feat: Districts table and geojson stub

internal/cli/import_districts.go

@@ -0,0 +1,97 @@
+package cli
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"gis/internal/config"
+	"gis/internal/repository/postgres"
+
+	"github.com/spf13/cobra"
+)
+
+// districtFeature is the subset of a GeoJSON feature we care about: the raw
+// geometry (handed to PostGIS verbatim) and the kato/name_ru properties. kato
+// arrives as a JSON number but is stored as text, so it is decoded as
+// json.Number to preserve its exact digits.
+type districtFeature struct {
+	Geometry json.RawMessage `json:"geometry"`
+	Props    struct {
+		Kato   json.Number `json:"kato"`
+		NameRU string      `json:"name_ru"`
+	} `json:"properties"`
+}
+
+type districtCollection struct {
+	Features []districtFeature `json:"features"`
+}
+
+var importDistrictsCmd = &cobra.Command{
+	Use:   "import-districts <geojson-file>",
+	Short: "Import district boundaries from a GeoJSON file",
+	Long: "Parse a districts GeoJSON FeatureCollection and upsert each feature\n" +
+		"into the districts table, keyed by KATO code. Each feature's name_ru\n" +
+		"and kato properties become name/kato; its geometry is stored as a\n" +
+		"MultiPolygon in EPSG:4326. Re-running upserts on kato, so existing\n" +
+		"districts have their name and geometry refreshed.\n\n" +
+		"Example:\n" +
+		"  gis import-districts districts.geojson",
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		raw, err := os.ReadFile(args[0])
+		if err != nil {
+			return fmt.Errorf("read geojson %q: %w", args[0], err)
+		}
+
+		var fc districtCollection
+		if err := json.Unmarshal(raw, &fc); err != nil {
+			return fmt.Errorf("parse geojson %q: %w", args[0], err)
+		}
+		if len(fc.Features) == 0 {
+			return fmt.Errorf("no features found in %q", args[0])
+		}
+
+		ctx, cancel := signalContext()
+		defer cancel()
+
+		cfg, err := config.Load()
+		if err != nil {
+			return err
+		}
+
+		pool, err := postgres.Connect(ctx, cfg.DB.URL)
+		if err != nil {
+			return fmt.Errorf("connect postgres: %w", err)
+		}
+		defer pool.Close()
+
+		const upsert = `
+			INSERT INTO districts (kato, name, coordinates)
+			VALUES ($1, $2, ST_Multi(ST_SetSRID(ST_GeomFromGeoJSON($3), 4326)))
+			ON CONFLICT (kato) DO UPDATE
+			SET name = EXCLUDED.name, coordinates = EXCLUDED.coordinates`
+
+		var imported int
+		for i, f := range fc.Features {
+			kato := f.Props.Kato.String()
+			if kato == "" {
+				return fmt.Errorf("feature %d: missing kato", i)
+			}
+			if f.Props.NameRU == "" {
+				return fmt.Errorf("feature %d (kato %s): missing name_ru", i, kato)
+			}
+			if len(f.Geometry) == 0 {
+				return fmt.Errorf("feature %d (kato %s): missing geometry", i, kato)
+			}
+
+			if _, err := pool.Exec(ctx, upsert, kato, f.Props.NameRU, string(f.Geometry)); err != nil {
+				return fmt.Errorf("upsert district kato %s: %w", kato, err)
+			}
+			imported++
+		}
+
+		fmt.Printf("imported %d districts from %s\n", imported, args[0])
+		return nil
+	},
+}