refactor: add tag and relation methods to node to enforce integrity

models/node.go

@@ -1,20 +1,171 @@
 package models
 
-import "strings"
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
 
 type Node struct {
-	ID        string              `json:"id"`
-	Title     string              `json:"title"`
-	Content   string              `json:"content,omitempty"`
-	DueDate   string              `json:"due_date,omitempty"`
-	CreatedAt string              `json:"created_at"`
-	UpdatedAt string              `json:"updated_at"`
-	Tags      []string            `json:"tags,omitempty"`
-	Relations map[string][]string `json:"relations,omitempty"`
+	ID        string `json:"id"`
+	Title     string `json:"title"`
+	Content   string `json:"content,omitempty"`
+	DueDate   string `json:"due_date,omitempty"`
+	CreatedAt string `json:"created_at"`
+	UpdatedAt string `json:"updated_at"`
+	tags      []string
+	relations map[string][]string
+}
+
+func NewNode() *Node {
+	return &Node{
+		relations: make(map[string][]string),
+	}
+}
+
+var PropertyPrefixes = []string{"_type::", "_status::", "_prio::"}
+
+func (n *Node) MarshalJSON() ([]byte, error) {
+	type Alias Node
+	return json.Marshal(&struct {
+		*Alias
+		Tags      []string            `json:"tags,omitempty"`
+		Relations map[string][]string `json:"relations,omitempty"`
+	}{
+		Alias:     (*Alias)(n),
+		Tags:      n.tags,
+		Relations: n.relations,
+	})
+}
+
+func (n *Node) UnmarshalJSON(data []byte) error {
+	type Alias Node
+	aux := &struct {
+		*Alias
+		Tags      []string            `json:"tags,omitempty"`
+		Relations map[string][]string `json:"relations,omitempty"`
+	}{
+		Alias: (*Alias)(n),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+	n.tags = aux.Tags
+	if aux.Relations != nil {
+		n.relations = aux.Relations
+	} else {
+		n.relations = make(map[string][]string)
+	}
+	return nil
+}
+
+func (n *Node) Tags() []string {
+	res := make([]string, len(n.tags))
+	copy(res, n.tags)
+	return res
+}
+
+func (n *Node) Relations() map[string][]string {
+	res := make(map[string][]string)
+	for k, v := range n.relations {
+		cv := make([]string, len(v))
+		copy(cv, v)
+		res[k] = cv
+	}
+	return res
+}
+
+func (n *Node) HasTag(tag string) bool {
+	for _, t := range n.tags {
+		if t == tag {
+			return true
+		}
+	}
+	return false
+}
+
+func (n *Node) AddTag(tag string) {
+	if tag == "" {
+		return
+	}
+	// check if it's a property tag
+	for _, prefix := range PropertyPrefixes {
+		if strings.HasPrefix(tag, prefix) {
+			// remove existing tags with this prefix
+			var newTags []string
+			for _, t := range n.tags {
+				if !strings.HasPrefix(t, prefix) {
+					newTags = append(newTags, t)
+				}
+			}
+			n.tags = newTags
+			break
+		}
+	}
+	if !n.HasTag(tag) {
+		n.tags = append(n.tags, tag)
+	}
+}
+
+func (n *Node) RemoveTag(tag string) error {
+	if strings.HasPrefix(tag, "_type::") {
+		return fmt.Errorf("cannot remove _type tag")
+	}
+	var newTags []string
+	for _, t := range n.tags {
+		if t != tag {
+			newTags = append(newTags, t)
+		}
+	}
+	n.tags = newTags
+	return nil
+}
+
+func (n *Node) HasRelation(relType RelType, target string) bool {
+	for _, tgt := range n.relations[string(relType)] {
+		if tgt == target {
+			return true
+		}
+	}
+	return false
+}
+
+func (n *Node) AddRelation(relType RelType, target string) {
+	if n.relations == nil {
+		n.relations = make(map[string][]string)
+	}
+	if relType == RelAssignee || relType == RelCreated {
+		n.relations[string(relType)] = []string{target}
+		return
+	}
+	if !n.HasRelation(relType, target) {
+		n.relations[string(relType)] = append(n.relations[string(relType)], target)
+	}
+}
+
+func (n *Node) RemoveRelation(relType RelType, target string) error {
+	if relType == RelCreated {
+		return fmt.Errorf("cannot remove created relation")
+	}
+	if n.relations == nil {
+		return nil
+	}
+	var newTgts []string
+	for _, tgt := range n.relations[string(relType)] {
+		if tgt != target {
+			newTgts = append(newTgts, tgt)
+		}
+	}
+	if len(newTgts) == 0 {
+		delete(n.relations, string(relType))
+	} else {
+		n.relations[string(relType)] = newTgts
+	}
+	return nil
 }
 
 func (n *Node) GetProperty(k string) string {
-	for _, t := range n.Tags {
+	for _, t := range n.tags {
 		if strings.HasPrefix(t, "_") {
 			if p := strings.SplitN(t[1:], "::", 2); len(p) == 2 && p[0] == k {
 				return p[1]
@@ -26,7 +177,7 @@ func (n *Node) GetProperty(k string) string {
 
 func (n *Node) GetDisplayTags() []string {
 	var tags []string
-	for _, t := range n.Tags {
+	for _, t := range n.tags {
 		if !strings.HasPrefix(t, "_") {
 			tags = append(tags, t)
 		}

models/rel_type.go

@@ -2,6 +2,11 @@ package models
 
 type RelType string
 
+type Rel struct {
+	Type   RelType
+	Target string
+}
+
 const (
 	RelBlocks      RelType = "blocks"
 	RelSubtask     RelType = "subtask"