db: use canonical link short name in stats

When loading stats from the database, map IDs back to their canonical
short name, which is what we want to show in the frontend.  This is only
called once on cold start, so performance of loading all links isn't a
big concern.

Fixes #13

Signed-off-by: Will Norris <[email protected]>

Author: willnorris

db.go

@@ -124,6 +124,15 @@ func (s *SQLiteDB) Save(link *Link) error {
 
 // LoadStats returns click stats for links.
 func (s *SQLiteDB) LoadStats() (ClickStats, error) {
+	allLinks, err := s.LoadAll()
+	if err != nil {
+		return nil, err
+	}
+	linkmap := make(map[string]string, len(allLinks)) // map ID => Short
+	for _, link := range allLinks {
+		linkmap[linkID(link.Short)] = link.Short
+	}
+
 	rows, err := s.db.Query("SELECT ID, sum(Clicks) FROM Stats GROUP BY ID")
 	if err != nil {
 		return nil, err
@@ -136,7 +145,8 @@ func (s *SQLiteDB) LoadStats() (ClickStats, error) {
 		if err != nil {
 			return nil, err
 		}
-		stats[id] = clicks
+		short := linkmap[id]
+		stats[short] = clicks
 	}
 	return stats, rows.Err()
 }

db_test.go

@@ -60,23 +60,25 @@ func Test_SQLiteDB_SaveLoadStats(t *testing.T) {
 	// preload some links
 	links := []*Link{
 		{Short: "a"},
-		{Short: "b"},
+		{Short: "B-c"},
 	}
 	for _, link := range links {
 		if err := db.Save(link); err != nil {
 			t.Error(err)
 		}
 	}
 
-	// stats to record and then retrieve
+	// Stats to record and then retrieve.
+	// Stats to store do not need to be their canonical short name,
+	// but returned stats always should be.
 	stats := []ClickStats{
 		{"a": 1},
-		{"b": 1},
-		{"a": 1, "b": 2},
+		{"b-c": 1},
+		{"a": 1, "bc": 2},
 	}
 	want := ClickStats{
-		"a": 2,
-		"b": 3,
+		"a":   2,
+		"B-c": 3,
 	}
 
 	for _, s := range stats {