use super::{InternalRecord, InternalRecords, Oid};
use crate::{
    action::{Action, CalcValue, Calculation, MsgAction, Query, Records, Reply, Update},
    document::{
        definition::{DocDef, DocFuncType},
        field::Field,
    },
    message::{wrapper::Message, MessageAction},
    mtterror::{ErrorID, MTTError},
    name::{NameID, NameType},
    queue::{
        data_director::{Include, Path, RegMsg, Register, RouteID},
        router::Queue,
    },
};
use std::{
    collections::{HashMap, HashSet},
    sync::mpsc::{channel, Receiver},
    thread::spawn,
};
use uuid::Uuid;

pub struct CreateDoc {
    queue: Queue,
    rx: Receiver<Message>,
}

impl CreateDoc {
    fn new(queue: Queue, rx: Receiver<Message>) -> Self {
        Self {
            queue: queue,
            rx: rx,
        }
    }

    pub fn start(mut queue: Queue) {
        let (tx, rx) = channel();
        let routes = [Path::new(
            Include::All,
            Include::All,
            Include::Just(Action::Create),
        )]
        .to_vec();
        let id = queue.add_sender(tx);
        for route in routes.iter() {
            let regmsg = Register::new(id.clone(), RegMsg::AddRoute(route.clone()));
            queue.send(Message::new(regmsg));
            rx.recv().unwrap();
        }
        let doc = CreateDoc::new(queue, rx);
        spawn(move || {
            doc.listen();
        });
    }

    fn listen(&self) {
        loop {
            let msg = self.rx.recv().unwrap();
            DocumentFile::start(self.queue.clone(), msg);
        }
    }
}

#[derive(Clone, Debug)]
pub enum IndexType {
    Index,
    Unique,
}

impl IndexType {
    fn create_index(&self) -> Index {
        match self {
            Self::Index => Index::new(),
            Self::Unique => Index::new_unique(),
        }
    }
}

#[derive(Debug)]
struct Index {
    data: HashMap<Field, HashSet<Oid>>,
    unique: bool,
}

impl Index {
    fn new() -> Self {
        Self {
            data: HashMap::new(),
            unique: false,
        }
    }

    fn new_unique() -> Self {
        Self {
            data: HashMap::new(),
            unique: true,
        }
    }

    fn internal_add(&mut self, field: &Field, oid: Oid) {
        let storage = match self.data.get_mut(field) {
            Some(data) => data,
            None => {
                let data = HashSet::new();
                self.data.insert(field.clone(), data);
                self.data.get_mut(field).unwrap()
            }
        };
        storage.insert(oid);
    }

    fn add(&mut self, field: Field, oid: Oid) -> Result<(), MTTError> {
        let oids = match self.data.get_mut(&field) {
            Some(data) => data,
            None => {
                self.data.insert(field.clone(), HashSet::new());
                self.data.get_mut(&field).unwrap()
            }
        };
        if self.unique && oids.len() > 0 {
            let err = MTTError::new(ErrorID::IndexEntryAlreadyExists(field.clone()));
            return Err(err);
        } else {
            oids.insert(oid);
        }
        Ok(())
    }

    fn pull(&self, calc: &Calculation) -> Result<HashSet<Oid>, MTTError> {
        let mut output = HashSet::new();
        for (key, value) in self.data.iter() {
            match calc.calculate(key) {
                Field::Boolean(data) => {
                    if data {
                        output = output.union(&value).cloned().collect();
                    }
                }
                _ => {
                    let err = MTTError::new(ErrorID::FieldInvalidType);
                    return Err(err);
                }
            }
        }
        Ok(output)
    }

    fn remove(&mut self, field: &Field, oid: &Oid) {
        match self.data.get_mut(field) {
            Some(oids) => {
                oids.remove(oid);
                if oids.len() == 0 {
                    self.data.remove(field);
                }
            }
            None => {}
        };
    }

