s3bot/src/bot/handlers/basic/currency_converter.rs

use std::{collections::HashMap, time::Duration};

use grammers_client::{Client, InputMessage, Update};
use regex::Regex;

use crate::{
    bot::{filters::base::Filter, handlers::Handler},
    utils::messages::get_message,
};

lazy_static::lazy_static! {
    static ref SUPPORTED_CURS: Vec<&'static str> = vec![
        "GBP",
        "HUF",
        "USD",
        "EUR",
        "CNY",
        "NOK",
        "UAH",
        "SEK",
        "CHF",
        "KRW",
        "JPY",
        "KZT",
        "PLN",
        "TRY",
        "AMD",
        "RSD",
    ];

    static ref CONVERTION_ALIASES: HashMap<&'static str, &'static str> = HashMap::from(
        [
            // GBP
            ("фунт", "GBP"),
            // USD
            ("бакс", "USD"),
            ("доллар", "USD"),
            // EUR
            ("евро", "EUR"),
            // JPY
            ("иен", "JPY"),
            ("йен", "JPY"),
            // KRW
            ("вон", "KRW"),
            // CHF
            ("франк", "CHF"),
            // SEK
            ("крон", "CHF"),
            // CNY
            ("юан", "CNY"),
            // UAH
            ("гривна", "UAH"),
            ("гривны", "UAH"),
            ("гривен", "UAH"),
            ("грiвен", "UAH"),
            // KZT
            ("тенге", "KZT"),
            ("тэнге", "KZT"),
            // PLN
            ("злот", "PLN"),
            // TRY
            ("лир", "TRY"),
            // AMD
            ("драм", "AMD"),
            // RSD
            ("динар", "RSD"),
        ]
    );

    static ref CUR_REGEX: Regex = {
        #[allow(clippy::clone_double_ref)]
        let a = CONVERTION_ALIASES.keys()
            .copied()
            .chain(SUPPORTED_CURS.iter().copied())
            .collect::<Vec<_>>()
            .join("|");
        Regex::new(format!(r"\s*(?P<cur_value>\d+([\.,]\d+)?)\s+(?P<cur_name>{a})").as_str()).unwrap()
    };
}

#[derive(Clone)]
pub struct CurrencyTextFilter;

#[derive(Clone)]
pub struct CurrencyConverter {
    client: reqwest::Client,
}

impl CurrencyConverter {
    pub fn new() -> anyhow::Result<Self> {
        let client = reqwest::ClientBuilder::new()
            .timeout(Duration::from_secs(2))
            .gzip(true)
            .build()?;
        Ok(Self { client })
    }
}

/// This filter check if the message matches regex for currencies.
impl Filter for CurrencyTextFilter {
    fn filter(&self, update: &Update) -> anyhow::Result<bool> {
        let Some(message) = get_message(update) else {
            return Ok(false);
        };
        Ok(CUR_REGEX.is_match(message.text()))
    }
}

#[async_trait::async_trait]
impl Handler for CurrencyConverter {
    async fn react(&self, _: &Client, update: &Update) -> anyhow::Result<()> {
        let Some(message) = get_message(update) else{ return  Ok(())};
        let response = self
            .client
            .get("https://www.cbr-xml-daily.ru/daily_json.js")
            .send()
            .await?
            .error_for_status()?
            .json::<serde_json::Value>()
            .await?;

        let Some(valutes) = response
            .get("Valute")
            .and_then(serde_json::Value::as_object) else{
                log::warn!("Can't get valutes fom response.");
                return Ok(());
            };

        let mut calucates = Vec::new();

        for capture in CUR_REGEX.captures_iter(message.text()) {
            // We parse supplied value from message
            let Some(num_value) = capture
                .name("cur_value")
                // Convert match to string.
                .map(|mtch| mtch.as_str())
                // Parse it.
                .and_then(|val| val.parse::<f64>().ok()) else{
                    continue;
                };
            let cur_name = capture.name("cur_name").map(|mtch| mtch.as_str());
            let Some(cur_name) = cur_name
                // We check if the value is an alias.
                .and_then(|val| CONVERTION_ALIASES.get(val).copied())
                // get previous value if not.
                .or(cur_name) else{
                    continue;
                };
            let calculated = valutes
                .get(cur_name)
                .and_then(|info| info.get("Value"))
                .map(ToString::to_string)
                .and_then(|value| value.as_str().parse::<f64>().ok())
                .map(|multiplier| multiplier * num_value);
            if let Some(value) = calculated {
                calucates.push(format!(
                    "<pre>{num_value} {cur_name} = {value:.2} RUB</pre><br>"
                ));
            }
        }

        if !calucates.is_empty() {
            let mut bot_response =
                String::from("<b>Полагаясь на текущий курс валют могу сказать следующее:</b>\n\n");
            for calc in calucates {
                bot_response.push_str(calc.as_str());
            }
            message
                // We send it as silent, so we can filter this message later.
                .reply(InputMessage::html(bot_response).silent(true))
                .await?;
        }

        Ok(())
    }
}