refactor: Convert to a dependency injection system for library sources, contexts, and backends

Signed-off-by: quexeky <git@quexeky.dev>

Cargo.lock

@@ -315,6 +315,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tinytemplate",
+ "tokio",
  "walkdir",
 ]
 
@@ -457,6 +458,22 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
+[[package]]
+name = "errno"
+version = "0.3.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
+dependencies = [
+ "libc",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.5"
@@ -824,6 +841,12 @@ version = "0.2.178"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37c93d8daa9d8a012fd8ab92f088405fb202ea0b6ab73ee2482ae66af4f42091"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df1d3c3b53da64cf5760482273a98e575c651a67eec7f77df96b5b642de8f039"
+
 [[package]]
 name = "litemap"
 version = "0.8.1"
@@ -1310,6 +1333,19 @@ dependencies = [
  "nom",
 ]
 
+[[package]]
+name = "rustix"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd15f8a2c5551a84d56efdc1cd049089e409ac19a3072d5037a17fd70719ff3e"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "rustls"
 version = "0.23.35"
@@ -1529,6 +1565,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.23.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d31c77bdf42a745371d260a26ca7163f1e0924b64afa0b688e61b5a9fa02f16"
+dependencies = [
+ "fastrand",
+ "getrandom 0.3.4",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -1690,15 +1739,18 @@ name = "torrential"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "async-trait",
  "axum",
  "criterion",
  "dashmap",
  "droplet-rs",
  "log",
+ "rand",
  "reqwest",
  "serde",
  "serde_json",
  "simple_logger",
+ "tempfile",
  "tokio",
  "tokio-util",
  "url",

Cargo.toml

@@ -3,6 +3,14 @@ name = "torrential"
 version = "0.1.0"
 edition = "2024"
 
+[lib]
+name = "torrential"
+path = "src/lib.rs"
+
+[[bin]]
+name = "torrential"
+path = "src/main.rs"
+
 [dependencies]
 axum = "0.8.7"
 log = "0.4.28"
@@ -21,6 +29,7 @@ anyhow = "1.0.100"
 serde_json = "1.0.145"
 url = { version = "2.5.7", default-features = false }
 tokio-util = { version = "0.7.17", features = ["io"] }
+async-trait = "0.1.89"
 
 [lints.clippy]
 pedantic = { level = "warn", priority = -1 }
@@ -41,4 +50,6 @@ name = "torrential"
 harness = false
 
 [dev-dependencies]
-criterion = "0.8.0"
+criterion = { version = "0.8.0", features = ["async", "async_tokio"] }
+rand = "0.9.2"
+tempfile = "3.23.0"

benches/torrential.rs

@@ -1,12 +1,44 @@
-use criterion::{criterion_group, criterion_main, Criterion};
+use std::{
+    cmp,
+    fs::File,
+    io::{BufWriter, Write},
+};
 
-fn torrential() {
+use criterion::{Criterion, criterion_group, criterion_main};
+use rand::{Rng, rng};
+use tempfile::tempfile;
+use tokio::runtime::Runtime;
 
+async fn torrential() {}
+
+fn generate_file() -> File {
+    let total_bytes = 312 * 1024 * 1024;
+    let tempfile = tempfile().unwrap();
+    let mut writer = BufWriter::new(tempfile);
+
+    let mut rng = rng();
+    let mut buffer = [0; 1024];
+    let mut remaining_size = total_bytes;
+
+    while remaining_size > 0 {
+        let to_write = cmp::min(remaining_size, buffer.len());
+        let buffer = &mut buffer[..to_write];
+        rng.fill(buffer);
+        writer.write(buffer).unwrap();
+
+        remaining_size -= to_write;
+    }
+    writer.into_inner().unwrap()
 }
-
 // The benchmark function setup
 fn benchmark(c: &mut Criterion) {
-    c.bench_function("fibonacci 20", |b| b.iter(|| torrential()));
+    let rt = Runtime::new().unwrap();
+
+    let file = generate_file();
+
+    c.bench_function("torrential download", |b| {
+        b.to_async(&rt).iter(|| torrential())
+    });
 }
 
