Organize D&D extensions by domain

internal/modules/dnd/shared/unit_refs.go

@@ -0,0 +1,118 @@
+package shared
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+)
+
+type UnitRef struct {
+	value      int
+	fromNumber bool
+}
+
+type SourceRefResponse struct {
+	SourceID    string  `json:"source_id"`
+	StartUnitID UnitRef `json:"start_unit_id"`
+	EndUnitID   UnitRef `json:"end_unit_id"`
+}
+
+func UnitRefFromString(value string) UnitRef {
+	parsed, _ := parseUnitRefNumber(value)
+	return UnitRef{value: parsed}
+}
+
+func UnitRefFromInt(value int) UnitRef {
+	return UnitRef{
+		value:      value,
+		fromNumber: true,
+	}
+}
+
+func (ref UnitRef) String() string {
+	if ref.value == 0 {
+		return ""
+	}
+	return strconv.Itoa(ref.value)
+}
+
+func (ref UnitRef) Int() int {
+	return ref.value
+}
+
+func (ref *UnitRef) UnmarshalJSON(raw []byte) error {
+	raw = bytes.TrimSpace(raw)
+	if len(raw) == 0 {
+		return fmt.Errorf("unit ref must be a string or integer")
+	}
+	if raw[0] == '"' {
+		var value string
+		if err := json.Unmarshal(raw, &value); err != nil {
+			return err
+		}
+		number, err := parseUnitRefNumber(value)
+		if err != nil {
+			return err
+		}
+		*ref = UnitRef{value: number}
+		return nil
+	}
+
+	number, err := parseUnitRefNumber(string(raw))
+	if err != nil {
+		return err
+	}
+	*ref = UnitRefFromInt(number)
+	return nil
+}
+
+func (ref UnitRef) MarshalJSON() ([]byte, error) {
+	if ref.fromNumber {
+		return []byte(strconv.Itoa(ref.value)), nil
+	}
+	return json.Marshal(ref.String())
+}
+
+func ResolveUnitID(doc *source.SourceDocument, field string, ref UnitRef) (int, error) {
+	if ref.value <= 0 {
+		return 0, fmt.Errorf("%s must be positive", field)
+	}
+	if _, ok := source.UnitIndex(doc, ref.value); !ok {
+		return 0, fmt.Errorf("%s %d was not found", field, ref.value)
+	}
+	return ref.value, nil
+}
+
+func SourceRefCandidate(doc *source.SourceDocument, ref SourceRefResponse) source.SourceRef {
+	return source.SourceRef{
+		SourceID:    strings.TrimSpace(ref.SourceID),
+		StartUnitID: unitIDCandidate(ref.StartUnitID),
+		EndUnitID:   unitIDCandidate(ref.EndUnitID),
+	}
+}
+
+func unitIDCandidate(ref UnitRef) int {
+	return ref.value
+}
+
+func parseUnitRefNumber(value string) (int, error) {
+	trimmed := strings.TrimSpace(value)
+	if trimmed == "" {
+		return 0, fmt.Errorf("unit ref must not be empty")
+	}
+	if trimmed != value {
+		return 0, fmt.Errorf("unit ref must not contain leading or trailing whitespace")
+	}
+	number, err := strconv.Atoi(value)
+	if err != nil {
+		return 0, fmt.Errorf("unit ref must be an integer")
+	}
+	if number <= 0 {
+		return 0, fmt.Errorf("unit ref must be positive")
+	}
+	return number, nil
+}