Add phash generation and dupe checking (#1158)

pkg/utils/phash.go

@@ -0,0 +1,57 @@
+package utils
+
+import (
+	"strconv"
+
+	"github.com/corona10/goimagehash"
+)
+
+type Phash struct {
+	SceneID   int   `db:"id"`
+	Hash      int64 `db:"phash"`
+	Neighbors []int
+	Bucket    int
+}
+
+func FindDuplicates(hashes []*Phash, distance int) [][]int {
+	for i, scene := range hashes {
+		sceneHash := goimagehash.NewImageHash(uint64(scene.Hash), goimagehash.PHash)
+		for j, neighbor := range hashes {
+			if i != j {
+				neighborHash := goimagehash.NewImageHash(uint64(neighbor.Hash), goimagehash.PHash)
+				neighborDistance, _ := sceneHash.Distance(neighborHash)
+				if neighborDistance <= distance {
+					scene.Neighbors = append(scene.Neighbors, j)
+				}
+			}
+		}
+	}
+
+	var buckets [][]int
+	for _, scene := range hashes {
+		if len(scene.Neighbors) > 0 && scene.Bucket == -1 {
+			bucket := len(buckets)
+			scenes := []int{scene.SceneID}
+			scene.Bucket = bucket
+			findNeighbors(bucket, scene.Neighbors, hashes, &scenes)
+			buckets = append(buckets, scenes)
+		}
+	}
+
+	return buckets
+}
+
+func findNeighbors(bucket int, neighbors []int, hashes []*Phash, scenes *[]int) {
+	for _, id := range neighbors {
+		hash := hashes[id]
+		if hash.Bucket == -1 {
+			hash.Bucket = bucket
+			*scenes = append(*scenes, hash.SceneID)
+			findNeighbors(bucket, hash.Neighbors, hashes, scenes)
+		}
+	}
+}
+
+func PhashToString(phash int64) string {
+	return strconv.FormatUint(uint64(phash), 16)
+}