    fn validate(&self, field: &Field) -> Result<(), MTTError> {
        if self.unique {
            match self.data.get(field) {
                Some(_) => {
                    let err = MTTError::new(ErrorID::IndexEntryAlreadyExists(field.clone()));
                    return Err(err);
                }
                None => {}
            }
        }
        Ok(())
    }
}

struct Indexes {
    data: HashMap<NameID, Index>,
}

impl Indexes {
    fn new(settings: &HashMap<NameID, IndexType>) -> Self {
        let mut output = HashMap::new();
        for (key, value) in settings.iter() {
            output.insert(key.clone(), value.create_index());
        }
        Self { data: output }
    }

    fn index_ids(&self) -> HashSet<&NameID> {
        self.data.keys().collect::<HashSet<&NameID>>()
    }

    fn pull(&self, field_id: &NameID, calc: &Calculation) -> Result<HashSet<Oid>, MTTError> {
        self.data.get(field_id).unwrap().pull(calc)
    }

    fn add_to_index(
        &mut self,
        field_name: &NameID,
        field: Field,
        oid: Oid,
    ) -> Result<(), MTTError> {
        let index = match self.data.get_mut(field_name) {
            Some(data) => data,
            None => return Ok(()),
        };
        index.add(field, oid)
    }

    fn validate(&self, field_name: &NameID, value: &Field) -> Result<(), MTTError> {
        match self.data.get(field_name) {
            Some(index) => match index.validate(value) {
                Ok(_) => {}
                Err(err) => return Err(err),
            },
            None => {}
        }
        Ok(())
    }

    fn iter_mut(&mut self) -> impl Iterator<Item = (&NameID, &mut Index)> {
        self.data.iter_mut()
    }
}

#[cfg(test)]
mod indexes {
    use super::*;
    use crate::action::{FieldType, Operand};

    fn get_fields(count: usize) -> Vec<Field> {
        let mut output = Vec::new();
        while output.len() < count {
            let field: Field = Uuid::new_v4().into();
            if !output.contains(&field) {
                output.push(field);
            }
        }
        output
    }

    fn get_oids(count: usize) -> Vec<Oid> {
        let mut output = Vec::new();
        while output.len() < count {
            let oid = Oid::new();
            if !output.contains(&oid) {
                output.push(oid);
            }
        }
        output
    }

    #[test]
    fn add_to_index() {
        let mut index = Index::new();
        let count = 3;
        let fields = get_fields(count);
        let oids = get_oids(count);
        for i in 0..count {
            index.add(fields[i].clone(), oids[i].clone()).unwrap();
        }
        for i in 0..count {
            let mut calc = Calculation::new(Operand::Equal);
            calc.add_value(fields[i].clone()).unwrap();
            calc.add_value(CalcValue::Existing(FieldType::Uuid))
                .unwrap();
            let result = index.pull(&calc).unwrap();
            assert_eq!(result.len(), 1);
            assert_eq!(result.iter().last().unwrap(), &oids[i]);
        }
    }

    #[test]
    fn index_can_handle_multiple_entries() {
        let mut index = Index::new();
        let count = 3;
        let fields = get_fields(1);
        let oids = get_oids(count);
        for i in 0..count {
            index.add(fields[0].clone(), oids[i].clone()).unwrap();
        }
        let mut calc = Calculation::new(Operand::Equal);
        calc.add_value(fields[0].clone()).unwrap();
        calc.add_value(CalcValue::Existing(FieldType::Uuid))
            .unwrap();
        let result = index.pull(&calc).unwrap();
        assert_eq!(result.len(), 3);
        for oid in oids {
            assert!(result.contains(&oid));
        }
    }

    #[test]
    fn can_remove_oid() {
        let mut index = Index::new();
        let count = 3;
        let pos = 1;
        let fields = get_fields(1);
        let oids = get_oids(count);
        for i in 0..count {
            index.add(fields[0].clone(), oids[i].clone()).unwrap();
        }
        index.remove(&fields[0], &oids[pos]);
        let mut calc = Calculation::new(Operand::Equal);
        calc.add_value(fields[0].clone()).unwrap();
        calc.add_value(CalcValue::Existing(FieldType::Uuid))
            .unwrap();
        let result = index.pull(&calc).unwrap();
        assert!(!result.contains(&oids[pos]), "should have removed oid");
    }

