prefer to serve raw files over html files

src/download.rs

@@ -3,11 +3,14 @@ use std::str::FromStr;
 use actix_files::NamedFile;
 use actix_web::{
     error,
-    http::header::{Charset, ContentDisposition, DispositionParam, DispositionType, ExtendedValue},
+    http::header::{
+        Accept, Charset, ContentDisposition, DispositionParam, DispositionType, ExtendedValue,
+        Header,
+    },
     web, Error, HttpRequest, HttpResponse,
 };
 use async_std::{fs, path::Path};
-use mime::Mime;
+use mime::{Mime, TEXT_HTML};
 use sqlx::postgres::PgPool;
 use url::Url;
 
@@ -19,24 +22,29 @@ const URL_VIEW_HTML: &str = include_str!("../template/url-view.html");
 
 const TEXT_VIEW_SIZE_LIMIT: u64 = 512 * 1024; // 512KiB
 
+enum ViewType {
+    Raw,
+    Download,
+    Html,
+}
+
 pub async fn download(
     req: HttpRequest,
     db: web::Data<PgPool>,
     config: web::Data<Config>,
 ) -> Result<HttpResponse, Error> {
     let id = req.match_info().query("id");
-    let (file_id, file_name, file_kind, delete_on_download) = load_file_info(id, &db).await?;
+    let (file_id, file_name, file_kind, delete) = load_file_info(id, &db).await?;
     let mut path = config.files_dir.clone();
     path.push(&file_id);
 
-    let download = delete_on_download || req.query_string().contains("dl");
-    let content_type = get_content_type(&path);
-    let response = if use_text_view(&file_kind, &content_type, &path, download).await {
-        build_text_response(&path).await
-    } else {
-        build_file_response(download, &file_name, path, content_type, req)
+    let file_mime = get_content_type(&path);
+    let response = match get_view_type(&req, &file_kind, &file_mime, &path, delete).await {
+        ViewType::Raw => build_file_response(false, &file_name, path, file_mime, &req),
+        ViewType::Download => build_file_response(true, &file_name, path, file_mime, &req),
+        ViewType::Html => build_text_response(&path).await,
     };
-    if delete_on_download {
+    if delete {
         deleter::delete_by_id(&db, &file_id, &config.files_dir)
             .await
             .map_err(|db_err| {
@@ -72,16 +80,44 @@ fn get_content_type(path: &Path) -> Mime {
         .expect("tree_magic_mini should not produce invalid mime")
 }
 
-async fn use_text_view(
+async fn get_view_type(
+    req: &HttpRequest,
     file_kind: &str,
-    content_type: &Mime,
+    file_mime: &Mime,
     file_path: &Path,
-    download: bool,
-) -> bool {
+    delete_on_download: bool,
+) -> ViewType {
+    if delete_on_download || req.query_string().contains("dl") {
+        return ViewType::Download;
+    }
     let is_text =
-        FileKind::from_str(file_kind) == Ok(FileKind::Text) || content_type.type_() == mime::TEXT;
-    let is_not_large = get_file_size(file_path).await < TEXT_VIEW_SIZE_LIMIT;
-    is_text && is_not_large && !download
+        FileKind::from_str(file_kind) == Ok(FileKind::Text) || file_mime.type_() == mime::TEXT;
+    if !is_text {
+        return ViewType::Raw;
+    }
+    if get_file_size(file_path).await >= TEXT_VIEW_SIZE_LIMIT {
+        return ViewType::Raw;
+    }
+    if let Ok(accept) = Accept::parse(req) {
+        for accept_mime in accept.mime_precedence() {
+            if mime_matches(&accept_mime, file_mime) {
+                return ViewType::Raw;
+            }
+            if accept_mime == TEXT_HTML {
+                break;
+            }
+        }
+    } else {
+        return ViewType::Raw;
+    }
+
+    ViewType::Html
+}
+
+fn mime_matches(accept: &Mime, content: &Mime) -> bool {
+    let type_matches = accept.type_() == content.type_() || accept.type_() == mime::STAR;
+    let subtype_matches = accept.subtype() == content.subtype() || accept.subtype() == mime::STAR;
+    type_matches && subtype_matches
 }
 
 async fn get_file_size(file_path: &Path) -> u64 {
@@ -114,7 +150,7 @@ fn build_file_response(
     file_name: &str,
     path: async_std::path::PathBuf,
     content_type: Mime,
-    req: HttpRequest,
+    req: &HttpRequest,
 ) -> Result<HttpResponse, Error> {
     let content_disposition = ContentDisposition {
         disposition: if download {
@@ -131,7 +167,7 @@ fn build_file_response(
         })?
         .set_content_type(content_type)
         .set_content_disposition(content_disposition);
-    file.into_response(&req)
+    file.into_response(req)
 }
 
 fn get_disposition_params(filename: &str) -> Vec<DispositionParam> {