use std::{collections::HashMap, future, hash::Hash};

use futures::{StreamExt, TryStreamExt};
use rocket_db_pools::mongodb::bson::to_bson;

use super::{prelude::*, util::PartyError};
use paste::paste;

api_routes!(
    create_event,
    stop_event,
    get_event,
    update_event,
    get_all_events,
    event_outcome,
);

#[derive(Clone, Debug, Default, Serialize, Deserialize, JsonSchema)]
#[serde(crate = "rocket::serde")]
pub struct EventOutcome {
    points: HashMap<String, i64>,
}

impl EventOutcome {
    pub async fn apply(&self, db: &Connection<Db>) -> Result<(), PartyError> {
        for (player, reward) in self.points.iter() {
            db.users()
                .update_one(
                    doc! { "id": player },
                    doc! { "$inc": { "score": reward } },
                    None,
                )
                .await?;
        }
        Ok(())
    }
}

/// # Event
///
/// An event in which participants can win or lose points
#[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
#[serde(crate = "rocket::serde")]
pub struct Event {
    /// Unique identifier of the event. This will be randomly generated and cannot be modified.
    #[serde(default = "uuid")]
    id: String,
    /// Has this event concluded?
    #[serde(default)]
    concluded: bool,
    /// Name of the event
    #[serde(default)]
    name: String,
    /// Description of the event
    #[serde(default)]
    description: String,
    /// Event type
    event_type: EventType,
}

impl Event {
    pub fn outcome(&self) -> EventOutcome {
        self.event_type.outcome()
    }

    pub fn conclude(&self) {}

    pub fn apply_update(&mut self, update: EventUpdate) -> Result<(), PartyError> {
        self.event_type.apply_update(update)
    }
}

fn uuid() -> String {
    uuid::Uuid::new_v4().to_string()
}

/// # EventSpec
///
/// A specification of an event
#[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
#[serde(crate = "rocket::serde")]
pub struct EventSpec {
    name: String,
    description: String,
    event_type: EventTypeSpec,
}

macro_rules! events {
    ($($module:ident => $name:ident),* $(,)?) => {
        paste! {
            /// # EventTypeSpec
            ///
            /// A specification of an event type
            #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
            #[serde(crate = "rocket::serde")]
            pub enum EventTypeSpec {
                $($name($module::[<$name Spec>]),)*
            }

            /// # EventUpdate
            ///
            /// An update that can be applied to an event
            #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
            #[serde(crate = "rocket::serde")]
            pub enum EventUpdate {
                $($name($module::[<$name Update>]),)*
            }

            /// # EventType
            ///
            /// An enumeration of event types
            #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
            #[serde(crate = "rocket::serde")]
            pub enum EventType {
                $($name($module::$name),)*
            }

            impl EventSpec {
                pub fn create_event(self) -> Result<Event, PartyError> {
                    let event_type = match self.event_type {
                        $(EventTypeSpec::$name(s) => {
                            EventType::$name($module::$name::from_spec(s))
                        })*
                    };

                    let event = Event {
                        id: uuid(),
                        name: self.name,
                        description: self.description,
                        concluded: false,
                        event_type,
                    };

                    Ok(event)
                }
            }

            impl EventType {
                pub fn apply_update(&mut self, update: EventUpdate) -> Result<(), PartyError> {
                    match (self, update) {
                        $((EventType::$name(s), EventUpdate::$name(u)) => {
                            s.apply_update(u)
                        })*
                        _ => Err(PartyError::Unknown("invalid update".into())),
                    }
                }

                pub fn outcome(&self) -> EventOutcome {
                    match self {
                        $(EventType::$name(s) => {
                            s.outcome()
                        })*
                    }
                }
            }
        }
    };
}

pub trait EventTrait {
    type Spec;
    type Update;

    fn from_spec(spec: Self::Spec) -> Self;

    fn apply_update(&mut self, _update: Self::Update) -> Result<(), PartyError> {
        Ok(())
    }

    fn outcome(&self) -> EventOutcome {
        EventOutcome::default()
    }
}

mod test {
    use super::*;

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct Test {
        num_players: i64,
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct TestSpec {
        num_players: i64,
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct TestUpdate {
        win_game: bool,
    }

    impl EventTrait for Test {
        type Spec = TestSpec;
        type Update = TestUpdate;

        fn from_spec(spec: TestSpec) -> Self {
            Test {
                num_players: spec.num_players,
            }
        }

        fn apply_update(&mut self, update: TestUpdate) -> Result<(), PartyError> {
            if update.win_game {
                self.num_players += 1;
            }
            Ok(())
        }

        fn outcome(&self) -> EventOutcome {
            let mut points = HashMap::new();
            points.insert("420".into(), self.num_players);
            EventOutcome { points }
        }
    }
}

mod team_game {
    use super::{
        free_for_all_game::{
            FreeForAllGame, FreeForAllGameSpec, FreeForAllGameUpdate,
            FreeForAllGameUpdateParticipants, FreeForAllGameUpdateRanking,
            FreeForAllGameUpdateRewards,
        },
        *,
    };