    #[test]
    fn are_empty_indexes_removed() {
        let mut index = Index::new();
        let field: Field = Uuid::new_v4().into();
        let oid = Oid::new();
        index.add(field.clone(), oid.clone()).unwrap();
        index.remove(&field, &oid);
        assert_eq!(index.data.len(), 0);
    }

    #[test]
    fn do_unique_indexes_error_on_duplicates() {
        let mut index = Index::new_unique();
        let field: Field = "fred".into();
        let oids = get_oids(2);
        index.add(field.clone(), oids[0].clone()).unwrap();
        match index.add(field.clone(), oids[0].clone()) {
            Ok(_) => unreachable!("should have been an error"),
            Err(err) => {
                let err_id = err.get_error_ids().back().unwrap();
                match err_id {
                    ErrorID::IndexEntryAlreadyExists(data) => assert_eq!(data, &field),
                    _ => unreachable!("got {:?}: should have been duplicate field", err),
                }
            }
        }
    }

    #[test]
    fn index_returns_validate() {
        let mut index = Index::new();
        let field: Field = "stuff".into();
        let oid = Oid::new();
        index.add(field.clone(), oid).unwrap();
        match index.validate(&field) {
            Ok(_) => {}
            Err(err) => unreachable!("got {:?}: should have returned without issue", err),
        }
    }

    #[test]
    fn unique_return_duplicate_error() {
        let mut index = Index::new_unique();
        let field: Field = "fred".into();
        let oid = Oid::new();
        index.add(field.clone(), oid).unwrap();
        match index.validate(&field) {
            Ok(_) => unreachable!("should have gotten a duplication error"),
            Err(err) => match err.get_error_ids().back().unwrap() {
                ErrorID::IndexEntryAlreadyExists(data) => assert_eq!(data, &field),
                _ => unreachable!("got {:?}: should have been duplicate field", err),
            },
        }
    }
}

struct DocumentFile {
    docdef: DocDef,
    docs: InternalRecords,
    indexes: Indexes,
    name_id: NameID,
    queue: Queue,
    routes: HashMap<RouteID, DocFuncType>,
    rx: Receiver<Message>,
}

impl DocumentFile {
    fn new(
        queue: Queue,
        rx: Receiver<Message>,
        docdef: DocDef,
        routes: HashMap<RouteID, DocFuncType>,
        name_id: NameID,
    ) -> Self {
        let indexes = Indexes::new(docdef.get_indexes());
        Self {
            docdef: docdef.clone(),
            docs: InternalRecords::new(),
            indexes: indexes,
            name_id: name_id,
            queue: queue,
            routes: routes,
            rx: rx,
        }
    }

    fn start(mut queue: Queue, msg: Message) {
        let (tx, rx) = channel();
        let action = msg.get_action();
        let docdef = match action {
            MsgAction::Create(data) => data.clone(),
            _ => unreachable!("got {:?}: should have been a create message", action),
        };
        let names = docdef.get_document_names();
        let id = queue.add_sender(tx);
        let reg_msg = Register::new(id, RegMsg::AddDocName(names.clone()));
        let rmsg = msg.response(reg_msg.clone());
        queue.send(rmsg.clone());
        let name_result = rx.recv().unwrap();
        let name_id = match name_result.get_action() {
            MsgAction::Register(data) => match data.get_msg() {
                RegMsg::DocumentNameID(data) => data,
                RegMsg::Error(err) => {
                    queue.remove_sender(&id);
                    queue.send(msg.response(err.clone()));
                    return;
                }
                _ => unreachable!("should only return a name id or an error"),
            },
            _ => unreachable!("should only return a name id or an error"),
        };
        let mut route_action: HashMap<RouteID, DocFuncType> = HashMap::new();
        for path_action in docdef.iter_routes() {
            let request = reg_msg.response(RegMsg::AddRoute(path_action.path()));
            let add_route = rmsg.response(request);
            queue.send(add_route);
            let result = rx.recv().unwrap();
            let route_id = match result.get_action() {
                MsgAction::Register(data) => match data.get_msg() {
                    RegMsg::RouteID(data) => data,
                    RegMsg::Error(err) => {
                        queue.remove_sender(&id);
                        queue.send(msg.response(err.clone()));
                        return;
                    }
                    _ => unreachable!("should only return a route id or an error"),
                },
                _ => unreachable!("should only return a route id or an error"),
            };
            route_action.insert(route_id.clone(), path_action.doc_function());
        }
        let mut doc = DocumentFile::new(
            queue.clone(),
            rx,
            docdef.clone(),
            route_action,
            name_id.clone(),
        );
        spawn(move || {
            doc.listen();
        });
        let reply = msg.response(MsgAction::DocumentCreated);
        queue.send(reply.clone());
    }

