use std::{any::Any, collections::HashMap, marker::PhantomData, mem, vec::IntoIter};

use log::warn;

use naia_shared::{
    Channel, ChannelKind, ComponentKind, EntityEvent, Message, MessageContainer, MessageKind,
    Replicate, Tick,
};

use super::user::{User, UserKey};

use crate::NaiaServerError;

pub struct Events<E: Copy> {
    connections: Vec<UserKey>,
    disconnections: Vec<(UserKey, User)>,
    ticks: Vec<Tick>,
    errors: Vec<NaiaServerError>,
    auths: HashMap<MessageKind, Vec<(UserKey, MessageContainer)>>,
    messages: HashMap<ChannelKind, HashMap<MessageKind, Vec<(UserKey, MessageContainer)>>>,
    spawns: Vec<(UserKey, E)>,
    despawns: Vec<(UserKey, E)>,
    inserts: HashMap<ComponentKind, Vec<(UserKey, E)>>,
    removes: HashMap<ComponentKind, Vec<(UserKey, E, Box<dyn Replicate>)>>,
    updates: HashMap<ComponentKind, Vec<(UserKey, E)>>,
    empty: bool,
}

impl<E: Copy> Events<E> {
    pub(crate) fn new() -> Self {
        Self {
            connections: Vec::new(),
            disconnections: Vec::new(),
            ticks: Vec::new(),
            errors: Vec::new(),
            auths: HashMap::new(),
            messages: HashMap::new(),
            spawns: Vec::new(),
            despawns: Vec::new(),
            inserts: HashMap::new(),
            removes: HashMap::new(),
            updates: HashMap::new(),
            empty: true,
        }
    }

    // Public

    pub fn is_empty(&self) -> bool {
        self.empty
    }

    pub fn read<V: Event<E>>(&mut self) -> V::Iter {
        return V::iter(self);
    }

    pub fn has<V: Event<E>>(&self) -> bool {
        return V::has(self);
    }

    // This method is exposed for adapter crates ... prefer using Events.read::<SomeEvent>() instead.
    pub fn has_messages(&self) -> bool {
        !self.messages.is_empty()
    }
    pub fn take_messages(
        &mut self,
    ) -> HashMap<ChannelKind, HashMap<MessageKind, Vec<(UserKey, MessageContainer)>>> {
        mem::take(&mut self.messages)
    }

    // This method is exposed for adapter crates ... prefer using Events.read::<SomeEvent>() instead.
    pub fn has_auths(&self) -> bool {
        !self.auths.is_empty()
    }
    pub fn take_auths(&mut self) -> HashMap<MessageKind, Vec<(UserKey, MessageContainer)>> {
        mem::take(&mut self.auths)
    }

    // These methods are exposed for adapter crates ... prefer using Events.read::<SomeEvent>() instead.
    pub fn has_inserts(&self) -> bool {
        !self.inserts.is_empty()
    }
    pub fn take_inserts(&mut self) -> Option<HashMap<ComponentKind, Vec<(UserKey, E)>>> {
        if self.inserts.is_empty() {
            return None;
        } else {
            return Some(mem::take(&mut self.inserts));
        }
    }

    // These methods are exposed for adapter crates ... prefer using Events.read::<SomeEvent>() instead.
    pub fn has_updates(&self) -> bool {
        !self.updates.is_empty()
    }
    pub fn take_updates(&mut self) -> Option<HashMap<ComponentKind, Vec<(UserKey, E)>>> {
        if self.updates.is_empty() {
            return None;
        } else {
            return Some(mem::take(&mut self.updates));
        }
    }

    // These method are exposed for adapter crates ... prefer using Events.read::<SomeEvent>() instead.
    pub fn has_removes(&self) -> bool {
        !self.removes.is_empty()
    }
    pub fn take_removes(
        &mut self,
    ) -> Option<HashMap<ComponentKind, Vec<(UserKey, E, Box<dyn Replicate>)>>> {
        if self.removes.is_empty() {
            return None;
        } else {
            return Some(mem::take(&mut self.removes));
        }
    }

