(999, map.get::<Magi<Mami>>().unwrap().0.guns);
}

#[test]
fn test_extensions() {
    #[derive(Debug, PartialEq)]
    struct MyType(i32);

    let mut extensions = Extensions::new();

    extensions.insert(5i32);
    extensions.insert(MyType(10));

    assert_eq!(extensions.get(), Some(&5i32));
    assert_eq!(extensions.get_mut(), Some(&mut 5i32));

    assert_eq!(extensions.remove::<i32>(), Some(5i32));
    assert!(extensions.get::<i32>().is_none());

    assert_eq!(extensions.get::<bool>(), None);
    assert_eq!(extensions.get(), Some(&MyType(10)));
}
