use std::{collections::HashMap, sync::{Arc, RwLock, mpsc::{Sender, Receiver, channel}}};
use uuid::Uuid;

#[derive(Clone, Debug)]
enum MTTError {
    DocumentAlreadyExists(String),
    DocumentNotFound(String),
}

#[derive(Clone, Debug, PartialEq)]
enum Action {
    New,
    Query,
    Reply,
    Update,
}

#[derive(Clone)]
enum DocumentID {
    ID(Uuid),
    Name(String),
}

impl From<&str> for DocumentID {
    fn from(value: &str) -> Self {
        Self::Name(value.to_string())
    }
}

impl From<String> for DocumentID {
    fn from(value: String) -> Self {
        Self::Name(value)
    }
}

impl From<Uuid> for DocumentID {
    fn from(value: Uuid) -> Self {
        Self::ID(value)
    }
}

#[derive(Clone)]
struct Message {
    msg_id: Uuid,
    document_id: DocumentID,
    action: Action,
    //instructions: ?,
}

impl Message {
    fn new<D>(doc_id: D, action: Action) -> Self where D: Into<DocumentID> {
        Self {
            msg_id: Uuid::new_v4(),
            document_id: doc_id.into(),
            action: action
        }
    }

    fn get_message_id(&self) -> &Uuid {
        &self.msg_id
    }

    fn get_document_id(&self) -> &DocumentID {
        &self.document_id
    }

    fn reply(&self) -> Self {
        Self {
            msg_id: self.msg_id.clone(),
            document_id: DocumentID::Name("fred".to_string()),
            action: Action::Update,
        }
    }
}

#[cfg(test)]
mod messages {
    use super::*;

    #[test]
    fn can_the_document_be_a_stringi_reference() {
        let dts = ["one", "two"];
        for document in dts.into_iter() {
            let msg = Message::new(document, Action::New);
            match msg.get_document_id() {
                DocumentID::ID(_) => unreachable!("should have been a string id"),
                DocumentID::Name(data) => assert_eq!(data, document),
            }
            assert_eq!(msg.action, Action::New);
        }
    }

    #[test]
    fn can_the_document_be_a_string() {
        let dts = ["one".to_string(), "two".to_string()];
        for document in dts.into_iter() {
            let msg = Message::new(document.clone(), Action::Update);
            match msg.get_document_id() {
                DocumentID::ID(_) => unreachable!("should have been a string id"),
                DocumentID::Name(data) => assert_eq!(data, &document),
            }
            assert_eq!(msg.action, Action::Update);
        }
    }

    #[test]
    fn can_the_document_be_an_id() {
        let document = Uuid::new_v4();
        let msg = Message::new(document.clone(), Action::Query);
        match msg.get_document_id() {
            DocumentID::ID(data) => assert_eq!(data, &document),
            DocumentID::Name(_) => unreachable!("should have been an id"),
        }
        assert_eq!(msg.action, Action::Query);
    }

    #[test]
    fn is_the_message_id_random() {
        let mut ids: Vec<Uuid> = Vec::new();
        for _ in 0..5 {
            let msg = Message::new("tester", Action::New);
            let id = msg.get_message_id().clone();
            assert!(!ids.contains(&id), "{:?} containts  {}", ids, id);
            ids.push(id);
        }
    }

    #[test]
    fn does_the_message_reply_have_the_same_message_id() {
        let msg = Message::new("tester", Action::New);
        let reply = msg.reply();
        assert_eq!(reply.get_message_id(), msg.get_message_id());
    }
}

struct QueueData {
    senders: HashMap<Uuid, Sender<Message>>,
    names: HashMap<String, Uuid>,
}

impl QueueData {
    fn new() -> Self {
        Self  {
            senders: HashMap::new(),
            names: HashMap::new(),
        }
    }

    fn register(&mut self, name: String, tx: Sender<Message>) -> Result<Uuid, MTTError> {
        match self.names.get(&name) {
            Some(_) => return Err(MTTError::DocumentAlreadyExists(name)),
            None => {},
        }
        let id = Uuid::new_v4();
        self.senders.insert(id.clone(), tx);
        self.names.insert(name, id.clone());
        Ok(id)
    }

    fn send(&self, msg: Message) -> Result<(), MTTError> {
        let tx = match msg.get_document_id() {
            DocumentID::ID(id) => self.senders.get(id).unwrap(),
            DocumentID::Name(name) => {
                let docid = match self.names.get(name) {
                    Some(id) => id,
                    None => {
                        return Err(MTTError::DocumentNotFound(name.to_string()));
                        &Uuid::new_v4()
                    }
                };
                self.senders.get(docid).unwrap()
            },
        };
        tx.send(msg).unwrap();
        Ok(())
    }
}

#[cfg(test)]
mod queuedatas {
    use super::*;
    use std::time::Duration;

    static TIMEOUT: Duration = Duration::from_millis(500);

    #[test]
    fn can_a_new_document_type_be_rgistered() {
        let name = Uuid::new_v4().to_string();
        let (tx, rx) = channel();
        let mut queuedata = QueueData::new();
        let id = queuedata.register(name.clone(), tx).unwrap();
        let msg = Message::new(name.clone(), Action::Query);
        queuedata.send(msg.clone()).unwrap();
        let result = rx.recv_timeout(TIMEOUT).unwrap();
        assert_eq!(result.get_message_id(), msg.get_message_id());
        let msg = Message::new(id.clone(), Action::Query);
        queuedata.send(msg.clone()).unwrap();
        let result = rx.recv_timeout(TIMEOUT).unwrap();
        assert_eq!(result.get_message_id(), msg.get_message_id());
    }

    #[test]
    fn does_a_bad_document_name_fail() {
        let docname = Uuid::new_v4().to_string();
        let queuedata = QueueData::new();
        let msg = Message::new(docname.clone(), Action::Query);
        match queuedata.send(msg) {
            Ok(_) => unreachable!("should have been an error"),
            Err(data) => match data {
                MTTError::DocumentNotFound(doc) => assert_eq!(doc, docname),
                _ => unreachable!("should have been a not found error"),
            },
        }
    }

    #[test]
    fn should_error_on_duplicate_name_registration() {
        let name = Uuid::new_v4().to_string();
        let (tx1, _) = channel();
        let (tx2, _) = channel();
        let mut queuedata = QueueData::new();
        queuedata.register(name.clone(), tx1).unwrap();
        match queuedata.register(name.clone(), tx2) {
            Ok(_) => unreachable!("should have been an weeoe"),
            Err(data) => match data {
                MTTError::DocumentAlreadyExists(output) => assert_eq!(output, name),
                _ => unreachable!("should have been an already exists errorr"),
            },
        }
    }
}

#[derive(Clone)]
struct Queue {
    queue_data: Arc<RwLock<QueueData>>,
}

impl Queue {
    fn new() -> Self {
        Self {
            queue_data: Arc::new(RwLock::new(QueueData::new())),
        }
    }
}

#[cfg(test)]
mod queues {
    use super::*;

    #[test]
    fn create_a_queue() {
        Queue::new();
    }
}

struct Document;

impl Document {
    fn new() -> Self {
        Self {}
    }

    fn start(queue: Queue) {
    }

    fn listen(&self) {
    }
}

#[cfg(test)]
mod documents {
    use super::*;

    #[test]
    fn create_document_creation() {
        let queue = Queue::new();
        Document::start(queue);
    }
}

// Create a double hash map. posswible names that leads to an id that is int eh ids 
// \and the second is the id and the sender to be used.and a third for who wants to 
// listen to what.  
//
// The queue has a read write lock on the abbove strucutee.  A clone of this is given to
// every process.