use axum::Router;
use axum::response::{IntoResponse, Response};
use axum::routing::get;
use axum_login::AuthUser;
use axum_login::{AuthManagerLayerBuilder, login_required};
use clap::{Parser, Subcommand, arg, command};
use sqlx::sqlite::{SqliteConnectOptions, SqlitePoolOptions};
use std::collections::HashMap;
use std::str::FromStr;
use std::sync::{Arc, RwLock};
use tokio::net::TcpListener;
use tokio::signal;
use tokio::task::AbortHandle;
use tower_http::services::ServeDir;
use tower_sessions::{ExpiredDeletion, Expiry, SessionManagerLayer, cookie::Key};
use tower_sessions_sqlx_store::SqliteStore;
use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};

mod models;
use models::contact::MentionTrie;
use models::user::{Backend, User};

mod db;
use db::{Database, DbId};

mod web;
use web::{auth, contact, group, home, ics, journal, settings};

#[derive(Clone)]
struct AppStateEntry {
    database: Arc<Database>,
    contact_search: Arc<RwLock<MentionTrie>>,
}

#[derive(Clone)]
struct AppState {
    map: Arc<RwLock<HashMap<DbId, AppStateEntry>>>,
}

struct NameReference {
    name: String,
    contact_id: DbId,
}
impl AppState {
    pub fn new() -> Self {
        AppState {
            map: Arc::new(RwLock::new(HashMap::new())),
        }
    }
    pub async fn init(&mut self, user: &User) -> Result<Option<AppStateEntry>, AppError> {
        let database = Database::for_user(&user).await?;
        let mut trie = radix_trie::Trie::new();
        let mentionable_names = sqlx::query_as!(
            NameReference,
            "select name, contact_id from (
                select contact_id, name, count(name) as ct from names group by name
            ) where ct = 1;",
        )
        .fetch_all(&database.pool)
        .await?;

        for row in mentionable_names {
            trie.insert(
                row.name,
                format!("/contact/{}", DbId::try_from(row.contact_id)?),
            );
        }

        let groups: Vec<(String, String)> =
            sqlx::query_as("select distinct name, slug from groups")
                .fetch_all(&database.pool)
                .await?;

        for (group, slug) in groups {
            // TODO urlencode
            trie.insert(group, format!("/group/{}", slug));
        }

        let mut map = self.map.write().expect("rwlock poisoned");
        Ok(map.insert(
            user.id(),
            crate::AppStateEntry {
                database: Arc::new(database),
                contact_search: Arc::new(RwLock::new(trie)),
            },
        ))
    }
    pub fn remove(&mut self, user: &impl AuthUser<Id = DbId>) {
        let mut map = self.map.write().expect("rwlock poisoned");
        map.remove(&user.id());
    }
    pub fn db(&self, user: &impl AuthUser<Id = DbId>) -> Arc<Database> {
        let map = self.map.read().expect("rwlock poisoned");
        map.get(&user.id()).unwrap().database.clone()
    }
    pub fn contact_search(&self, user: &impl AuthUser<Id = DbId>) -> Arc<RwLock<MentionTrie>> {
        let map = self.map.read().expect("rwlock poisoned");
        map.get(&user.id()).unwrap().contact_search.clone()
    }
}

pub struct AppError(anyhow::Error);

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        (
            axum::http::StatusCode::INTERNAL_SERVER_ERROR,
            format!("Something went wrong: {}", self.0),
        )
            .into_response()
    }
}
impl<E> From<E> for AppError
where
    E: Into<anyhow::Error>,
{
    fn from(err: E) -> Self {
        Self(err.into())
    }
}

#[derive(Parser, Debug)]
#[command(version, about, long_about = None)]
struct Cli {
    #[command(subcommand)]
    command: Option<Commands>,
}

#[derive(Subcommand, Debug)]
enum Commands {
    /// run mascarpone server (default)
    Serve {
        /// port to bind
        #[arg(short, long, default_value_t = 3000)]
        port: u32,
    },

    SetPassword {
        /// username to create or set password
        username: String,
    },
}

async fn serve(port: &u32) -> Result<(), anyhow::Error> {
    let users_db = {
        let db_options = SqliteConnectOptions::from_str("users.db")?
            .create_if_missing(true)
            .to_owned();

        let db = SqlitePoolOptions::new().connect_with(db_options).await?;
        sqlx::migrate!("./migrations/users.db").run(&db).await?;
        db
    };

    let state = AppState::new();
    let session_store = SqliteStore::new(users_db.clone());
    session_store.migrate().await?;

    let deletion_task = tokio::task::spawn(
        session_store
            .clone()
            .continuously_delete_expired(tokio::time::Duration::from_secs(600)),
    );

    // Generate a cryptographic key to sign the session cookie.
    let key = Key::generate();

    let session_layer = SessionManagerLayer::new(session_store)
        .with_secure(false)
        .with_expiry(Expiry::OnInactivity(time::Duration::days(10)))
        .with_signed(key);

    let backend = Backend::new(users_db.clone());
    let auth_layer = AuthManagerLayerBuilder::new(backend, session_layer).build();

    tracing_subscriber::registry()
        .with(
            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| {
                format!(
                    "{}=debug,tower_http=debug,axum=trace,sqlx=debug",
                    env!("CARGO_CRATE_NAME")
                )
                .into()
            }),
        )
        .with(tracing_subscriber::fmt::layer().without_time())
        .init();

    let app = Router::new()
        .route("/", get(home::get::home))
        .merge(contact::router())
        .merge(group::router())
        .merge(journal::router())
        .merge(settings::router())
        .route_layer(login_required!(Backend, login_url = "/login"))
        .merge(auth::router())
        .merge(ics::router())
        .nest_service("/static", ServeDir::new("./hashed_static"))
        .layer(auth_layer)
        .with_state(state);

    let listener = TcpListener::bind(format!("0.0.0.0:{}", port)).await?;
    tracing::debug!("Starting axum on 0.0.0.0:{}...", port);
    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal(deletion_task.abort_handle()))
        .await
        .unwrap();

    deletion_task.await??;

    Ok(())
}

#[tokio::main]
async fn main() -> Result<(), anyhow::Error> {
    let cli = Cli::parse();

    match &cli.command {
        Some(Commands::SetPassword { username }) => {
            let users_db = {
                let db_options = SqliteConnectOptions::from_str("users.db")?
                    .create_if_missing(true)
                    .to_owned();

                let db = SqlitePoolOptions::new().connect_with(db_options).await?;
                sqlx::migrate!("./migrations/users.db").run(&db).await?;
                db
            };

            let password =
                rpassword::prompt_password(format!("New password for {}: ", username)).unwrap();

            let update = sqlx::query(
                "insert into users (username, password) values ($1, $2) on conflict do update set password=excluded.password",
            )
            .bind(username)
            .bind(password_auth::generate_hash(password))
            .execute(&users_db)
            .await?;

            if update.rows_affected() > 0 {
                println!("Updated password for {}.", username);
            } else {
                println!("No update was made; probably something went wrong.");
            }
        }
        Some(Commands::Serve { port }) => {
            serve(port).await?;
        }
        None => {
            serve(&3000).await?;
        }
    }

    Ok(())
}

async fn shutdown_signal(deletion_task_abort_handle: AbortHandle) {
    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 => { deletion_task_abort_handle.abort() },
        _ = terminate => { deletion_task_abort_handle.abort() },
    }
}