controllers/helpers/pagination: Add seek! helper macro

Author: eth3lbert

Cargo.lock

@@ -97,6 +97,7 @@ object_store = { version = "=0.9.0", features = ["aws"] }
 once_cell = "=1.19.0"
 p256 = "=0.13.2"
 parking_lot = "=0.12.1"
+paste = "=1.0.14"
 prometheus = { version = "=0.13.3", default-features = false }
 rand = "=0.8.5"
 reqwest = { version = "=0.11.23", features = ["gzip", "json"] }

Cargo.toml

@@ -395,6 +395,73 @@ impl<T, C> PaginatedQueryWithCountSubq<T, C> {
     }
 }
 
+macro_rules! seek {
+    (
+        $vis:vis enum $name:ident {
+            $(
+                $variant:ident($($(#[$field_meta:meta])? $ty:ty),*)
+            )*
+        }
+    ) => {
+        paste::item! {
+            $(
+                #[derive(Debug, Default, Deserialize, Serialize, PartialEq)]
+                $vis struct $variant($($(#[$field_meta])? pub(super) $ty),*);
+            )*
+
+            #[derive(Debug, Deserialize, Serialize, PartialEq)]
+            #[serde(untagged)]
+            $vis enum [<$name Payload>] {
+                $(
+                    $variant($variant),
+                )*
+            }
+
+            #[derive(Debug, PartialEq)]
+            $vis enum $name {
+                $(
+                    $variant,
+                )*
+            }
+
+            $(
+                impl From<$variant> for [<$name Payload>] {
+                    fn from(value: $variant) -> Self {
+                        [<$name Payload>]::$variant(value)
+                    }
+                }
+            )*
+            impl From<[<$name Payload>]> for $name {
+                fn from(value: [<$name Payload>]) -> Self {
+                    match value {
+                        $(
+                            [<$name Payload>]::$variant(_) => $name::$variant,
+                        )*
+                    }
+                }
+            }
+
+            use crate::util::errors::AppResult;
+            use crate::controllers::helpers::pagination::Page;
+            impl $name {
+                pub fn after(&self, page: &Page) -> AppResult<Option<[<$name Payload>]>> {
+                    let Page::Seek(ref encoded) = *page else {
+                        return Ok(None);
+                    };
+
+                    Ok(Some(match self {
+                        $(
+                            $name::$variant => encoded.decode::<$variant>()?.into(),
+                        )*
+                    }))
+                }
+            }
+        }
+    };
+}
+
+pub(crate) use seek;
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -499,6 +566,66 @@ mod tests {
         );
     }
 
+    mod seek {
+        use chrono::naive::serde::ts_microseconds;
+        seek! {
+            pub(super) enum Seek {
+                Id(i32)
+                New(#[serde(with="ts_microseconds")] chrono::NaiveDateTime, i32)
+                RecentDownloads(Option<i64>, i32)
+            }
+        }
+    }
+
+    #[test]
+    fn test_seek_macro_encode_and_decode() {
+        use chrono::{NaiveDate, NaiveDateTime};
+        use seek::*;
+
+        let assert_decode_after = |seek: Seek, query: &str, expect| {
+            let pagination = PaginationOptions::builder()
+                .enable_seek(true)
+                .gather(&mock(query))
+                .unwrap();
+            let decoded = seek.after(&pagination.page).unwrap();
+            assert_eq!(decoded, expect);
+        };
+
+        let seek = Seek::Id;
+        let payload = SeekPayload::Id(Id(1234));
+        let query = format!("seek={}", encode_seek(&payload).unwrap());
+        assert_decode_after(seek, &query, Some(payload));
+
+        let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2016, 7, 8)
+            .unwrap()
+            .and_hms_opt(9, 10, 11)
+            .unwrap();
+        let seek = Seek::New;
+        let payload = SeekPayload::New(New(dt, 1234));
+        let query = format!("seek={}", encode_seek(&payload).unwrap());
+        assert_decode_after(seek, &query, Some(payload));
+
+        let seek = Seek::RecentDownloads;
+        let payload = SeekPayload::RecentDownloads(RecentDownloads(Some(5678), 1234));
+        let query = format!("seek={}", encode_seek(&payload).unwrap());
+        assert_decode_after(seek, &query, Some(payload));
+
+        let seek = Seek::Id;
+        assert_decode_after(seek, "", None);
+
+        let seek = Seek::Id;
+        let payload = SeekPayload::RecentDownloads(RecentDownloads(Some(5678), 1234));
+        let query = format!("seek={}", encode_seek(payload).unwrap());
+        let pagination = PaginationOptions::builder()
+            .enable_seek(true)
+            .gather(&mock(&query))
+            .unwrap();
+        let error = seek.after(&pagination.page).unwrap_err();
+        assert_eq!(error.to_string(), "invalid seek parameter");
+        let response = error.response();
+        assert_eq!(response.status(), StatusCode::BAD_REQUEST);
+    }
+
     fn mock(query: &str) -> Request<()> {
         Request::builder()
             .method(Method::GET)