 // Grouping your benchmarks

src/download.rs

@@ -4,20 +4,37 @@ use droplet_rs::versions::{create_backend_constructor, types::VersionBackend};
 use reqwest::StatusCode;
 
 use crate::{
-    AppInitData, DownloadContext,
-    remote::{ContextResponseBody, LibraryBackend, fetch_download_context},
+    remote::{ContextResponseBody, LibraryBackend, ContextProvider},
+    state::AppInitData,
     util::ErrorOption,
 };
 
+pub struct DownloadContext {
+    pub(crate) chunk_lookup_table: HashMap<String, (String, usize, usize)>,
+    pub(crate) backend: Box<dyn VersionBackend + Send + Sync + 'static>,
+    last_access: Instant,
+}
+impl DownloadContext {
+    pub fn last_access(&self) -> Instant {
+        self.last_access
+    }
+    pub fn reset_last_access(&mut self) {
+        self.last_access = Instant::now()
+    }
+}
+
 pub async fn create_download_context(
+    metadata_provider: &dyn ContextProvider,
+    backend_factory: &dyn BackendFactory,
     init_data: &AppInitData,
     game_id: String,
     version_name: String,
 ) -> Result<DownloadContext, ErrorOption> {
-    let context =
-        fetch_download_context(init_data.token.clone(), game_id, version_name.clone()).await?;
+    let context = metadata_provider
+        .fetch_context(init_data.token(), game_id, version_name.clone())
+        .await?;
 
-    let backend = generate_backend(init_data, &context, &version_name)??;
+    let backend = backend_factory.create_backend(init_data, &context, &version_name)?;
 
     let mut chunk_lookup_table = HashMap::with_capacity_and_hasher(
         context.manifest.values().map(|v| v.ids.len()).sum(),
@@ -41,25 +58,39 @@ pub async fn create_download_context(
     Ok(download_context)
 }
 
-fn generate_backend(
-    init_data: &AppInitData,
-    context: &ContextResponseBody,
-    version_name: &String,
-) -> Result<Result<Box<dyn VersionBackend + Send + Sync>, anyhow::Error>, StatusCode> {
-    let (version_path, backend) = init_data
-        .libraries
-        .get(&context.library_id)
-        .ok_or(StatusCode::NOT_FOUND)?;
-
-    let version_path = version_path.join(&context.library_path);
-    let version_path = match backend {
-        LibraryBackend::Filesystem => version_path.join(version_name),
-        LibraryBackend::FlatFilesystem => version_path,
-    };
-    
-    let backend =
-        create_backend_constructor(&version_path).ok_or(StatusCode::INTERNAL_SERVER_ERROR)?;
-
-    let backend = backend();
-    Ok(backend)
+pub trait BackendFactory: Send + Sync {
+    fn create_backend(
+        &self,
+        init_data: &AppInitData,
+        context: &ContextResponseBody,
+        version_name: &String,
+    ) -> Result<Box<dyn VersionBackend + Send + Sync>, StatusCode>;
+}
+
+pub struct DropBackendFactory;
+impl BackendFactory for DropBackendFactory {
+    fn create_backend(
+        &self,
+        init_data: &AppInitData,
+        context: &ContextResponseBody,
+        version_name: &String,
+    ) -> Result<Box<dyn VersionBackend + Send + Sync>, StatusCode> {
+        let (version_path, backend) = init_data
+            .libraries()
+            .get(&context.library_id)
+            .ok_or(StatusCode::NOT_FOUND)?;
+
+        let version_path = version_path.join(&context.library_path);
+        let version_path = match backend {
+            LibraryBackend::Filesystem => version_path.join(version_name),
+            LibraryBackend::FlatFilesystem => version_path,
+        };
+
+        let backend =
+            create_backend_constructor(&version_path).ok_or(StatusCode::INTERNAL_SERVER_ERROR)?;
+
+        // TODO: Not eat this error
+        let backend = backend().map_err(|_e| StatusCode::INTERNAL_SERVER_ERROR)?;
+        Ok(backend)
+    }
 }

