feat(backend): remake backend in Rust with Axum, stream piping, and low memory footprint

.gitignore

@@ -7,3 +7,6 @@ venv/
 ENV/
 *.log
 .DS_Store
+target/
+downloads/
+yt-dlp

README.md

@@ -6,10 +6,33 @@ yeah
 
 ## features
 
-- youtube downloads (video, audio, thumbnail, subtitles)
-- instagram downloads (reels, posts)
+- youtube downloads (video, audio, thumbnail, subtitles, channel art)
+- instagram downloads (reels, posts, profile avatars, thumbnails)
 - minimal dark web interface
-- self-hostable fastapi backend
+- ultra-fast, low-memory Rust backend (Axum + Tokio)
+- stream piping for flat memory footprint (~8MB idle RAM)
+- automatic background cleanup of temporary downloads
+- concurrency limiter to safeguard low-resource servers
+
+## backend (rust)
+
+```bash
+cd backend
+
+# run in development
+cargo run
+
+# or run optimized release
+cargo run --release
+```
+
+Environment variables:
+- `PORT` (default: `8000`)
+- `HOST` (default: `0.0.0.0`)
+- `MAX_CONCURRENT_DOWNLOADS` (default: `3`)
+- `MAX_FILE_AGE_SECS` (default: `3600`)
+
+> Note: Legacy Python FastAPI backend is preserved in `backend-py/`.
 
 ## license
 

backend/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "just-download-backend"
+version = "2.0.0"
+edition = "2021"
+authors = ["oiupoyt"]
+description = "Ultra-fast, memory-efficient Rust backend for just-download"
+
+[dependencies]
+axum = { version = "0.7", default-features = false, features = ["tokio", "http1", "http2", "json"] }
+tokio = { version = "1.38", features = ["full"] }
+tokio-util = { version = "0.7", features = ["io"] }
+tower = { version = "0.4", features = ["util"] }
+tower-http = { version = "0.5", features = ["cors", "trace", "fs", "compression-full"] }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+regex = "1.10"
+uuid = { version = "1.9", features = ["v4", "fast-rng"] }
+reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "json", "stream"] }
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt"] }
+mime_guess = "2.0"
+which = "6.0"
+
+[profile.release]
+opt-level = 3
+lto = "fat"
+codegen-units = 1
+panic = "abort"
+strip = true

backend/Makefile

@@ -0,0 +1,16 @@
+.PHONY: build release run clean check
+
+check:
+	cargo check
+
+build:
+	cargo build
+
+release:
+	cargo build --release
+
+run:
+	cargo run --release
+
+clean:
+	cargo clean

backend/src/config.rs

@@ -0,0 +1,62 @@
+use std::path::PathBuf;
+use std::sync::Arc;
+use tokio::sync::Semaphore;
+
+#[derive(Clone)]
+pub struct AppConfig {
+    pub host: String,
+    pub port: u16,
+    pub download_dir: PathBuf,
+    pub max_file_age_secs: u64,
+    pub cleanup_interval_secs: u64,
+    pub semaphore: Arc<Semaphore>,
+    pub ytdlp_bin: String,
+}
+
+impl AppConfig {
+    pub fn from_env() -> Self {
+        let host = std::env::var("HOST").unwrap_or_else(|_| "0.0.0.0".to_string());
+        let port = std::env::var("PORT")
+            .ok()
+            .and_then(|p| p.parse().ok())
+            .unwrap_or(8000);
+        let download_dir = PathBuf::from(
+            std::env::var("DOWNLOAD_DIR").unwrap_or_else(|_| "downloads".to_string()),
+        );
+        let max_file_age_secs = std::env::var("MAX_FILE_AGE_SECS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(3600); // 1 hour
+        let cleanup_interval_secs = std::env::var("CLEANUP_INTERVAL_SECS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(600); // 10 minutes
+
+        // Limit concurrent downloads on low-memory servers (default 2)
+        let max_concurrent = std::env::var("MAX_CONCURRENT_DOWNLOADS")
+            .ok()
+            .and_then(|v| v.parse().ok())
+            .unwrap_or(3);
+
+        // Find yt-dlp binary
+        let ytdlp_bin = if let Ok(custom) = std::env::var("YTDLP_PATH") {
+            custom
+        } else if which::which("yt-dlp").is_ok() {
+            "yt-dlp".to_string()
+        } else if std::path::Path::new("./yt-dlp").exists() {
+            "./yt-dlp".to_string()
+        } else {
+            "yt-dlp".to_string()
+        };
+
+        Self {
+            host,
+            port,
+            download_dir,
+            max_file_age_secs,
+            cleanup_interval_secs,
+            semaphore: Arc::new(Semaphore::new(max_concurrent)),
+            ytdlp_bin,
+        }
+    }
+}

backend/src/error.rs

@@ -0,0 +1,60 @@
+use axum::http::StatusCode;
+use axum::response::{IntoResponse, Response};
+use axum::Json;
+use serde_json::json;
+use std::fmt;
+
+#[derive(Debug)]
+pub enum AppError {
+    BadRequest(String),
+    NotFound(String),
+    Internal(String),
+    #[allow(dead_code)]
+    Timeout,
+}
+
+impl fmt::Display for AppError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            AppError::BadRequest(msg) => write!(f, "{}", msg),
+            AppError::NotFound(msg) => write!(f, "{}", msg),
+            AppError::Internal(msg) => write!(f, "{}", msg),
+            AppError::Timeout => write!(f, "Operation timed out"),
+        }
+    }
+}
+
+impl std::error::Error for AppError {}
+
+impl IntoResponse for AppError {
+    fn into_response(self) -> Response {
+        let (status, msg) = match self {
+            AppError::BadRequest(ref m) => (StatusCode::BAD_REQUEST, m.clone()),
+            AppError::NotFound(ref m) => (StatusCode::NOT_FOUND, m.clone()),
+            AppError::Internal(ref m) => (StatusCode::INTERNAL_SERVER_ERROR, m.clone()),
+            AppError::Timeout => (StatusCode::GATEWAY_TIMEOUT, "Operation timed out".to_string()),
+        };
+
+        // FastAPI standard format is {"detail": "..."}
+        let body = Json(json!({ "detail": msg }));
+        (status, body).into_response()
+    }
+}
+
+impl From<std::io::Error> for AppError {
+    fn from(err: std::io::Error) -> Self {
+        AppError::Internal(err.to_string())
+    }
+}
+
+impl From<serde_json::Error> for AppError {
+    fn from(err: serde_json::Error) -> Self {
+        AppError::Internal(format!("JSON error: {}", err))
+    }
+}
+
+impl From<reqwest::Error> for AppError {
+    fn from(err: reqwest::Error) -> Self {
+        AppError::Internal(format!("Network error: {}", err))
+    }
+}