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct TeamGame {
        /// Map of teams with a name as key and an array of players as value
        teams: HashMap<String, Vec<String>>,

        #[serde(flatten)]
        ffa_game: FreeForAllGame,
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct TeamGameSpec {
        /// Map of teams with a name as key and an array of players as value
        teams: HashMap<String, Vec<String>>,

        /// Rewards for winning the game (first element for first place, second element for second
        /// place, etc.)
        #[schemars(example = "super::free_for_all_game::example_win_rewards")]
        win_rewards: Vec<i64>,
        /// Rewards for losing the game (first element for last place, second element for second to
        /// last place, etc.)
        #[schemars(example = "super::free_for_all_game::example_lose_rewards")]
        lose_rewards: Vec<i64>,
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub enum TeamGameUpdateInner {
        /// Add or replace a team with the given name and array of members
        SetTeam { team: String, members: Vec<String> },

        /// Remove team with given name
        RemoveTeam(String),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    #[serde(untagged)]
    pub enum TeamGameFfaInheritedUpdate {
        /// Change the ranking and scores
        Ranking(FreeForAllGameUpdateRanking),
        /// Update rewards
        Rewards(FreeForAllGameUpdateRewards),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    #[serde(untagged)]
    pub enum TeamGameUpdate {
        /// Team specific updates
        Team(TeamGameUpdateInner),
        /// Inherited from FreeForAllGame
        Ffa(TeamGameFfaInheritedUpdate),
    }

    impl EventTrait for TeamGame {
        type Spec = TeamGameSpec;
        type Update = TeamGameUpdate;

        fn from_spec(spec: TeamGameSpec) -> Self {
            let ffa_game_spec = FreeForAllGameSpec {
                participants: spec.teams.keys().cloned().collect(),
                win_rewards: spec.win_rewards,
                lose_rewards: spec.lose_rewards,
            };

            TeamGame {
                teams: spec.teams,
                ffa_game: FreeForAllGame::from_spec(ffa_game_spec),
            }
        }

        fn apply_update(&mut self, update: Self::Update) -> Result<(), PartyError> {
            match update {
                TeamGameUpdate::Ffa(update) => match update {
                    TeamGameFfaInheritedUpdate::Ranking(u) => {
                        self.ffa_game.apply_update(FreeForAllGameUpdate::Ranking(u))
                    }
                    TeamGameFfaInheritedUpdate::Rewards(u) => {
                        self.ffa_game.apply_update(FreeForAllGameUpdate::Rewards(u))
                    }
                },
                TeamGameUpdate::Team(update) => match update {
                    TeamGameUpdateInner::SetTeam { team, members } => {
                        self.ffa_game
                            .apply_update(FreeForAllGameUpdate::Participants(
                                FreeForAllGameUpdateParticipants::AddParticipant(team.clone()),
                            ))?;
                        self.teams.insert(team, members);
                        Ok(())
                    }
                    TeamGameUpdateInner::RemoveTeam(team) => {
                        self.ffa_game
                            .apply_update(FreeForAllGameUpdate::Participants(
                                FreeForAllGameUpdateParticipants::RemoveParticipant(team.clone()),
                            ))?;
                        self.teams.remove(&team);
                        Ok(())
                    }
                },
            }
        }

        fn outcome(&self) -> EventOutcome {
            let ffa_outcome = self.ffa_game.outcome();

            let mut points = HashMap::new();

            for (team, reward) in ffa_outcome.points.iter() {
                if let Some(team) = self.teams.get(team) {
                    for player in team {
                        let score = points.get(player).unwrap_or(&0);
                        points.insert(player.clone(), score + reward);
                    }
                }
            }

            EventOutcome { points }
        }
    }
}

mod free_for_all_game {
    use std::collections::HashSet;

    use super::*;

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub enum FreeForAllGameRanking {
        /// Ranking of participants by user id or team name (first element is first place, second element is second
        /// place, etc.)
        Ranking(Vec<String>),
        /// Score based ranking of participants/teams
        Scores(HashMap<String, i64>),
    }

    impl FreeForAllGameRanking {
        pub fn is_valid(&self, participants: &HashSet<String>) -> bool {
            match self {
                Self::Ranking(v) => v.iter().all(|p| participants.contains(p)),
                Self::Scores(m) => m.keys().all(|p| participants.contains(p)),
            }
        }
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct FreeForAllGame {
        /// Ranking of participants by user id or team name (first element is first place, second element is second
        /// place, etc.)
        ranking: Option<FreeForAllGameRanking>,

