use super::ThreadType;
use crate::{
    config::{Config, ALPACA_CRYPTO_DATA_API_URL, ALPACA_STOCK_DATA_API_URL},
    database,
    types::{
        alpaca::{
            api,
            shared::{Sort, Source},
        },
        news::Prediction,
        Backfill, Bar, Class, News,
    },
    utils::{duration_until, last_minute, FIFTEEN_MINUTES, ONE_MINUTE, ONE_SECOND},
};
use async_trait::async_trait;
use futures_util::future::join_all;
use log::{error, info, warn};
use std::{collections::HashMap, sync::Arc};
use time::OffsetDateTime;
use tokio::{
    spawn,
    sync::{mpsc, oneshot, Mutex},
    task::{block_in_place, JoinHandle},
    time::sleep,
    try_join,
};

pub enum Action {
    Backfill,
    Purge,
}

impl From<super::Action> for Action {
    fn from(action: super::Action) -> Self {
        match action {
            super::Action::Add => Self::Backfill,
            super::Action::Remove => Self::Purge,
        }
    }
}

pub struct Message {
    pub action: Action,
    pub symbols: Vec<String>,
    pub response: oneshot::Sender<()>,
}

impl Message {
    pub fn new(action: Action, symbols: Vec<String>) -> (Self, oneshot::Receiver<()>) {
        let (sender, receiver) = oneshot::channel::<()>();
        (
            Self {
                action,
                symbols,
                response: sender,
            },
            receiver,
        )
    }
}

#[async_trait]
pub trait Handler: Send + Sync {
    async fn select_latest_backfill(
        &self,
        symbol: String,
    ) -> Result<Option<Backfill>, clickhouse::error::Error>;
    async fn delete_backfills(&self, symbol: &[String]) -> Result<(), clickhouse::error::Error>;
    async fn delete_data(&self, symbol: &[String]) -> Result<(), clickhouse::error::Error>;
    async fn queue_backfill(&self, symbol: &str, fetch_to: OffsetDateTime);
    async fn backfill(&self, symbol: String, fetch_from: OffsetDateTime, fetch_to: OffsetDateTime);
    fn log_string(&self) -> &'static str;
}

pub async fn run(handler: Arc<Box<dyn Handler>>, mut receiver: mpsc::Receiver<Message>) {
    let backfill_jobs = Arc::new(Mutex::new(HashMap::new()));

    loop {
        let message = receiver.recv().await.unwrap();

        spawn(handle_backfill_message(
            handler.clone(),
            backfill_jobs.clone(),
            message,
        ));
    }
}

async fn handle_backfill_message(
    handler: Arc<Box<dyn Handler>>,
    backfill_jobs: Arc<Mutex<HashMap<String, JoinHandle<()>>>>,
    message: Message,
) {
    let mut backfill_jobs = backfill_jobs.lock().await;

    match message.action {
        Action::Backfill => {
            let log_string = handler.log_string();

            for symbol in message.symbols {
                if let Some(job) = backfill_jobs.get(&symbol) {
                    if !job.is_finished() {
                        warn!(
                            "Backfill for {} {} is already running, skipping.",
                            symbol, log_string
                        );
                        continue;
                    }
                }

                let handler = handler.clone();
                backfill_jobs.insert(
                    symbol.clone(),
                    spawn(async move {
                        let fetch_from = match handler
                            .select_latest_backfill(symbol.clone())
                            .await
                            .unwrap()
                        {
                            Some(latest_backfill) => latest_backfill.time + ONE_SECOND,
                            None => OffsetDateTime::UNIX_EPOCH,
                        };

                        let fetch_to = last_minute();

                        if fetch_from > fetch_to {
                            info!("No need to backfill {} {}.", symbol, log_string,);
                            return;
                        }