    fn listen(&mut self) {
        loop {
            let msg = self.rx.recv().unwrap();
            let route = msg.get_route();
            for (route_id, doc_func) in self.routes.clone().iter() {
                if route == route_id.into() {
                    match doc_func {
                        DocFuncType::Add => self.add_document(&msg),
                        DocFuncType::Delete => self.delete(&msg),
                        DocFuncType::Query => self.query(&msg),
                        DocFuncType::Show => self.queue.send(
                            msg.response(Reply::new(self.docdef.get_document_names()[0].clone())),
                        ),
                        DocFuncType::Update => self.update(&msg),
                        DocFuncType::ExistingQuery(action) => self.existing_query(&msg, action),
                        DocFuncType::Trigger(action) => self.trigger(&msg, action),
                    }
                }
            }
        }
    }

    fn validate<NT>(&self, field_name: NT, value: &Field) -> Result<Field, MTTError>
    where
        NT: Into<NameType>,
    {
        let id_holder = field_name.into();
        let field_id = match self.docdef.get_field_id(id_holder.clone()) {
            Ok(data) => data,
            Err(err) => return Err(err),
        };
        let output = match self.docdef.validate(id_holder.clone(), value) {
            Ok(data) => data,
            Err(err) => return Err(err),
        };
        match self.indexes.validate(&field_id, &output) {
            Ok(_) => {}
            Err(err) => return Err(err),
        }
        Ok(output)
    }

    fn add_document(&mut self, msg: &Message) {
        let addition = match msg.get_action() {
            MsgAction::Addition(data) => data,
            _ => return,
        };
        let mut holder = InternalRecord::new();

        let mut field_ids = self.docdef.get_field_ids();
        for (name, value) in addition.iter() {
            let field_id = match self.docdef.get_field_id(name) {
                Ok(id) => id,
                Err(mut err) => {
                    err.add_parent(ErrorID::Field(name.clone()));
                    err.add_parent(ErrorID::Document(msg.doc_name().clone()));
                    let reply = msg.response(err);
                    self.queue.send(reply);
                    return;
                }
            };
            let corrected = match self.validate(field_id.clone(), &value.get(&Field::None)) {
                Ok(data) => data,
                Err(mut err) => {
                    err.add_parent(ErrorID::Field(name.clone().into()));
                    err.add_parent(ErrorID::Document(msg.doc_name().clone()));
                    let reply = msg.response(err);
                    self.queue.send(reply);
                    return;
                }
            };
            holder.insert(field_id.clone(), corrected.clone());
            field_ids.remove(&field_id);
        }
        for field_id in field_ids.iter() {
            let corrected = match self.validate(field_id, &Field::None) {
                Ok(data) => data,
                Err(mut err) => {
                    err.add_parent(ErrorID::Field(field_id.clone().into()));
                    err.add_parent(ErrorID::Document(msg.doc_name().clone()));
                    let reply = msg.response(err);
                    self.queue.send(reply);
                    return;
                }
            };
            holder.insert(field_id.clone(), corrected.clone());
        }
        let mut records = Records::new(
            self.docdef.get_document_names().clone(),
            self.docdef.get_field_names().clone(),
        );
        if !holder.is_empty() {
            let mut oid = Oid::new();
            while self.docs.contains_key(&oid) {
                oid = Oid::new();
            }
            for (field_id, oids) in self.indexes.iter_mut() {
                let value = holder.get(field_id).unwrap();
                oids.internal_add(value, oid.clone());
            }
            self.docs.insert(oid.clone(), holder.clone());
            records.insert(oid, holder);
        }
        self.queue.send(msg.response(records.clone()));
        self.queue
            .send(msg.response(MsgAction::OnAddition(records)));
    }