        /// Specification of the game
        #[serde(flatten)]
        spec: FreeForAllGameSpec,
    }

    pub fn example_win_rewards() -> Vec<i64> {
        vec![10, 7, 5, 3, 2, 1]
    }

    pub fn example_lose_rewards() -> Vec<i64> {
        vec![-3, -2, -1]
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub struct FreeForAllGameSpec {
        /// Array of user ids that participate in the game
        pub(crate) participants: HashSet<String>,

        /// Rewards for winning the game (first element for first place, second element for second
        /// place, etc.)
        #[schemars(example = "example_win_rewards")]
        pub(crate) win_rewards: Vec<i64>,
        /// Rewards for losing the game (first element for last place, second element for second to
        /// last place, etc.)
        #[schemars(example = "example_lose_rewards")]
        pub(crate) lose_rewards: Vec<i64>,
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub enum FreeForAllGameUpdateRanking {
        /// Replace the current ranking with the given ranking
        SetRanking(FreeForAllGameRanking),

        /// If the current ranking is of type `Scores`, apply the given score deltas
        ScoreDelta(HashMap<String, i64>),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub enum FreeForAllGameUpdateRewards {
        /// Set rewards for winning the game
        SetWinRewards(Vec<i64>),

        /// Set rewards for losing the game
        SetLoseRewards(Vec<i64>),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    pub enum FreeForAllGameUpdateParticipants {
        /// Set list of participants participating in the game
        SetParticipants(HashSet<String>),

        /// Add participant by id
        AddParticipant(String),

        /// Remove participant by id
        RemoveParticipant(String),
    }

    #[derive(Clone, Debug, Serialize, Deserialize, JsonSchema)]
    #[serde(crate = "rocket::serde")]
    #[serde(untagged)]
    pub enum FreeForAllGameUpdate {
        /// Change the ranking and scores
        Ranking(FreeForAllGameUpdateRanking),
        /// Update rewards
        Rewards(FreeForAllGameUpdateRewards),
        /// Update participants
        Participants(FreeForAllGameUpdateParticipants),
    }

    impl EventTrait for FreeForAllGame {
        type Spec = FreeForAllGameSpec;
        type Update = FreeForAllGameUpdate;

        fn from_spec(spec: Self::Spec) -> Self {
            FreeForAllGame {
                ranking: None,
                spec,
            }
        }

        fn apply_update(&mut self, update: Self::Update) -> Result<(), PartyError> {
            match update {
                FreeForAllGameUpdate::Ranking(update) => match update {
                    FreeForAllGameUpdateRanking::SetRanking(r) => {
                        if !r.is_valid(&self.spec.participants) {
                            return Err(PartyError::Unknown("invalid ranking, all participants mentioned in ranking must be participating".into()));
                        }
                        self.ranking = Some(r)
                    }
                    FreeForAllGameUpdateRanking::ScoreDelta(d) => match &mut self.ranking {
                        Some(FreeForAllGameRanking::Ranking(_)) | None => {
                            return Err(PartyError::Unknown("cannot apply score delta".into()))
                        }
                        Some(FreeForAllGameRanking::Scores(s)) => {
                            for (participant, delta) in d.iter() {
                                if let Some(value) = s.get(participant) {
                                    s.insert(participant.clone(), value + delta);
                                }
                            }
                        }
                    },
                },
                FreeForAllGameUpdate::Participants(update) => match update {
                    FreeForAllGameUpdateParticipants::AddParticipant(id) => {
                        self.spec.participants.insert(id);
                    }
                    FreeForAllGameUpdateParticipants::RemoveParticipant(id) => {
                        self.spec.participants.remove(&id);

                        if !self
                            .ranking
                            .as_ref()
                            .map(|r| r.is_valid(&self.spec.participants))
                            .unwrap_or(true)
                        {
                            self.spec.participants.insert(id);
                            return Err(PartyError::Unknown("cannot remove participant, all participants mentioned in ranking must be participating".into()));
                        }
                    }
                    FreeForAllGameUpdateParticipants::SetParticipants(participants) => {
                        if !self
                            .ranking
                            .as_ref()
                            .map(|r| r.is_valid(&participants))
                            .unwrap_or(true)
                        {
                            return Err(PartyError::Unknown("invalid list of participants, all participants mentioned in ranking must be participating".into()));
                        }
                        self.spec.participants = participants;
                    }
                },
                FreeForAllGameUpdate::Rewards(update) => match update {
                    FreeForAllGameUpdateRewards::SetWinRewards(rewards) => {
                        self.spec.win_rewards = rewards;
                    }
                    FreeForAllGameUpdateRewards::SetLoseRewards(rewards) => {
                        self.spec.lose_rewards = rewards;
                    }
                },
            }
            Ok(())
        }