                        handler.queue_backfill(&symbol, fetch_to).await;
                        handler.backfill(symbol, fetch_from, fetch_to).await;
                    }),
                );
            }
        }
        Action::Purge => {
            for symbol in &message.symbols {
                if let Some(job) = backfill_jobs.remove(symbol) {
                    if !job.is_finished() {
                        job.abort();
                    }
                    let _ = job.await;
                }
            }

            try_join!(
                handler.delete_backfills(&message.symbols),
                handler.delete_data(&message.symbols)
            )
            .unwrap();
        }
    }

    message.response.send(()).unwrap();
}

struct BarHandler {
    config: Arc<Config>,
    data_url: &'static str,
    api_query_constructor: fn(
        config: &Arc<Config>,
        symbol: String,
        fetch_from: OffsetDateTime,
        fetch_to: OffsetDateTime,
        next_page_token: Option<String>,
    ) -> api::outgoing::bar::Bar,
}

fn us_equity_query_constructor(
    config: &Arc<Config>,
    symbol: String,
    fetch_from: OffsetDateTime,
    fetch_to: OffsetDateTime,
    next_page_token: Option<String>,
) -> api::outgoing::bar::Bar {
    api::outgoing::bar::Bar::UsEquity {
        symbols: vec![symbol],
        timeframe: ONE_MINUTE,
        start: Some(fetch_from),
        end: Some(fetch_to),
        limit: Some(10000),
        adjustment: None,
        asof: None,
        feed: Some(config.alpaca_source),
        currency: None,
        page_token: next_page_token,
        sort: Some(Sort::Asc),
    }
}

fn crypto_query_constructor(
    _: &Arc<Config>,
    symbol: String,
    fetch_from: OffsetDateTime,
    fetch_to: OffsetDateTime,
    next_page_token: Option<String>,
) -> api::outgoing::bar::Bar {
    api::outgoing::bar::Bar::Crypto {
        symbols: vec![symbol],
        timeframe: ONE_MINUTE,
        start: Some(fetch_from),
        end: Some(fetch_to),
        limit: Some(10000),
        page_token: next_page_token,
        sort: Some(Sort::Asc),
    }
}

#[async_trait]
impl Handler for BarHandler {
    async fn select_latest_backfill(
        &self,
        symbol: String,
    ) -> Result<Option<Backfill>, clickhouse::error::Error> {
        database::backfills_bars::select_where_symbol(&self.config.clickhouse_client, &symbol).await
    }

    async fn delete_backfills(&self, symbols: &[String]) -> Result<(), clickhouse::error::Error> {
        database::backfills_bars::delete_where_symbols(&self.config.clickhouse_client, symbols)
            .await
    }

    async fn delete_data(&self, symbols: &[String]) -> Result<(), clickhouse::error::Error> {
        database::bars::delete_where_symbols(&self.config.clickhouse_client, symbols).await
    }

    async fn queue_backfill(&self, symbol: &str, fetch_to: OffsetDateTime) {
        if self.config.alpaca_source == Source::Iex {
            let run_delay = duration_until(fetch_to + FIFTEEN_MINUTES + ONE_MINUTE);
            info!("Queing bar backfill for {} in {:?}.", symbol, run_delay);
            sleep(run_delay).await;
        }
    }

    async fn backfill(&self, symbol: String, fetch_from: OffsetDateTime, fetch_to: OffsetDateTime) {
        info!("Backfilling bars for {}.", symbol);

        let mut bars = vec![];
        let mut next_page_token = None;

        loop {
            let Ok(message) = api::incoming::bar::get_historical(
                &self.config,
                self.data_url,
                &(self.api_query_constructor)(
                    &self.config,
                    symbol.clone(),
                    fetch_from,
                    fetch_to,
                    next_page_token.clone(),
                ),
                None,
            )
            .await
            else {
                error!("Failed to backfill bars for {}.", symbol);
                return;
            };

            message.bars.into_iter().for_each(|(symbol, bar_vec)| {
                for bar in bar_vec {
                    bars.push(Bar::from((bar, symbol.clone())));
                }
            });

            if message.next_page_token.is_none() {
                break;
            }
            next_page_token = message.next_page_token;
        }

        if bars.is_empty() {
            info!("No bars to backfill for {}.", symbol);
            return;
        }

        let backfill = bars.last().unwrap().clone().into();

        database::bars::upsert_batch(&self.config.clickhouse_client, &bars)
            .await
            .unwrap();
        database::backfills_bars::upsert(&self.config.clickhouse_client, &backfill)
            .await
            .unwrap();