    // Crate-public

    pub(crate) fn push_connection(&mut self, user_key: &UserKey) {
        self.connections.push(*user_key);
        self.empty = false;
    }

    pub(crate) fn push_disconnection(&mut self, user_key: &UserKey, user: User) {
        self.disconnections.push((*user_key, user));
        self.empty = false;
    }

    pub(crate) fn push_auth(&mut self, user_key: &UserKey, auth_message: MessageContainer) {
        let message_type_id = auth_message.kind();
        if !self.auths.contains_key(&message_type_id) {
            self.auths.insert(message_type_id, Vec::new());
        }
        let list = self.auths.get_mut(&message_type_id).unwrap();
        list.push((*user_key, auth_message));
        self.empty = false;
    }

    pub(crate) fn push_message(
        &mut self,
        user_key: &UserKey,
        channel_kind: &ChannelKind,
        message: MessageContainer,
    ) {
        push_message(&mut self.messages, user_key, channel_kind, message);
        self.empty = false;
    }

    pub(crate) fn push_tick(&mut self, tick: Tick) {
        self.ticks.push(tick);
        self.empty = false;
    }

    pub(crate) fn push_error(&mut self, error: NaiaServerError) {
        self.errors.push(error);
        self.empty = false;
    }

    pub(crate) fn push_spawn(&mut self, user_key: &UserKey, entity: &E) {
        self.spawns.push((*user_key, *entity));
        self.empty = false;
    }

    pub(crate) fn push_despawn(&mut self, user_key: &UserKey, entity: &E) {
        self.despawns.push((*user_key, *entity));
        self.empty = false;
    }

    pub(crate) fn push_insert(
        &mut self,
        user_key: &UserKey,
        entity: &E,
        component_kind: &ComponentKind,
    ) {
        if !self.inserts.contains_key(component_kind) {
            self.inserts.insert(*component_kind, Vec::new());
        }
        let list = self.inserts.get_mut(&component_kind).unwrap();
        list.push((*user_key, *entity));
        self.empty = false;
    }

    pub(crate) fn push_remove(
        &mut self,
        user_key: &UserKey,
        entity: &E,
        component: Box<dyn Replicate>,
    ) {
        let component_kind = component.kind();

        if !self.removes.contains_key(&component_kind) {
            self.removes.insert(component_kind, Vec::new());
        }
        let list = self.removes.get_mut(&component_kind).unwrap();
        list.push((*user_key, *entity, component));
        self.empty = false;
    }

    pub(crate) fn push_update(
        &mut self,
        user_key: &UserKey,
        entity: &E,
        component_kind: &ComponentKind,
    ) {
        if !self.updates.contains_key(component_kind) {
            self.updates.insert(*component_kind, Vec::new());
        }
        let list = self.updates.get_mut(component_kind).unwrap();
        list.push((*user_key, *entity));
        self.empty = false;
    }

    pub(crate) fn receive_entity_events(
        &mut self,
        user_key: &UserKey,
        entity_events: Vec<EntityEvent<E>>,
    ) {
        for event in entity_events {
            match event {
                EntityEvent::SpawnEntity(entity) => {
                    self.push_spawn(user_key, &entity);
                }
                EntityEvent::DespawnEntity(entity) => {
                    self.push_despawn(user_key, &entity);
                }
                EntityEvent::InsertComponent(entity, component_kind) => {
                    self.push_insert(user_key, &entity, &component_kind);
                }
                EntityEvent::RemoveComponent(entity, component_box) => {
                    self.push_remove(user_key, &entity, component_box);
                }
                EntityEvent::UpdateComponent(_tick, entity, component_kind) => {
                    self.push_update(user_key, &entity, &component_kind);
                }
            }
        }
    }
}