src/handlers.rs

@@ -0,0 +1,126 @@
+use std::sync::Arc;
+
+use axum::{
+    body::Body,
+    extract::{Path, State},
+    response::{AppendHeaders, IntoResponse},
+};
+use dashmap::{DashMap, mapref::one::RefMut};
+use droplet_rs::versions::types::{MinimumFileObject, VersionFile};
+use log::{error, info};
+use reqwest::{StatusCode, header};
+use tokio::sync::SemaphorePermit;
+use tokio_util::io::ReaderStream;
+
+use crate::{
+    DownloadContext, GLOBAL_CONTEXT_SEMAPHORE, download::create_download_context, state::AppState,
+};
+
+pub async fn serve_file(
+    State(state): State<Arc<AppState>>,
+    Path((game_id, version_name, chunk_id)): Path<(String, String, String)>,
+) -> Result<impl IntoResponse, StatusCode> {
+    let context_cache = &state.context_cache;
+
+    let mut context = get_or_generate_context(&state, context_cache, game_id, version_name).await?;
+    context.reset_last_access();
+
+    let (relative_filename, start, end) = lookup_chunk(&chunk_id, &context)?;
+    let reader = get_file_reader(&mut context, relative_filename, start, end).await?;
+
+    let stream = ReaderStream::new(reader);
+    let body: Body = Body::from_stream(stream);
+
+    let headers: AppendHeaders<[(header::HeaderName, String); 2]> = AppendHeaders([
+        (header::CONTENT_TYPE, "application/octet-stream".to_owned()),
+        (header::CONTENT_LENGTH, (end - start).to_string()),
+    ]);
+
+    Ok((headers, body))
+}
+
+pub async fn healthcheck(State(state): State<Arc<AppState>>) -> StatusCode {
+    let initialised = state.token.initialized();
+    if !initialised {
+        return StatusCode::SERVICE_UNAVAILABLE;
+    }
+    StatusCode::OK
+}
+
+async fn acquire_permit<'a>() -> SemaphorePermit<'a> {
+    return GLOBAL_CONTEXT_SEMAPHORE
+        .acquire()
+        .await
+        .expect("failed to acquire semaphore");
+}
+fn lookup_chunk(
+    chunk_id: &String,
+    context: &RefMut<'_, (String, String), DownloadContext>,
+) -> Result<(String, usize, usize), StatusCode> {
+    context
+        .chunk_lookup_table
+        .get(chunk_id)
+        .cloned()
+        .ok_or(StatusCode::NOT_FOUND)
+}
+async fn get_file_reader(
+    context: &mut RefMut<'_, (String, String), DownloadContext>,
+    relative_filename: String,
+    start: usize,
+    end: usize,
+) -> Result<Box<dyn MinimumFileObject>, StatusCode> {
+    context
+        .backend
+        .reader(
+            &VersionFile {
+                relative_filename: relative_filename.clone(),
+                permission: 0,
+                size: 0,
+            },
+            start as u64,
+            end as u64,
+        )
+        .await
+        .map_err(|v| {
+            error!("reader error: {v:?}");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })
+}
+async fn get_or_generate_context<'a>(
+    state: &Arc<AppState>,
+    context_cache: &'a DashMap<(String, String), DownloadContext>,
+    game_id: String,
+    version_name: String,
+) -> Result<RefMut<'a, (String, String), DownloadContext>, StatusCode> {
+    let initialisation_data = state.token.get().ok_or(StatusCode::SERVICE_UNAVAILABLE)?;
+    let key = (game_id.clone(), version_name.clone());
+
+    if let Some(context) = context_cache.get_mut(&key) {
+        Ok(context)
+    } else {
+        let permit = acquire_permit().await;
+
+        // Check if it's been done while we've been sitting here
+        if let Some(already_done) = context_cache.get_mut(&key) {
+            Ok(already_done)
+        } else {
+            info!("generating context...");
+            let context_result = create_download_context(
+                &*state.metadata_provider,
+                &*state.backend_factory,
+                initialisation_data,
+                game_id.clone(),
+                version_name.clone(),
+            )
+            .await?;
+
+            state.context_cache.insert(key.clone(), context_result);
+
+            info!("continuing download");
+
+            drop(permit);
+
+            Ok(context_cache.get_mut(&key).unwrap())
+        }
+    }
+}