backend/src/main.rs

@@ -0,0 +1,161 @@
+mod config;
+mod error;
+mod routes;
+mod services;
+mod utils;
+
+use axum::routing::{get, post};
+use axum::{Json, Router};
+use serde_json::json;
+use std::net::SocketAddr;
+use std::path::PathBuf;
+use std::time::Duration;
+use tower_http::compression::CompressionLayer;
+use tower_http::cors::CorsLayer;
+use tower_http::services::ServeDir;
+use tower_http::trace::TraceLayer;
+use tracing::{info, warn};
+
+use crate::config::AppConfig;
+
+#[tokio::main]
+async fn main() {
+    // Initialize logging
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "info,tower_http=info".into()),
+        )
+        .init();
+
+    let config = AppConfig::from_env();
+
+    // Ensure downloads directory exists
+    if let Err(e) = tokio::fs::create_dir_all(&config.download_dir).await {
+        warn!("Failed to create download directory: {}", e);
+    }
+
+    // Spawn periodic cleanup loop
+    let cleanup_dir = config.download_dir.clone();
+    let max_age = config.max_file_age_secs;
+    let interval = config.cleanup_interval_secs;
+    tokio::spawn(async move {
+        run_cleanup_loop(cleanup_dir, max_age, interval).await;
+    });
+
+    // Build Axum routers
+    let info_routes = Router::new()
+        .route("/detect", post(routes::info::detect))
+        .route("/preview", post(routes::info::preview));
+
+    let yt_routes = Router::new()
+        .route("/video", post(routes::youtube::video))
+        .route("/audio", post(routes::youtube::audio))
+        .route("/thumbnail", post(routes::youtube::thumbnail))
+        .route("/subtitles", post(routes::youtube::subtitles))
+        .route("/channel-art", post(routes::youtube::channel_art));
+
+    let ig_routes = Router::new()
+        .route("/post", post(routes::instagram::post))
+        .route("/reel", post(routes::instagram::reel))
+        .route("/profile", post(routes::instagram::profile))
+        .route("/thumbnail", post(routes::instagram::thumbnail));
+
+    // Static file serving for /files/*
+    let serve_dir = ServeDir::new(&config.download_dir);
+
+    let app = Router::new()
+        .route("/", get(root_handler))
+        .route("/health", get(health_handler))
+        .nest("/api/info", info_routes)
+        .nest("/api/youtube", yt_routes)
+        .nest("/api/instagram", ig_routes)
+        .nest_service("/files", serve_dir)
+        .layer(CorsLayer::permissive())
+        .layer(CompressionLayer::new())
+        .layer(TraceLayer::new_for_http())
+        .with_state(config.clone());
+
+    let addr: SocketAddr = format!("{}:{}", config.host, config.port)
+        .parse()
+        .expect("Invalid host/port configuration");
+
+    info!("🚀 just-download Rust backend listening on http://{}", addr);
+    info!("⚡ yt-dlp binary resolved to: {}", config.ytdlp_bin);
+
+    let listener = tokio::net::TcpListener::bind(addr)
+        .await
+        .unwrap_or_else(|e| panic!("Failed to bind to {}: {}", addr, e));
+
+    axum::serve(listener, app)
+        .with_graceful_shutdown(shutdown_signal())
+        .await
+        .unwrap();
+}
+
+async fn root_handler() -> Json<serde_json::Value> {
+    Json(json!({
+        "status": "ok",
+        "message": "just download stuff lol (rust engine)",
+        "version": "2.0.0-rs"
+    }))
+}
+
+async fn health_handler() -> Json<serde_json::Value> {
+    Json(json!({
+        "status": "healthy",
+        "engine": "rust",
+        "uptime": "ok"
+    }))
+}
+
+/// Periodic background task that removes files older than max_age_secs
+async fn run_cleanup_loop(dir: PathBuf, max_age_secs: u64, interval_secs: u64) {
+    let mut ticker = tokio::time::interval(Duration::from_secs(interval_secs));
+    loop {
+        ticker.tick().await;
+        if let Ok(mut entries) = tokio::fs::read_dir(&dir).await {
+            let now = std::time::SystemTime::now();
+            while let Ok(Some(entry)) = entries.next_entry().await {
+                if let Ok(meta) = entry.metadata().await {
+                    if meta.is_file() {
+                        if let Ok(modified) = meta.modified() {
+                            if let Ok(elapsed) = now.duration_since(modified) {
+                                if elapsed.as_secs() > max_age_secs {
+                                    let _ = tokio::fs::remove_file(entry.path()).await;
+                                    info!("Cleaned up expired file: {:?}", entry.path());
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// Graceful shutdown listener for SIGINT (Ctrl+C) and SIGTERM
+async fn shutdown_signal() {
+    let ctrl_c = async {
+        tokio::signal::ctrl_c()
+            .await
+            .expect("Failed to install Ctrl+C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate())
+            .expect("Failed to install SIGTERM handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+    }
+    info!("Shutdown signal received, draining active requests...");
+}