    fn delete(&mut self, msg: &Message) {
        let delete = match msg.get_action() {
            MsgAction::Delete(data) => data,
            _ => unreachable!("should always be delete action"),
        };
        let records = match self.run_query(delete.get_query()) {
            Ok(data) => data,
            Err(mut err) => {
                err.add_parent(ErrorID::Document(msg.doc_name().into()));
                let reply = msg.response(err);
                self.queue.send(reply);
                return;
            }
        };
        for (oid, record) in records.iter() {
            for (field_id, index) in self.indexes.iter_mut() {
                index.remove(record.get(field_id).unwrap(), oid);
            }
            self.docs.remove(oid);
        }
        let rec = Records::with_data(
            self.docdef.get_document_names().clone(),
            self.docdef.get_field_names().clone(),
            records,
        );
        self.queue.send(msg.response(rec.clone()));
        self.queue.send(msg.response(MsgAction::OnDelete(rec)));
    }

    fn run_query(&self, query: &Query) -> Result<InternalRecords, MTTError> {
        let indexed_ids = self.indexes.index_ids();
        let mut indexed: HashMap<NameID, Calculation> = HashMap::new();
        let mut unindexed: HashMap<NameID, Calculation> = HashMap::new();
        for (field, data) in query.iter() {
            let id = match self.docdef.get_field_id(field.clone()) {
                Ok(fid) => {
                    let expected_type = self.docdef.get_field_type(field.clone()).unwrap();
                    if &data.get_type() != expected_type {
                        let mut err =
                            MTTError::new(ErrorID::FieldTypeExpected(expected_type.clone()));
                        err.add_parent(ErrorID::Field(field.clone()));
                        return Err(err);
                    }
                    fid
                }
                Err(mut err) => {
                    err.add_parent(ErrorID::Field(field.clone()));
                    return Err(err);
                }
            };
            if indexed_ids.contains(&id) {
                indexed.insert(id, data.clone());
            } else {
                unindexed.insert(id, data.clone());
            }
        }
        let mut oids: HashSet<Oid> = self.docs.keys().cloned().collect();
        for (field_id, calculation) in indexed.iter() {
            let holder = match self.indexes.pull(field_id, calculation) {
                Ok(data) => data,
                Err(err) => return Err(err),
            };
            oids = oids.intersection(&holder).cloned().collect();
        }
        let mut records = InternalRecords::new();
        for oid in oids.iter() {
            records.insert(oid.clone(), self.docs.get(oid).unwrap().clone());
        }
        let holder = oids.clone();
        for (oid, record) in records.iter() {
            for (field_id, calc) in unindexed.iter() {
                match calc.calculate(record.get(field_id).unwrap()) {
                    Field::Boolean(data) => {
                        if !data {
                            oids.remove(oid);
                            break;
                        }
                    }
                    _ => {
                        oids.remove(oid);
                        break;
                    }
                }
            }
        }
        let removals = holder.difference(&oids);
        for oid in removals {
            records.remove(oid);
        }
        Ok(records)
    }

