use std::collections::BTreeMap;
use std::collections::HashMap;
use std::fmt::Debug;
use std::io::Cursor;
use std::ops::RangeBounds;
use std::sync::Arc;
use std::sync::Mutex;

use libmcaptcha::AddVisitorResult;
use libmcaptcha::MCaptcha;
use openraft::async_trait::async_trait;
use openraft::storage::LogState;
use openraft::storage::Snapshot;
use openraft::AnyError;
use openraft::BasicNode;
use openraft::Entry;
use openraft::EntryPayload;
use openraft::ErrorSubject;
use openraft::ErrorVerb;
use openraft::LogId;
use openraft::RaftLogReader;
use openraft::RaftSnapshotBuilder;
use openraft::RaftStorage;
use openraft::SnapshotMeta;
use openraft::StorageError;
use openraft::StorageIOError;
use openraft::StoredMembership;
use openraft::Vote;
use serde::Deserialize;
use serde::Serialize;
use sqlx::Statement;
use tokio::sync::RwLock;
use url::quirks::set_pathname;

use crate::ExampleNodeId;
use crate::ExampleTypeConfig;

use actix::prelude::*;
use libmcaptcha::master::messages::{
    AddSite as AddCaptcha, AddVisitor, GetInternalData, RemoveCaptcha, Rename as RenameCaptcha,
    SetInternalData,
};
use libmcaptcha::{master::embedded::master::Master as EmbeddedMaster, system::System, HashCache};

pub mod system;

/**
 * Here you will set the types of request that will interact with the raft nodes.
 * For example the `Set` will be used to write data (key and value) to the raft database.
 * The `AddNode` will append a new node to the current existing shared list of nodes.
 * You will want to add any request that can write data in all nodes here.
 */
#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum ExampleRequest {
    //Set { key: String, value: String },
    AddVisitor(AddVisitor),
    AddCaptcha(AddCaptcha),
    RenameCaptcha(RenameCaptcha),
    RemoveCaptcha(RemoveCaptcha),
}

/**
 * Here you will defined what type of answer you expect from reading the data of a node.
 * In this example it will return a optional value from a given key in
 * the `ExampleRequest.Set`.
 *
 * TODO: Should we explain how to create multiple `AppDataResponse`?
 *
 */
#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum ExampleResponse {
    AddVisitorResult(Option<AddVisitorResult>),
    Empty,
    //    AddCaptchaResult, All returns ()
    //    RenameCaptchaResult,
    //    RemoveCaptchaResult,
}

#[derive(Debug)]
pub struct ExampleSnapshot {
    pub meta: SnapshotMeta<ExampleNodeId, BasicNode>,

    /// The data of the state machine at the time of this snapshot.
    pub data: Vec<u8>,
}

/**
 * Here defines a state machine of the raft, this state represents a copy of the data
 * between each node. Note that we are using `serde` to serialize the `data`, which has
 * a implementation to be serialized. Note that for this test we set both the key and
 * value as String, but you could set any type of value that has the serialization impl.
 */
pub struct ExampleStateMachine {
    pub last_applied_log: Option<LogId<ExampleNodeId>>,

    pub last_membership: StoredMembership<ExampleNodeId, BasicNode>,

    /// Application data.
    pub data: Arc<System<HashCache, EmbeddedMaster>>,
}

#[derive(Serialize, Deserialize, Clone)]
struct PersistableStateMachine {
    last_applied_log: Option<LogId<ExampleNodeId>>,

    last_membership: StoredMembership<ExampleNodeId, BasicNode>,

    /// Application data.
    data: HashMap<String, MCaptcha>,
}

impl PersistableStateMachine {
    async fn from_statemachine(m: &ExampleStateMachine) -> Self {
        let internal_data = m
            .data
            .master
            .send(GetInternalData)
            .await
            .unwrap()
            .await
            .unwrap()
            .unwrap();
        Self {
            last_applied_log: m.last_applied_log.clone(),
            last_membership: m.last_membership.clone(),
            data: internal_data,
        }
    }

    async fn to_statemachine(
        self,
        data: Arc<System<HashCache, EmbeddedMaster>>,
    ) -> ExampleStateMachine {
        data.master
            .send(SetInternalData {
                mcaptcha: self.data,
            })
            .await
            .unwrap();
        ExampleStateMachine {
            last_applied_log: self.last_applied_log,
            last_membership: self.last_membership,
            data,
        }
    }
}

pub struct ExampleStore {
    last_purged_log_id: RwLock<Option<LogId<ExampleNodeId>>>,

