use anyhow::{Context as _, Result};
use askama::Template;
use axum::{
    extract::State,
    http::{header::CACHE_CONTROL, HeaderValue},
    response::{Html, IntoResponse as _, Response},
    routing::get,
    Router,
};
use catalogs::{
    pg_class::{self, PgClass},
    pg_namespace,
    pg_roles::{self, PgRole},
    table_privileges::{self, TablePrivilege},
};
use diesel::{prelude::*, sql_query};
use tower::ServiceBuilder;
use tower_http::{
    services::{ServeDir, ServeFile},
    set_header::SetResponseHeaderLayer,
};

use crate::{
    abstract_::{class_privileges_for_grantees, escape_identifier},
    app_error::AppError,
    app_state::{AppState, DbConn},
    auth,
    settings::Settings,
    users::CurrentUser,
};

pub fn new_router(state: AppState) -> Router<()> {
    let base_path = state.settings.base_path.clone();
    let app = Router::new()
        .route("/", get(landing_page))
        .nest("/auth", auth::new_router())
        .layer(SetResponseHeaderLayer::if_not_present(
            CACHE_CONTROL,
            HeaderValue::from_static("no-cache"),
        ))
        .fallback_service(
            ServiceBuilder::new()
                .layer(SetResponseHeaderLayer::if_not_present(
                    CACHE_CONTROL,
                    HeaderValue::from_static("max-age=21600, stale-while-revalidate=86400"),
                ))
                .service(
                    ServeDir::new("static").not_found_service(
                        ServiceBuilder::new()
                            .layer(SetResponseHeaderLayer::if_not_present(
                                CACHE_CONTROL,
                                HeaderValue::from_static("no-cache"),
                            ))
                            .service(ServeFile::new("static/_404.html")),
                    ),
                ),
        )
        .with_state(state);
    if base_path.is_empty() {
        app
    } else {
        Router::new().nest(&base_path, app).fallback_service(
            ServeDir::new("static").not_found_service(ServeFile::new("static/_404.html")),
        )
    }
}

async fn landing_page(
    State(Settings {
        base_path,
        pg_user_role_prefix,
        ..
    }): State<Settings>,
    DbConn(db_conn): DbConn,
    CurrentUser(current_user): CurrentUser,
) -> Result<Response, AppError> {
    let grantees = vec![format!(
        "{}{}",
        pg_user_role_prefix,
        current_user.id.simple()
    )];
    let visible_tables = db_conn
        .interact(move |conn| -> Result<Vec<PgClass>> {
            let role = PgRole::all()
                .filter(pg_roles::dsl::rolname.eq(format!(
                    "{}{}",
                    pg_user_role_prefix,
                    current_user.id.simple()
                )))
                .first(conn)
                .optional()
                .context("error reading role")?;
            if role.is_none() {
                sql_query(format!(
                    "CREATE ROLE {}",
                    escape_identifier(&format!(
                        "{}{}",
                        pg_user_role_prefix,
                        current_user.id.simple()
                    ))
                ))
                .execute(conn)
                .context("error creating role")?;
            }
            sql_query(format!(
                "SET ROLE {}",
                escape_identifier(&format!(
                    "{}{}",
                    pg_user_role_prefix,
                    current_user.id.simple()
                ))
            ))
            .execute(conn)
            .context("error setting role to user")?;
            let privileges = class_privileges_for_grantees(grantees)
                .load(conn)
                .context("error reading classes")?;
            Ok(privileges.into_iter().map(|value| value.class).collect())
        })
        .await
        .unwrap()?;
    #[derive(Template)]
    #[template(path = "tmp.html")]
    struct ResponseTemplate {
        base_path: String,
        relations: Vec<PgClass>,
    }
    Ok(Html(
        ResponseTemplate {
            base_path,
            relations: visible_tables,
        }
        .render()?,
    )
    .into_response())
}