// This example demonstrates how to deal with messages and callback queries
// within a single dialogue.
//
// # Example
// ```
// - /start
// - Let's start! What's your full name?
// - John Doe
// - Select a product:
//   [Apple, Banana, Orange, Potato]
// - <A user selects "Banana">
// - John Doe, product 'Banana' has been purchased successfully!
// ```

use teloxide::{
    dispatching::{dialogue, dialogue::InMemStorage, UpdateHandler},
    prelude::*,
    types::{InlineKeyboardButton, InlineKeyboardMarkup},
    utils::command::BotCommands,
};

type MyDialogue = Dialogue<State, InMemStorage<State>>;
type HandlerResult = Result<(), Box<dyn std::error::Error + Send + Sync>>;

#[derive(Clone, Default)]
pub enum State {
    #[default]
    Start,
    ReceiveFullName,
    ReceiveProductChoice {
        full_name: String,
    },
}

#[derive(BotCommands, Clone)]
#[command(rename_rule = "lowercase", description = "These commands are supported:")]
enum Command {
    #[command(description = "display this text.")]
    Help,
    #[command(description = "start the purchase procedure.")]
    Start,
    #[command(description = "cancel the purchase procedure.")]
    Cancel,
}

#[tokio::main]
async fn main() {
    pretty_env_logger::init();
    log::info!("Starting purchase bot...");

    let bot = Bot::from_env();

    Dispatcher::builder(bot, schema())
        .dependencies(dptree::deps![InMemStorage::<State>::new()])
        .enable_ctrlc_handler()
        .build()
        .dispatch()
        .await;
}

fn schema() -> UpdateHandler<Box<dyn std::error::Error + Send + Sync + 'static>> {
    use dptree::case;

    let command_handler = teloxide::filter_command::<Command, _>()
        .branch(
            case![State::Start]
                .branch(case![Command::Help].endpoint(help))
                .branch(case![Command::Start].endpoint(start)),
        )
        .branch(case![Command::Cancel].endpoint(cancel));

    let message_handler = Update::filter_message()
        .branch(command_handler)
        .branch(case![State::ReceiveFullName].endpoint(receive_full_name))
        .branch(dptree::endpoint(invalid_state));

    let callback_query_handler = Update::filter_callback_query().branch(
        case![State::ReceiveProductChoice { full_name }].endpoint(receive_product_selection),
    );

    dialogue::enter::<Update, InMemStorage<State>, State, _>()
        .branch(message_handler)
        .branch(callback_query_handler)
}

async fn start(bot: Bot, dialogue: MyDialogue, msg: Message) -> HandlerResult {
    bot.send_message(msg.chat.id, "Let's start! What's your full name?").await?;
    dialogue.update(State::ReceiveFullName).await?;
    Ok(())
}

async fn help(bot: Bot, msg: Message) -> HandlerResult {
    bot.send_message(msg.chat.id, Command::descriptions().to_string()).await?;
    Ok(())
}

async fn cancel(bot: Bot, dialogue: MyDialogue, msg: Message) -> HandlerResult {
    bot.send_message(msg.chat.id, "Cancelling the dialogue.").await?;
    dialogue.exit().await?;
    Ok(())
}

async fn invalid_state(bot: Bot, msg: Message) -> HandlerResult {
    bot.send_message(msg.chat.id, "Unable to handle the message. Type /help to see the usage.")
        .await?;
    Ok(())
}

async fn receive_full_name(bot: Bot, dialogue: MyDialogue, msg: Message) -> HandlerResult {
    match msg.text().map(ToOwned::to_owned) {
        Some(full_name) => {
            let products = ["Apple", "Banana", "Orange", "Potato"]
                .map(|product| InlineKeyboardButton::callback(product, product));

            bot.send_message(msg.chat.id, "Select a product:")
                .reply_markup(InlineKeyboardMarkup::new([products]))
                .await?;
            dialogue.update(State::ReceiveProductChoice { full_name }).await?;
        }
        None => {
            bot.send_message(msg.chat.id, "Please, send me your full name.").await?;
        }
    }

    Ok(())
}

async fn receive_product_selection(
    bot: Bot,
    dialogue: MyDialogue,
    full_name: String, // Available from `State::ReceiveProductChoice`.
    q: CallbackQuery,
) -> HandlerResult {
    if let Some(product) = &q.data {
        bot.send_message(
            dialogue.chat_id(),
            format!("{full_name}, product '{product}' has been purchased successfully!"),
        )
        .await?;
        dialogue.exit().await?;
    }

    Ok(())
}