From 3c4af12fa13c8e37940616b6e4be230f7b3c3989 Mon Sep 17 00:00:00 2001
From: Jef Roosens <roosensjef@gmail.com>
Date: Mon, 24 Feb 2025 13:24:23 +0100
Subject: [PATCH] feat: implement custom deserializer for path segments with
 format extension

---
 src/server/gpodder/advanced/devices.rs | 26 +++++------
 src/server/gpodder/format.rs           | 65 ++++++++++++++++++++++++++
 src/server/gpodder/mod.rs              |  1 +
 3 files changed, 79 insertions(+), 13 deletions(-)
 create mode 100644 src/server/gpodder/format.rs

diff --git a/src/server/gpodder/advanced/devices.rs b/src/server/gpodder/advanced/devices.rs
index 7be52ef..7df6ec1 100644
--- a/src/server/gpodder/advanced/devices.rs
+++ b/src/server/gpodder/advanced/devices.rs
@@ -6,11 +6,12 @@ use axum::{
 };
 
 use crate::{
-    db::{self, User},
+    db,
     server::{
         error::{AppError, AppResult},
         gpodder::{
             auth_middleware,
+            format::{Format, StringWithFormat},
             models::{Device, DevicePatch, DeviceType},
         },
         Context,
@@ -26,14 +27,14 @@ pub fn router(ctx: Context) -> Router<Context> {
 
 async fn get_devices(
     State(ctx): State<Context>,
-    Path(username): Path<String>,
-    Extension(user): Extension<User>,
+    Path(username): Path<StringWithFormat>,
+    Extension(user): Extension<db::User>,
 ) -> AppResult<Json<Vec<Device>>> {
-    // Check suffix is present and return 404 otherwise; axum doesn't support matching part of a
-    // route segment
-    let username = username.strip_suffix(".json").ok_or(AppError::NotFound)?;
+    if username.format != Format::Json {
+        return Err(AppError::NotFound);
+    }
 
-    if username != user.username {
+    if *username != user.username {
         return Err(AppError::BadRequest);
     }
 
@@ -55,14 +56,13 @@ async fn get_devices(
 
 async fn post_device(
     State(ctx): State<Context>,
-    Path((_username, id)): Path<(String, String)>,
-    Extension(user): Extension<User>,
+    Path((_username, id)): Path<(String, StringWithFormat)>,
+    Extension(user): Extension<db::User>,
     Json(patch): Json<DevicePatch>,
 ) -> AppResult<()> {
-    let id = id
-        .strip_suffix(".json")
-        .ok_or(AppError::NotFound)?
-        .to_string();
+    if id.format != Format::Json {
+        return Err(AppError::NotFound);
+    }
 
     tokio::task::spawn_blocking(move || {
         if let Some(mut device) = db::Device::by_device_id(&ctx.pool, user.id, &id)? {
diff --git a/src/server/gpodder/format.rs b/src/server/gpodder/format.rs
new file mode 100644
index 0000000..4c2a5de
--- /dev/null
+++ b/src/server/gpodder/format.rs
@@ -0,0 +1,65 @@
+use std::ops::Deref;
+
+use serde::{
+    de::{value::StrDeserializer, Visitor},
+    Deserialize,
+};
+
+#[derive(Deserialize, Debug, PartialEq, Eq)]
+#[serde(rename_all = "lowercase")]
+pub enum Format {
+    Json,
+    OPML,
+    Plaintext,
+}
+
+#[derive(Debug)]
+pub struct StringWithFormat {
+    pub s: String,
+    pub format: Format,
+}
+
+impl Deref for StringWithFormat {
+    type Target = String;
+
+    fn deref(&self) -> &Self::Target {
+        &self.s
+    }
+}
+
+impl<'de> Deserialize<'de> for StringWithFormat {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        struct StrVisitor;
+
+        impl<'de> Visitor<'de> for StrVisitor {
+            type Value = StringWithFormat;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str(
+                    "`text.ext` format, with `ext` being one of `json`, `opml` or `plaintext`",
+                )
+            }
+
+            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+            where
+                E: serde::de::Error,
+            {
+                if let Some((text, ext)) = v.rsplit_once('.') {
+                    let format = Format::deserialize(StrDeserializer::new(ext))?;
+
+                    Ok(StringWithFormat {
+                        s: text.to_string(),
+                        format,
+                    })
+                } else {
+                    Err(E::custom(format!("invalid format '{}'", v)))
+                }
+            }
+        }
+
+        deserializer.deserialize_str(StrVisitor)
+    }
+}
diff --git a/src/server/gpodder/mod.rs b/src/server/gpodder/mod.rs
index 7b2ba67..00f1d6b 100644
--- a/src/server/gpodder/mod.rs
+++ b/src/server/gpodder/mod.rs
@@ -1,4 +1,5 @@
 mod advanced;
+mod format;
 mod models;
 mod simple;