// Copyright 2022 Daniel Arbuckle
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Run with `cargo run --example todolist --features examples`

use std::{
    collections::BTreeMap,
    future::Future,
    net::TcpListener,
    sync::{Arc, Mutex},
};

use axum::{
    extract::{Form, Path},
    http::StatusCode,
    response::{Html, IntoResponse},
    routing::{delete, get, get_service, post, put},
    Extension, Router, Server,
};
use sailfish::TemplateOnce;
use tokio::sync::oneshot::{channel, Sender};
use toml;
use ulid::Ulid;

mod components;

#[derive(serde::Serialize, serde::Deserialize, Debug, Default)]
#[serde(default)]
pub struct Item {
    done: bool,
    label: String,
}

pub type ItemMap<'state> = &'state Mutex<BTreeMap<Ulid, Item>>;

struct State {
    shutdown: Mutex<Option<Sender<()>>>,
    items: Mutex<BTreeMap<Ulid, Item>>,
}

impl State {
    fn save(self: Arc<State>) -> impl Future {
        tokio::fs::write(
            "examples/todolist/items.toml",
            toml::to_string(&*self.items.lock().unwrap()).expect("serialize items"),
        )
    }
}

async fn index(Extension(state): Extension<Arc<State>>) -> impl IntoResponse {
    Html(
        components::Layout {
            items: &state.items,
        }
        .render_once()
        .unwrap_or_else(|_| "Error during page rendering".into()),
    )
}

async fn todo_list(Extension(state): Extension<Arc<State>>) -> impl IntoResponse {
    Html(
        components::Items {
            items: &state.items,
        }
        .render_once()
        .unwrap_or_else(|_| "Error during list rendering".into()),
    )
}

async fn todo_add(
    Extension(state): Extension<Arc<State>>,
    Form(item): Form<Item>,
) -> impl IntoResponse {
    let id = Ulid::new();
    state.items.lock().unwrap().insert(id, item);
    state.save().await;

    (
        [("HX-Trigger", "refresh-list")],
        Html(
            components::NewForm {}
                .render_once()
                .unwrap_or_else(|_| "Error during form rendering".into()),
        ),
    )
}

async fn get_todo_item(
    Extension(state): Extension<Arc<State>>,
    Path(id): Path<Ulid>,
) -> impl IntoResponse {
    if let Some(item) = state.items.lock().unwrap().get(&id) {
        Html(
            components::Item {
                id: &id,
                item: &item,
            }
            .render_once()
            .unwrap_or_else(|_| "Error during item rendering".into()),
        )
    } else {
        Html(String::from("No such item"))
    }
}

async fn set_todo_item(
    Extension(state): Extension<Arc<State>>,
    Path(id): Path<Ulid>,
    Form(item): Form<Item>,
) -> impl IntoResponse {
    let rendered = Html(
        components::Item {
            id: &id,
            item: &item,
        }
        .render_once()
        .unwrap_or_else(|_| "Error during new item rendering".into()),
    );

    state.items.lock().unwrap().insert(id, item);
    state.save().await;

    rendered
}

async fn del_todo_item(
    Extension(state): Extension<Arc<State>>,
    Path(id): Path<Ulid>,
) -> impl IntoResponse {
    state.items.lock().unwrap().remove(&id);
    state.save().await;

    [("HX-Trigger", "refresh-list")]
}

async fn shutdown(Extension(state): Extension<Arc<State>>) -> impl IntoResponse {
    if let Some(shutdown) = state.shutdown.lock().unwrap().take() {
        let _ = shutdown.send(());
        "Shutting down"
    } else {
        "Shutdown already initiated"
    }
}

fn main() {
    // Non-async set up. We can do any server configuration that
    // doesn't need an async context here, parse the command line,
    // etc.

    let (shutdown_tx, shutdown_rx) = channel::<()>();

    let state = Arc::new(State {
        shutdown: Mutex::new(Some(shutdown_tx)),
        items: toml::from_str(
            &std::fs::read_to_string("examples/todolist/items.toml")
                .unwrap_or_else(|_| String::new()),
        )
        .expect("items.toml should be valid TOML"),
    });

    let app = Router::new()
        .route("/", get(index))
        .route("/todo", get(todo_list))
        .route("/todo", post(todo_add))
        .route("/todo/:id", get(get_todo_item))
        .route("/todo/:id", put(set_todo_item))
        .route("/todo/:id", delete(del_todo_item))
        .route("/shutdown", post(shutdown))
        // We use a nested router so that request path is rewritten
        // for the ServeDir service. If we just routed to the service
        // directly, the request path received by the service would
        // contain the service mount point at the beginning.
        .nest(
            "/static",
            Router::new().route(
                "/*path",
                get_service(tower_http::services::ServeDir::new(
                    "examples/todolist/static",
                ))
                .handle_error(|error: std::io::Error| async move {
                    (StatusCode::INTERNAL_SERVER_ERROR, format!("{}", error))
                }),
            ),
        )
        .layer(Extension(state.clone()));

    // Pick a random available port on the loopback interface. Not
    // actually required, but usually a good idea.

    let ear = TcpListener::bind("127.0.0.1:0").expect("bind port");
    let addr = ear.local_addr().expect("retrieve port");

    // Here we start up the webview and actually run the server. The
    // async block is the asynchronous entry point for the program
    // (like tokio::main or async_std::main), so any server set up
    // code that needs to run in an async context should be there, as
    // well as the code to actually run the server. When the async
    // block finishes executing, the program will close.

    drteeth::launch("To Do List", addr, async move {
        Server::from_tcp(ear)
            .unwrap()
            .serve(app.into_make_service())
            .with_graceful_shutdown(async {
                shutdown_rx.await.ok();
            })
            .await
            .unwrap();
    })
    .unwrap();
}