src/lib.rs

@@ -0,0 +1,17 @@
+use tokio::sync::Semaphore;
+mod download;
+pub mod handlers;
+mod manifest;
+mod remote;
+pub mod state;
+mod token;
+mod util;
+
+pub use download::DownloadContext;
+pub use download::{BackendFactory, DropBackendFactory};
+pub use remote::{
+    DropLibraryProvider, DropContextProvider, LibraryConfigurationProvider, ContextProvider,
+};
+pub use token::set_token;
+
+static GLOBAL_CONTEXT_SEMAPHORE: Semaphore = Semaphore::const_new(1);

src/main.rs

@@ -1,54 +1,21 @@
-use anyhow::Result;
-use dashmap::{DashMap, mapref::one::RefMut};
-use droplet_rs::versions::types::{MinimumFileObject, VersionBackend, VersionFile};
-use reqwest::header;
-use simple_logger::SimpleLogger;
 use std::{
-    collections::HashMap, env::set_current_dir, path::PathBuf, str::FromStr as _, sync::Arc,
-    time::Instant,
+    env::{self, set_current_dir},
+    sync::Arc,
 };
-use tokio_util::io::ReaderStream;
 
 use axum::{
-    Json, Router,
-    body::Body,
-    extract::{Path, State},
-    http::StatusCode,
-    response::{AppendHeaders, IntoResponse},
+    Router,
     routing::{get, post},
 };
-use log::{error, info};
-use serde::Deserialize;
-use tokio::sync::{OnceCell, Semaphore, SemaphorePermit};
-
-use crate::{
-    download::create_download_context,
-    remote::{LibraryBackend, LibrarySource, fetch_library_sources},
+use dashmap::DashMap;
+use log::info;
+use simple_logger::SimpleLogger;
+use tokio::sync::OnceCell;
+use torrential::{
+    DropBackendFactory, DropLibraryProvider, DropContextProvider, handlers, set_token,
+    state::AppState,
 };
-
-mod download;
-mod manifest;
-mod remote;
-mod util;
-
-static GLOBAL_CONTEXT_SEMAPHORE: Semaphore = Semaphore::const_new(1);
-
-struct DownloadContext {
-    chunk_lookup_table: HashMap<String, (String, usize, usize)>,
-    backend: Box<dyn VersionBackend + Send + Sync + 'static>,
-    last_access: Instant,
-}
-
-#[derive(Debug)]
-struct AppInitData {
-    token: String,
-    libraries: HashMap<String, (PathBuf, LibraryBackend)>,
-}
-
-struct AppState {
-    token: OnceCell<AppInitData>,
-    context_cache: DashMap<(String, String), DownloadContext>,
-}
+use url::Url;
 
 #[tokio::main]
 async fn main() {
@@ -58,9 +25,15 @@ async fn main() {
         set_current_dir(working_directory).expect("failed to change working directory");
     }
 
+    let remote_url = get_remote_url();
+
     let shared_state = Arc::new(AppState {
         token: OnceCell::new(),
         context_cache: DashMap::new(),
+
+        metadata_provider: Arc::new(DropContextProvider::new(remote_url.clone())),
+        backend_factory: Arc::new(DropBackendFactory),
+        library_provider: Arc::new(DropLibraryProvider::new(remote_url)),
     });
 
     let app = setup_app(shared_state);
@@ -72,65 +45,19 @@ fn setup_app(shared_state: Arc<AppState>) -> Router {
     Router::new()
         .route(
             "/api/v1/depot/{game_id}/{version_name}/{chunk_id}",
-            get(serve_file),
+            get(handlers::serve_file),
         )
         .route("/token", post(set_token))
-        .route("/healthcheck", get(healthcheck))
+        .route("/healthcheck", get(handlers::healthcheck))
         .with_state(shared_state)
 }
+
 async fn serve(app: Router) -> Result<(), std::io::Error> {
     let listener = tokio::net::TcpListener::bind("0.0.0.0:5000").await.unwrap();
     info!("started depot server");
     axum::serve(listener, app).await
 }
 
