use base64::Engine;
use kittybox::{database::Storage, indieauth::backend::AuthBackend, media::storage::MediaStore, webmentions::Webmention, compose_kittybox};
use tokio::{sync::Mutex, task::JoinSet};
use std::{env, time::Duration, sync::Arc};
use tracing::error;


#[tokio::main]
async fn main() {
    use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter, Registry};

    let tracing_registry = Registry::default()
        .with(EnvFilter::from_default_env())
        .with(
            #[cfg(debug_assertions)]
            tracing_tree::HierarchicalLayer::new(2)
                .with_bracketed_fields(true)
                .with_indent_lines(true)
                .with_verbose_exit(true),
            #[cfg(not(debug_assertions))]
            tracing_subscriber::fmt::layer().json()
                .with_ansi(std::io::IsTerminal::is_terminal(&std::io::stdout().lock()))
        );
    // In debug builds, also log to JSON, but to file.
    #[cfg(debug_assertions)]
    let tracing_registry = tracing_registry.with(
        tracing_subscriber::fmt::layer()
            .json()
            .with_writer({
                let instant = std::time::SystemTime::now()
                        .duration_since(std::time::UNIX_EPOCH)
                        .unwrap();
                move || std::fs::OpenOptions::new()
                    .append(true)
                    .create(true)
                    .open(
                        format!(
                            "{}.log.json",
                            instant
                            .as_secs_f64()
                            .to_string()
                            .replace('.', "_")
                        )
                    ).unwrap()
            })
    );
    tracing_registry.init();

    tracing::info!("Starting the kittybox server...");

    let backend_uri: url::Url = env::var("BACKEND_URI")
        .as_deref()
        .map(|s| url::Url::parse(s).expect("BACKEND_URI malformed"))
        .unwrap_or_else(|_| {
            error!("BACKEND_URI is not set, cannot find a database");
            std::process::exit(1);
        });
    let blobstore_uri: url::Url = env::var("BLOBSTORE_URI")
        .as_deref()
        .map(|s| url::Url::parse(s).expect("BLOBSTORE_URI malformed"))
        .unwrap_or_else(|_| {
            error!("BLOBSTORE_URI is not set, can't find media store");
            std::process::exit(1);
        });

    let authstore_uri: url::Url = env::var("AUTH_STORE_URI")
        .as_deref()
        .map(|s| url::Url::parse(s).expect("AUTH_STORE_URI malformed"))
        .unwrap_or_else(|_| {
            error!("AUTH_STORE_URI is not set, can't find authentication store");
            std::process::exit(1);
        });

    let job_queue_uri: url::Url = env::var("JOB_QUEUE_URI")
        .as_deref()
        .map(|s| url::Url::parse(s).expect("JOB_QUEUE_URI malformed"))
        .unwrap_or_else(|_| {
            error!("JOB_QUEUE_URI is not set, can't find job queue");
            std::process::exit(1);
        });

    // TODO: load from environment
    let cookie_key = axum_extra::extract::cookie::Key::from(&env::var("COOKIE_KEY")
        .as_deref()
        .map(|s| base64::prelude::BASE64_STANDARD.decode(s.as_bytes())
            .expect("Invalid cookie key: must be base64 encoded")
        )
        .unwrap()
    );

    let cancellation_token = tokio_util::sync::CancellationToken::new();
    let jobset: Arc<Mutex<JoinSet<()>>> = Default::default();

    let http: reqwest::Client = {
        #[allow(unused_mut)]
        let mut builder = reqwest::Client::builder()
            .user_agent(concat!(
                env!("CARGO_PKG_NAME"),
                "/",
                env!("CARGO_PKG_VERSION")
            ));
        if let Ok(certs) = std::env::var("KITTYBOX_CUSTOM_PKI_ROOTS") {
            // TODO: add a root certificate if there's an environment variable pointing at it
            for path in certs.split(':') {
                let metadata = match tokio::fs::metadata(path).await {
                    Ok(metadata) => metadata,
                    Err(err) if err.kind() == std::io::ErrorKind::NotFound => {
                        tracing::error!("TLS root certificate {} not found, skipping...", path);
                        continue;
                    }
                    Err(err) => panic!("Error loading TLS certificates: {}", err)
                };
                if metadata.is_dir() {
                    let mut dir = tokio::fs::read_dir(path).await.unwrap();
                    while let Ok(Some(file)) = dir.next_entry().await {
                        let pem = tokio::fs::read(file.path()).await.unwrap();
                        builder = builder.add_root_certificate(
                            reqwest::Certificate::from_pem(&pem).unwrap()
                        );
                    }
                } else {
                    let pem = tokio::fs::read(path).await.unwrap();
                    builder = builder.add_root_certificate(
                        reqwest::Certificate::from_pem(&pem).unwrap()
                    );
                }
            }
        }

