server: fix backward pagination

server/Cargo.toml

@@ -17,7 +17,7 @@ log = "0.4.17"
 tokio = "1.26.0"
 glog = "0.1.0"
 urlencoding = "2.1.3"
-async-graphql = "6.0.11"
+async-graphql = { version = "6.0.11", features = ["log"] }
 async-graphql-rocket = "6.0.11"
 rocket_cors = "0.6.0"
 rayon = "1.8.0"

server/src/bin/server.rs

@@ -167,6 +167,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
 
     let schema = Schema::build(QueryRoot, EmptyMutation, EmptySubscription)
         .data(Notmuch::default())
+        .extension(async_graphql::extensions::Logger)
         .finish();
 
     let _ = rocket::build()

server/src/graphql.rs

@@ -64,31 +64,20 @@ impl QueryRoot {
             last,
             |after, before, first, last| async move {
                 info!("{after:?} {before:?} {first:?} {last:?} {query}");
-                let mut start = 0usize;
                 let total = nm.count(&query)?;
-                let page_size = first.unwrap_or(20);
 
-                if let Some(after) = after {
+                let mut start = after.map(|after| after + 1).unwrap_or(0);
-                    if after >= total {
+                let mut end = before.unwrap_or(total);
-                        return Ok(Connection::new(false, false));
+                if let Some(first) = first {
-                    }
+                    end = (start + first).min(end);
-                    start = after + 1;
                 }
-                let mut end = start + page_size;
+                if let Some(last) = last {
-                if end > total {
+                    start = if last > end - start { end } else { end - last };
-                    end = total;
-                }
-
-                // TODO(wathiede): handle last/end.
-                if let Some(before) = before {
-                    if before == 0 {
-                        return Ok(Connection::new(false, false));
-                    }
-                    end = before;
                 }
 
+                let count = end - start;
                 let slice: Vec<ThreadSummary> = nm
-                    .search(&query, start, first.unwrap_or(20))?
+                    .search(&query, start, count)?
                     .0
                     .into_iter()
                     .map(|ts| ThreadSummary {