use axum::extract::{Query, State};
use axum::response::IntoResponse;
use axum::routing::get;
use axum::Router;
use futures_util::{stream, StreamExt};
use hemplate::Hemplate;
use slhx::{IntoEffect, SafeHtml};
use slhx_axum::{
    interactions, runtime_js, sse, DispatchRegistry, DispatchRejection, EffectResponse,
    InteractionRequest, PageRequest,
};
use slhx_kanban_example::ui::{self, board as board_ui};
use slhx_kanban_example::ui::board::{forms, handles, slots};
use slhx_kanban_example::ui::board_card::handles as card_handles;
use std::collections::BTreeMap;
use std::convert::Infallible;
use std::net::SocketAddr;
use std::sync::{Arc, Mutex};
use std::time::Duration;

const COLUMNS: [(&str, &str); 3] = [("backlog", "Backlog"), ("doing", "Doing"), ("done", "Done")];

#[derive(Default)]
struct AppState {
    board: Mutex<BoardState>,
}

#[derive(Default, Clone)]
struct BoardState {
    next_id: u64,
    cards: Vec<Card>,
}

#[derive(Clone)]
struct Card {
    id: u64,
    title: String,
    column: usize,
}

#[derive(Hemplate)]
struct AppShell {
    body: SafeHtml,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct BoardColumns {
    columns: Vec<BoardColumn>,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct BoardColumn {
    title: &'static str,
    cards: Vec<BoardCard>,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct BoardCard {
    id: u64,
    title: String,
    left_disabled: bool,
    right_disabled: bool,
}

#[derive(Hemplate)]
struct Board {
    options: SafeHtml,
    board: SafeHtml,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct ColumnOptions {
    options: Vec<ColumnOption>,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct ColumnOption {
    id: &'static str,
    title: &'static str,
}

#[derive(Hemplate)]
#[hemplate = "partials"]
struct Presence {
    count: u64,
}

#[tokio::main]
async fn main() {
    let state = Arc::new(AppState {
        board: Mutex::new(BoardState {
            next_id: 4,
            cards: vec![
                Card { id: 1, title: "Write requirements".into(), column: 0 },
                Card { id: 2, title: "Build browser example".into(), column: 1 },
                Card { id: 3, title: "Verify with HTTP".into(), column: 2 },
            ],
        }),
    });

    let app = Router::new()
        .route("/", get(home).post(interact))
        .route("/events", get(events))
        .route("/slhx.js", get(runtime))
        .with_state(state);

    let addr = SocketAddr::from(([127, 0, 0, 1], 3001));
    let listener = tokio::net::TcpListener::bind(addr).await.unwrap();
    println!("slhx Kanban example: http://{addr}");
    axum::serve(listener, app).await.unwrap();
}

// req: examples/001 req: component/003
async fn home(State(state): State<Arc<AppState>>, request: PageRequest) -> impl IntoResponse {
    let board = state.board.lock().unwrap().clone();
    request
        .page_html(page_html(&board), shell)
        .title("slhx Kanban")
        .fingerprint(ui::BUILD_FINGERPRINT)
}

async fn runtime() -> impl IntoResponse {
    runtime_js()
}

async fn interact(
    State(state): State<Arc<AppState>>,
    request: InteractionRequest,
) -> Result<EffectResponse, DispatchRejection> {
    request.dispatch(registry(state))
}

// req: push/001 req: push/003 req: examples/001
async fn events(Query(params): Query<BTreeMap<String, String>>) -> impl IntoResponse {
    if params.contains_key("once") {
        let effect = slots::presence.html(ui::render(&Presence { count: 1 }));
        return sse(stream::iter([Ok::<_, Infallible>(effect.into_batch(ui::BUILD_FINGERPRINT))]).boxed());
    }

    let batches = stream::unfold(1_u64, |count| async move {
        tokio::time::sleep(Duration::from_secs(4)).await;
        let effect = slots::presence.html(ui::render(&Presence { count }));
        Some((Ok::<_, Infallible>(effect.into_batch(ui::BUILD_FINGERPRINT)), count + 1))
    })
    .boxed();
    sse(batches)
}

fn registry(state: Arc<AppState>) -> impl DispatchRegistry {
    interactions(ui::BUILD_FINGERPRINT)
        .on(handles::create_card, {
            let state = state.clone();
            move |form| {
                // req: examples/001 req: form/002
                let title = form.value("title").unwrap_or("").trim();
                let column = parse_column(form.value("column"));
                let mut board = state.board.lock().unwrap();
                if !title.is_empty() {
                    let id = board.next_id;
                    board.next_id += 1;
                    board.cards.push(Card { id, title: title.into(), column });
                }
                board_effects(&board, "Card added")
            }
        })
        .on(card_handles::move_left, {
            let state = state.clone();
            move |form| {
                // req: examples/001 req: list/003
                let mut board = state.board.lock().unwrap();
                let moved = update_card(&mut board, form.parse("card_id"), |card| {
                    card.column = card.column.saturating_sub(1);
                });
                board_effects(&board, if moved { "Card moved left" } else { "Card not found" })
            }
        })
        .on(card_handles::move_right, {
            let state = state.clone();
            move |form| {
                // req: examples/001 req: list/003
                let mut board = state.board.lock().unwrap();
                let moved = update_card(&mut board, form.parse("card_id"), |card| {
                    card.column = (card.column + 1).min(COLUMNS.len() - 1);
                });
                board_effects(&board, if moved { "Card moved right" } else { "Card not found" })
            }
        })
        .on(card_handles::delete_card, {
            let state = state.clone();
            move |form| {
                // req: examples/001 req: list/003
                let mut board = state.board.lock().unwrap();
                let before = board.cards.len();
                if let Some(id) = form.parse::<u64>("card_id") {
                    board.cards.retain(|card| card.id != id);
                }
                board_effects(&board, if board.cards.len() < before { "Card deleted" } else { "Card not found" })
            }
        })
}