        builder.build().unwrap()
    };

    let backend_type = backend_uri.scheme();
    let blobstore_type = blobstore_uri.scheme();
    let authstore_type = authstore_uri.scheme();
    let job_queue_type = job_queue_uri.scheme();

    macro_rules! compose_kittybox {
        ($auth:ty, $store:ty, $media:ty, $queue:ty) => { {
            type AuthBackend = $auth;
            type Storage = $store;
            type MediaStore = $media;
            type JobQueue = $queue;

            let state = kittybox::AppState {
                auth_backend: match AuthBackend::new(&authstore_uri).await {
                    Ok(auth) => auth,
                    Err(err) => {
                        error!("Error creating auth backend: {:?}", err);
                        std::process::exit(1);
                    }
                },
                storage: match Storage::new(&backend_uri).await {
                    Ok(db) => db,
                    Err(err) => {
                        error!("Error creating database: {:?}", err);
                        std::process::exit(1);
                    }
                },
                media_store: match MediaStore::new(&blobstore_uri).await {
                    Ok(media) => media,
                    Err(err) => {
                        error!("Error creating media store: {:?}", err);
                        std::process::exit(1);
                    }
                },
                job_queue: match JobQueue::new(&job_queue_uri).await {
                    Ok(queue) => queue,
                    Err(err) => {
                        error!("Error creating webmention job queue: {:?}", err);
                        std::process::exit(1);
                    }
                },
                http,
                background_jobs: jobset.clone(),
                cookie_key
            };

            type St = kittybox::AppState<AuthBackend, Storage, MediaStore, JobQueue>;
            let stateful_router = compose_kittybox::<St, AuthBackend, Storage, MediaStore, JobQueue>().await;
            let task = kittybox::webmentions::supervised_webmentions_task::<St, Storage, JobQueue>(&state, cancellation_token.clone());
            let router = stateful_router.with_state(state);

            (router, task)
        } }
    }

    let (router, webmentions_task): (axum::Router<()>, kittybox::webmentions::SupervisedTask) = match (authstore_type, backend_type, blobstore_type, job_queue_type) {
        ("file", "file", "file", "postgres") => {
            compose_kittybox!(
                kittybox::indieauth::backend::fs::FileBackend,
                kittybox::database::FileStorage,
                kittybox::media::storage::file::FileStore,
                kittybox::webmentions::queue::PostgresJobQueue<Webmention>
            )
        },
        ("file", "postgres", "file", "postgres") => {
            compose_kittybox!(
                kittybox::indieauth::backend::fs::FileBackend,
                kittybox::database::PostgresStorage,
                kittybox::media::storage::file::FileStore,
                kittybox::webmentions::queue::PostgresJobQueue<Webmention>
            )
        },
        (_, _, _, _) => {
            // TODO: refine this error.
            panic!("Invalid type for AUTH_STORE_URI, BACKEND_URI, BLOBSTORE_URI or JOB_QUEUE_URI");
        }
    };

    let mut servers: Vec<hyper::server::Server<hyper::server::conn::AddrIncoming, _>> = vec![];

    let build_hyper = |tcp: std::net::TcpListener| {
        tracing::info!("Listening on {}", tcp.local_addr().unwrap());
        // Set the socket to non-blocking so tokio can poll it
        // properly -- this is the async magic!
        tcp.set_nonblocking(true).unwrap();

        hyper::server::Server::from_tcp(tcp).unwrap()
            // Otherwise Chrome keeps connections open for too long
            .tcp_keepalive(Some(Duration::from_secs(30 * 60)))
            .serve(router.clone().into_make_service())
    };

    let mut listenfd = listenfd::ListenFd::from_env();
    for i in 0..(listenfd.len()) {
        match listenfd.take_tcp_listener(i) {
            Ok(Some(tcp)) => servers.push(build_hyper(tcp)),
            Ok(None) => {},
            Err(err) => tracing::error!("Error binding to socket in fd {}: {}", i, err)
        }
    }
    // TODO this requires the `hyperlocal` crate
    //#[rustfmt::skip]
    /*#[cfg(unix)] {
        let build_hyper_unix = |unix: std::os::unix::net::UnixListener| {
            {
                use std::os::linux::net::SocketAddrExt;