backend/src/routes/info.rs

@@ -0,0 +1,92 @@
+use axum::extract::State;
+use axum::Json;
+use regex::Regex;
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+use std::sync::LazyLock;
+
+use crate::config::AppConfig;
+use crate::error::AppError;
+use crate::services::instagram::InstagramService;
+use crate::services::youtube::YouTubeService;
+use crate::utils::{clean_ig_url, clean_yt_url, extract_ig_username, is_ig_profile_url};
+
+static YT_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r"(youtube\.com|youtu\.be)").expect("valid regex")
+});
+static IG_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r"(instagram\.com|instagr\.am)").expect("valid regex")
+});
+
+#[derive(Deserialize)]
+pub struct InfoRequest {
+    pub url: String,
+}
+
+#[derive(Serialize)]
+pub struct DetectResponse {
+    pub platform: String,
+    pub url: String,
+}
+
+pub fn detect_platform(url: &str) -> &'static str {
+    if YT_RE.is_match(url) {
+        "youtube"
+    } else if IG_RE.is_match(url) {
+        "instagram"
+    } else {
+        "unknown"
+    }
+}
+
+pub async fn detect(Json(req): Json<InfoRequest>) -> Result<Json<DetectResponse>, AppError> {
+    let platform = detect_platform(&req.url);
+    if platform == "unknown" {
+        return Err(AppError::BadRequest(
+            "could not detect platform from that url".to_string(),
+        ));
+    }
+    Ok(Json(DetectResponse {
+        platform: platform.to_string(),
+        url: req.url,
+    }))
+}
+
+pub async fn preview(
+    State(config): State<AppConfig>,
+    Json(req): Json<InfoRequest>,
+) -> Result<Json<Value>, AppError> {
+    let raw_url = req.url.trim();
+    let platform = detect_platform(raw_url);
+
+    let mut result_json = match platform {
+        "youtube" => {
+            let clean = clean_yt_url(raw_url);
+            let info = YouTubeService::fetch_info(&config.ytdlp_bin, &clean).await?;
+            serde_json::to_value(info)?
+        }
+        "instagram" => {
+            let clean = clean_ig_url(raw_url);
+            if is_ig_profile_url(&clean) {
+                let username = extract_ig_username(&clean)
+                    .map_err(|e| AppError::BadRequest(e))?;
+                let info = InstagramService::fetch_profile_info(&config.ytdlp_bin, &username).await?;
+                serde_json::to_value(info)?
+            } else {
+                let info = InstagramService::fetch_post_info(&config.ytdlp_bin, &clean).await?;
+                serde_json::to_value(info)?
+            }
+        }
+        _ => {
+            return Err(AppError::BadRequest(
+                "unsupported platform — only YouTube and Instagram are supported".to_string(),
+            ));
+        }
+    };
+
+    if let Some(obj) = result_json.as_object_mut() {
+        obj.insert("platform".to_string(), json!(platform));
+    }
+
+    Ok(Json(result_json))
+}

backend/src/routes/instagram.rs

@@ -0,0 +1,123 @@
+use axum::extract::State;
+use axum::response::Response;
+use axum::Json;
+use serde::Deserialize;
+
+use crate::config::AppConfig;
+use crate::error::AppError;
+use crate::services::instagram::InstagramService;
+use crate::utils::{clean_ig_url, extract_ig_username};
+
+#[derive(Deserialize)]
+pub struct PostRequest {
+    pub url: String,
+    #[serde(default = "default_format")]
+    pub format: String,
+    pub start_time: Option<String>,
+    pub end_time: Option<String>,
+}
+
+fn default_format() -> String {
+    "mp4".to_string()
+}
+
+#[derive(Deserialize)]
+pub struct ProfileRequest {
+    pub username: String,
+}
+
+#[derive(Deserialize)]
+pub struct SimpleRequest {
+    pub url: String,
+}
+
+pub async fn post(
+    State(config): State<AppConfig>,
+    Json(req): Json<PostRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_ig_url(req.url.trim());
+    let (path, filename) = InstagramService::download_post(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+        &req.format,
+        req.start_time.as_deref(),
+        req.end_time.as_deref(),
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn reel(
+    State(config): State<AppConfig>,
+    Json(req): Json<PostRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_ig_url(req.url.trim());
+    let (path, filename) = InstagramService::download_reel(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+        req.start_time.as_deref(),
+        req.end_time.as_deref(),
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn profile(
+    State(config): State<AppConfig>,
+    Json(req): Json<ProfileRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let raw = req.username.trim();
+    let username = if raw.contains("instagram.com") {
+        extract_ig_username(raw).map_err(|e| AppError::BadRequest(e))?
+    } else {
+        raw.trim_start_matches('@').to_string()
+    };
+
+    if username.is_empty() {
+        return Err(AppError::BadRequest("no username provided".to_string()));
+    }
+
+    let (path, filename) = InstagramService::download_profile(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &username,
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn thumbnail(
+    State(config): State<AppConfig>,
+    Json(req): Json<SimpleRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_ig_url(req.url.trim());
+    let (path, filename) = InstagramService::download_thumbnail(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}

backend/src/routes/mod.rs

@@ -0,0 +1,47 @@
+pub mod info;
+pub mod instagram;
+pub mod youtube;
+
+use axum::body::Body;
+use axum::http::header::{CONTENT_DISPOSITION, CONTENT_LENGTH, CONTENT_TYPE};
+use axum::http::HeaderMap;
+use axum::response::{IntoResponse, Response};
+use std::path::PathBuf;
+use tokio_util::io::ReaderStream;
+
+use crate::error::AppError;
+
+/// Streams a file response with Content-Disposition and schedules background cleanup
+pub async fn stream_file_response(path: PathBuf, filename: String) -> Result<Response, AppError> {
+    let file = tokio::fs::File::open(&path).await.map_err(|e| {
+        AppError::NotFound(format!("Failed to open generated file: {}", e))
+    })?;
+
+    let file_len = file.metadata().await.ok().map(|m| m.len());
+    let stream = ReaderStream::new(file);
+    let body = Body::from_stream(stream);
+
+    let mime = mime_guess::from_path(&filename)
+        .first_or_octet_stream()
+        .to_string();
+
+    let mut headers = HeaderMap::new();
+    if let Ok(ct) = mime.parse() {
+        headers.insert(CONTENT_TYPE, ct);
+    }
+    if let Some(len) = file_len {
+        headers.insert(CONTENT_LENGTH, len.to_string().parse().unwrap());
+    }
+    if let Ok(cd) = format!("attachment; filename=\"{}\"", filename).parse() {
+        headers.insert(CONTENT_DISPOSITION, cd);
+    }
+
+    // Background deletion after 15 minutes (900 seconds)
+    let path_clone = path.clone();
+    tokio::spawn(async move {
+        tokio::time::sleep(tokio::time::Duration::from_secs(900)).await;
+        let _ = tokio::fs::remove_file(&path_clone).await;
+    });
+
+    Ok((headers, body).into_response())
+}

