add: (wip) balances query API

internal/public/api.go

@@ -0,0 +1,28 @@
+package public
+
+import (
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/labstack/echo/v4"
+	"github.com/nleof/goyesql"
+)
+
+type api struct {
+	db *pgxpool.Pool
+	q  goyesql.Queries
+}
+
+func InitPublicApi(e *echo.Echo, db *pgxpool.Pool, queries goyesql.Queries) {
+	g := e.Group("/public")
+
+	g.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			c.Set("api", &api{
+				db: db,
+				q:  queries,
+			})
+			return next(c)
+		}
+	})
+
+	g.GET("/balances/:address", handleBalancesQuery)
+}

internal/public/balances.go

@@ -0,0 +1,31 @@
+package public
+
+import (
+	"context"
+	"github.com/georgysavva/scany/pgxscan"
+	"github.com/labstack/echo/v4"
+	"net/http"
+)
+
+type dbRes struct {
+	TokenSymbol  string `db:"token_symbol"`
+	TokenAddress string `db:"token_address"`
+}
+
+func handleBalancesQuery(c echo.Context) error {
+	var (
+		api  = c.Get("api").(*api)
+		data []dbRes
+	)
+
+	rows, err := api.db.Query(context.Background(), api.q["all-known-tokens"], c.Param("address"))
+	if err != nil {
+		return err
+	}
+
+	if err := pgxscan.ScanAll(&data, rows); err != nil {
+		return err
+	}
+
+	return c.JSON(http.StatusOK, data)
+}