-async fn set_token(
-    State(state): State<Arc<AppState>>,
-    Json(payload): Json<TokenPayload>,
-) -> Result<StatusCode, StatusCode> {
-    if check_token_exists(&state, &payload) {
-        return Ok(StatusCode::OK);
-    }
-
-    let token = payload.token;
-
-    let library_sources = fetch_library_sources(&token).await.map_err(|v| {
-        error!("{v:?}");
-        StatusCode::INTERNAL_SERVER_ERROR
-    })?;
-
-    let valid_library_sources = filter_library_sources(library_sources);
-
-    set_generated_token(&state, token, valid_library_sources)?;
-
-    info!("connected to drop server successfully");
-
-    Ok(StatusCode::OK)
-}
-
-async fn serve_file(
-    State(state): State<Arc<AppState>>,
-    Path((game_id, version_name, chunk_id)): Path<(String, String, String)>,
-) -> Result<impl IntoResponse, StatusCode> {
-    let context_cache = &state.context_cache;
-
-    let mut context = get_or_generate_context(&state, context_cache, game_id, version_name).await?;
-    context.last_access = Instant::now();
-
-    let (relative_filename, start, end) = lookup_chunk(&chunk_id, &context)?;
-    let reader = get_file_reader(&mut context, relative_filename, start, end).await?;
-
-    let stream = ReaderStream::new(reader);
-    let body: Body = Body::from_stream(stream);
-
-    let headers: AppendHeaders<[(header::HeaderName, String); 2]> = AppendHeaders([
-        (header::CONTENT_TYPE, "application/octet-stream".to_owned()),
-        (header::CONTENT_LENGTH, (end - start).to_string()),
-    ]);
-
-    Ok((headers, body))
-}
-
 fn initialise_logger() {
     SimpleLogger::new()
         .with_level(log::LevelFilter::Info)
@@ -138,140 +65,14 @@ fn initialise_logger() {
         .unwrap();
 }
 
-async fn acquire_permit<'a>() -> SemaphorePermit<'a> {
-    return GLOBAL_CONTEXT_SEMAPHORE
-        .acquire()
-        .await
-        .expect("failed to acquire semaphore")
-}
-fn lookup_chunk(
-    chunk_id: &String,
-    context: &RefMut<'_, (String, String), DownloadContext>,
-) -> Result<(String, usize, usize), StatusCode> {
-    context
-        .chunk_lookup_table
-        .get(chunk_id)
-        .cloned()
-        .ok_or(StatusCode::NOT_FOUND)
-}
-async fn get_file_reader(
-    context: &mut RefMut<'_, (String, String), DownloadContext>,
-    relative_filename: String,
-    start: usize,
-    end: usize,
-) -> Result<Box<dyn MinimumFileObject>, StatusCode> {
-    context
-        .backend
-        .reader(
-            &VersionFile {
-                relative_filename: relative_filename.clone(),
-                permission: 0,
-                size: 0,
-            },
-            start as u64,
-            end as u64,
-        )
-        .await
-        .map_err(|v| {
-            error!("reader error: {v:?}");
-            StatusCode::INTERNAL_SERVER_ERROR
-        })
-}
-async fn get_or_generate_context<'a>(
-    state: &Arc<AppState>,
-    context_cache: &'a DashMap<(String, String), DownloadContext>,
-    game_id: String,
-    version_name: String,
-) -> Result<RefMut<'a, (String, String), DownloadContext>, StatusCode> {
-    let initialisation_data = state.token.get().ok_or(StatusCode::SERVICE_UNAVAILABLE)?;
-    let key = (game_id.clone(), version_name.clone());
-
-    if let Some(context) = context_cache.get_mut(&key) {
-        Ok(context)
-    } else {
-        let permit = acquire_permit().await;
-
-        // Check if it's been done while we've been sitting here
-        if let Some(already_done) = context_cache.get_mut(&key) {
-            Ok(already_done)
-        } else {
-            info!("generating context...");
-            let context_result =
-                create_download_context(initialisation_data, game_id.clone(), version_name.clone())
-                    .await?;
-
-            state.context_cache.insert(key.clone(), context_result);
-
-            info!("continuing download");
-
-            drop(permit);
-
-            Ok(context_cache.get_mut(&key).unwrap())
-        }
-    }
-}
-
-#[derive(Deserialize)]
-struct TokenPayload {
-    token: String,
-}
-
-async fn healthcheck(State(state): State<Arc<AppState>>) -> StatusCode {
-    let initialised = state.token.initialized();
-    if !initialised {
-        return StatusCode::SERVICE_UNAVAILABLE;
-    }
-    StatusCode::OK
-}
-
-fn check_token_exists(state: &Arc<AppState>, payload: &TokenPayload) -> bool {
-    if let Some(existing_data) = state.token.get() {
-        assert!(
-            existing_data.token == payload.token,
-            "already set up but provided with a different token"
-        );
-        return true;
-    }
-    false
-}
-fn filter_library_sources(
-    library_sources: Vec<LibrarySource>,
-) -> HashMap<String, (PathBuf, LibraryBackend)> {
-    library_sources
-        .into_iter()
-        .filter(|v| {
-            matches!(
-                v.backend,
-                remote::LibraryBackend::Filesystem | remote::LibraryBackend::FlatFilesystem
-            )
-        })
-        .map(|v| {
-            let path = PathBuf::from_str(
-                v.options
-                    .as_object()
-                    .unwrap()
-                    .get("baseDir")
-                    .unwrap()
-                    .as_str()
-                    .unwrap(),
-            )
-            .unwrap();
-
-            (v.id, (path, v.backend))
-        })
-        .collect()
-}
-fn set_generated_token(
-    state: &Arc<AppState>,
-    token: String,
-    libraries: HashMap<String, (PathBuf, LibraryBackend)>,
-) -> Result<(), StatusCode> {
-    state
-        .token
-        .set(AppInitData { token, libraries })
-        .map_err(|err| {
-            error!("failed to set token: {err:?}");
-            StatusCode::INTERNAL_SERVER_ERROR
-        })?;
-    Ok(())
+fn get_remote_url() -> Url {
+    let user_provided = env::var("DROP_SERVER_URL");
+    let url = Url::parse(
+        user_provided
+            .as_ref()
+            .map_or("http://localhost:3000", |v| v),
+    )
+    .expect("failed to parse URL");
+    info!("using Drop server url {url}");
+    url
 }