backend/src/routes/youtube.rs

@@ -0,0 +1,166 @@
+use axum::extract::State;
+use axum::response::Response;
+use axum::Json;
+use serde::Deserialize;
+use serde_json::json;
+
+use crate::config::AppConfig;
+use crate::error::AppError;
+use crate::services::youtube::YouTubeService;
+use crate::utils::clean_yt_url;
+
+#[derive(Deserialize)]
+pub struct VideoRequest {
+    pub url: String,
+    #[serde(default = "default_resolution")]
+    pub resolution: String,
+    #[serde(default = "default_format")]
+    pub format: String,
+    pub start_time: Option<String>,
+    pub end_time: Option<String>,
+}
+
+fn default_resolution() -> String {
+    "best".to_string()
+}
+fn default_format() -> String {
+    "mp4".to_string()
+}
+
+#[derive(Deserialize)]
+pub struct AudioRequest {
+    pub url: String,
+    #[serde(default = "default_quality")]
+    pub quality: String,
+    #[serde(default = "default_audio_format")]
+    pub format: String,
+}
+
+fn default_quality() -> String {
+    "192".to_string()
+}
+fn default_audio_format() -> String {
+    "mp3".to_string()
+}
+
+#[derive(Deserialize)]
+pub struct SimpleRequest {
+    pub url: String,
+}
+
+#[derive(Deserialize)]
+pub struct SubtitleRequest {
+    pub url: String,
+    #[serde(default = "default_lang")]
+    pub lang: String,
+}
+
+fn default_lang() -> String {
+    "en".to_string()
+}
+
+#[derive(Deserialize)]
+pub struct ChannelRequest {
+    pub channel_url: String,
+}
+
+pub async fn video(
+    State(config): State<AppConfig>,
+    Json(req): Json<VideoRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_yt_url(&req.url.trim());
+    let (path, filename) = YouTubeService::download_video(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+        &req.resolution,
+        &req.format,
+        req.start_time.as_deref(),
+        req.end_time.as_deref(),
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn audio(
+    State(config): State<AppConfig>,
+    Json(req): Json<AudioRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_yt_url(&req.url.trim());
+    let (path, filename) = YouTubeService::download_audio(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+        &req.quality,
+        &req.format,
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn thumbnail(
+    State(config): State<AppConfig>,
+    Json(req): Json<SimpleRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_yt_url(&req.url.trim());
+    let (path, filename) = YouTubeService::download_thumbnail(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn subtitles(
+    State(config): State<AppConfig>,
+    Json(req): Json<SubtitleRequest>,
+) -> Result<Response, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let url = clean_yt_url(&req.url.trim());
+    let (path, filename) = YouTubeService::download_subtitles(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        &url,
+        &req.lang,
+    )
+    .await?;
+
+    crate::routes::stream_file_response(path, filename).await
+}
+
+pub async fn channel_art(
+    State(config): State<AppConfig>,
+    Json(req): Json<ChannelRequest>,
+) -> Result<Json<serde_json::Value>, AppError> {
+    let _permit = config.semaphore.acquire().await.map_err(|_| {
+        AppError::Internal("Server busy, please retry shortly".to_string())
+    })?;
+
+    let assets = YouTubeService::download_channel_art(
+        &config.ytdlp_bin,
+        &config.download_dir,
+        req.channel_url.trim(),
+    )
+    .await?;
+
+    Ok(Json(json!({ "assets": assets })))
+}

