use std::time::{Duration, SystemTime};

use rocket::futures::lock::Mutex;
use tokio_postgres::{Client, Error, Statement};

use crate::GlobalState;

pub const STATEMENT_GET_LINK: usize = 0;
pub const STATEMENT_ADD_LINK: usize = 1;
pub const STATEMENT_ADD_TEMP_LINK: usize = 2;
pub const STATEMENT_DELETE_EXPIRED: usize = 3;
pub const N_STATEMENTS: usize = 4;

pub async fn get_link(state: &Mutex<GlobalState>, link: &str) -> Result<Option<String>, Error> {
    let lock = state.lock().await;
    Ok(lock
        .db_client
        .query_opt(&lock.statements[STATEMENT_GET_LINK], &[&link])
        .await?
        .map(|row| row.get(0)))
}

pub async fn add_link(state: &Mutex<GlobalState>, link: &str, url: &str) -> Result<(), Error> {
    let lock = state.lock().await;
    lock.db_client
        .execute(&lock.statements[STATEMENT_ADD_LINK], &[&link, &url])
        .await?;
    Ok(())
}

pub async fn add_temporary_link(
    state: &Mutex<GlobalState>,
    link: &str,
    url: &str,
    ttl: u64,
) -> Result<(), Error> {
    let time = SystemTime::now() + Duration::from_secs(ttl);
    let lock = state.lock().await;
    lock.db_client
        .execute(
            &lock.statements[STATEMENT_ADD_TEMP_LINK],
            &[&link, &url, &time],
        )
        .await?;
    Ok(())
}

pub async fn delete_expired_links(state: &Mutex<GlobalState>) -> Result<(), Error> {
    let lock = state.lock().await;
    lock.db_client
        .execute(&lock.statements[STATEMENT_DELETE_EXPIRED], &[])
        .await?;
    Ok(())
}

pub async fn prepare_statements(db: &Client) -> Result<[Statement; N_STATEMENTS], Error> {
    Ok([
        db.prepare("SELECT url FROM links WHERE id = $1").await?,
        db.prepare("INSERT INTO links (id, url) VALUES ($1, $2)")
            .await?,
        db.prepare("INSERT INTO links (id, url, valid_until) VALUES ($1, $2, $3)")
            .await?,
        db.prepare("DELETE FROM links WHERE valid_until < NOW()")
            .await?,
    ])
}

pub async fn prepare_tables(db: &Client) -> Result<(), Error> {
    db.execute("CREATE TABLE IF NOT EXISTS links (id TEXT PRIMARY KEY, url TEXT NOT NULL, valid_until TIMESTAMP NOT NULL)", &[]).await?;
    Ok(())
}