impl<E: Copy> Drop for Events<E> {
    fn drop(&mut self) {
        if !self.spawns.is_empty() {
            warn!("Dropped Server Spawn Event(s)! Make sure to handle these through `events.read::<SpawnEntityEvent>()`, and note that this may be an attack vector.");
        }
        if !self.inserts.is_empty() {
            warn!("Dropped Server Insert Event(s)! Make sure to handle these through `events.read::<InsertComponentEvent<Component>>()`, and note that this may be an attack vector.");
        }
        if !self.updates.is_empty() {
            warn!("Dropped Server Update Event(s)! Make sure to handle these through `events.read::<UpdateComponentEvent<Component>>()`, and note that this may be an attack vector.");
        }
    }
}

// Event Trait
pub trait Event<E: Copy> {
    type Iter;

    fn iter(events: &mut Events<E>) -> Self::Iter;

    fn has(events: &Events<E>) -> bool;
}

// ConnectEvent
pub struct ConnectEvent;
impl<E: Copy> Event<E> for ConnectEvent {
    type Iter = IntoIter<UserKey>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.connections);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.connections.is_empty()
    }
}

// DisconnectEvent
pub struct DisconnectEvent;
impl<E: Copy> Event<E> for DisconnectEvent {
    type Iter = IntoIter<(UserKey, User)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.disconnections);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.disconnections.is_empty()
    }
}

// Tick Event
pub struct TickEvent;
impl<E: Copy> Event<E> for TickEvent {
    type Iter = IntoIter<Tick>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.ticks);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.ticks.is_empty()
    }
}

// Error Event
pub struct ErrorEvent;
impl<E: Copy> Event<E> for ErrorEvent {
    type Iter = IntoIter<NaiaServerError>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.errors);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.errors.is_empty()
    }
}

// Auth Event
pub struct AuthEvent<M: Message> {
    phantom_m: PhantomData<M>,
}
impl<E: Copy, M: Message> Event<E> for AuthEvent<M> {
    type Iter = IntoIter<(UserKey, M)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let message_kind: MessageKind = MessageKind::of::<M>();
        return if let Some(messages) = events.auths.remove(&message_kind) {
            IntoIterator::into_iter(read_messages(messages))
        } else {
            IntoIterator::into_iter(Vec::new())
        };
    }

    fn has(events: &Events<E>) -> bool {
        let message_kind: MessageKind = MessageKind::of::<M>();
        return events.auths.contains_key(&message_kind);
    }
}

// Message Event
pub struct MessageEvent<C: Channel, M: Message> {
    phantom_c: PhantomData<C>,
    phantom_m: PhantomData<M>,
}
impl<E: Copy, C: Channel, M: Message> Event<E> for MessageEvent<C, M> {
    type Iter = IntoIter<(UserKey, M)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let output = read_channel_messages::<C, M>(&mut events.messages);
        return IntoIterator::into_iter(output);
    }

    fn has(events: &Events<E>) -> bool {
        let channel_kind: ChannelKind = ChannelKind::of::<C>();
        if let Some(channel_map) = events.messages.get(&channel_kind) {
            let message_kind: MessageKind = MessageKind::of::<M>();
            return channel_map.contains_key(&message_kind);
        }
        return false;
    }
}

pub(crate) fn read_channel_messages<C: Channel, M: Message>(
    messages: &mut HashMap<ChannelKind, HashMap<MessageKind, Vec<(UserKey, MessageContainer)>>>,
) -> Vec<(UserKey, M)> {
    let channel_kind: ChannelKind = ChannelKind::of::<C>();
    if let Some(channel_map) = messages.get_mut(&channel_kind) {
        let message_kind: MessageKind = MessageKind::of::<M>();
        if let Some(messages) = channel_map.remove(&message_kind) {
            return read_messages(messages);
        }
    }

    return Vec::new();
}

pub(crate) fn read_messages<M: Message>(
    messages: Vec<(UserKey, MessageContainer)>,
) -> Vec<(UserKey, M)> {
    let mut output_list: Vec<(UserKey, M)> = Vec::new();