    fn query(&self, msg: &Message) {
        let query = match msg.get_action() {
            MsgAction::Query(data) => data,
            _ => unreachable!("should receive a query"),
        };
        let records = match self.run_query(query) {
            Ok(data) => data,
            Err(mut err) => {
                err.add_parent(ErrorID::Document(msg.doc_name().into()));
                let reply = msg.response(err);
                self.queue.send(reply);
                return;
            }
        };
        let recs = Records::with_data(
            self.docdef.get_document_names().clone(),
            self.docdef.get_field_names().clone(),
            records,
        );
        self.queue.send(msg.response(recs.clone()));
        self.queue.send(msg.response(MsgAction::OnQuery(recs)));
    }

    fn run_update(
        &mut self,
        original: &InternalRecords,
        update: &Update,
        msg: &Message,
    ) -> Result<Records, MTTError> {
        let mut changes: HashMap<NameID, &CalcValue> = HashMap::new();
        for (key, value) in update.get_values().iter() {
            let field_id = match self.docdef.get_field_id(key) {
                Ok(id) => {
                    let expected_type = self.docdef.get_field_type(key.clone()).unwrap();
                    if &value.get_type() != expected_type {
                        let mut err =
                            MTTError::new(ErrorID::FieldTypeExpected(expected_type.clone()));
                        err.add_parent(ErrorID::Field(key.clone()));
                        return Err(err);
                    }
                    id
                }
                Err(mut err) => {
                    err.add_parent(ErrorID::Field(key.clone()));
                    return Err(err);
                }
            };
            changes.insert(field_id, value);
        }
        let mut indexes = Indexes::new(self.docdef.get_indexes());
        let mut updates = InternalRecords::new();
        for (oid, record) in original.iter() {
            let mut holder = record.clone();
            for (field_id, value) in changes.iter() {
                let field = value.get(holder.get(field_id).unwrap());
                let correction = match self.validate(field_id, &field) {
                    Ok(data) => data,
                    Err(err) => return Err(err),
                };
                holder.insert(field_id.clone(), correction.clone());
                match indexes.add_to_index(&field_id, correction, oid.clone()) {
                    Ok(_) => {}
                    Err(err) => return Err(err),
                }
            }
            updates.insert(oid.clone(), holder);
        }
        for (oid, new_rec) in updates.iter() {
            let old_rec = original.get(oid).unwrap();
            for (field_id, index) in self.indexes.iter_mut() {
                index.remove(old_rec.get(field_id).unwrap(), oid);
                index
                    .add(new_rec.get(field_id).unwrap().clone(), oid.clone())
                    .unwrap();
            }
            self.docs.insert(oid.clone(), new_rec.clone());
        }
        let recs = Records::with_data(
            self.docdef.get_document_names().clone(),
            self.docdef.get_field_names().clone(),
            updates,
        );
        self.queue
            .send(msg.response(MsgAction::OnUpdate(recs.clone())));
        Ok(recs)
    }

    fn update(&mut self, msg: &Message) {
        let update = match msg.get_action() {
            MsgAction::Update(data) => data,
            _ => unreachable!("should receive a update"),
        };
        let original = match self.run_query(update.get_query()) {
            Ok(result) => result,
            Err(mut err) => {
                err.add_parent(ErrorID::Document(msg.doc_name().into()));
                let reply = msg.response(err);
                self.queue.send(reply);
                return;
            }
        };
        let data = match self.run_update(&original, update, msg) {
            Ok(output) => output,
            Err(mut err) => {
                err.add_parent(ErrorID::Document(msg.doc_name().into()));
                let reply = msg.response(err);
                self.queue.send(reply);
                return;
            }
        };
        self.queue.send(msg.response(data));
    }

    fn existing_query(&mut self, msg: &Message, action: &MsgAction) {
        let recs = match msg.get_action() {
            MsgAction::OnQuery(data) => data,
            _ => unreachable!("should only receive on messages"),
        };
        match action {
            MsgAction::Update(change) => self
                .run_update(recs.get_internal_records(), change, msg)
                .unwrap(),
            _ => panic!("should not get here"),
        };
    }

    fn trigger(&self, msg: &Message, action: &MsgAction) {
        self.queue
            .send(msg.forward(self.name_id.clone(), action.clone()));
    }
}