fn board_effects(board: &BoardState, notice: &'static str) -> impl IntoEffect {
    (
        slots::board.html(ui::render(&board_view(board))),
        slots::notice.text(notice),
        forms::create_card.clear("title"),
    )
}

fn update_card(
    board: &mut BoardState,
    card_id: Option<u64>,
    update: impl FnOnce(&mut Card),
) -> bool {
    let Some(id) = card_id else {
        return false;
    };
    let Some(card) = board.cards.iter_mut().find(|card| card.id == id) else {
        return false;
    };
    update(card);
    true
}

fn parse_column(value: Option<&str>) -> usize {
    let id = value.unwrap_or(COLUMNS[0].0);
    COLUMNS
        .iter()
        .position(|(column_id, _)| *column_id == id)
        .unwrap_or(0)
}

fn page_html(board: &BoardState) -> SafeHtml {
    // req: html_safety/002 req: view/001
    board_ui::render(&Board {
        options: render_options(),
        board: ui::render(&board_view(board)),
    })
}

fn shell(body: SafeHtml) -> SafeHtml {
    // req: html_safety/001 req: html_safety/002 req: axum_integration/001
    slhx::render(&AppShell { body })
}

fn render_options() -> SafeHtml {
    // req: html_safety/002 req: view/001
    ui::render(&ColumnOptions {
        options: COLUMNS
            .iter()
            .map(|(id, title)| ColumnOption { id, title })
            .collect(),
    })
}

fn board_view(board: &BoardState) -> BoardColumns {
    // req: html_safety/002 req: view/001
    BoardColumns {
        columns: COLUMNS
            .iter()
            .enumerate()
            .map(|(idx, (_, title))| BoardColumn {
                title,
                cards: board
                    .cards
                    .iter()
                    .filter(|card| card.column == idx)
                    .map(render_card)
                    .collect(),
            })
            .collect(),
    }
}

fn render_card(card: &Card) -> BoardCard {
    BoardCard {
        id: card.id,
        title: card.title.clone(),
        left_disabled: card.column == 0,
        right_disabled: card.column + 1 == COLUMNS.len(),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use scraper::{Html, Selector};

    fn selector(value: &str) -> Selector {
        Selector::parse(value).expect("test selector parses")
    }

    // req: html_safety/002 req: view/001 req: test/005
    #[test]
    fn kanban_page_is_composed_by_a_hemplate_view() {
        let html = page_html(&BoardState::default());
        assert!(!html.as_str().contains("__OPTIONS__"));
        assert!(!html.as_str().contains("__BOARD__"));

        let document = Html::parse_fragment(html.as_str());
        assert_eq!(document.select(&selector("section[data-slhx-root=\"kanban\"]")).count(), 1);
        assert_eq!(document.select(&selector("select[name=\"column\"] > option")).count(), 3);
        assert_eq!(document.select(&selector("[data-sid]")).count(), 3);
        assert_eq!(document.select(&selector("[data-hid]")).count(), 1);
    }

    // req: html_safety/002 req: view/001 req: test/005
    #[test]
    fn board_payload_is_rendered_by_a_hemplate_view() {
        let board = BoardState {
            next_id: 2,
            cards: vec![Card {
                id: 1,
                title: "<b>Compile checked</b>".to_owned(),
                column: 0,
            }],
        };

        let html = ui::render(&board_view(&board));
        let document = Html::parse_fragment(html.as_str());
        assert_eq!(document.select(&selector(".columns > section.column")).count(), 3);
        let card = document
            .select(&selector("article.card[data-key=\"1\"]"))
            .next()
            .expect("card renders");
        let title = card.select(&selector("strong")).next().expect("card title renders");
        assert_eq!(title.text().collect::<String>(), "<b>Compile checked</b>");
        assert!(card.select(&selector("b")).next().is_none());
        assert_eq!(card.select(&selector("button[disabled]")).count(), 1);
    }

    // req: html_safety/002 req: view/001 req: test/005
    #[test]
    fn presence_payload_is_rendered_by_a_hemplate_view() {
        let html = ui::render(&Presence { count: 7 });
        let document = Html::parse_fragment(html.as_str());
        assert_eq!(document.select(&selector("span.presence")).count(), 2);
        assert_eq!(
            document
                .select(&selector("small"))
                .next()
                .map(|small| small.text().collect::<String>()),
            Some("tick #7".to_owned())
        );
    }
}