fix: Fix geometry parsing

internal/raster/gdal.go

@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os/exec"
+	"path/filepath"
 	"strings"
 )
 
@@ -56,3 +57,52 @@ func (c *GDALConverter) Footprint(ctx context.Context, src string) ([]byte, erro
 	}
 	return info.Wgs84Extent, nil
 }
+
+// VectorGeometry reads every feature of a vector file and returns their combined
+// geometry as a GeoJSON GeometryCollection reprojected to EPSG:4326, or nil if
+// the file has no features. The caller (PostGIS) dissolves the collection into
+// the union of all features. Zipped ESRI shapefiles are read in place via GDAL's
+// /vsizip/ virtual filesystem; GeoJSON and GeoPackage are read directly.
+func (c *GDALConverter) VectorGeometry(ctx context.Context, src string) ([]byte, error) {
+	input := src
+	if strings.EqualFold(filepath.Ext(src), ".zip") {
+		input = "/vsizip/" + src
+	}
+
+	cmd := exec.CommandContext(ctx, "ogr2ogr",
+		"-f", "GeoJSON",
+		"-t_srs", "EPSG:4326",
+		"/vsistdout/", input,
+	)
+	var stderr strings.Builder
+	cmd.Stderr = &stderr
+	out, err := cmd.Output()
+	if err != nil {
+		return nil, fmt.Errorf("ogr2ogr: %w: %s", err, strings.TrimSpace(stderr.String()))
+	}
+
+	var fc struct {
+		Features []struct {
+			Geometry json.RawMessage `json:"geometry"`
+		} `json:"features"`
+	}
+	if err := json.Unmarshal(out, &fc); err != nil {
+		return nil, fmt.Errorf("parse ogr2ogr output: %w", err)
+	}
+
+	geoms := make([]json.RawMessage, 0, len(fc.Features))
+	for _, f := range fc.Features {
+		if len(f.Geometry) == 0 || string(f.Geometry) == "null" {
+			continue
+		}
+		geoms = append(geoms, f.Geometry)
+	}
+	if len(geoms) == 0 {
+		return nil, nil
+	}
+
+	return json.Marshal(struct {
+		Type       string            `json:"type"`
+		Geometries []json.RawMessage `json:"geometries"`
+	}{Type: "GeometryCollection", Geometries: geoms})
+}