src/remote.rs

@@ -1,9 +1,8 @@
-use std::{env, sync::LazyLock};
-
 use anyhow::{Result, anyhow};
-use log::info;
-use reqwest::{Client, ClientBuilder, StatusCode, Url};
+use async_trait::async_trait;
+use reqwest::StatusCode;
 use serde::{Deserialize, Serialize};
+use url::Url;
 
 use crate::{manifest::DropletManifest, util::ErrorOption};
 
@@ -21,60 +20,6 @@ pub struct ContextQuery {
     version: String,
 }
 
-static CLIENT: LazyLock<Client> = LazyLock::new(|| {
-    ClientBuilder::new()
-        .build()
-        .expect("failed to build client")
-});
-
-static REMOTE_URL: LazyLock<Url> = LazyLock::new(|| {
-    let user_provided = env::var("DROP_SERVER_URL");
-    let url = Url::parse(
-        user_provided
-            .as_ref()
-            .map_or("http://localhost:3000", |v| v),
-    )
-    .expect("failed to parse URL");
-    info!("using Drop server url {url}");
-    url
-});
-
-pub async fn fetch_download_context(
-    token: String,
-    game_id: String,
-    version_name: String,
-) -> Result<ContextResponseBody, ErrorOption> {
-    let context_response = CLIENT
-        .get(REMOTE_URL.join("/api/v1/admin/depot/context")?)
-        .query(&ContextQuery {
-            game: game_id,
-            version: version_name,
-        })
-        .header("Authorization", format!("Bearer {token}"))
-        .send()
-        .await?;
-
-    if !context_response.status().is_success() {
-        if context_response.status() == StatusCode::BAD_REQUEST {
-            return Err(StatusCode::NOT_FOUND.into());
-        }
-
-        return Err(anyhow!(
-            "Fetching context failed with non-success code: {}, {}",
-            context_response.status(),
-            context_response
-                .text()
-                .await
-                .unwrap_or("(failed to read body)".to_owned())
-        )
-        .into());
-    }
-
-    let context: ContextResponseBody = context_response.json().await?;
-
-    Ok(context)
-}
-
 #[derive(Deserialize, Debug)]
 #[non_exhaustive]
 pub enum LibraryBackend {
@@ -89,25 +34,110 @@ pub struct LibrarySource {
     pub backend: LibraryBackend,
 }
 
