feat(api): add sort parameter to list issues API (#7211)

- Add the `sort` parameter to the `/api/v1/{repo}/{owner}/issues` API endpoint. Default behavior is preserved.
- Resolves forgejo/forgejo#4173
- Add (non-exhaustive) integration testing.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7211
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

modules/indexer/issues/indexer.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"os"
 	"runtime/pprof"
+	"strings"
 	"sync/atomic"
 	"time"
 
@@ -280,6 +281,33 @@ const (
 	SortByDeadlineAsc  = internal.SortByDeadlineAsc
 )
 
+// ParseSortBy parses the `sortBy` string and returns the associated `SortBy`
+// value, if one exists. Otherwise return `defaultSortBy`.
+func ParseSortBy(sortBy string, defaultSortBy internal.SortBy) internal.SortBy {
+	switch strings.ToLower(sortBy) {
+	case "relevance":
+		return SortByScore
+	case "latest":
+		return SortByCreatedDesc
+	case "oldest":
+		return SortByCreatedAsc
+	case "recentupdate":
+		return SortByUpdatedDesc
+	case "leastupdate":
+		return SortByUpdatedAsc
+	case "mostcomment":
+		return SortByCommentsDesc
+	case "leastcomment":
+		return SortByCommentsAsc
+	case "nearduedate":
+		return SortByDeadlineAsc
+	case "farduedate":
+		return SortByDeadlineDesc
+	default:
+		return defaultSortBy
+	}
+}
+
 // SearchIssues search issues by options.
 func SearchIssues(ctx context.Context, opts *SearchOptions) ([]int64, int64, error) {
 	indexer := *globalIndexer.Load()