                let local_addr = unix.local_addr().unwrap();
                if let Some(pathname) = local_addr.as_pathname() {
                    tracing::info!("Listening on unix:{}", pathname.display());
                } else if let Some(name) = {
                    #[cfg(linux)]
                    local_addr.as_abstract_name();
                    #[cfg(not(linux))]
                    None::<&[u8]>
                } {
                    tracing::info!("Listening on unix:@{}", String::from_utf8_lossy(name));
                } else {
                    tracing::info!("Listening on unnamed unix socket");
                }
            }
            unix.set_nonblocking(true).unwrap();

            hyper::server::Server::builder(unix)
                .serve(router.clone().into_make_service())
        };
        for i in 0..(listenfd.len()) {
            match listenfd.take_unix_listener(i) {
                Ok(Some(unix)) => servers.push(build_hyper_unix(unix)),
                Ok(None) => {},
                Err(err) => tracing::error!("Error binding to socket in fd {}: {}", i, err)
            }
        }
    }*/
    if servers.is_empty() {
        servers.push(build_hyper({
            let listen_addr = env::var("SERVE_AT")
                .ok()
                .unwrap_or_else(|| "[::]:8080".to_string())
                .parse::<std::net::SocketAddr>()
                .unwrap_or_else(|e| {
                    error!("Cannot parse SERVE_AT: {}", e);
                    std::process::exit(1);
                });

            std::net::TcpListener::bind(listen_addr).unwrap()
        }))
    }
    // Drop the remaining copy of the router
    // to get rid of an extra reference to `jobset`
    drop(router);
    // Polling streams mutates them
    let mut servers_futures = Box::pin(servers.into_iter()
        .map(
            #[cfg(not(tokio_unstable))] |server| tokio::task::spawn(
                server.with_graceful_shutdown(cancellation_token.clone().cancelled_owned())
            ),
            #[cfg(tokio_unstable)] |server| {
                tokio::task::Builder::new()
                    .name(format!("Kittybox HTTP acceptor: {}", server.local_addr()).as_str())
                    .spawn(
                        server.with_graceful_shutdown(
                            cancellation_token.clone().cancelled_owned()
                        )
                    )
                    .unwrap()
            }
        )
        .collect::<futures_util::stream::FuturesUnordered<tokio::task::JoinHandle<Result<(), hyper::Error>>>>()
    );

    #[cfg(not(unix))]
    let shutdown_signal = tokio::signal::ctrl_c();
    #[cfg(unix)]
    let shutdown_signal = {
        use tokio::signal::unix::{signal, SignalKind};

        async move {
            let mut interrupt = signal(SignalKind::interrupt())
                .expect("Failed to set up SIGINT handler");
            let mut terminate = signal(SignalKind::terminate())
                .expect("Failed to setup SIGTERM handler");

            tokio::select! {
                _ = terminate.recv() => {},
                _ = interrupt.recv() => {},
            }
        }
    };
    use futures_util::stream::StreamExt;

    let exitcode: i32 = tokio::select! {
        // Poll the servers stream for errors.
        // If any error out, shut down the entire operation
        //
        // We do this because there might not be a good way
        // to recover from some errors without external help
        Some(Err(e)) = servers_futures.next() => {
            tracing::error!("Error in HTTP server: {}", e);
            tracing::error!("Shutting down because of error.");
            cancellation_token.cancel();

            1
        }
        _ = cancellation_token.cancelled() => {
            tracing::info!("Signal caught from watchdog.");

            0
        }
        _ = shutdown_signal => {
            tracing::info!("Shutdown requested by signal.");
            cancellation_token.cancel();

            0
        }
    };

    tracing::info!("Waiting for unfinished background tasks...");

    let _ = tokio::join!(
        webmentions_task,
        Box::pin(futures_util::future::join_all(
            servers_futures.iter_mut().collect::<Vec<_>>()
        )),
    );
    let mut jobset: tokio::task::JoinSet<()> = Arc::try_unwrap(jobset)
        .expect("Dangling jobset references present")
        .into_inner();
    while (jobset.join_next().await).is_some() {}
    tracing::info!("Shutdown complete, exiting.");
    std::process::exit(exitcode);
}