Add support for removing favorites from posts (#9)

* Add post_unfavorite

* Update src/post.rs

* Update src/client.rs

---------

Co-authored-by: nasso <11479594+nasso@users.noreply.github.com>

src/client.rs

@@ -6,7 +6,8 @@ mod rate_limit;
 mod rate_limit;
 
 use futures::Future;
-use reqwest::Url;
+use reqwest::{Response, Url};
+use serde::Serialize;
 
 use {
     super::error::{Error, Result},
@@ -138,7 +139,7 @@ impl Client {
         Ok(url)
     }
 
-    pub(crate) async fn post_form<T>(&self, endpoint: &str, body: &T) -> Result<serde_json::Value>
+    async fn post_response<T>(&self, endpoint: &str, body: &T) -> Result<Response>
     where
         T: serde::Serialize,
     {
@@ -162,9 +163,7 @@ impl Client {
                     .map_err(|e| Error::CannotSendRequest(format!("{}", e)))?;
 
                 if res.status().is_success() {
-                    res.json()
-                        .await
-                        .map_err(|e| Error::Serial(format!("{}", e)))
+                    Ok(res)
                 } else {
                     Err(Error::Http {
                         url,
@@ -179,6 +178,30 @@ impl Client {
             .await
     }
 
+    pub(crate) async fn post_form<T>(&self, endpoint: &str, body: &T) -> Result<serde_json::Value>
+    where
+        T: serde::Serialize,
+    {
+        self.post_response(endpoint, body)
+            .await?
+            .json()
+            .await
+            .map_err(|e| Error::Serial(format!("{e}")))
+    }
+
+    pub(crate) async fn delete(&self, endpoint: &str) -> Result<()> {
+        #[derive(Serialize)]
+        struct Form {
+            _method: &'static str,
+        }
+
+        // Can't use HTTP DELETE because e621's CORS headers aren't permissive enough. Thankfully
+        // ruby on rails has a workaround for exactly this purpose.
+        self.post_response(endpoint, &Form { _method: "delete" })
+            .await?;
+        Ok(())
+    }
+
     pub fn get_json_endpoint(
         &self,
         endpoint: &str,

src/post.rs

@@ -637,6 +637,25 @@ impl Client {
         serde_json::from_value(value).map_err(|e| Error::Serial(format!("{}", e)))
     }
 
+    /// Mark a [`Post`] (identified by `id`) as no longer particularly liked.
+    ///
+    /// ```no_run
+    /// # use {
+    /// #     rs621::client::Client,
+    /// #     futures::prelude::*,
+    /// # };
+    /// # #[tokio::main]
+    /// # async fn main() -> rs621::error::Result<()> {
+    /// let client = Client::new("https://e926.net", "MyProject/1.0 (by username on e621)")?;
+    ///
+    /// client.post_unfavorite(1234).await?;
+    /// # Ok(()) }
+    /// ```
+    pub async fn post_unfavorite(&self, id: u64) -> Result<(), Error> {
+        self.delete(&format!("/favorites/{id}.json")).await?;
+        Ok(())
+    }
+
     /// Vote a [`Post`] (identified by `id`) up or down.
     ///
     /// Use [`VoteDir::Toggle`] to clear an existing vote.
@@ -746,6 +765,21 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn post_unfavorite() {
+        let mut client = Client::new(&mockito::server_url(), b"rs621/unit_test").unwrap();
+        client.login("foo".into(), "bar".into());
+
+        let _m = mock(
+            "POST",
+            Matcher::Exact("/favorites/3758515.json?login=foo&api_key=bar".into()),
+        )
+        .match_body("_method=delete")
+        .create();
+
+        client.post_unfavorite(3758515).await.unwrap();
+    }
+
     #[tokio::test]
     async fn search_ordered() {
         let client = Client::new(&mockito::server_url(), b"rs621/unit_test").unwrap();