Add D&D NPC artifact contract and identity codec

internal/modules/dnd/codec/npcs/codec.go

@@ -0,0 +1,149 @@
+package npcs
+
+import (
+	"bytes"
+	"embed"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/npcs/identity"
+)
+
+const (
+	SchemaID      = "notarius.dnd.npcs"
+	SchemaName    = "notarius_dnd_npcs_v1"
+	SchemaVersion = "v1"
+	MediaType     = "application/json"
+)
+
+//go:embed assets/schemas/dnd_npcs.v1.json
+var schemaAssets embed.FS
+
+var _ contracts.ArtifactCodec[dnd.NPCList] = (*Codec)(nil)
+
+type Codec struct{}
+
+func New() *Codec { return &Codec{} }
+
+func (c *Codec) Kind() contracts.ArtifactKind { return dnd.NPCListKind }
+
+func (c *Codec) Schema() contracts.ArtifactSchema {
+	raw, err := schemaAssets.ReadFile("assets/schemas/dnd_npcs.v1.json")
+	if err != nil {
+		return contracts.ArtifactSchema{}
+	}
+	return contracts.ArtifactSchema{
+		ID:         SchemaID,
+		Name:       SchemaName,
+		Version:    SchemaVersion,
+		JSONSchema: append([]byte(nil), raw...),
+	}
+}
+
+func (c *Codec) MediaType() string { return MediaType }
+
+func (c *Codec) Metadata(value dnd.NPCList) map[string]any {
+	return map[string]any{"npc_count": len(value.NPCs)}
+}
+
+func (c *Codec) Encode(value dnd.NPCList) ([]byte, error) {
+	if err := validate(value); err != nil {
+		return nil, fmt.Errorf("encode dnd npc list: %w", err)
+	}
+	return c.EncodeCandidate(value)
+}
+
+// EncodeCandidate provides the durable representation before semantic
+// validators have approved a value.
+func (c *Codec) EncodeCandidate(value dnd.NPCList) ([]byte, error) {
+	content, err := json.Marshal(value)
+	if err != nil {
+		return nil, fmt.Errorf("encode dnd npc list: %w", err)
+	}
+	return content, nil
+}
+
+func (c *Codec) Decode(content []byte) (dnd.NPCList, error) {
+	value, err := c.DecodeCandidate(content)
+	if err != nil {
+		return dnd.NPCList{}, err
+	}
+	if err := validate(value); err != nil {
+		return dnd.NPCList{}, fmt.Errorf("decode dnd npc list: %w", err)
+	}
+	return value, nil
+}
+
+// DecodeCandidate reads one strict durable JSON value before semantic
+// validators have approved it.
+func (c *Codec) DecodeCandidate(content []byte) (dnd.NPCList, error) {
+	decoder := json.NewDecoder(bytes.NewReader(content))
+	decoder.DisallowUnknownFields()
+	var value dnd.NPCList
+	if err := decoder.Decode(&value); err != nil {
+		return dnd.NPCList{}, fmt.Errorf("decode dnd npc list: %w", err)
+	}
+	var trailing any
+	if err := decoder.Decode(&trailing); err != io.EOF {
+		return dnd.NPCList{}, fmt.Errorf("decode dnd npc list: multiple JSON values")
+	}
+	return value, nil
+}
+
+func validate(value dnd.NPCList) error {
+	if value.NPCs == nil {
+		return fmt.Errorf("npcs must be present")
+	}
+	for index, npc := range value.NPCs {
+		prefix := fmt.Sprintf("npcs[%d]", index)
+		if !identity.IsValidID(npc.ID) {
+			return fmt.Errorf("%s.id must match npc ID pattern", prefix)
+		}
+		if strings.TrimSpace(npc.Name) == "" {
+			return fmt.Errorf("%s.name must not be empty", prefix)
+		}
+		if npc.Aliases == nil {
+			return fmt.Errorf("%s.aliases must be present", prefix)
+		}
+		for aliasIndex, alias := range npc.Aliases {
+			if strings.TrimSpace(alias) == "" {
+				return fmt.Errorf("%s.aliases[%d] must not be empty", prefix, aliasIndex)
+			}
+		}
+		if strings.TrimSpace(npc.Description) == "" {
+			return fmt.Errorf("%s.description must not be empty", prefix)
+		}
+		if npc.Relationships == nil {
+			return fmt.Errorf("%s.relationships must be present", prefix)
+		}
+		for relationshipIndex, relationship := range npc.Relationships {
+			relationshipPrefix := fmt.Sprintf("%s.relationships[%d]", prefix, relationshipIndex)
+			if strings.TrimSpace(relationship.Target) == "" {
+				return fmt.Errorf("%s.target must not be empty", relationshipPrefix)
+			}
+			if strings.TrimSpace(relationship.Relationship) == "" {
+				return fmt.Errorf("%s.relationship must not be empty", relationshipPrefix)
+			}
+		}
+		if len(npc.SourceRefs) == 0 {
+			return fmt.Errorf("%s.source_refs must not be empty", prefix)
+		}
+		for refIndex, ref := range npc.SourceRefs {
+			refPrefix := fmt.Sprintf("%s.source_refs[%d]", prefix, refIndex)
+			if strings.TrimSpace(ref.SourceID) == "" {
+				return fmt.Errorf("%s.source_id must not be empty", refPrefix)
+			}
+			if ref.StartUnitID <= 0 {
+				return fmt.Errorf("%s.start_unit_id must be positive", refPrefix)
+			}
+			if ref.EndUnitID <= 0 {
+				return fmt.Errorf("%s.end_unit_id must be positive", refPrefix)
+			}
+		}
+	}
+	return nil
+}