#![feature(trait_upcasting)]

use std::{any::TypeId, any::Any, cell::{Ref, RefMut}};

use lyra_ecs::{AtomicRef, AtomicRefMut, World};

extern crate self as lyra_reflect;

pub use lyra_reflect_derive::*;

#[allow(unused_imports)]
pub(crate) mod lyra_engine {
    pub(crate) mod reflect {
        pub use super::super::*;
    }
}

pub mod reflected_struct;
pub use reflected_struct::*;

pub mod reflected_enum;
pub use reflected_enum::*;

pub mod reflected_tuple;
pub use reflected_tuple::*;

pub mod reflected_array;
pub use reflected_array::*;

pub mod reflected_list;
pub use reflected_list::*;

pub mod dynamic_tuple;
pub use dynamic_tuple::*;

pub mod reflected_hashmap;
pub use reflected_hashmap::*;

pub mod component;
pub use component::*;

pub mod resource;
pub use resource::*;

pub mod util;
pub mod field;
pub use field::*;
pub mod method;
pub use method::*;
pub mod registry;
pub use registry::*;

pub mod impls;

pub trait Reflect: Any {
    fn name(&self) -> String;
    fn type_id(&self) -> TypeId;

    fn as_any(&self) -> &dyn Any;
    fn as_any_mut(&mut self) -> &mut dyn Any;
    fn as_boxed_any(self: Box<Self>) -> Box<dyn Any>;
    
    /// Apply a value to this object.
    /// 
    /// # Panics
    /// 
    /// The method panics if
    /// * the type of `val` is not the same type as `self`
    // TODO: instead of taking as reference, it would make more sense to take a Box<dyn Reflect>.
    fn apply(&mut self, val: &dyn Reflect);

    /// Clone self into a [`Box<dyn Reflect>`]
    fn clone_inner(&self) -> Box<dyn Reflect>;

    /// Returns a reflected reference of the value of `self`
    fn reflect_ref(&self) -> ReflectRef;

    /// Returns a reflected mutable reference of the value of `self`
    fn reflect_mut(&mut self) -> ReflectMut;

    fn reflect_val(&self) -> &dyn Reflect;

    fn reflect_val_mut(&mut self) -> &mut dyn Reflect;

    /// Returns a boolean indicating if this reflected object is `other_typeid`
    /// 
    /// I can't use a generic here because this trait needs to be object safe
    fn is(&self, other_typeid: TypeId) -> bool {
        TypeId::of::<Self>() == other_typeid
    }
}

pub enum ReflectRef<'a> {
    Struct(&'a dyn Struct),
    Enum(&'a dyn Enum),
    Tuple(&'a dyn Tuple),
    Array(&'a dyn Array),
    List(&'a dyn List),
    Value(&'a dyn Reflect),
    Map(&'a dyn ReflectedMap),
}

impl<'a> ReflectRef<'a> {
    /// Gets the reflected reference as a struct.
    /// 
    /// # Safety
    /// * If `self` is not a `Struct` variant, this will panic
    pub fn as_struct(&self) -> &dyn Struct {
        match self {
            ReflectRef::Struct(s) => *s,
            _ => panic!("`self` is not a struct variant!"),
        }
    }
}

pub enum ReflectMut<'a> {
    Struct(&'a mut dyn Struct),
    Enum(&'a mut dyn Enum),
    Tuple(&'a mut dyn Tuple),
    Array(&'a mut dyn Array),
    List(&'a mut dyn List),
    Value(&'a mut dyn Reflect),
    Map(&'a dyn ReflectedMap),
}

impl<'a> ReflectMut<'a> {
    /// Retrieves self as a [`ReflectRef`].
    pub fn as_ref(&self) -> ReflectRef {
        match self {
            ReflectMut::Struct(v) => ReflectRef::Struct(*v),
            ReflectMut::Enum(v) => ReflectRef::Enum(*v),
            ReflectMut::Tuple(v) => ReflectRef::Tuple(*v),
            ReflectMut::Array(v) => ReflectRef::Array(*v),
            ReflectMut::List(v) => ReflectRef::List(*v),
            ReflectMut::Value(v) => ReflectRef::Value(*v),
            ReflectMut::Map(v) => ReflectRef::Map(*v),
        }
    }

    /// Gets the reflected reference as a struct.
    /// 
    /// # Safety
    /// * If `self` is not a `Struct` variant, this will panic
    pub fn as_struct(&self) -> &dyn Struct {
        match self {
            ReflectMut::Struct(s) => *s,
            _ => panic!("`self` is not a struct variant!"),
        }
    }