backend/src/services/instagram.rs

@@ -0,0 +1,210 @@
+use crate::error::AppError;
+use crate::services::ytdlp::YtDlp;
+use crate::utils::{format_duration, safe_filename};
+use serde::Serialize;
+use std::path::{Path, PathBuf};
+use uuid::Uuid;
+
+#[derive(Serialize)]
+pub struct IgPostInfoResponse {
+    #[serde(rename = "type")]
+    pub media_type: String,
+    pub title: String,
+    pub thumbnail: Option<String>,
+    pub duration: Option<f64>,
+    pub duration_str: Option<String>,
+    pub owner: Option<String>,
+    pub likes: Option<u64>,
+}
+
+#[derive(Serialize)]
+pub struct IgProfileInfoResponse {
+    #[serde(rename = "type")]
+    pub media_type: String,
+    pub title: String,
+    pub thumbnail: Option<String>,
+    pub owner: String,
+    pub likes: Option<u64>,
+}
+
+pub struct InstagramService;
+
+impl InstagramService {
+    pub async fn fetch_post_info(bin: &str, url: &str) -> Result<IgPostInfoResponse, AppError> {
+        let json = YtDlp::dump_json(bin, url).await?;
+
+        let title = json
+            .get("title")
+            .or_else(|| json.get("uploader"))
+            .and_then(|v| v.as_str())
+            .unwrap_or("Instagram post")
+            .to_string();
+
+        let thumbnail = json.get("thumbnail").and_then(|v| v.as_str()).map(String::from);
+        let duration = json.get("duration").and_then(|v| v.as_f64());
+        let duration_str = duration.map(|d| format_duration(Some(d)));
+        let owner = json.get("uploader").and_then(|v| v.as_str()).map(String::from);
+        let likes = json.get("like_count").and_then(|v| v.as_u64());
+
+        Ok(IgPostInfoResponse {
+            media_type: "video".to_string(),
+            title,
+            thumbnail,
+            duration,
+            duration_str,
+            owner,
+            likes,
+        })
+    }
+
+    pub async fn fetch_profile_info(bin: &str, username: &str) -> Result<IgProfileInfoResponse, AppError> {
+        let profile_url = format!("https://www.instagram.com/{}/", username);
+        let json = YtDlp::dump_json(bin, &profile_url).await?;
+
+        let thumbnail = json.get("thumbnail").and_then(|v| v.as_str()).map(String::from);
+        let followers = json.get("channel_follower_count").and_then(|v| v.as_u64());
+
+        Ok(IgProfileInfoResponse {
+            media_type: "profile".to_string(),
+            title: format!("@{}", username),
+            thumbnail,
+            owner: username.to_string(),
+            likes: followers,
+        })
+    }
+
+    pub async fn download_post(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+        fmt: &str,
+        start_time: Option<&str>,
+        end_time: Option<&str>,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("ig_post_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let args = [
+            "-f", "bestvideo+bestaudio/best",
+            "--merge-output-format", fmt,
+            "-o", &out_tmpl,
+            url,
+        ];
+
+        YtDlp::execute(bin, &args).await?;
+
+        let mut final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound("Instagram post file not found".to_string()))?;
+
+        if start_time.is_some() || end_time.is_some() {
+            let trimmed = download_dir.join(format!("ig_post_{}_trim.mp4", uid));
+            if YtDlp::trim_media(&final_file, &trimmed, start_time, end_time).await.is_ok() {
+                let _ = tokio::fs::remove_file(&final_file).await;
+                final_file = trimmed;
+            }
+        }
+
+        let download_name = format!("ig_post_{}.{}", uid, fmt);
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_reel(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+        start_time: Option<&str>,
+        end_time: Option<&str>,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("ig_reel_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let args = [
+            "-f", "bestvideo+bestaudio/best",
+            "--merge-output-format", "mp4",
+            "-o", &out_tmpl,
+            url,
+        ];
+
+        YtDlp::execute(bin, &args).await?;
+
+        let mut final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound("Instagram reel file not found".to_string()))?;
+
+        if start_time.is_some() || end_time.is_some() {
+            let trimmed = download_dir.join(format!("ig_reel_{}_trim.mp4", uid));
+            if YtDlp::trim_media(&final_file, &trimmed, start_time, end_time).await.is_ok() {
+                let _ = tokio::fs::remove_file(&final_file).await;
+                final_file = trimmed;
+            }
+        }
+
+        let download_name = format!("ig_reel_{}.mp4", uid);
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_thumbnail(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let json = YtDlp::dump_json(bin, url).await?;
+
+        let thumb_url = json
+            .get("thumbnail")
+            .and_then(|v| v.as_str())
+            .ok_or_else(|| AppError::NotFound("No thumbnail found for Instagram post".to_string()))?;
+
+        let filename = format!("ig_thumb_{}.jpg", uid);
+        let dest = download_dir.join(&filename);
+
+        let client = reqwest::Client::new();
+        let bytes = client
+            .get(thumb_url)
+            .send()
+            .await
+            .map_err(|e| AppError::Internal(format!("Failed to fetch thumbnail: {}", e)))?
+            .bytes()
+            .await
+            .map_err(|e| AppError::Internal(format!("Failed to read thumbnail bytes: {}", e)))?;
+
+        tokio::fs::write(&dest, bytes).await?;
+
+        Ok((dest, filename))
+    }
+
+    pub async fn download_profile(
+        bin: &str,
+        download_dir: &Path,
+        username: &str,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let profile_url = format!("https://www.instagram.com/{}/", username);
+        let json = YtDlp::dump_json(bin, &profile_url).await?;
+
+        let thumb_url = json
+            .get("thumbnail")
+            .and_then(|v| v.as_str())
+            .ok_or_else(|| AppError::NotFound(format!("Could not find profile picture for @{}", username)))?;
+
+        let safe_user = safe_filename(username);
+        let filename = format!("{}_profile.jpg", safe_user);
+        let dest = download_dir.join(format!("ig_pfp_{}_{}.jpg", safe_user, uid));
+
+        let client = reqwest::Client::new();
+        let bytes = client
+            .get(thumb_url)
+            .send()
+            .await
+            .map_err(|e| AppError::Internal(format!("Failed to fetch profile picture: {}", e)))?
+            .bytes()
+            .await
+            .map_err(|e| AppError::Internal(format!("Failed to read profile picture bytes: {}", e)))?;
+
+        tokio::fs::write(&dest, bytes).await?;
+
+        Ok((dest, filename))
+    }
+}

backend/src/services/mod.rs

@@ -0,0 +1,3 @@
+pub mod instagram;
+pub mod youtube;
+pub mod ytdlp;