    /// The Raft log.
    log: RwLock<BTreeMap<u64, Entry<ExampleTypeConfig>>>,

    /// The Raft state machine.
    pub state_machine: RwLock<ExampleStateMachine>,

    /// The current granted vote.
    vote: RwLock<Option<Vote<ExampleNodeId>>>,

    snapshot_idx: Arc<Mutex<u64>>,

    current_snapshot: RwLock<Option<ExampleSnapshot>>,
}

impl ExampleStore {
    pub fn new(salt: String) -> Self {
        let state_machine = RwLock::new(ExampleStateMachine {
            last_applied_log: Default::default(),
            last_membership: Default::default(),
            data: system::init_system(salt),
        });

        Self {
            last_purged_log_id: Default::default(),
            log: Default::default(),
            state_machine,
            vote: Default::default(),
            snapshot_idx: Default::default(),
            current_snapshot: Default::default(),
        }
    }
}

#[async_trait]
impl RaftLogReader<ExampleTypeConfig> for Arc<ExampleStore> {
    async fn get_log_state(
        &mut self,
    ) -> Result<LogState<ExampleTypeConfig>, StorageError<ExampleNodeId>> {
        let log = self.log.read().await;
        let last = log.iter().rev().next().map(|(_, ent)| ent.log_id);

        let last_purged = *self.last_purged_log_id.read().await;

        let last = match last {
            None => last_purged,
            Some(x) => Some(x),
        };

        Ok(LogState {
            last_purged_log_id: last_purged,
            last_log_id: last,
        })
    }

    async fn try_get_log_entries<RB: RangeBounds<u64> + Clone + Debug + Send + Sync>(
        &mut self,
        range: RB,
    ) -> Result<Vec<Entry<ExampleTypeConfig>>, StorageError<ExampleNodeId>> {
        let log = self.log.read().await;
        let response = log
            .range(range.clone())
            .map(|(_, val)| val.clone())
            .collect::<Vec<_>>();
        Ok(response)
    }
}

#[async_trait]
impl RaftSnapshotBuilder<ExampleTypeConfig, Cursor<Vec<u8>>> for Arc<ExampleStore> {
    #[tracing::instrument(level = "trace", skip(self))]
    async fn build_snapshot(
        &mut self,
    ) -> Result<Snapshot<ExampleNodeId, BasicNode, Cursor<Vec<u8>>>, StorageError<ExampleNodeId>>
    {
        let data;
        let last_applied_log;
        let last_membership;

        {
            // Serialize the data of the state machine.
            let state_machine = self.state_machine.read().await;
            let persistable_state_machine =
                PersistableStateMachine::from_statemachine(&state_machine).await;

            data = serde_json::to_vec(&persistable_state_machine).map_err(|e| {
                StorageIOError::new(
                    ErrorSubject::StateMachine,
                    ErrorVerb::Read,
                    AnyError::new(&e),
                )
            })?;

            last_applied_log = state_machine.last_applied_log;
            last_membership = state_machine.last_membership.clone();
        }

        let snapshot_idx = {
            let mut l = self.snapshot_idx.lock().unwrap();
            *l += 1;
            *l
        };

        let snapshot_id = if let Some(last) = last_applied_log {
            format!("{}-{}-{}", last.leader_id, last.index, snapshot_idx)
        } else {
            format!("--{}", snapshot_idx)
        };

        let meta = SnapshotMeta {
            last_log_id: last_applied_log,
            last_membership,
            snapshot_id,
        };

        let snapshot = ExampleSnapshot {
            meta: meta.clone(),
            data: data.clone(),
        };

