use std::{
    env::VarError,
    ffi::OsString,
    io::Write,
    net::{Ipv4Addr, SocketAddr},
};

use axum::{
    extract::{Path, State},
    http::{header::REFERER, HeaderMap},
    routing::get,
    Router,
};
use clap::Parser;
use sqlx::sqlite::{SqliteConnectOptions, SqlitePool, SqlitePoolOptions};
use tokio::net::TcpListener;
use url::Url;

#[tokio::main]
async fn main() {
    init();

    let pool = db().await;
    let app = Router::new()
        .route("/hit", get(register_hit))
        .route("/hits", get(get_hits))
        .route("/hits/:period", get(get_hits))
        .with_state(pool.clone())
        .into_make_service();
    let listener = mklistener().await;
    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal())
        .await
        .unwrap();

    pool.close().await;
}

async fn register_hit(State(db): State<SqlitePool>, headers: HeaderMap) -> String {
    let now = chrono::Utc::now();
    let referer = headers.get(REFERER);
    let page = if let Some(referer) = referer {
        let p = referer.to_str().unwrap_or("/").to_string();
        if let Ok(path) = Url::parse(&p) {
            path.path().to_string()
        } else {
            return "".to_string();
        }
    } else {
        return "".to_string();
    };
    let page = &page;

    let now = now.to_rfc3339();
    let now = &now;

    sqlx::query!("insert into hits (page, accessed) values (?, ?)", page, now)
        .execute(&db)
        .await
        .unwrap_or_default();

    "".to_string()
}

#[axum::debug_handler]
async fn get_hits(
    State(db): State<SqlitePool>,
    period: Option<Path<String>>,
    headers: HeaderMap,
) -> String {
    let now = chrono::Utc::now();
    let referer = headers.get(REFERER);
    let page = if let Some(referer) = referer {
        let p = referer.to_str().unwrap_or("/").to_string();
        if let Ok(path) = Url::parse(&p) {
            path.path().to_string()
        } else {
            return "".to_string();
        }
    } else {
        return "".to_string();
    };
    let page = &page;

    let count = match period.unwrap_or(Path("all".to_string())).as_str() {
        "day" => {
            let then = now - chrono::Duration::try_hours(24).unwrap();
            let then = then.to_rfc3339();
            get_period_hits(&db, page, &then).await
        }
        "week" => {
            let then = now - chrono::Duration::try_days(7).unwrap();
            let then = then.to_rfc3339();
            get_period_hits(&db, page, &then).await
        }
        _ => sqlx::query_scalar!("select count(*) from hits where page = ?", page)
            .fetch_one(&db)
            .await
            .unwrap_or(1),
    };

    format!("{count}")
}

async fn get_period_hits(db: &SqlitePool, page: &str, when: &str) -> i32 {
    sqlx::query_scalar!(
        "select count(*) from hits where page = ? and accessed > ?",
        page,
        when
    )
    .fetch_one(db)
    .await
    .unwrap_or(0)
}

//-************************************************************************
// li'l helpers
//-************************************************************************
#[derive(Debug, Parser)]
#[clap(version, about)]
struct Cli {
    #[clap(
        long,
        short,
        help = "Path to environment file.",
        default_value = ".env"
    )]
    pub env: OsString,
}

fn init() {
    let cli = Cli::parse();
    dotenvy::from_path_override(cli.env).expect("Could not read .env file.");
    env_logger::builder()
        .format(|buf, record| {
            let ts = buf.timestamp();
            writeln!(buf, "{}: {}", ts, record.args())
        })
        .init();
}

async fn db() -> SqlitePool {
    let dbfile = std::env::var("DATABASE_FILE").unwrap();
    let opts = SqliteConnectOptions::new()
        .foreign_keys(true)
        .create_if_missing(true)
        .journal_mode(sqlx::sqlite::SqliteJournalMode::Wal)
        .filename(&dbfile)
        .optimize_on_close(true, None);
    let pool = SqlitePoolOptions::new()
        .connect_with(opts.clone())
        .await
        .unwrap();

    sqlx::migrate!().run(&pool).await.unwrap();

    let count = sqlx::query_scalar!("select count(*) from hits")
        .fetch_one(&pool)
        .await
        .expect("could not get hit count from DB");
    log::info!("Connected to DB, found {count} total hits.");

    pool
}

async fn mklistener() -> TcpListener {
    let ip =
        std::env::var("LISTENING_ADDR").expect("Could not find $LISTENING_ADDR in environment");
    let ip: Ipv4Addr = ip
        .parse()
        .unwrap_or_else(|_| panic!("Could not parse {ip} as an IP address"));
    let port: u16 = std::env::var("LISTENING_PORT")
        .and_then(|p| p.parse().map_err(|_| VarError::NotPresent))
        .unwrap_or_else(|_| {
            panic!("Could not find LISTENING_PORT in env or parse if present");
        });
    let addr = SocketAddr::from((ip, port));
    TcpListener::bind(&addr).await.unwrap()
}

async fn shutdown_signal() {
    use tokio::signal;
    let ctrl_c = async {
        signal::ctrl_c()
            .await
            .expect("failed to install Ctrl+C handler");
    };

    #[cfg(unix)]
    let terminate = async {
        signal::unix::signal(signal::unix::SignalKind::terminate())
            .expect("failed to install signal handler")
            .recv()
            .await;
    };

    #[cfg(not(unix))]
    let terminate = std::future::pending::<()>();

    tokio::select! {
        _ = ctrl_c => {log::info!("shutting down")},
        _ = terminate => {},
    }
}