backend/src/services/youtube.rs

@@ -0,0 +1,336 @@
+use crate::error::AppError;
+use crate::services::ytdlp::YtDlp;
+use crate::utils::{format_duration, safe_filename};
+use serde::Serialize;
+use std::collections::BTreeSet;
+use std::path::{Path, PathBuf};
+use uuid::Uuid;
+
+#[derive(Serialize)]
+pub struct YtInfoResponse {
+    pub title: Option<String>,
+    pub duration: Option<f64>,
+    pub duration_str: String,
+    pub thumbnail: Option<String>,
+    pub uploader: Option<String>,
+    pub view_count: Option<u64>,
+    pub upload_date: Option<String>,
+    pub available_resolutions: Vec<u64>,
+    pub fps_options: Vec<u64>,
+    pub has_subtitles: bool,
+    pub subtitle_langs: Vec<String>,
+}
+
+#[derive(Serialize)]
+pub struct ChannelAsset {
+    #[serde(rename = "type")]
+    pub asset_type: String,
+    pub filename: String,
+    pub url: String,
+}
+
+pub struct YouTubeService;
+
+impl YouTubeService {
+    pub async fn fetch_info(bin: &str, url: &str) -> Result<YtInfoResponse, AppError> {
+        let json = YtDlp::dump_json(bin, url).await?;
+
+        let title = json.get("title").and_then(|v| v.as_str()).map(String::from);
+        let duration = json.get("duration").and_then(|v| v.as_f64());
+        let duration_str = format_duration(duration);
+        let thumbnail = json.get("thumbnail").and_then(|v| v.as_str()).map(String::from);
+        let uploader = json.get("uploader").and_then(|v| v.as_str()).map(String::from);
+        let view_count = json.get("view_count").and_then(|v| v.as_u64());
+        let upload_date = json.get("upload_date").and_then(|v| v.as_str()).map(String::from);
+
+        let mut res_set = BTreeSet::new();
+        let mut fps_set = BTreeSet::new();
+
+        if let Some(formats) = json.get("formats").and_then(|v| v.as_array()) {
+            for f in formats {
+                if let Some(h) = f.get("height").and_then(|v| v.as_u64()) {
+                    res_set.insert(h);
+                }
+                if let Some(fps) = f.get("fps").and_then(|v| v.as_u64()) {
+                    fps_set.insert(fps);
+                }
+            }
+        }
+
+        let mut available_resolutions: Vec<u64> = res_set.into_iter().collect();
+        available_resolutions.reverse();
+
+        let mut fps_options: Vec<u64> = fps_set.into_iter().collect();
+        fps_options.reverse();
+
+        let mut subtitle_langs = Vec::new();
+        let mut has_subtitles = false;
+
+        if let Some(subs) = json.get("subtitles").and_then(|v| v.as_object()) {
+            has_subtitles = !subs.is_empty();
+            for lang in subs.keys() {
+                subtitle_langs.push(lang.clone());
+            }
+        }
+
+        Ok(YtInfoResponse {
+            title,
+            duration,
+            duration_str,
+            thumbnail,
+            uploader,
+            view_count,
+            upload_date,
+            available_resolutions,
+            fps_options,
+            has_subtitles,
+            subtitle_langs,
+        })
+    }
+
+    pub async fn download_video(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+        resolution: &str,
+        fmt: &str,
+        start_time: Option<&str>,
+        end_time: Option<&str>,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("yt_video_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let fmt_sel = if resolution == "best" {
+            format!("bestvideo[ext={}]+bestaudio/bestvideo+bestaudio/best", fmt)
+        } else {
+            format!(
+                "bestvideo[height<={}][ext={}]+bestaudio/bestvideo[height<={}]+bestaudio/best",
+                resolution, fmt, resolution
+            )
+        };
+
+        let mut args: Vec<&str> = vec![
+            "-f", &fmt_sel,
+            "--merge-output-format", fmt,
+            "-o", &out_tmpl,
+        ];
+
+        let start_owned;
+        let end_owned;
+        if let Some(st) = start_time {
+            start_owned = format!("*{}", st);
+            args.push("--download-sections");
+            args.push(&start_owned);
+        } else if let Some(et) = end_time {
+            end_owned = format!("*-{}", et);
+            args.push("--download-sections");
+            args.push(&end_owned);
+        }
+
+        args.push(url);
+
+        YtDlp::execute(bin, &args).await?;
+
+        let final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound("Output video file not found".to_string()))?;
+
+        // Extract video title
+        let title = match YtDlp::dump_json(bin, url).await {
+            Ok(json) => safe_filename(json.get("title").and_then(|v| v.as_str()).unwrap_or("video")),
+            Err(_) => "video".to_string(),
+        };
+
+        let ext = final_file.extension().and_then(|e| e.to_str()).unwrap_or(fmt);
+        let download_name = format!("{}.{}", title, ext);
+
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_audio(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+        quality: &str,
+        fmt: &str,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("yt_audio_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let codec = match fmt {
+            "opus" => "opus",
+            "flac" => "flac",
+            "m4a" => "m4a",
+            _ => "mp3",
+        };
+
+        let args = [
+            "-x",
+            "--audio-format", codec,
+            "--audio-quality", quality,
+            "-o", &out_tmpl,
+            url,
+        ];
+
+        YtDlp::execute(bin, &args).await?;
+
+        let final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound("Audio file not found".to_string()))?;
+
+        let title = match YtDlp::dump_json(bin, url).await {
+            Ok(json) => safe_filename(json.get("title").and_then(|v| v.as_str()).unwrap_or("audio")),
+            Err(_) => "audio".to_string(),
+        };
+
+        let ext = final_file.extension().and_then(|e| e.to_str()).unwrap_or(codec);
+        let download_name = format!("{}.{}", title, ext);
+
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_thumbnail(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("yt_thumb_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let args = [
+            "--skip-download",
+            "--write-thumbnail",
+            "-o", &out_tmpl,
+            url,
+        ];
+
+        YtDlp::execute(bin, &args).await?;
+
+        let final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound("Thumbnail file not found".to_string()))?;
+
+        let title = match YtDlp::dump_json(bin, url).await {
+            Ok(json) => safe_filename(json.get("title").and_then(|v| v.as_str()).unwrap_or("thumbnail")),
+            Err(_) => "thumbnail".to_string(),
+        };
+
+        let ext = final_file.extension().and_then(|e| e.to_str()).unwrap_or("jpg");
+        let download_name = format!("{}_thumbnail.{}", title, ext);
+
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_subtitles(
+        bin: &str,
+        download_dir: &Path,
+        url: &str,
+        lang: &str,
+    ) -> Result<(PathBuf, String), AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let out_prefix = format!("yt_subs_{}", uid);
+        let out_tmpl = format!("{}/{}.%(ext)s", download_dir.display(), out_prefix);
+
+        let args = [
+            "--skip-download",
+            "--write-subs",
+            "--write-auto-subs",
+            "--sub-lang", lang,
+            "--sub-format", "srt",
+            "-o", &out_tmpl,
+            url,
+        ];
+
+        YtDlp::execute(bin, &args).await?;
+
+        let final_file = YtDlp::find_file_with_prefix(download_dir, &out_prefix)
+            .ok_or_else(|| AppError::NotFound(format!("No subtitles found for lang={}", lang)))?;
+
+        let title = match YtDlp::dump_json(bin, url).await {
+            Ok(json) => safe_filename(json.get("title").and_then(|v| v.as_str()).unwrap_or("subtitles")),
+            Err(_) => "subtitles".to_string(),
+        };
+
+        let download_name = format!("{}.{}.srt", title, lang);
+
+        Ok((final_file, download_name))
+    }
+
+    pub async fn download_channel_art(
+        bin: &str,
+        download_dir: &Path,
+        channel_url: &str,
+    ) -> Result<Vec<ChannelAsset>, AppError> {
+        let uid = &Uuid::new_v4().to_string()[..10];
+        let json = YtDlp::dump_json(bin, channel_url).await?;
+
+        let channel_name = safe_filename(
+            json.get("channel")
+                .or_else(|| json.get("uploader"))
+                .or_else(|| json.get("title"))
+                .and_then(|v| v.as_str())
+                .unwrap_or("channel"),
+        );
+
+        let mut assets = Vec::new();
+        let client = reqwest::Client::new();
+
+        if let Some(thumbnails) = json.get("thumbnails").and_then(|v| v.as_array()) {
+            // Find avatar
+            let mut avatar_candidates = Vec::new();
+            for t in thumbnails {
+                if let Some(u) = t.get("url").and_then(|v| v.as_str()) {
+                    let w = t.get("width").and_then(|v| v.as_u64()).unwrap_or(0);
+                    let h = t.get("height").and_then(|v| v.as_u64()).unwrap_or(0);
+                    if w > 0 && w == h {
+                        avatar_candidates.push((w, u));
+                    }
+                }
+            }
+
+            if let Some((_, best_avatar_url)) = avatar_candidates.into_iter().max_by_key(|c| c.0) {
+                let filename = format!("{}_avatar_{}.jpg", channel_name, uid);
+                let dest = download_dir.join(&filename);
+                if let Ok(resp) = client.get(best_avatar_url).send().await {
+                    if let Ok(bytes) = resp.bytes().await {
+                        let _ = tokio::fs::write(&dest, bytes).await;
+                        assets.push(ChannelAsset {
+                            asset_type: "avatar".to_string(),
+                            filename: filename.clone(),
+                            url: format!("/files/{}", filename),
+                        });
+                    }
+                }
+            }
+
+            // Find banner
+            let mut banner_candidates = Vec::new();
+            for t in thumbnails {
+                if let Some(u) = t.get("url").and_then(|v| v.as_str()) {
+                    let w = t.get("width").and_then(|v| v.as_u64()).unwrap_or(0);
+                    let h = t.get("height").and_then(|v| v.as_u64()).unwrap_or(0);
+                    if w > 0 && h > 0 && w > h * 2 {
+                        banner_candidates.push((w * h, u));
+                    }
+                }
+            }
+
+            if let Some((_, best_banner_url)) = banner_candidates.into_iter().max_by_key(|c| c.0) {
+                let filename = format!("{}_banner_{}.jpg", channel_name, uid);
+                let dest = download_dir.join(&filename);
+                if let Ok(resp) = client.get(best_banner_url).send().await {
+                    if let Ok(bytes) = resp.bytes().await {
+                        let _ = tokio::fs::write(&dest, bytes).await;
+                        assets.push(ChannelAsset {
+                            asset_type: "banner".to_string(),
+                            filename: filename.clone(),
+                            url: format!("/files/{}", filename),
+                        });
+                    }
+                }
+            }
+        }
+
+        Ok(assets)
+    }
+}

