Initial drafts for Smart Playlists

model/smartplaylist.go

@@ -0,0 +1,106 @@
+package model
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+type SmartPlaylist struct {
+	RuleGroup
+	Order string `json:"order,omitempty"`
+	Limit int    `json:"limit,omitempty"`
+}
+
+type RuleGroup struct {
+	Combinator string `json:"combinator"`
+	Rules      Rules  `json:"rules"`
+}
+
+type Rules []IRule
+
+type IRule interface {
+	Fields() []string
+}
+
+type Rule struct {
+	Field    string      `json:"field"`
+	Operator string      `json:"operator"`
+	Value    interface{} `json:"value,omitempty"`
+}
+
+func (r Rule) Fields() []string {
+	return []string{r.Field}
+}
+
+func (rg RuleGroup) Fields() []string {
+	var result []string
+	unique := map[string]struct{}{}
+	for _, r := range rg.Rules {
+		for _, f := range r.Fields() {
+			if _, added := unique[f]; !added {
+				result = append(result, f)
+				unique[f] = struct{}{}
+			}
+		}
+	}
+	return result
+}
+
+func (rs *Rules) UnmarshalJSON(data []byte) error {
+	var rawRules []json.RawMessage
+	if err := json.Unmarshal(data, &rawRules); err != nil {
+		return err
+	}
+	rules := make(Rules, len(rawRules))
+	for i, rawRule := range rawRules {
+		var r Rule
+		if err := json.Unmarshal(rawRule, &r); err == nil && r.Field != "" {
+			rules[i] = r
+			continue
+		}
+		var g RuleGroup
+		if err := json.Unmarshal(rawRule, &g); err == nil && g.Combinator != "" {
+			rules[i] = g
+			continue
+		}
+		return errors.New("Invalid json. Neither a Rule nor a RuleGroup: " + string(rawRule))
+	}
+	*rs = rules
+	return nil
+}
+
+var SmartPlaylistFields = []string{
+	"title",
+	"album",
+	"artist",
+	"albumartist",
+	"albumartwork",
+	"tracknumber",
+	"discnumber",
+	"year",
+	"size",
+	"compilation",
+	"dateadded",
+	"datemodified",
+	"discsubtitle",
+	"comment",
+	"lyrics",
+	"sorttitle",
+	"sortalbum",
+	"sortartist",
+	"sortalbumartist",
+	"albumtype",
+	"albumcomment",
+	"catalognumber",
+	"filepath",
+	"filetype",
+	"duration",
+	"bitrate",
+	"bpm",
+	"channels",
+	"genre",
+	"loved",
+	"lastplayed",
+	"playcount",
+	"rating",
+}