use regex::Regex;
use twilight_http::Client;
use twilight_gateway::Shard;
use twilight_mention::ParseMention;
use twilight_model::channel::Message;
use twilight_model::id::{marker::{ChannelMarker, UserMarker}, Id};
use std::{collections::HashMap, sync::Arc};
use tokio::sync::Mutex;
use futures::future::join_all;

#[derive(Clone)]
pub struct Member {
    pub discord_token: String,
    pub user_id: Arc<Mutex<Option<Id<UserMarker>>>>,
    pub message_pattern: Regex,
    pub shard: Arc<Mutex<Shard>>,
    pub client: Arc<Mutex<Client>>,
}

#[derive(Clone)]
pub struct System {
    pub followed_user: Id<UserMarker>,
    pub command_prefix: String,
    pub members: Vec<Member>,
    pub message_cache: Arc<Mutex<HashMap<Id<ChannelMarker>, (Member, Message)>>>
}

#[derive(Clone)]
pub enum Response {
    DefaultNoop,
    ExplicitNoop { delete_source: bool, member: Option<Member> },
    Proxy {member: Member, content: String},
}

pub enum SystemThreadCommand {
    Restart,
    ReloadConfig,
    ShutdownSystem,
    ShutdownAll,
}

impl System {
    pub async fn resolve_mention<'system>(&'system self, maybe_mention: Option<&str>) -> Option<&'system Member> {
        if let Some(mention) = maybe_mention {
            if let Ok(mention) = Id::<UserMarker>::parse(mention) {
                return self.get_member_by_id(mention).await;
            }
        }

        None
    }

    pub async fn get_member_by_id<'system>(&'system self, search_id: Id<UserMarker>) -> Option<&'system Member> {
        for member in &self.members {
            let is_member = {member.user_id.lock().await.map(|id| id == search_id).unwrap_or(false)};

            if is_member {
                return Some(&member)
            }
        }

        return None
    }

    pub async fn cache_most_recent_message(&self, channel: Id<ChannelMarker>, message: Message, member: Member) {
        self.message_cache.lock().await.insert(channel, (member, message));
    }

    pub async fn get_most_recent_message(&self, channel: Id<ChannelMarker>) -> Option<(Message, Member)> {
        self.message_cache.lock().await.get(&channel).map(|(member, message)| (message.clone(), member.clone()))
    }

    // Returns either the most recent message or replied message, with bool to indicate
    // if it was the most recent message (and the cache should be updated if that's modified)
    pub async fn resolve_message_target(&self, message: &Message) -> Option<(Message, bool)> {
        let most_recent_message = self.get_most_recent_message(message.channel_id).await;

        if let Some(result) = async {
            match message.kind {
                twilight_model::channel::message::MessageType::Regular => Some((most_recent_message?.0, true)),
                twilight_model::channel::message::MessageType::Reply => Some((
                    message.referenced_message.as_ref()?.as_ref().clone(),
                    message.referenced_message.as_ref()?.id == most_recent_message?.0.id
                )),
                _ => return None,
            }
        }.await {
            return Some(result)
        } else {
            let member_ids = join_all(self.members.iter().map(|member| async {
                member.user_id.lock().await.clone()
            })).await.iter().filter_map(|opt| *opt).collect::<Vec<_>>();

            for member in &self.members {
                let client = member.client.lock().await; 

                let lookup: Result<Vec<Message>, LookupError> = async {
                    Ok(client
                        .channel_messages(message.channel_id)
                        .limit(10)?
                        .await?
                        .model()
                        .await?
                    )
                }.await;

                if let Ok(recent_messages) = lookup {
                    let recent_message = recent_messages.into_iter().find(
                        |message| member_ids.contains(&message.author.id)
                    );

                    if let Some(most_recent_message) = recent_message {
                        return Some((most_recent_message, true))
                    } else {
                        // Successful lookup, but no recent messages, there's no point
                        // checking with the other members
                        return None
                    }
                }
            }

            None
        }
    }
}

struct LookupError;

impl From<twilight_validate::request::ValidationError> for LookupError {
    fn from(_value: twilight_validate::request::ValidationError) -> Self {
        Self
    }
}

impl From<twilight_http::Error> for LookupError {
    fn from(_value: twilight_http::Error) -> Self {
        Self
    }
}

impl From<twilight_http::response::DeserializeBodyError> for LookupError {
    fn from(_value: twilight_http::response::DeserializeBodyError) -> Self {
        Self
    }
}