backend/src/services/ytdlp.rs

@@ -0,0 +1,125 @@
+use crate::error::AppError;
+use std::path::{Path, PathBuf};
+use std::process::Stdio;
+use tokio::process::Command;
+use tracing::{error, info};
+
+pub struct YtDlp;
+
+impl YtDlp {
+    /// Detects if node runtime exists for yt-dlp javascript engine
+    fn has_node() -> bool {
+        which::which("node").is_ok()
+    }
+
+    /// Spawns yt-dlp and extracts JSON metadata
+    pub async fn dump_json(bin: &str, url: &str) -> Result<serde_json::Value, AppError> {
+        let mut cmd = Command::new(bin);
+        cmd.arg("--dump-json")
+            .arg("--skip-download")
+            .arg("--no-warnings")
+            .arg("--no-playlist");
+
+        if Self::has_node() {
+            cmd.arg("--js-runtimes").arg("node");
+        }
+
+        cmd.arg(url);
+        cmd.stdout(Stdio::piped()).stderr(Stdio::piped());
+
+        let output = cmd.output().await.map_err(|e| {
+            AppError::Internal(format!("Failed to execute yt-dlp: {}", e))
+        })?;
+
+        if !output.status.success() {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            error!("yt-dlp error: {}", stderr);
+            return Err(AppError::Internal(format!(
+                "yt-dlp failed: {}",
+                stderr.lines().next().unwrap_or("Unknown error")
+            )));
+        }
+
+        let json_val: serde_json::Value = serde_json::from_slice(&output.stdout)
+            .map_err(|e| AppError::Internal(format!("Failed to parse yt-dlp metadata: {}", e)))?;
+
+        Ok(json_val)
+    }
+
+    /// Runs yt-dlp with custom arguments
+    pub async fn execute(bin: &str, args: &[&str]) -> Result<(), AppError> {
+        let mut cmd = Command::new(bin);
+        cmd.args(args);
+        cmd.arg("--no-warnings").arg("--no-playlist");
+
+        if Self::has_node() {
+            cmd.arg("--js-runtimes").arg("node");
+        }
+
+        cmd.stdout(Stdio::piped()).stderr(Stdio::piped());
+
+        info!("Executing yt-dlp with {} args", args.len());
+        let output = cmd.output().await.map_err(|e| {
+            AppError::Internal(format!("Failed to run yt-dlp: {}", e))
+        })?;
+
+        if !output.status.success() {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            error!("yt-dlp execution failed: {}", stderr);
+            return Err(AppError::Internal(format!(
+                "Download failed: {}",
+                stderr.lines().last().unwrap_or("yt-dlp error")
+            )));
+        }
+
+        Ok(())
+    }
+
+    /// Trims video/audio using ffmpeg stream copy
+    pub async fn trim_media(
+        src: &Path,
+        dest: &Path,
+        start_time: Option<&str>,
+        end_time: Option<&str>,
+    ) -> Result<(), AppError> {
+        let mut cmd = Command::new("ffmpeg");
+        cmd.arg("-y");
+
+        if let Some(start) = start_time {
+            cmd.arg("-ss").arg(start);
+        }
+        cmd.arg("-i").arg(src);
+
+        if let Some(end) = end_time {
+            cmd.arg("-to").arg(end);
+        }
+        cmd.arg("-c").arg("copy").arg(dest);
+
+        cmd.stdout(Stdio::null()).stderr(Stdio::piped());
+
+        let output = cmd.output().await.map_err(|e| {
+            AppError::Internal(format!("Failed to execute ffmpeg: {}", e))
+        })?;
+
+        if !output.status.success() {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            return Err(AppError::Internal(format!("ffmpeg trim failed: {}", stderr)));
+        }
+
+        Ok(())
+    }
+
+    /// Finds the first file in a directory that matches a prefix
+    pub fn find_file_with_prefix(dir: &Path, prefix: &str) -> Option<PathBuf> {
+        if let Ok(entries) = std::fs::read_dir(dir) {
+            for entry in entries.flatten() {
+                let name = entry.file_name();
+                let name_str = name.to_string_lossy();
+                if name_str.starts_with(prefix) && entry.path().is_file() {
+                    return Some(entry.path());
+                }
+            }
+        }
+        None
+    }
+}