-pub async fn fetch_library_sources(token: &String) -> Result<Vec<LibrarySource>> {
-    let source_response = CLIENT
-        .get(REMOTE_URL.join("/api/v1/admin/library/sources")?)
-        .header("Authorization", format!("Bearer {token}"))
-        .send()
-        .await?;
-
-    if !source_response.status().is_success() {
-        return Err(anyhow!(
-            "Fetching library sources failed with non-success code: {}, {}",
-            source_response.status(),
-            source_response
-                .text()
-                .await
-                .unwrap_or("(failed to read body)".to_owned())
-        ));
-    }
-
-    let library_sources: Vec<LibrarySource> = source_response.json().await?;
-
-    Ok(library_sources)
+pub struct DropContextProvider {
+    client: reqwest::Client,
+    base_url: Url,
+}
+impl DropContextProvider {
+    pub fn new(url: Url) -> Self {
+        Self {
+            client: reqwest::Client::new(),
+            base_url: url,
+        }
+    }
+}
+#[async_trait]
+impl ContextProvider for DropContextProvider {
+    async fn fetch_context(
+        &self,
+        token: String,
+        game_id: String,
+        version_name: String,
+    ) -> Result<ContextResponseBody, ErrorOption> {
+        let context_response = self
+            .client
+            .get(self.base_url.join("/api/v1/admin/depot/context")?)
+            .query(&ContextQuery {
+                game: game_id,
+                version: version_name,
+            })
+            .header("Authorization", format!("Bearer {token}"))
+            .send()
+            .await?;
+
+        if !context_response.status().is_success() {
+            if context_response.status() == StatusCode::BAD_REQUEST {
+                return Err(StatusCode::NOT_FOUND.into());
+            }
+
+            return Err(anyhow!(
+                "Fetching context failed with non-success code: {}, {}",
+                context_response.status(),
+                context_response
+                    .text()
+                    .await
+                    .unwrap_or("(failed to read body)".to_owned())
+            )
+            .into());
+        }
+
+        let context: ContextResponseBody = context_response.json().await?;
+
+        Ok(context)
+    }
+}
+
+#[async_trait]
+pub trait ContextProvider: Send + Sync {
+    /// Fetches the manifest for a specific game version.
+    async fn fetch_context(
+        &self,
+        token: String,
+        game_id: String,
+        version_name: String,
+    ) -> Result<ContextResponseBody, ErrorOption>;
+}
+
+#[async_trait]
+pub trait LibraryConfigurationProvider: Send + Sync {
+    async fn fetch_sources(&self, token: &String) -> anyhow::Result<Vec<LibrarySource>>;
+}
+pub struct DropLibraryProvider {
+    client: reqwest::Client,
+    base_url: Url,
+}
+impl DropLibraryProvider {
+    pub fn new(url: Url) -> Self {
+        Self {
+            client: reqwest::Client::new(),
+            base_url: url,
+        }
+    }
+}
+
+#[async_trait]
+impl LibraryConfigurationProvider for DropLibraryProvider {
+    async fn fetch_sources(&self, token: &String) -> anyhow::Result<Vec<LibrarySource>> {
+        let source_response = self
+            .client
+            .get(self.base_url.join("/api/v1/admin/library/sources")?)
+            .header("Authorization", format!("Bearer {token}"))
+            .send()
+            .await?;
+
+        if !source_response.status().is_success() {
+            return Err(anyhow!(
+                "Fetching library sources failed with non-success code: {}, {}",
+                source_response.status(),
+                source_response
+                    .text()
+                    .await
+                    .unwrap_or("(failed to read body)".to_owned())
+            ));
+        }
+
+        let library_sources: Vec<LibrarySource> = source_response.json().await?;
+
+        Ok(library_sources)
+    }
 }

