use futures::StreamExt;
use sea_orm::{
    ColumnTrait, DatabaseConnection, DbErr, EntityTrait, IntoActiveModel, PaginatorTrait,
    QueryFilter,
};
use thiserror::Error;

use crate::{
    amf::service::{
        information_req::{AMFRequest, AMFRequestType},
        pdf::AMFPdfError,
    },
    model::{in_process_transaction, transaction},
    repo::in_process_transaction::{InProcessTransactionError, NewInProcessTransaction},
};

pub struct GetAMFTransactions {
    max_req_size: u32,
}

#[derive(Debug, Error)]
pub enum GetAMFTransactionsError {
    #[error("The transaction {0} contains no pdf document")]
    NoDocument(String),
    #[error("Database error: {0}")]
    Database(DbErr),
    #[error("Error extracting information from pdf at {0} : {1}")]
    InformationExtraction(String, AMFPdfError),
}

impl Default for GetAMFTransactions {
    fn default() -> Self {
        GetAMFTransactions { max_req_size: 100 }
    }
}

impl GetAMFTransactions {
    pub fn new(max_req_size: u32) -> Self {
        GetAMFTransactions { max_req_size }
    }

    /// This task will extract the information from all AMF transactions until one is already found
    /// in the database. Another function should be used to download individual records.
    pub async fn run(&self, db: &DatabaseConnection) -> Result<(), GetAMFTransactionsError> {
        info!("Starting AMF transaction download task");
        let mut from = 0;

        let req = AMFRequest::new(AMFRequestType::DD, 0, 10);
        match req.get_list().await {
            Ok(_) => (),
            Err(e) => warn!("The AMF transaction public api is not available: {}", e),
        };

        let mut req = AMFRequest::new(AMFRequestType::DD, from, self.max_req_size);
        let mut tr_to_process = Vec::new();

        'outer: while let Ok(resp) = req.get_list().await {
            info!(
                "Downloading hit list from {} to {}",
                from,
                self.max_req_size + from
            );

            let list = resp.get_hits();

            for hit in list.iter() {
                let number = &hit.source.numero;

                if transaction::Entity::find()
                    .filter(transaction::Column::ForeignId.eq(number.to_owned()))
                    .one(db)
                    .await
                    .map_err(GetAMFTransactionsError::Database)?
                    .is_some()
                {
                    // We've saved this transaction before, so we stop here.
                    break 'outer;
                }

                if in_process_transaction::Entity::find()
                    .filter(in_process_transaction::Column::ForeignId.eq(number.to_owned()))
                    .one(db)
                    .await
                    .map_err(GetAMFTransactionsError::Database)?
                    .is_some()
                {
                    // We've registered this transaction before, so we stop here.
                    break 'outer;
                }

                tr_to_process.push(
                    NewInProcessTransaction::new(
                        &hit.get_foreign_id(),
                        &hit.get_documents()[0].path,
                        false,
                        None,
                    )
                    .into_active_model(),
                );
            }
            from += self.max_req_size;
            req = AMFRequest::new(AMFRequestType::DD, from, self.max_req_size);
        }

        if !tr_to_process.is_empty() {
            in_process_transaction::Entity::insert_many(tr_to_process)
                .exec(db)
                .await
                .map_err(GetAMFTransactionsError::Database)?;
        }

        let mut to_run = in_process_transaction::Entity::find()
            .filter(in_process_transaction::Column::Failed.eq(0))
            .paginate(db, 100);

        let n_not_failed = to_run
            .num_items()
            .await
            .map_err(GetAMFTransactionsError::Database)?;

        if n_not_failed == 0 {
            info!("No new transactions to process since last run");
            return Ok(());
        }

        info!("{} transactions will be processed", n_not_failed);

        while let Some(page) = to_run
            .fetch_and_next()
            .await
            .map_err(GetAMFTransactionsError::Database)?
        {
            let mut futures = Vec::new();
            for tr in page.iter() {
                futures.push(async move { tr.clone().process(db).await });
            }
            let stream = futures::stream::iter(futures).buffer_unordered(100);
            let _results: Vec<Result<(), InProcessTransactionError>> = stream.collect().await;
        }

        info!("AMF transactions download task finished execution");

        Ok(())
    }
}