Support repo code search without setting up an indexer (#29998)

By using git's ability, end users (especially small instance users) do
not need to enable the indexer, they could also benefit from the code
searching feature.

Fix #29996

![image](https://github.com/go-gitea/gitea/assets/2114189/11b7e458-88a4-480d-b4d7-72ee59406dd1)

![image](https://github.com/go-gitea/gitea/assets/2114189/0fe777d5-c95c-4288-a818-0427680805b6)

---------

Co-authored-by: silverwind <me@silverwind.io>

1 files changed, 47 insertions, 14 deletions

diff --git a/routers/web/repo/search.go b/routers/web/repo/search.go
index 404d6f93f9..6e70428547 100644
--- a/routers/web/repo/search.go
+++ b/routers/web/repo/search.go
@@ -5,9 +5,11 @@ package repo
 
 import (
 	"net/http"
+	"strings"
 
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/git"
 	code_indexer "code.gitea.io/gitea/modules/indexer/code"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/services/context"
@@ -17,11 +19,6 @@ const tplSearch base.TplName = "repo/search"
 
 // Search render repository search page
 func Search(ctx *context.Context) {
-	if !setting.Indexer.RepoIndexerEnabled {
-		ctx.Redirect(ctx.Repo.RepoLink)
-		return
-	}
-
 	language := ctx.FormTrim("l")
 	keyword := ctx.FormTrim("q")
 
@@ -41,19 +38,55 @@ func Search(ctx *context.Context) {
 	if page <= 0 {
 		page = 1
 	}
-	
-	total, searchResults, searchResultLanguages, err := code_indexer.PerformSearch(ctx, []int64{ctx.Repo.Repository.ID},
-		language, keyword, page, setting.UI.RepoSearchPagingNum, isMatch)
-	if err != nil {
-		if code_indexer.IsAvailable(ctx) {
-			ctx.ServerError("SearchResults", err)
-			return
+
+	var total int
+	var searchResults []*code_indexer.Result
+	var searchResultLanguages []*code_indexer.SearchResultLanguages
+	if setting.Indexer.RepoIndexerEnabled {
+		var err error
+		total, searchResults, searchResultLanguages, err = code_indexer.PerformSearch(ctx, &code_indexer.SearchOptions{
+			RepoIDs:        []int64{ctx.Repo.Repository.ID},
+			Keyword:        keyword,
+			IsKeywordFuzzy: isFuzzy,
+			Language:       language,
+			Paginator: &db.ListOptions{
+				Page:     page,
+				PageSize: setting.UI.RepoSearchPagingNum,
+			},
+		})
+		if err != nil {
+			if code_indexer.IsAvailable(ctx) {
+				ctx.ServerError("SearchResults", err)
+				return
+			}
+			ctx.Data["CodeIndexerUnavailable"] = true
+		} else {
+			ctx.Data["CodeIndexerUnavailable"] = !code_indexer.IsAvailable(ctx)
 		}
-		ctx.Data["CodeIndexerUnavailable"] = true
 	} else {
-		ctx.Data["CodeIndexerUnavailable"] = !code_indexer.IsAvailable(ctx)
+		res, err := git.GrepSearch(ctx, ctx.Repo.GitRepo, keyword, git.GrepOptions{ContextLineNumber: 3, IsFuzzy: isFuzzy})
+		if err != nil {
+			ctx.ServerError("GrepSearch", err)
+			return
+		}
+		total = len(res)
+		pageStart := min((page-1)*setting.UI.RepoSearchPagingNum, len(res))
+		pageEnd := min(page*setting.UI.RepoSearchPagingNum, len(res))
+		res = res[pageStart:pageEnd]
+		for _, r := range res {
+			searchResults = append(searchResults, &code_indexer.Result{
+				RepoID:   ctx.Repo.Repository.ID,
+				Filename: r.Filename,
+				CommitID: ctx.Repo.CommitID,
+				// UpdatedUnix: not supported yet
+				// Language:    not supported yet
+				// Color:       not supported yet
+				Lines: code_indexer.HighlightSearchResultCode(r.Filename, r.LineNumbers, strings.Join(r.LineCodes, "\n")),
+			})
+		}
 	}
 
+	ctx.Data["CodeIndexerEnabled"] = setting.Indexer.RepoIndexerEnabled
 	ctx.Data["Repo"] = ctx.Repo.Repository
 	ctx.Data["SourcePath"] = ctx.Repo.Repository.Link()
 	ctx.Data["SearchResults"] = searchResults