velocimeter/src/local.rs

use std::{os::unix::ffi::OsStrExt, path::Path, sync::Arc};

use reqwest::{multipart, Url};
use serde::{Deserialize, Serialize};
use tokio::{sync::Semaphore, task::JoinSet};
use tracing::{error, info};

use crate::db::FileCache;

#[derive(Clone, Deserialize, Serialize, Debug)]
#[serde(rename_all = "camelCase")]
struct InfoPayload {
    device_name: String,
    known_file_extensions: Vec<String>,
    supported_mimetypes: Vec<String>,
    app_name: String,
    app_version: u32,
}

macro_rules! multi_error {
    ($name:tt { $($variant:tt($t:ty)),+ $(,)? }) => {
        #[derive(Debug)]
        pub enum $name {
            $($variant($t)),+
        }

        impl ::std::fmt::Display for $name {
            fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
                match self {
                    $(
                        Self::$variant(x) => x.fmt(f)
                    ),+
                }
            }
        }

        impl ::std::error::Error for $name {}

        $(
            impl From<$t> for $name {
                fn from(value: $t) -> Self {
                    Self::$variant(value)
                }
            }
        )+
    };
}

multi_error!(
    Error {
        Io(std::io::Error),
        Http(reqwest::Error),
    }
);

/// Represents a connection to the server running on the mobile device.
pub struct LocalServer {
    base_uri: reqwest::Url,
    info: InfoPayload,
    client: reqwest::Client,
    cache: FileCache,
    tasks: JoinSet<Result<(), Error>>,
    semaphore: Arc<Semaphore>,
}

impl LocalServer {
    pub async fn new(
        uri: impl AsRef<str>,
        cache: FileCache,
    ) -> Result<LocalServer, Box<dyn std::error::Error>> {
        let base_uri = Url::parse(uri.as_ref())?;
        let info: InfoPayload = reqwest::get(base_uri.join("info").unwrap())
            .await?
            .json()
            .await?;
        Ok(LocalServer {
            base_uri,
            info,
            cache,
            client: reqwest::Client::new(),
            tasks: JoinSet::new(),
            semaphore: Arc::new(Semaphore::new(10)),
        })
    }

    pub fn should_upload(&self, path: impl AsRef<Path>) -> bool {
        if let Some(extension) = path.as_ref().extension() {
            let extension = extension.as_bytes();
            if self
                .info
                .known_file_extensions
                .iter()
                .any(|ex| ex.as_bytes() == extension)
            {
                if let Ok(false) = self.cache.has_path(path.as_ref()) {
                    return true;
                }
            }
        }
        false
    }

    /// Adds an upload task to the queue. The task will be spawned immediately,
    /// but only a certain amount will run at a time.
    ///
    /// Use `wait_on_queue` to wait for errors or completion.
    pub async fn queue_upload(
        &mut self,
        path: impl AsRef<Path>,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let path = path.as_ref();
        if !self.should_upload(path) {
            return Err(Box::new(std::io::Error::new(
                std::io::ErrorKind::InvalidInput,
                "Invalid file type",
            )));
        }
        let filename = path.file_name().unwrap().to_string_lossy().to_string();
        let client = self.client.clone();
        let base_uri = self.base_uri.clone();
        let semaphore = self.semaphore.clone();
        let cache = self.cache.clone();
        let path = path.to_owned();

        // The actual upload task
        self.tasks.spawn(async move {
            let _permit = semaphore.acquire_owned().await.unwrap();
            let fd = tokio::fs::OpenOptions::new()
                .read(true)
                .open(path.to_owned())
                .await?;

            let form = multipart::Form::new()
                .part("filename", multipart::Part::text(filename.to_string()))
                .part("file", multipart::Part::stream(fd).file_name(filename));
            let response = client
                .post(base_uri.join("upload").unwrap())
                .multipart(form)
                .send()
                .await?;

            response.error_for_status()?;

            if let Err(err) = cache.store(&path).await {
                error!("unable to cache {}: {}", path.display(), err);
            } else {
                info!("Uploaded {}.", path.display());
            }

            Ok(())
        });

        Ok(())
    }

    /// Provides an awaitable function for the task queue. This function will
    /// only return once the queue is empty or if an error occurs.
    pub async fn wait_on_queue(&mut self) -> Result<(), Error> {
        while let Some(task) = self.tasks.join_next().await {
            task.expect("upload task spawn error")?;
        }

        Ok(())
    }
}