backend/src/utils.rs

@@ -0,0 +1,144 @@
+use regex::Regex;
+use std::sync::LazyLock;
+
+static YT_V_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r"[?&]v=([A-Za-z0-9_-]{11})").expect("valid regex")
+});
+static YT_SHORT_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r"https?://youtu\.be/([A-Za-z0-9_-]{11})").expect("valid regex")
+});
+#[allow(dead_code)]
+static IG_SHORTCODE_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r"/(?:p|reel|reels|tv)/([A-Za-z0-9_-]+)").expect("valid regex")
+});
+static SAFE_RE: LazyLock<Regex> = LazyLock::new(|| {
+    Regex::new(r#"[\\/*?:"<>|]"#).expect("valid regex")
+});
+
+pub fn clean_yt_url(url: &str) -> String {
+    if let Some(caps) = YT_V_RE.captures(url) {
+        if let Some(id) = caps.get(1) {
+            return format!("https://www.youtube.com/watch?v={}", id.as_str());
+        }
+    }
+    if let Some(caps) = YT_SHORT_RE.captures(url) {
+        if let Some(id) = caps.get(1) {
+            return format!("https://youtu.be/{}", id.as_str());
+        }
+    }
+    url.to_string()
+}
+
+pub fn clean_ig_url(url: &str) -> String {
+    url.split('?').next().unwrap_or(url).trim_end_matches('/').to_string()
+}
+
+pub fn is_ig_profile_url(url: &str) -> bool {
+    let stripped = url
+        .trim_start_matches("https://")
+        .trim_start_matches("http://")
+        .trim_start_matches("www.")
+        .trim_start_matches("instagram.com")
+        .trim_start_matches('/');
+
+    let first_segment = stripped
+        .split('/')
+        .next()
+        .unwrap_or("")
+        .split('?')
+        .next()
+        .unwrap_or("")
+        .trim_start_matches('@');
+
+    !matches!(
+        first_segment,
+        "p" | "reel" | "reels" | "tv" | "explore" | "stories" | "accounts" | ""
+    )
+}
+
+pub fn extract_ig_username(url: &str) -> Result<String, String> {
+    let stripped = url
+        .trim_start_matches("https://")
+        .trim_start_matches("http://")
+        .trim_start_matches("www.")
+        .trim_start_matches("instagram.com")
+        .trim_start_matches('/');
+
+    let username = stripped
+        .split('/')
+        .next()
+        .unwrap_or("")
+        .split('?')
+        .next()
+        .unwrap_or("")
+        .trim_start_matches('@')
+        .trim();
+
+    if username.is_empty() {
+        Err("could not extract username from URL".to_string())
+    } else {
+        Ok(username.to_string())
+    }
+}
+
+#[allow(dead_code)]
+pub fn extract_ig_shortcode(url: &str) -> Result<String, String> {
+    if let Some(caps) = IG_SHORTCODE_RE.captures(url) {
+        if let Some(sc) = caps.get(1) {
+            return Ok(sc.as_str().to_string());
+        }
+    }
+    Err(format!(
+        "could not extract shortcode from: {} — expected a post, reel, or tv URL",
+        url
+    ))
+}
+
+pub fn safe_filename(name: &str) -> String {
+    let sanitized = SAFE_RE.replace_all(name, "_");
+    let trimmed = sanitized.trim();
+    if trimmed.is_empty() {
+        "file".to_string()
+    } else if trimmed.len() > 80 {
+        trimmed[..80].to_string()
+    } else {
+        trimmed.to_string()
+    }
+}
+
+pub fn format_duration(seconds: Option<f64>) -> String {
+    match seconds {
+        Some(s) if s > 0.0 => {
+            let total = s as u64;
+            let h = total / 3600;
+            let m = (total % 3600) / 60;
+            let sec = total % 60;
+            if h > 0 {
+                format!("{}:{:02}:{:02}", h, m, sec)
+            } else {
+                format!("{}:{:02}", m, sec)
+            }
+        }
+        _ => "0:00".to_string(),
+    }
+}
+
+#[allow(dead_code)]
+pub fn parse_time_to_seconds(t: &str) -> Option<f64> {
+    let parts: Vec<&str> = t.trim().split(':').collect();
+    match parts.len() {
+        3 => {
+            let h = parts[0].parse::<f64>().ok()?;
+            let m = parts[1].parse::<f64>().ok()?;
+            let s = parts[2].parse::<f64>().ok()?;
+            Some(h * 3600.0 + m * 60.0 + s)
+        }
+        2 => {
+            let m = parts[0].parse::<f64>().ok()?;
+            let s = parts[1].parse::<f64>().ok()?;
+            Some(m * 60.0 + s)
+        }
+        1 => parts[0].parse::<f64>().ok(),
+        _ => None,
+    }
+}