From a0f274afe1d0499c79336636e38bd5954ab04522 Mon Sep 17 00:00:00 2001
From: Richard Kettelerij <richard@mindloops.nl>
Date: Fri, 20 Sep 2024 10:06:18 +0200
Subject: [PATCH] feat(oaf): Add support to return feature properties in a
 specific order + take relations into account.

---
 internal/ogc/features/domain/mapper.go |  7 ++--
 internal/ogc/features/domain/props.go  | 47 +++++++++++++++++++-------
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/internal/ogc/features/domain/mapper.go b/internal/ogc/features/domain/mapper.go
index b24b346e..9fcc16dc 100644
--- a/internal/ogc/features/domain/mapper.go
+++ b/internal/ogc/features/domain/mapper.go
@@ -58,7 +58,7 @@ func MapRowsToFeatures(rows *sqlx.Rows, fidColumn string, externalFidColumn stri
 		return result, nil, err
 	}
 
-	orderProps := propConfig != nil && propConfig.PropertiesInSpecificOrder
+	propertiesOrder := propConfig != nil && propConfig.PropertiesInSpecificOrder
 	firstRow := true
 	var prevNextID *PrevNextFID
 	for rows.Next() {
@@ -66,7 +66,7 @@ func MapRowsToFeatures(rows *sqlx.Rows, fidColumn string, externalFidColumn stri
 		if values, err = rows.SliceScan(); err != nil {
 			return result, nil, err
 		}
-		feature := &Feature{Properties: NewFeatureProperties(orderProps)}
+		feature := &Feature{Properties: NewFeatureProperties(propertiesOrder)}
 		np, err := mapColumnsToFeature(firstRow, feature, columns, values, fidColumn, externalFidColumn,
 			geomColumn, mapGeom, mapRel)
 		if err != nil {
@@ -173,7 +173,8 @@ func mapExternalFid(columns []string, values []any, externalFidColumn string, fe
 			// it as a relation to another feature.
 			newColumnName, newColumnValue := mapRel(columnName, columnValue, externalFidColumn)
 			if newColumnName != "" {
-				feature.Properties.Set(newColumnName, newColumnValue)
+				columnNameWithoutExternalFID := strings.ReplaceAll(columnName, externalFidColumn, "")
+				feature.Properties.SetRelation(newColumnName, newColumnValue, columnNameWithoutExternalFID)
 				feature.Properties.Delete(columnName)
 			}
 		}
diff --git a/internal/ogc/features/domain/props.go b/internal/ogc/features/domain/props.go
index 86502b0b..05719dd8 100644
--- a/internal/ogc/features/domain/props.go
+++ b/internal/ogc/features/domain/props.go
@@ -2,14 +2,15 @@ package domain
 
 import (
 	"slices"
+	"strings"
 
 	"github.com/PDOK/gokoala/internal/engine/util"
 	perfjson "github.com/goccy/go-json"
 	orderedmap "github.com/wk8/go-ordered-map/v2"
 )
 
-// FeatureProperties the properties of a GeoJSON Feature
-// Either unordered (= default, and has the best performance) or in a specific order when configured as such.
+// FeatureProperties the properties of a GeoJSON Feature. Properties are either unordered
+// (default, and has the best performance!) or ordered in a specific way as described in the config.
 type FeatureProperties struct {
 	unordered map[string]any
 	ordered   orderedmap.OrderedMap[string, any]
@@ -34,20 +35,11 @@ func NewFeaturePropertiesWithData(order bool, data map[string]any) FeatureProper
 func (p *FeatureProperties) MarshalJSON() ([]byte, error) {
 	if p.unordered != nil {
 		// properties are allowed to contain anything, including for example XML/GML.
-		b, e := perfjson.MarshalWithOption(p.unordered, perfjson.DisableHTMLEscape())
-		return b, e
+		return perfjson.MarshalWithOption(p.unordered, perfjson.DisableHTMLEscape())
 	}
 	return p.ordered.MarshalJSON()
 }
 
-func (p *FeatureProperties) Set(key string, value any) {
-	if p.unordered != nil {
-		p.unordered[key] = value
-	} else {
-		p.ordered.Set(key, value)
-	}
-}
-
 func (p *FeatureProperties) Value(key string) any {
 	if p.unordered != nil {
 		return p.unordered[key]
@@ -63,6 +55,37 @@ func (p *FeatureProperties) Delete(key string) {
 	}
 }
 
+func (p *FeatureProperties) Set(key string, value any) {
+	if p.unordered != nil {
+		p.unordered[key] = value
+	} else {
+		p.ordered.Set(key, value)
+	}
+}
+
+func (p *FeatureProperties) SetRelation(key string, value any, existingKeyPrefix string) {
+	p.Set(key, value)
+	p.moveKeyBeforePrefix(key, existingKeyPrefix)
+}
+
+// moveKeyBeforePrefix best-effort algorithm to place the feature relation BEFORE any similarly named keys.
+// For example, places "building.href" before "building_fk" or "building_fid".
+func (p *FeatureProperties) moveKeyBeforePrefix(key string, keyPrefix string) {
+	if p.unordered != nil {
+		return
+	}
+	var existingKey string
+	for pair := p.ordered.Oldest(); pair != nil; pair = pair.Next() {
+		if strings.HasPrefix(pair.Key, keyPrefix) {
+			existingKey = pair.Key
+			break
+		}
+	}
+	if existingKey != "" {
+		_ = p.ordered.MoveBefore(key, existingKey)
+	}
+}
+
 // Keys of the Feature properties.
 //
 // Note: In the future we might replace this with Go 1.23 iterators (range-over-func) however at the moment this