fix(subscriptions): reject concurrent duplicate rules

Fixes #66

internal/model/download_subscription.go

@@ -34,6 +34,7 @@ type DownloadTask struct {
 type Subscription struct {
 	Base
 	UserID        string `gorm:"index;size:36" json:"user_id"`
+	IdentityKey   string `gorm:"size:64" json:"-"`
 	Name          string `gorm:"size:128;not null" json:"name"`
 	FeedURL       string `gorm:"size:2048;not null" json:"feed_url"`
 	Filter        string `gorm:"size:512" json:"filter"`

internal/model/subscription_identity.go

@@ -0,0 +1,90 @@
+package model
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"strings"
+)
+
+type subscriptionIdentityPayload struct {
+	Name          string  `json:"name"`
+	FeedURL       string  `json:"feed_url"`
+	Filter        string  `json:"filter"`
+	MediaType     string  `json:"media_type"`
+	MediaCategory string  `json:"media_category"`
+	SavePath      string  `json:"save_path"`
+	SearchMode    string  `json:"search_mode"`
+	IMDBID        string  `json:"imdb_id"`
+	Resolution    string  `json:"resolution"`
+	Quality       string  `json:"quality"`
+	Effects       string  `json:"effects"`
+	ReleaseGroups string  `json:"release_groups"`
+	ExcludeWords  string  `json:"exclude_words"`
+	MinSeeders    int     `json:"min_seeders"`
+	MaxSeeders    int     `json:"max_seeders"`
+	MinSizeGB     float64 `json:"min_size_gb"`
+	MaxSizeGB     float64 `json:"max_size_gb"`
+	FreeOnly      bool    `json:"free_only"`
+	WashEnabled   bool    `json:"wash_enabled"`
+	WashPriority  string  `json:"wash_priority"`
+	Priority      int     `json:"priority"`
+}
+
+// SubscriptionIdentityKey identifies one functional subscription rule. It
+// intentionally excludes display metadata and runtime/archive state because
+// those fields are backfilled or changed automatically after creation.
+func SubscriptionIdentityKey(sub *Subscription) string {
+	if sub == nil {
+		return ""
+	}
+	payload := subscriptionIdentityPayload{
+		Name:          subscriptionIdentityFold(sub.Name),
+		FeedURL:       strings.TrimSpace(sub.FeedURL),
+		Filter:        strings.TrimSpace(sub.Filter),
+		MediaType:     subscriptionIdentityFold(sub.MediaType),
+		MediaCategory: subscriptionIdentityFold(sub.MediaCategory),
+		SavePath:      strings.TrimSpace(sub.SavePath),
+		SearchMode:    subscriptionIdentityFold(sub.SearchMode),
+		IMDBID:        subscriptionIdentityFold(sub.IMDBID),
+		Resolution:    subscriptionIdentityFold(sub.Resolution),
+		Quality:       subscriptionIdentityFold(sub.Quality),
+		Effects:       subscriptionIdentityList(sub.Effects),
+		ReleaseGroups: subscriptionIdentityList(sub.ReleaseGroups),
+		ExcludeWords:  subscriptionIdentityList(sub.ExcludeWords),
+		MinSeeders:    sub.MinSeeders,
+		MaxSeeders:    sub.MaxSeeders,
+		MinSizeGB:     sub.MinSizeGB,
+		MaxSizeGB:     sub.MaxSizeGB,
+		FreeOnly:      sub.FreeOnly,
+		WashEnabled:   sub.WashEnabled,
+		WashPriority:  subscriptionIdentityFold(sub.WashPriority),
+		Priority:      sub.Priority,
+	}
+	raw, _ := json.Marshal(payload)
+	sum := sha256.Sum256(raw)
+	return hex.EncodeToString(sum[:])
+}
+
+func RefreshSubscriptionIdentity(sub *Subscription) string {
+	key := SubscriptionIdentityKey(sub)
+	if sub != nil {
+		sub.IdentityKey = key
+	}
+	return key
+}
+
+func subscriptionIdentityFold(value string) string {
+	return strings.ToLower(strings.TrimSpace(value))
+}
+
+func subscriptionIdentityList(value string) string {
+	parts := strings.Split(value, ",")
+	out := make([]string, 0, len(parts))
+	for _, part := range parts {
+		if part = subscriptionIdentityFold(part); part != "" {
+			out = append(out, part)
+		}
+	}
+	return strings.Join(out, ",")
+}

internal/model/subscription_identity_test.go

@@ -0,0 +1,45 @@
+package model
+
+import "testing"
+
+func TestSubscriptionIdentityKeyNormalizesEquivalentRules(t *testing.T) {
+	base := Subscription{
+		Name:          " Example Show ",
+		FeedURL:       "site-search://search?keyword=Example",
+		Filter:        " Example.*Show ",
+		MediaType:     "TV",
+		MediaCategory: " 欧美剧 ",
+		SearchMode:    "KEYWORD",
+		Resolution:    "1080P",
+		Effects:       " HDR, Atmos ",
+		ExcludeWords:  " CAM, TS ",
+		WashPriority:  "Balanced",
+		Priority:      50,
+	}
+	equivalent := base
+	equivalent.Name = "example show"
+	equivalent.MediaType = "tv"
+	equivalent.MediaCategory = "欧美剧"
+	equivalent.SearchMode = "keyword"
+	equivalent.Resolution = "1080p"
+	equivalent.Effects = "hdr,atmos"
+	equivalent.ExcludeWords = "cam,ts"
+	equivalent.WashPriority = "balanced"
+	if got, want := SubscriptionIdentityKey(&equivalent), SubscriptionIdentityKey(&base); got != want {
+		t.Fatalf("equivalent keys differ: %s != %s", got, want)
+	}
+
+	differentRule := base
+	differentRule.Resolution = "2160p"
+	if SubscriptionIdentityKey(&differentRule) == SubscriptionIdentityKey(&base) {
+		t.Fatal("different resolution should produce a different identity")
+	}
+
+	displayOnly := base
+	displayOnly.PosterURL = "https://example.test/poster.jpg"
+	displayOnly.Overview = "new overview"
+	displayOnly.TotalEpisodes = 24
+	if SubscriptionIdentityKey(&displayOnly) != SubscriptionIdentityKey(&base) {
+		t.Fatal("display/runtime metadata should not change identity")
+	}
+}