From 23ea9981473774eb5910f723aaf72e4635e94fc7 Mon Sep 17 00:00:00 2001
From: Maksym Pavlenko <pavlenko.maksym@gmail.com>
Date: Sat, 5 Aug 2017 15:02:26 -0700
Subject: [PATCH] Create hash id from feed parameters

---
 web/pkg/database/pg.go      |  2 +-
 web/pkg/database/pg_test.go | 35 +++++++++++++++++++++++++----------
 web/pkg/id/hashids.go       | 30 ++++++++++++++++++++++--------
 web/pkg/id/hashids_test.go  | 26 +++++++++++++++++++++++---
 4 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/web/pkg/database/pg.go b/web/pkg/database/pg.go
index 16b8d28..fe8b26a 100644
--- a/web/pkg/database/pg.go
+++ b/web/pkg/database/pg.go
@@ -21,7 +21,7 @@ type PgStorage struct {
 
 func (p *PgStorage) CreateFeed(feed *Feed) error {
 	feed.LastAccess = time.Now().UTC()
-	_, err := p.db.Model(feed).Insert()
+	_, err := p.db.Model(feed).OnConflict("DO NOTHING").Insert()
 	if err != nil {
 		return errors.Wrap(err, "failed to create feed")
 	}
diff --git a/web/pkg/database/pg_test.go b/web/pkg/database/pg_test.go
index aab017b..19e2235 100644
--- a/web/pkg/database/pg_test.go
+++ b/web/pkg/database/pg_test.go
@@ -18,6 +18,31 @@ func TestCreate(t *testing.T) {
 	require.True(t, feed.Id > 0)
 }
 
+func TestCreateDuplicate(t *testing.T) {
+	feed := &Feed{
+		HashId: "123",
+		URL:    "http://youtube.com",
+	}
+
+	client := createClient(t)
+	err := client.CreateFeed(feed)
+	require.NoError(t, err)
+
+	// Ensure 1 record
+	count, err := client.db.Model(&Feed{}).Count()
+	require.NoError(t, err)
+	require.Equal(t, 1, count)
+
+	// Insert duplicated feed
+	err = client.CreateFeed(feed)
+	require.NoError(t, err)
+
+	// Check no duplicates inserted
+	count, err = client.db.Model(&Feed{}).Count()
+	require.NoError(t, err)
+	require.Equal(t, 1, count)
+}
+
 func TestGetFeed(t *testing.T) {
 	feed := &Feed{
 		HashId: "xyz",
@@ -57,16 +82,6 @@ func TestUpdateLastAccess(t *testing.T) {
 	require.True(t, last.LastAccess.Unix() > lastAccess.Unix())
 }
 
-func TestUniqueHashId(t *testing.T) {
-	client := createClient(t)
-
-	err := client.CreateFeed(&Feed{HashId: "xyz", URL: "url"})
-	require.NoError(t, err)
-
-	err = client.CreateFeed(&Feed{HashId: "xyz", URL: "url"})
-	require.Error(t, err)
-}
-
 const TestDatabaseConnectionUrl = "postgres://postgres:@localhost/podsync?sslmode=disable"
 
 func createClient(t *testing.T) *PgStorage {
diff --git a/web/pkg/id/hashids.go b/web/pkg/id/hashids.go
index 0f364d4..7287c9b 100644
--- a/web/pkg/id/hashids.go
+++ b/web/pkg/id/hashids.go
@@ -1,6 +1,9 @@
 package id
 
 import (
+	"hash/fnv"
+
+	"github.com/mxpv/podsync/web/pkg/database"
 	hd "github.com/speps/go-hashids"
 )
 
@@ -14,9 +17,24 @@ type hashId struct {
 	hid *hd.HashID
 }
 
-func (h *hashId) Encode(x ...int) (string, error) {
-	var d []int
-	return h.hid.Encode(append(d, x...))
+func hashString(s string) int {
+	h := fnv.New32a()
+	h.Write([]byte(s))
+	return int(h.Sum32())
+}
+
+func (h *hashId) Encode(feed *database.Feed) (string, error) {
+	// Don't create duplicate urls for same playlist/settings
+	// https://github.com/podsync/issues/issues/6
+	numbers := []int{
+		hashString(feed.UserId),
+		hashString(feed.URL),
+		feed.PageSize,
+		hashString(string(feed.Quality)),
+		hashString(string(feed.Format)),
+	}
+
+	return h.hid.Encode(numbers)
 }
 
 func NewIdGenerator() (*hashId, error) {
@@ -24,10 +42,6 @@ func NewIdGenerator() (*hashId, error) {
 	data.MinLength = minLength
 	data.Salt = salt
 	data.Alphabet = alphabet
-	hid, err := hd.NewWithData(data)
-	if err != nil {
-		return nil, err
-	}
-
+	hid := hd.NewWithData(data)
 	return &hashId{hid}, nil
 }
diff --git a/web/pkg/id/hashids_test.go b/web/pkg/id/hashids_test.go
index 237791f..0d95eb9 100644
--- a/web/pkg/id/hashids_test.go
+++ b/web/pkg/id/hashids_test.go
@@ -1,15 +1,35 @@
 package id
 
 import (
-	"github.com/stretchr/testify/require"
 	"testing"
+
+	"github.com/mxpv/podsync/web/pkg/database"
+	"github.com/stretchr/testify/require"
 )
 
 func TestEncode(t *testing.T) {
 	hid, err := NewIdGenerator()
 	require.NoError(t, err)
 
-	hash, err := hid.Encode(1)
+	feed := &database.Feed{
+		UserId:   "1",
+		URL:      "https://www.youtube.com/channel/UC2yTVSttx7lxAOAzx1opjoA",
+		PageSize: 10,
+		Quality:  database.HighQuality,
+		Format:   database.AudioFormat,
+	}
+
+	hash1, err := hid.Encode(feed)
 	require.NoError(t, err)
-	require.NotEmpty(t, hash)
+	require.NotEmpty(t, hash1)
+
+	// Ensure we have same hash for same feed/parameters
+	hash2, err := hid.Encode(feed)
+	require.NoError(t, err)
+	require.Equal(t, hash1, hash2)
+
+	feed.UserId = ""
+	hash3, err := hid.Encode(feed)
+	require.NoError(t, err)
+	require.NotEqual(t, hash1, hash3)
 }