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use super::{events::EventType, notification::Notification, scope::Scope};
use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
use serde::{Deserialize, Serialize};
use std::fmt::Display;
use std::{
    any::Any,
    fmt::Debug,
    hash::{Hash, Hasher},
    sync::Arc,
};

pub mod array;
pub mod compounded;
pub mod single;

#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, BorshSerialize, BorshDeserialize, BorshSchema)]
pub enum Command {
    Start = 0,
    Stop = 1,
}

impl Display for Command {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let label = match self {
            Command::Start => "start",
            Command::Stop => "stop",
        };
        write!(f, "{label}")
    }
}

impl From<Command> for i32 {
    fn from(item: Command) -> Self {
        item as i32
    }
}

impl From<i32> for Command {
    // We make this conversion infallible by falling back to Start from any unexpected value.
    fn from(item: i32) -> Self {
        if item == 1 {
            Command::Stop
        } else {
            Command::Start
        }
    }
}

/// A subscription mutation including a start/stop command and
/// a notification scope.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Mutation {
    pub command: Command,
    pub scope: Scope,
}

impl Mutation {
    pub fn new(command: Command, scope: Scope) -> Self {
        Self { command, scope }
    }

    #[inline(always)]
    pub fn active(&self) -> bool {
        self.command == Command::Start
    }

    #[inline(always)]
    pub fn event_type(&self) -> EventType {
        (&self.scope).into()
    }
}

pub trait Subscription {
    fn event_type(&self) -> EventType;
    fn active(&self) -> bool;
    fn scope(&self) -> Scope;
}

pub trait Compounded: Subscription + AsAny + DynEq + CompoundedClone + Debug + Send + Sync {
    fn compound(&mut self, mutation: Mutation) -> Option<Mutation>;
}

impl PartialEq for dyn Compounded {
    fn eq(&self, other: &dyn Compounded) -> bool {
        DynEq::dyn_eq(self, other.as_any())
    }
}
impl Eq for dyn Compounded {}

pub type CompoundedSubscription = Box<dyn Compounded>;

pub trait Single: Subscription + AsAny + DynHash + DynEq + SingleClone + Debug + Send + Sync {
    fn mutate(&mut self, mutation: Mutation) -> Option<Vec<Mutation>>;
}

impl Hash for dyn Single {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.dyn_hash(state);
    }
}
impl PartialEq for dyn Single {
    fn eq(&self, other: &dyn Single) -> bool {
        DynEq::dyn_eq(self, other.as_any())
    }
}
impl Eq for dyn Single {}

pub type SingleSubscription = Box<dyn Single>;
pub type DynSubscription = Arc<dyn Single>;

pub trait AsAny {
    fn as_any(&self) -> &dyn Any;
}
impl<T: Any> AsAny for T {
    fn as_any(&self) -> &dyn Any {
        self
    }
}

pub trait DynHash {
    fn dyn_hash(&self, state: &mut dyn Hasher);
}
impl<H: Hash + ?Sized> DynHash for H {
    fn dyn_hash(&self, mut state: &mut dyn Hasher) {
        self.hash(&mut state);
    }
}

pub trait DynEq {
    fn dyn_eq(&self, other: &dyn Any) -> bool;
}
impl<T: Eq + Any> DynEq for T {
    fn dyn_eq(&self, other: &dyn Any) -> bool {
        if let Some(other) = other.downcast_ref::<Self>() {
            self == other
        } else {
            false
        }
    }
}

pub trait CompoundedClone {
    fn clone_arc(&self) -> Arc<dyn Compounded>;
    fn clone_box(&self) -> Box<dyn Compounded>;
}

impl<T> CompoundedClone for T
where
    T: 'static + Compounded + Clone,
{
    fn clone_arc(&self) -> Arc<dyn Compounded> {
        Arc::new(self.clone())
    }

    fn clone_box(&self) -> Box<dyn Compounded> {
        Box::new(self.clone())
    }
}

pub trait SingleClone {
    fn clone_arc(&self) -> Arc<dyn Single>;
    fn clone_box(&self) -> Box<dyn Single>;
}

impl<T> SingleClone for T
where
    T: 'static + Single + Clone,
{
    fn clone_arc(&self) -> Arc<dyn Single> {
        Arc::new(self.clone())
    }

    fn clone_box(&self) -> Box<dyn Single> {
        Box::new(self.clone())
    }
}

pub trait ApplyTo {
    fn apply_to<N: Notification>(&self, notification: &N) -> Option<N>;
}