telegram_files_server/src/core/file_utils.rs

use std::pin::Pin;

use axum::body::Bytes;
use futures::TryStreamExt;
use serde::Serialize;
use teloxide::{
    net::Download,
    requests::Requester,
    types::{ChatId, InputFile, MessageId},
    Bot,
};
use tokio::io::AsyncRead;
use tokio_util::compat::FuturesAsyncReadCompatExt;
use tracing::log;

use super::bot::ROUND_ROBIN_BOT;
use crate::config::CONFIG;

#[derive(Serialize)]
pub struct UploadedFile {
    pub backend: String,
    pub data: MessageInfo,
}

#[derive(Serialize)]
pub struct MessageInfo {
    pub chat_id: i64,
    pub message_id: i32,
}

pub async fn upload_file(
    file: Bytes,
    filename: String,
    caption: Option<String>,
) -> Result<UploadedFile, String> {
    let bot = ROUND_ROBIN_BOT.get_bot();
    let document = InputFile::memory(file).file_name(filename);

    let mut request = bot.send_document(ChatId(CONFIG.telegram_chat_id), document);
    request.caption = caption;

    let result = request.await;

    match result {
        Ok(message) => Ok(UploadedFile {
            backend: "bot".to_string(),
            data: MessageInfo {
                chat_id: message.chat.id.0,
                message_id: message.id.0,
            },
        }),
        Err(err) => Err(err.to_string()),
    }
}

pub async fn download_file(chat_id: i64, message_id: i32) -> Option<BotDownloader> {
    let bot = ROUND_ROBIN_BOT.get_bot();

    let forwarded_message = match bot
        .forward_message(
            ChatId(CONFIG.telegram_temp_chat_id),
            ChatId(chat_id),
            MessageId(message_id),
        )
        .await
    {
        Ok(v) => v,
        Err(err) => {
            log::error!("Error: {}", err);
            return None;
        }
    };

    let file_id = match forwarded_message.document() {
        Some(v) => v.file.id.clone(),
        None => {
            log::error!("Document not found!");
            return None;
        }
    };
    
    let path = match bot.get_file(file_id.clone()).await {
        Ok(v) => v.path,
        Err(err) => {
            log::error!("Error: {}", err);
            return None;
        }
    };

    return Some(BotDownloader::new(bot, path));
}

pub struct BotDownloader {
    bot: Bot,
    file_path: String,
}

impl BotDownloader {
    pub fn new(bot: Bot, file_path: String) -> Self {
        Self { bot, file_path }
    }

    pub fn get_async_read(self) -> Pin<Box<dyn AsyncRead + Send>> {
        let stream = self.bot.download_file_stream(&self.file_path);

        Box::pin(
            stream
                .map_err(|e| std::io::Error::new(std::io::ErrorKind::Other, e))
                .into_async_read()
                .compat(),
        )
    }
}