src/state.rs

@@ -0,0 +1,38 @@
+use std::{collections::HashMap, path::PathBuf, sync::Arc};
+
+use dashmap::DashMap;
+use tokio::sync::OnceCell;
+
+use crate::{
+    BackendFactory, DownloadContext, LibraryConfigurationProvider, ContextProvider,
+    remote::LibraryBackend,
+};
+
+pub struct AppState {
+    pub token: OnceCell<AppInitData>,
+    pub context_cache: DashMap<(String, String), DownloadContext>,
+
+    pub metadata_provider: Arc<dyn ContextProvider>,
+    pub backend_factory: Arc<dyn BackendFactory>,
+    pub library_provider: Arc<dyn LibraryConfigurationProvider>,
+}
+
+#[derive(Debug)]
+pub struct AppInitData {
+    token: String,
+    libraries: HashMap<String, (PathBuf, LibraryBackend)>,
+}
+impl AppInitData {
+    pub fn new(token: String, libraries: HashMap<String, (PathBuf, LibraryBackend)>) -> Self {
+        Self { token, libraries }
+    }
+    pub fn token(&self) -> String {
+        self.token.clone()
+    }
+    pub fn set_token(&mut self, token: String) {
+        self.token = token
+    }
+    pub fn libraries(&self) -> &HashMap<String, (PathBuf, LibraryBackend)> {
+        &self.libraries
+    }
+}

src/token.rs

@@ -0,0 +1,94 @@
+use std::{collections::HashMap, path::PathBuf, str::FromStr, sync::Arc};
+
+use axum::{Json, extract::State};
+use log::{error, info};
+use reqwest::StatusCode;
+use serde::Deserialize;
+
+use crate::remote::{self, LibraryBackend, LibrarySource};
+use crate::state::{AppInitData, AppState};
+
+#[derive(Deserialize)]
+pub struct TokenPayload {
+    token: String,
+}
+
+pub async fn set_token(
+    State(state): State<Arc<AppState>>,
+    Json(payload): Json<TokenPayload>,
+) -> Result<StatusCode, StatusCode> {
+    if check_token_exists(&state, &payload) {
+        return Ok(StatusCode::OK);
+    }
+
+    let token = payload.token;
+
+    let library_sources = state
+        .library_provider
+        .fetch_sources(&token)
+        .await
+        .map_err(|v| {
+            error!("{v:?}");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
+
+    let valid_library_sources = filter_library_sources(library_sources);
+
+    set_generated_token(&state, token, valid_library_sources)?;
+
+    info!("connected to drop server successfully");
+
+    Ok(StatusCode::OK)
+}
+
+fn check_token_exists(state: &Arc<AppState>, payload: &TokenPayload) -> bool {
+    if let Some(existing_data) = state.token.get() {
+        assert!(
+            *existing_data.token() == payload.token,
+            "already set up but provided with a different token"
+        );
+        return true;
+    }
+    false
+}
+fn filter_library_sources(
+    library_sources: Vec<LibrarySource>,
+) -> HashMap<String, (PathBuf, LibraryBackend)> {
+    library_sources
+        .into_iter()
+        .filter(|v| {
+            matches!(
+                v.backend,
+                remote::LibraryBackend::Filesystem | remote::LibraryBackend::FlatFilesystem
+            )
+        })
+        .map(|v| {
+            let path = PathBuf::from_str(
+                v.options
+                    .as_object()
+                    .unwrap()
+                    .get("baseDir")
+                    .unwrap()
+                    .as_str()
+                    .unwrap(),
+            )
+            .unwrap();
+
+            (v.id, (path, v.backend))
+        })
+        .collect()
+}
+fn set_generated_token(
+    state: &Arc<AppState>,
+    token: String,
+    libraries: HashMap<String, (PathBuf, LibraryBackend)>,
+) -> Result<(), StatusCode> {
+    state
+        .token
+        .set(AppInitData::new(token, libraries))
+        .map_err(|err| {
+            error!("failed to set token: {err:?}");
+            StatusCode::INTERNAL_SERVER_ERROR
+        })?;
+    Ok(())
+}