        fn outcome(&self) -> EventOutcome {
            let ranking = match &self.ranking {
                Some(FreeForAllGameRanking::Ranking(r)) => r.clone(),
                Some(FreeForAllGameRanking::Scores(s)) => {
                    let mut results: Vec<(_, _)> = s.iter().collect();
                    results.sort_by(|a, b| b.1.cmp(a.1));
                    results.into_iter().map(|(k, _)| k.clone()).collect()
                }
                None => return EventOutcome::default(),
            };

            let mut points = HashMap::new();

            for (participant, reward) in ranking.iter().zip(self.spec.win_rewards.iter()) {
                let score = points.get(participant).unwrap_or(&0);
                points.insert(participant.clone(), score + reward);
            }

            for (participant, reward) in ranking.iter().rev().zip(self.spec.lose_rewards.iter()) {
                let score = points.get(participant).unwrap_or(&0);
                points.insert(participant.clone(), score + reward);
            }

            EventOutcome { points }
        }
    }
}

events!(test => Test, team_game => TeamGame, free_for_all_game => FreeForAllGame);

/// # Create event
///
/// If an `id` is supplied, it will be replaced by a randomly generated
/// one.
///
/// Returns the created event.
#[openapi(tag = "Event")]
#[post("/", data = "<event>")]
pub async fn create_event(
    _api_key: ApiKey,
    db: Connection<Db>,
    event: Json<EventSpec>,
) -> Result<Json<Event>, PartyError> {
    let event = event.into_inner().create_event()?;
    db.events().insert_one(&event, None).await?;
    Ok(Json(event))
}

/// # Update event
///
/// Update the supplied values in the event with the given id. The `id` of an event cannot be
/// changed and `concluded` will always be false.
#[openapi(tag = "Event")]
#[post("/<id>", data = "<update>")]
pub async fn update_event(
    _api_key: ApiKey,
    db: Connection<Db>,
    id: String,
    update: Json<EventUpdate>,
) -> Result<Status, PartyError> {
    let mut event = db
        .events()
        .find_one(doc! { "id": &id }, None)
        .await?
        .ok_or(PartyError::EventNotFound(id.clone()))?;

    event.apply_update(update.into_inner())?;

    db.events()
        .update_one(doc! { "id": &id }, doc! { "$set": to_bson(&event)? }, None)
        .await?;

    Ok(Status::Ok)
}

/// # Get event
///
/// Returns the event with the given id
#[openapi(tag = "Event")]
#[get("/<id>")]
pub async fn get_event(
    _api_key: ApiKey,
    db: Connection<Db>,
    id: String,
) -> Result<Json<Event>, PartyError> {
    Ok(Json(
        db.events()
            .find_one(doc! { "id": &id }, None)
            .await?
            .ok_or(PartyError::EventNotFound(id))?,
    ))
}

/// # Get events
///
/// Returns all events
#[openapi(tag = "Event")]
#[get("/?<concluded>")]
pub async fn get_all_events(
    _api_key: ApiKey,
    db: Connection<Db>,
    concluded: Option<bool>,
) -> Result<Json<Vec<Event>>, PartyError> {
    let filter = if let Some(concluded) = concluded {
        doc! { "concluded": concluded }
    } else {
        doc! {}
    };
    Ok(Json(
        db.events()
            .find(filter, None)
            .await?
            .filter(|e| future::ready(e.is_ok()))
            .try_collect()
            .await?,
    ))
}

/// # Get outcome
///
/// Returns the outcome of an event.
#[openapi(tag = "Event")]
#[get("/<id>/outcome")]
pub async fn event_outcome(
    _api_key: ApiKey,
    db: Connection<Db>,
    id: String,
) -> Result<Json<EventOutcome>, PartyError> {
    let event = db
        .events()
        .find_one(doc! { "id": &id }, None)
        .await?
        .ok_or(PartyError::EventNotFound(id.clone()))?;
    Ok(Json(event.outcome()))
}

/// # Stop event
///
/// This will conclude the event, apply the outcome to the users and return the outcome.
#[openapi(tag = "Event")]
#[post("/<id>/stop")]
pub async fn stop_event(
    _api_key: ApiKey,
    db: Connection<Db>,
    id: String,
) -> Result<Json<EventOutcome>, PartyError> {
    let event = db
        .events()
        .find_one(doc! { "id": &id }, None)
        .await?
        .ok_or(PartyError::EventNotFound(id.clone()))?;
    event.conclude();
    db.events()
        .update_one(
            doc! { "id": &id },
            doc! { "$set": { "concluded": true } },
            None,
        )
        .await?;
    let outcome = event.outcome();
    outcome.apply(&db).await?;

    Ok(Json(outcome))
}