From 791e53c84f1ed2b4c4d920932dbe5f8a1726cf12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20G=C4=85tkowski?= <gatkowski.michal@gmail.com>
Date: Fri, 5 Aug 2022 22:24:55 +0200
Subject: [PATCH] Implemented ( not so great ) search for PostgreSQL

---
 pkg/persistence/postgres.go | 47 +++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/pkg/persistence/postgres.go b/pkg/persistence/postgres.go
index d83dd35..2917d31 100644
--- a/pkg/persistence/postgres.go
+++ b/pkg/persistence/postgres.go
@@ -198,7 +198,6 @@ func (db *postgresDatabase) QueryTorrents(
 	lastOrderedValue *float64,
 	lastID *uint64,
 ) ([]TorrentMetadata, error) {
-
 	if query == "" && orderBy == ByRelevance {
 		return nil, fmt.Errorf("torrents cannot be ordered by relevance when the query is empty")
 	}
@@ -216,8 +215,23 @@ func (db *postgresDatabase) QueryTorrents(
 			 , total_size
 			 , discovered_on
 			 , (SELECT COUNT(*) FROM files WHERE torrents.id = files.torrent_id) AS n_files
-		FROM torrents {{ if not .FirstPage }}
-        WHERE {{.OrderOn}} {{GTEorLTE .Ascending}} {{.LastOrderedValue}} {{ end }}
+			{{ if .QueryExists }}
+			, similarity(name, '{{ .Query }}') * -1 as relevance 
+			{{ else }}
+			 , 0
+			{{ end }}
+		FROM torrents 
+		{{ if not .FirstPage }}
+        	WHERE
+			{{ if not .QueryExists }}
+				{{.OrderOn}}
+			{{ else }}
+				similarity(name, '{{ .Query }}') * -1
+			{{ end }}
+{{GTEorLTE .Ascending}} {{.LastOrderedValue}} 
+			{{ if .QueryExists }} AND {{ end }}
+		{{ end }}
+			{{ if and .QueryExists .FirstPage }} WHERE {{ end }}{{ if .QueryExists }} to_tsvector(replace(name, '.', ' ')) @@ plainto_tsquery('{{ .Query }}') {{ end }}
 		ORDER BY {{.OrderOn}} {{AscOrDesc .Ascending}}
 		LIMIT {{.Limit}};
 	`, struct {
@@ -226,12 +240,16 @@ func (db *postgresDatabase) QueryTorrents(
 		Ascending        bool
 		Limit            uint
 		LastOrderedValue *float64
+		QueryExists      bool
+		Query            string
 	}{
 		FirstPage:        firstPage,
-		OrderOn:          orderOn(orderBy),
+		OrderOn:          orderOnPostgreSQL(orderBy),
 		Ascending:        ascending,
 		Limit:            limit,
 		LastOrderedValue: lastOrderedValue,
+		QueryExists:      query != "",
+		Query:            query,
 	}, template.FuncMap{
 		"GTEorLTE": func(ascending bool) string {
 			if ascending {
@@ -266,7 +284,7 @@ func (db *postgresDatabase) QueryTorrents(
 			&torrent.Size,
 			&torrent.DiscoveredOn,
 			&torrent.NFiles,
-			//&torrent.Relevance,
+			&torrent.Relevance,
 		)
 		if err != nil {
 			return nil, err
@@ -277,6 +295,25 @@ func (db *postgresDatabase) QueryTorrents(
 	return torrents, nil
 }
 
+func orderOnPostgreSQL(orderBy OrderingCriteria) string {
+	switch orderBy {
+	case ByRelevance:
+		return "relevance"
+
+	case ByTotalSize:
+		return "total_size"
+
+	case ByDiscoveredOn:
+		return "discovered_on"
+
+	case ByNFiles:
+		return "n_files"
+
+	default:
+		panic(fmt.Sprintf("unknown orderBy: %v", orderBy))
+	}
+}
+
 func (db *postgresDatabase) GetTorrent(infoHash []byte) (*TorrentMetadata, error) {
 	rows, err := db.conn.Query(`
 		SELECT