        info!("Backfilled bars for {}.", symbol);
    }

    fn log_string(&self) -> &'static str {
        "bars"
    }
}

struct NewsHandler {
    config: Arc<Config>,
}

#[async_trait]
impl Handler for NewsHandler {
    async fn select_latest_backfill(
        &self,
        symbol: String,
    ) -> Result<Option<Backfill>, clickhouse::error::Error> {
        database::backfills_news::select_where_symbol(&self.config.clickhouse_client, &symbol).await
    }

    async fn delete_backfills(&self, symbols: &[String]) -> Result<(), clickhouse::error::Error> {
        database::backfills_news::delete_where_symbols(&self.config.clickhouse_client, symbols)
            .await
    }

    async fn delete_data(&self, symbols: &[String]) -> Result<(), clickhouse::error::Error> {
        database::news::delete_where_symbols(&self.config.clickhouse_client, symbols).await
    }

    async fn queue_backfill(&self, symbol: &str, fetch_to: OffsetDateTime) {
        let run_delay = duration_until(fetch_to + FIFTEEN_MINUTES + ONE_MINUTE);
        info!("Queing news backfill for {} in {:?}.", symbol, run_delay);
        sleep(run_delay).await;
    }

    async fn backfill(&self, symbol: String, fetch_from: OffsetDateTime, fetch_to: OffsetDateTime) {
        info!("Backfilling news for {}.", symbol);

        let mut news = vec![];
        let mut next_page_token = None;

        loop {
            let Ok(message) = api::incoming::news::get_historical(
                &self.config,
                &api::outgoing::news::News {
                    symbols: vec![symbol.clone()],
                    start: Some(fetch_from),
                    end: Some(fetch_to),
                    limit: Some(50),
                    include_content: Some(true),
                    exclude_contentless: Some(false),
                    page_token: next_page_token.clone(),
                    sort: Some(Sort::Asc),
                },
                None,
            )
            .await
            else {
                error!("Failed to backfill news for {}.", symbol);
                return;
            };

            message.news.into_iter().for_each(|news_item| {
                news.push(News::from(news_item));
            });

            if message.next_page_token.is_none() {
                break;
            }
            next_page_token = message.next_page_token;
        }

        if news.is_empty() {
            info!("No news to backfill for {}.", symbol);
            return;
        }

        let inputs = news
            .iter()
            .map(|news| format!("{}\n\n{}", news.headline, news.content))
            .collect::<Vec<_>>();

        let predictions = join_all(inputs.chunks(self.config.max_bert_inputs).map(|inputs| {
            let sequence_classifier = self.config.sequence_classifier.clone();
            async move {
                let sequence_classifier = sequence_classifier.lock().await;
                block_in_place(|| {
                    sequence_classifier
                        .predict(inputs.iter().map(String::as_str).collect::<Vec<_>>())
                        .into_iter()
                        .map(|label| Prediction::try_from(label).unwrap())
                        .collect::<Vec<_>>()
                })
            }
        }))
        .await
        .into_iter()
        .flatten();

        let news = news
            .into_iter()
            .zip(predictions)
            .map(|(news, prediction)| News {
                sentiment: prediction.sentiment,
                confidence: prediction.confidence,
                ..news
            })
            .collect::<Vec<_>>();

        let backfill = (news.last().unwrap().clone(), symbol.clone()).into();

        database::news::upsert_batch(&self.config.clickhouse_client, &news)
            .await
            .unwrap();
        database::backfills_news::upsert(&self.config.clickhouse_client, &backfill)
            .await
            .unwrap();

        info!("Backfilled news for {}.", symbol);
    }

    fn log_string(&self) -> &'static str {
        "news"
    }
}

pub fn create_handler(thread_type: ThreadType, config: Arc<Config>) -> Box<dyn Handler> {
    match thread_type {
        ThreadType::Bars(Class::UsEquity) => Box::new(BarHandler {
            config,
            data_url: ALPACA_STOCK_DATA_API_URL,
            api_query_constructor: us_equity_query_constructor,
        }),
        ThreadType::Bars(Class::Crypto) => Box::new(BarHandler {
            config,
            data_url: ALPACA_CRYPTO_DATA_API_URL,
            api_query_constructor: crypto_query_constructor,
        }),
        ThreadType::News => Box::new(NewsHandler { config }),
    }
}