fix: image proxy on web ui (#154)

I found that the image proxy is not applied when requested through web
ui. The cause is that the endpoint parameter is not extracted correctly,
such that the `base` field is always missing. This PR fixes the issue.

In addition I realized the app base inference logic doesn't match what's
defined in the documentation. I've updated the logic to match the
documentation.

src/server/endpoint.rs

@@ -188,10 +188,21 @@ impl EndpointParam {
   }
 
   fn get_base(req: &Parts) -> Option<Url> {
+    if let Some(url) = Self::base_from_env().as_ref() {
+      return Some(url.clone());
+    }
+
+    if let Some(url) = Self::base_from_reverse_proxy(req) {
+      return Some(url);
+    }
+
+    Self::base_from_host(req)
+  }
+
+  fn base_from_reverse_proxy(req: &Parts) -> Option<Url> {
     let host = req
       .headers
       .get("X-Forwarded-Host")
-      .or_else(|| req.headers.get(HOST))
       .and_then(|x| x.to_str().ok())?;
 
     let proto = req
@@ -204,6 +215,27 @@ impl EndpointParam {
     let base = base.parse().ok()?;
     Some(base)
   }
+
+  fn base_from_host(req: &Parts) -> Option<Url> {
+    let host = req.headers.get(HOST)?.to_str().ok()?;
+    let base = format!("http://{}/", host);
+    let base = base.parse().ok()?;
+    Some(base)
+  }
+
+  fn base_from_env() -> &'static Option<Url> {
+    use std::env;
+    use std::sync::OnceLock;
+
+    static APP_BASE_URL: OnceLock<Option<Url>> = OnceLock::new();
+    APP_BASE_URL.get_or_init(|| {
+      let var = env::var("RSS_FUNNEL_APP_BASE").ok();
+      var.map(|v| {
+        v.parse()
+          .expect("Invalid base url specified in RSS_FUNNEL_APP_BASE")
+      })
+    })
+  }
 }
 
 impl Service<Request> for EndpointService {

src/server/web.rs

@@ -5,7 +5,7 @@ mod login;
 use std::borrow::Cow;
 
 use axum::{
-  extract::{rejection::QueryRejection, Path, Query},
+  extract::Path,
   response::{IntoResponse, Redirect, Response},
   routing, Extension, Router,
 };
@@ -70,14 +70,13 @@ async fn handle_endpoint(
   _: Auth,
   Path(path): Path<String>,
   Extension(service): Extension<FeedService>,
-  param: Result<Query<EndpointParam>, QueryRejection>,
+  param: EndpointParam,
 ) -> Result<Markup, Response> {
   let endpoint = service.get_endpoint(&path).await.ok_or_else(|| {
     (StatusCode::NOT_FOUND, format!("Endpoint {path} not found"))
       .into_response()
   })?;
 
-  let param = param.map(|q| q.0).map_err(|e| e.body_text());
   Ok(endpoint::render_endpoint_page(endpoint, path, param).await)
 }
 

src/server/web/endpoint.rs

@@ -13,25 +13,17 @@ use crate::{
 pub async fn render_endpoint_page(
   endpoint: EndpointService,
   path: String,
-  param: Result<EndpointParam, String>,
+  param: EndpointParam,
 ) -> Markup {
   // render source control
   let source = source_control_fragment(&path, endpoint.source(), &param);
 
   // render config
-  let config = render_config_fragment(&path, param.as_ref().ok(), &endpoint);
+  let config = render_config_fragment(&path, &param, &endpoint);
   let config_tags = render_config_header_tags(&endpoint);
 
   // render normalized feed
-  let feed = match param {
-    Ok(param) => fetch_and_render_feed(endpoint, param).await,
-    Err(e) => html! {
-      div .flash.error {
-        header { b { "Invalid request params" } }
-        p { (e) }
-      }
-    },
-  };
+  let feed = fetch_and_render_feed(endpoint, param).await;
 
   html! {
     (DOCTYPE)
@@ -91,7 +83,7 @@ pub async fn render_endpoint_page(
 fn source_control_fragment(
   path: &str,
   source: &Source,
-  param: &Result<EndpointParam, String>,
+  param: &EndpointParam,
 ) -> Markup {
   match source {
     Source::Dynamic => html! {
@@ -100,7 +92,7 @@ fn source_control_fragment(
         type="text"
         name="source"
         placeholder="Source URL"
-        value=[param.as_ref().ok().and_then(|p| p.source()).map(|url| url.as_str())]
+        value=[param.source().map(|url| url.as_str())]
         hx-get=(format!("/_/endpoint/{path}"))
         hx-trigger="keyup changed delay:500ms"
         hx-push-url="true"
@@ -114,7 +106,7 @@ fn source_control_fragment(
     Source::RelativeUrl(url) => html! {div title="Source" .source { (url) }},
     Source::Templated(templated) => html! {
       div .source-template-container {
-        @let queries = param.as_ref().ok().map(|p| p.extra_queries());
+        @let queries = param.extra_queries();
         (source_template_fragment(templated, path, queries));
       }
     },
@@ -154,14 +146,14 @@ fn from_scratch_fragment(scratch: &FromScratch) -> Markup {
 fn source_template_fragment(
   templated: &crate::source::Templated,
   path: &str,
-  queries: Option<&HashMap<String, String>>,
+  queries: &HashMap<String, String>,
 ) -> Markup {
   html! {
     @for fragment in templated.fragments() {
       @match fragment {
         Either::Left(plain) => span style="white-space: nowrap" { (plain) },
         Either::Right((name, Some(placeholder))) => {
-          @let value=queries.and_then(|q| q.get(name));
+          @let value=queries.get(name);
           @let default_value=placeholder.default.as_ref();
           @let value=value.or(default_value);
           @let validation=placeholder.validation.as_ref();
@@ -203,12 +195,12 @@ fn render_config_header_tags(endpoint: &EndpointService) -> Markup {
 
 fn render_config_fragment(
   path: &str,
-  param: Option<&EndpointParam>,
+  param: &EndpointParam,
   endpoint: &EndpointService,
 ) -> Markup {
   let config = endpoint.config();
   let filter_enabled = |i| {
-    if let Some(f) = param.and_then(|p| p.filter_skip()) {
+    if let Some(f) = param.filter_skip() {
       f.allows_filter(i) as u8
     } else {
       true as u8