use crate::classifier::Classifier;
use crate::db::{Db, IsSpam};
use crate::scrape;
use forgejo_api::Forgejo;
use std::collections::HashMap;
use std::path::Path;
use std::sync::{Arc, Mutex};

use crate::FORGEJO_POLL_DELAY;
use crate::GRACE_PERIOD;
use crate::{GUESS_LEGIT_THRESHOLD, GUESS_SPAM_THRESHOLD};

// Worker to refresh user data by periodically polling Forgejo

async fn try_refresh_user_data(
    forge: &Forgejo,
    db: Arc<Mutex<Db>>,
    classifier: Arc<Mutex<Classifier>>,
) -> anyhow::Result<()> {
    {
        let db = &db.lock().unwrap();
        let d = db.last_scrape.elapsed()?;
        if d < FORGEJO_POLL_DELAY {
            return Ok(());
        }
    }

    eprintln!("Fetching user data");
    let users = scrape::get_user_data(forge).await?;

    let db: &mut Db = &mut *db.lock().unwrap();
    let classifier = &classifier.lock().unwrap();

    // NB: Some user accounts may have been deleted since last fetch (hopefully
    // they were spammers).
    // Such users will appear in the current [db] but not in the new [users].
    // We don't want to keep them in the database, so we rebuild a fresh [db]
    // containing only data for users who still exist.

    let mut newdb = Db::from_users(users, HashMap::new(), classifier);

    // Import spam classification from the previous Db
    for (&user_id, user_data) in &newdb.users {
        let &score = newdb.score.get(&user_id).unwrap();
        if let Some(&user_was_spam) = db.is_spam.get(&user_id) {
            if (user_was_spam.as_bool() && score < GUESS_SPAM_THRESHOLD)
                || (!user_was_spam.as_bool() && score > GUESS_LEGIT_THRESHOLD)
            {
                eprintln!(
                    "Score for user {} changed past threshold; discarding our current classification",
                    user_data.login
                );
            } else {
                newdb.is_spam.insert(user_id, user_was_spam);
            }
        }
    }

    // switch to [newdb]
    let _ = std::mem::replace(db, newdb);

    db.store_to_path(Path::new("db.json")).unwrap(); // FIXME

    Ok(())
}

pub async fn refresh_user_data(
    forge: Arc<Forgejo>,
    db: Arc<Mutex<Db>>,
    classifier: Arc<Mutex<Classifier>>,
) {
    loop {
        tokio::time::sleep(FORGEJO_POLL_DELAY.mul_f32(0.1)).await;
        if let Err(e) = try_refresh_user_data(&forge, db.clone(), classifier.clone()).await {
            eprintln!("Error refreshing user data: {:?}", e);
        }
    }
}

// Worker to delete spam accounts after their grace period expired

async fn try_purge_account(forge: &Forgejo, login: &str) -> anyhow::Result<()> {
    forge
        .admin_delete_user(
            login,
            forgejo_api::structs::AdminDeleteUserQuery { purge: Some(true) },
        )
        .await?;
    Ok(())
}

pub async fn purge_spammer_accounts(forge: Arc<Forgejo>, db: Arc<Mutex<Db>>) {
    loop {
        tokio::time::sleep(std::time::Duration::from_secs(3600)).await;

        let mut classified_users = Vec::new();
        {
            let db = &db.lock().unwrap();
            for (id, user, is_spam) in db.classified_users() {
                classified_users.push((id, user.login.clone(), is_spam));
            }
        }

        for (user_id, login, is_spam) in classified_users {
            if let IsSpam::Spam { classified_at } = is_spam {
                match classified_at.elapsed() {
                    Ok(duration) if duration > GRACE_PERIOD => {
                        if let Err(e) = try_purge_account(&forge, &login).await {
                            eprintln!("Error while deleting spammer account {login}: {:?}", e)
                        } else {
                            eprintln!("Deleted spammer account {login}");
                            let db = &mut db.lock().unwrap();
                            db.users.remove(&user_id);
                            db.is_spam.remove(&user_id);
                            db.score.remove(&user_id);
                            db.tokens.remove(&user_id);
                            db.store_to_path(Path::new("db.json")).unwrap(); // FIXME
                        }
                    }
                    _ => (),
                }
            }
        }
    }
}