        {
            let mut current_snapshot = self.current_snapshot.write().await;
            *current_snapshot = Some(snapshot);
        }

        Ok(Snapshot {
            meta,
            snapshot: Box::new(Cursor::new(data)),
        })
    }
}

#[async_trait]
impl RaftStorage<ExampleTypeConfig> for Arc<ExampleStore> {
    type SnapshotData = Cursor<Vec<u8>>;
    type LogReader = Self;
    type SnapshotBuilder = Self;

    #[tracing::instrument(level = "trace", skip(self))]
    async fn save_vote(
        &mut self,
        vote: &Vote<ExampleNodeId>,
    ) -> Result<(), StorageError<ExampleNodeId>> {
        let mut v = self.vote.write().await;
        *v = Some(*vote);
        Ok(())
    }

    async fn read_vote(
        &mut self,
    ) -> Result<Option<Vote<ExampleNodeId>>, StorageError<ExampleNodeId>> {
        Ok(*self.vote.read().await)
    }

    #[tracing::instrument(level = "trace", skip(self, entries))]
    async fn append_to_log(
        &mut self,
        entries: &[&Entry<ExampleTypeConfig>],
    ) -> Result<(), StorageError<ExampleNodeId>> {
        let mut log = self.log.write().await;
        for entry in entries {
            log.insert(entry.log_id.index, (*entry).clone());
        }
        Ok(())
    }

    #[tracing::instrument(level = "debug", skip(self))]
    async fn delete_conflict_logs_since(
        &mut self,
        log_id: LogId<ExampleNodeId>,
    ) -> Result<(), StorageError<ExampleNodeId>> {
        tracing::debug!("delete_log: [{:?}, +oo)", log_id);

        let mut log = self.log.write().await;
        let keys = log
            .range(log_id.index..)
            .map(|(k, _v)| *k)
            .collect::<Vec<_>>();
        for key in keys {
            log.remove(&key);
        }

        Ok(())
    }

    #[tracing::instrument(level = "debug", skip(self))]
    async fn purge_logs_upto(
        &mut self,
        log_id: LogId<ExampleNodeId>,
    ) -> Result<(), StorageError<ExampleNodeId>> {
        tracing::debug!("delete_log: [{:?}, +oo)", log_id);

        {
            let mut ld = self.last_purged_log_id.write().await;
            assert!(*ld <= Some(log_id));
            *ld = Some(log_id);
        }

        {
            let mut log = self.log.write().await;

            let keys = log
                .range(..=log_id.index)
                .map(|(k, _v)| *k)
                .collect::<Vec<_>>();
            for key in keys {
                log.remove(&key);
            }
        }

        Ok(())
    }

    async fn last_applied_state(
        &mut self,
    ) -> Result<
        (
            Option<LogId<ExampleNodeId>>,
            StoredMembership<ExampleNodeId, BasicNode>,
        ),
        StorageError<ExampleNodeId>,
    > {
        let state_machine = self.state_machine.read().await;
        Ok((
            state_machine.last_applied_log,
            state_machine.last_membership.clone(),
        ))
    }

    #[tracing::instrument(level = "trace", skip(self, entries))]
    async fn apply_to_state_machine(
        &mut self,
        entries: &[&Entry<ExampleTypeConfig>],
    ) -> Result<Vec<ExampleResponse>, StorageError<ExampleNodeId>> {
        let mut res = Vec::with_capacity(entries.len());

        let mut sm = self.state_machine.write().await;

        for entry in entries {
            tracing::debug!(%entry.log_id, "replicate to sm");

            sm.last_applied_log = Some(entry.log_id);