    for (user_key, message) in messages {
        let message: M = Box::<dyn Any + 'static>::downcast::<M>(message.to_boxed_any())
            .ok()
            .map(|boxed_m| *boxed_m)
            .unwrap();
        output_list.push((user_key, message));
    }

    output_list
}

pub(crate) fn push_message(
    messages: &mut HashMap<ChannelKind, HashMap<MessageKind, Vec<(UserKey, MessageContainer)>>>,
    user_key: &UserKey,
    channel_kind: &ChannelKind,
    message: MessageContainer,
) {
    if !messages.contains_key(&channel_kind) {
        messages.insert(*channel_kind, HashMap::new());
    }
    let channel_map = messages.get_mut(&channel_kind).unwrap();
    let message_type_id = message.kind();
    if !channel_map.contains_key(&message_type_id) {
        channel_map.insert(message_type_id, Vec::new());
    }
    let list = channel_map.get_mut(&message_type_id).unwrap();
    list.push((*user_key, message));
}

// Spawn Event
pub struct SpawnEntityEvent;
impl<E: Copy> Event<E> for SpawnEntityEvent {
    type Iter = IntoIter<(UserKey, E)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.spawns);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.spawns.is_empty()
    }
}

// Despawn Event
pub struct DespawnEntityEvent;
impl<E: Copy> Event<E> for DespawnEntityEvent {
    type Iter = IntoIter<(UserKey, E)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let list = std::mem::take(&mut events.despawns);
        return IntoIterator::into_iter(list);
    }

    fn has(events: &Events<E>) -> bool {
        !events.despawns.is_empty()
    }
}

// Insert Event
pub struct InsertComponentEvent<C: Replicate> {
    phantom_c: PhantomData<C>,
}
impl<E: Copy, C: Replicate> Event<E> for InsertComponentEvent<C> {
    type Iter = IntoIter<(UserKey, E)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        if let Some(boxed_list) = events.inserts.remove(&component_kind) {
            return IntoIterator::into_iter(boxed_list);
        }

        return IntoIterator::into_iter(Vec::new());
    }

    fn has(events: &Events<E>) -> bool {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        events.inserts.contains_key(&component_kind)
    }
}

// Update Event
pub struct UpdateComponentEvent<C: Replicate> {
    phantom_c: PhantomData<C>,
}
impl<E: Copy, C: Replicate> Event<E> for UpdateComponentEvent<C> {
    type Iter = IntoIter<(UserKey, E)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        if let Some(boxed_list) = events.updates.remove(&component_kind) {
            return IntoIterator::into_iter(boxed_list);
        }

        return IntoIterator::into_iter(Vec::new());
    }

    fn has(events: &Events<E>) -> bool {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        events.updates.contains_key(&component_kind)
    }
}

// Remove Event
pub struct RemoveComponentEvent<C: Replicate> {
    phantom_c: PhantomData<C>,
}
impl<E: Copy, C: Replicate> Event<E> for RemoveComponentEvent<C> {
    type Iter = IntoIter<(UserKey, E, C)>;

    fn iter(events: &mut Events<E>) -> Self::Iter {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        if let Some(boxed_list) = events.removes.remove(&component_kind) {
            let mut output_list: Vec<(UserKey, E, C)> = Vec::new();

            for (user_key, entity, boxed_component) in boxed_list {
                let boxed_any = boxed_component.to_boxed_any();
                let component = boxed_any.downcast::<C>().unwrap();
                output_list.push((user_key, entity, *component));
            }

            return IntoIterator::into_iter(output_list);
        }

        return IntoIterator::into_iter(Vec::new());
    }

    fn has(events: &Events<E>) -> bool {
        let component_kind: ComponentKind = ComponentKind::of::<C>();
        events.removes.contains_key(&component_kind)
    }
}