extern crate toml;
extern crate crossbeam;
extern crate discord;
extern crate rand;
extern crate pvn;
extern crate echobox;
extern crate transformable_channels;
extern crate stc;
extern crate regex;

#[macro_use]
extern crate hlua;

use std::collections::BTreeMap;
use toml::Table;

mod modules;
use modules::Module;
use modules::loader::{ModuleLoader, ModuleLoaderError};

mod event;
use event::Envelope;

use std::sync::Arc;
use std::sync::mpsc;
use std::sync::mpsc::Sender;

use std::rc::Rc;
use std::cell::{Cell, RefCell};

use transformable_channels::mpsc::TransformableSender;

mod helpers;

use std::collections::btree_set::BTreeSet;

#[macro_use]
extern crate log;

pub struct Tenquestionmarks {
    subscriptions: BTreeMap<String, Subscription>
}

impl Tenquestionmarks {
    pub fn with_modules (modules: BTreeMap<String, Module>) -> Tenquestionmarks {
        let tqm = Tenquestionmarks {
            subscriptions: modules.into_iter().map(|(key, module)| {
                (key.clone(), Subscription::new(key.clone(), module))
            }).collect()
        };

        tqm
    }

    pub fn from_configuration (configuration: Table) -> Result<Tenquestionmarks, ModuleLoaderError> {
        let loader = ModuleLoader::new();
        let modules = loader.load_from_configuration(configuration)?;
        Result::Ok(Tenquestionmarks::with_modules(modules))
    }

    pub fn run (&self) {
        crossbeam::scope(|scope| {
            // Our main event channel.
            // Modules push events to tenquestionmarks using this channel.
            let (ref main_sender, ref main_receiver) = transformable_channels::mpsc::channel();

            // Module threads.
            // Each Module will produce events which tenquestionmarks will push
            // into all other Modules.
            // tenquestionmarks propagates all events to each Module through these
            // channels.
            let module_senders: BTreeMap<&str, Sender<Arc<Envelope>>> = self.subscriptions.iter().map(|(key, subscription)| {
                let from = key.clone();
                let main_sender_mapped = main_sender.map(move |envelope: Envelope| {
                    Envelope {
                        from: Some(from.clone()),
                        event: envelope.event,
                        to: envelope.to,
                        tags: envelope.tags
                    }
                });

                let (module_sender, module_receiver) = mpsc::channel();
                info!("Spawning thread for \"{}\"", key);
                scope.spawn(move || {
                    subscription.module.run(Box::new(main_sender_mapped), module_receiver);
                    info!("Thread for \"{}\" is exiting", key);
                });
                (&key[..], module_sender)
            }).collect();

            // tenquestionmarks main event loop.
            // tenquestionmarks receives events produced by Modules and pushes them
            // into all other Modules
            loop {
                match main_receiver.recv() {
                    Ok(envelope) => {
                        /*
                         * Check if the target module is a valid destination for the envelope.
                         * We want to deliver this envelope if all of the following are true:
                         *    1. The target module is not the originator of the envelope
                         *    2. The envelope's list of allowed recipients is empty, or specifically
                         *       names the target module.
                         */
                        let arc_envelope = Arc::new(envelope);
                        for (key, sender) in &module_senders {
                            let from_this = String::from(*key);
                            match self.subscriptions.get::<String>(&from_this) {
                                Some(subscription) => {
                                    if subscription.can_handle_event(&arc_envelope) {
                                        match sender.send(arc_envelope.clone()) {
                                            Err(err) => debug!("Failed to dispatch event to module \"{}\": {:?}", key, err),
                                            Ok(_) => {}
                                        }
                                    }
                                },
                                None => debug!("Failed to dispatch event to module \"{}\": No such module found!", key)
                            }
                        }
                    },
                    Err(err) => { error!("Failed to receive event in main event loop: {:?}", err); }
                }
            }
        });
    }
}

#[derive(Debug)]
pub struct Message {
    content: String,
    author: User,
    channel: Option<Channel>
}

impl Message {
    fn reply (&self, message: &str) {
        match self.channel {
            Some(ref channel) => channel.send(message),
            None => self.author.send(message)
        }
    }
}

#[derive(Debug)]
pub struct Channel {
    name: String,
    description: String,
    topic: String,
    sender: Box<MessageSender>
}

impl Channel {
    pub fn send (&self, message: &str) {
        self.sender.send_message(message);
    }
}

#[derive(Debug)]
pub struct User {
    name: String,
    sender: Box<MessageSender>
}

impl User {
    pub fn send (&self, message: &str) {
        self.sender.send_message(message);
    }
}

pub trait MessageSender : Sync + Send + std::fmt::Debug {
    fn send_message (&self, _: &str) {}
}

struct Subscription {
    pub module: Module,
    pub name: String,
    pub filters: BTreeSet<String>
}

impl Subscription {
    pub fn new (name: String, module: Module) -> Subscription {
        let filters: BTreeSet<String> = module.config.get("filters")
                                                     .and_then(|value| value.as_slice())
                                                     .map(|value| value.to_vec())
                                                     .unwrap_or(vec![])
                                                     .into_iter()
                                                     .map(|value| { String::from(value.as_str().unwrap()) })
                                                     .collect();

        Subscription {
            module: module,
            name: name,
            filters: filters
        }
    }

    pub fn can_handle_event (&self, envelope: &Envelope) -> bool {
        if Some(&self.name) == envelope.from.as_ref() {
            debug!("Refusing to transmit event to its originator ({:?})", self.name);
            return false;
        }
        else if !(envelope.to.is_empty() || !envelope.to.contains(&self.name)) {
            debug!(
                "Refusing to transmit envelope from {:?} to {:?} since it is not on the list of allowed recipients ({:?})",
                envelope.from,
                self.name,
                envelope.to
            );
            return false;
        }
        else if !(self.filters.is_empty() || self.filters.intersection(&envelope.tags).count() > 0) {
            debug!(
                "Refusing to transmit envelope from {:?} to {:?} since envelope was filtered out",
                envelope.from,
                self.name
            );
            return false;
        }

        true
    }
}