    /// Gets the reflected reference mutable as a struct.
    /// 
    /// # Safety
    /// * If `self` is not a `Struct` variant, this will panic
    pub fn as_struct_mut(&mut self) -> &mut dyn Struct {
        match self {
            ReflectMut::Struct(s) => *s,
            _ => panic!("`self` is not a struct variant!"),
        }
    }
}

pub enum ReflectEither<'a> {
    Ref(ReflectRef<'a>),
    Mut(ReflectMut<'a>),
}

impl<'a> ReflectEither<'a> {
    /// Converts `self` into a [`ReflectRef`]. Both variants can be retrieved as a reference.
    /* pub fn into_ref(self) -> ReflectRef<'a> {
        match self {
            Self::Ref(v) => v,
            Self::Mut(v) => v.as_ref()
        }
    } */

    /// Attempts to get `self` as a [`ReflectMut`].
    /// 
    /// If `self` is a `Ref`, `None` will be returned
    pub fn try_into_mut(self) -> Option<ReflectMut<'a>> {
        match self {
            Self::Mut(v) => Some(v),
            Self::Ref(_) => None
        }
    }

    /* pub fn as_ref(&self) -> &ReflectRef<'a> {
        match self {
            Self::Ref(v) => v,
            Self::Mut(v) => &v.as_ref()
        }
    } */

    pub fn is_mut(&self) -> bool {
        match self {
            ReflectEither::Ref(_) => false,
            ReflectEither::Mut(_) => true,
        }
    }
}

#[allow(dead_code)]
pub struct Value {
    inner: Box<dyn Reflect>,
    type_id: TypeId,
    ref_type_id: TypeId,
}

impl Value {
    pub fn new<T: Reflect>(val: T) -> Self {
        Self {
            inner: Box::new(val),
            type_id: TypeId::of::<T>(),
            ref_type_id: TypeId::of::<&T>(),
        }
    }

    /// Remove the stored object from Value
    pub fn take<T: Reflect>(self) -> Option<T> {
        (self.inner as Box<dyn Any>).downcast::<T>().ok().map(|v| *v)
    }

    pub fn get<T: Reflect>(&self) -> Option<&T> {
        self.inner.as_any().downcast_ref::<T>()
    }

    pub fn get_mut<T: Reflect>(&mut self) -> Option<&mut T> {
        self.inner.as_any_mut().downcast_mut::<T>()
    }
}

pub trait IntoValue {
    fn into_value(self) -> Value;
    fn type_id() -> TypeId;
}

impl<T: Reflect> IntoValue for T {
    fn into_value(self) -> Value {
        Value::new(self)
    }

    fn type_id() -> TypeId {
        TypeId::of::<T>()
    }
}

pub trait FromType<T> {
    fn from_type() -> Self;
}

pub trait ReflectWorldExt {
    /// Retrieves the type registry from the world.
    fn get_type_registry(&self) -> AtomicRef<TypeRegistry>;
    /// Retrieves the type registry mutably from the world.
    fn get_type_registry_mut(&self) -> AtomicRefMut<TypeRegistry>;
    /// Get a registered type from the type registry. Returns `None` if the type is not registered
    fn get_type<T>(&self, type_id: TypeId) -> Option<AtomicRef<RegisteredType>>;
    /// Get a mutable registered type from the type registry in the world. returns `None` if the type is not registered.
    fn get_type_mut<T>(&self, type_id: TypeId) -> Option<AtomicRefMut<RegisteredType>>;
    /// Get a registered type, or register a new type and return it.
    fn get_type_or_default<T>(&self, type_id: TypeId) -> AtomicRefMut<RegisteredType>;
}

impl ReflectWorldExt for World {
    fn get_type_registry(&self) -> AtomicRef<TypeRegistry> {
        self.get_resource::<TypeRegistry>()
    }
    
    fn get_type_registry_mut(&self) -> AtomicRefMut<TypeRegistry> {
        self.get_resource_mut::<TypeRegistry>()
    }
    
    fn get_type<T>(&self, type_id: TypeId) -> Option<AtomicRef<RegisteredType>> {
        let r = self.get_resource::<TypeRegistry>();
        if r.has_type(type_id) {
            Some(AtomicRef::map(r, |tr| tr.get_type(type_id).unwrap()))
        } else {
            None
        }
    }

    fn get_type_mut<T>(&self, type_id: TypeId) -> Option<AtomicRefMut<RegisteredType>> {
        let r = self.get_resource_mut::<TypeRegistry>();
        if r.has_type(type_id) {
            Some(AtomicRefMut::map(r, |tr| tr.get_type_mut(type_id).unwrap()))
        } else {
            None
        }
    }

    fn get_type_or_default<T>(&self, type_id: TypeId) -> AtomicRefMut<RegisteredType> {
        let r = self.get_resource_mut::<TypeRegistry>();
        AtomicRefMut::map(r, |tr| tr.get_type_or_default(type_id))
    }
}