            match entry.payload {
                EntryPayload::Blank => res.push(ExampleResponse::Empty),
                EntryPayload::Normal(ref req) => match req {
                    ExampleRequest::AddVisitor(msg) => {
                        let sm = self.state_machine.read().await;
                        res.push(ExampleResponse::AddVisitorResult(
                            sm.data
                                .master
                                .send(msg.clone())
                                .await
                                .unwrap()
                                .await
                                .unwrap()
                                .unwrap(),
                        ));
                    }
                    ExampleRequest::AddCaptcha(msg) => {
                        let sm = self.state_machine.read().await;
                        sm.data
                            .master
                            .send(msg.clone())
                            .await
                            .unwrap()
                            .await
                            .unwrap()
                            .unwrap();
                        res.push(ExampleResponse::Empty);
                    }
                    ExampleRequest::RenameCaptcha(msg) => {
                        let sm = self.state_machine.read().await;
                        sm.data
                            .master
                            .send(msg.clone())
                            .await
                            .unwrap()
                            .await
                            .unwrap()
                            .unwrap();
                        res.push(ExampleResponse::Empty);
                    }
                    ExampleRequest::RemoveCaptcha(msg) => {
                        let sm = self.state_machine.read().await;
                        sm.data
                            .master
                            .send(msg.clone())
                            .await
                            .unwrap()
                            .await
                            .unwrap()
                            .unwrap();
                        res.push(ExampleResponse::Empty);
                    }
                },
                EntryPayload::Membership(ref mem) => {
                    sm.last_membership = StoredMembership::new(Some(entry.log_id), mem.clone());
                    res.push(ExampleResponse::Empty)
                }
            };
        }
        Ok(res)
    }

    #[tracing::instrument(level = "trace", skip(self))]
    async fn begin_receiving_snapshot(
        &mut self,
    ) -> Result<Box<Self::SnapshotData>, StorageError<ExampleNodeId>> {
        Ok(Box::new(Cursor::new(Vec::new())))
    }

    #[tracing::instrument(level = "trace", skip(self, snapshot))]
    async fn install_snapshot(
        &mut self,
        meta: &SnapshotMeta<ExampleNodeId, BasicNode>,
        snapshot: Box<Self::SnapshotData>,
    ) -> Result<(), StorageError<ExampleNodeId>> {
        tracing::info!(
            { snapshot_size = snapshot.get_ref().len() },
            "decoding snapshot for installation"
        );

        let new_snapshot = ExampleSnapshot {
            meta: meta.clone(),
            data: snapshot.into_inner(),
        };

        // Update the state machine.
        {
            let updated_persistable_state_machine: PersistableStateMachine =
                serde_json::from_slice(&new_snapshot.data).map_err(|e| {
                    StorageIOError::new(
                        ErrorSubject::Snapshot(new_snapshot.meta.signature()),
                        ErrorVerb::Read,
                        AnyError::new(&e),
                    )
                })?;

            let mut state_machine = self.state_machine.write().await;
            let updated_state_machine = updated_persistable_state_machine
                .to_statemachine(state_machine.data.clone())
                .await;
            *state_machine = updated_state_machine;
        }

        // Update current snapshot.
        let mut current_snapshot = self.current_snapshot.write().await;
        *current_snapshot = Some(new_snapshot);
        Ok(())
    }

    #[tracing::instrument(level = "trace", skip(self))]
    async fn get_current_snapshot(
        &mut self,
    ) -> Result<
        Option<Snapshot<ExampleNodeId, BasicNode, Self::SnapshotData>>,
        StorageError<ExampleNodeId>,
    > {
        match &*self.current_snapshot.read().await {
            Some(snapshot) => {
                let data = snapshot.data.clone();
                Ok(Some(Snapshot {
                    meta: snapshot.meta.clone(),
                    snapshot: Box::new(Cursor::new(data)),
                }))
            }
            None => Ok(None),
        }
    }

    async fn get_log_reader(&mut self) -> Self::LogReader {
        self.clone()
    }

    async fn get_snapshot_builder(&mut self) -> Self::SnapshotBuilder {
        self.clone()
    }
}