add simple postcode lookup (#196)

postcode/handler/postcode.go

@@ -0,0 +1,54 @@
+package handler
+
+import (
+	"context"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/micro/micro/v3/service/errors"
+	"github.com/micro/micro/v3/service/logger"
+	pb "github.com/micro/services/postcode/proto"
+)
+
+var (
+	PostcodeAPI = "https://api.postcodes.io/postcodes/"
+)
+
+type Postcode struct{}
+
+func (e *Postcode) Lookup(ctx context.Context, req *pb.LookupRequest, rsp *pb.LookupResponse) error {
+	if len(req.Postcode) == 0 {
+		return errors.BadRequest("postcode.lookup", "missing postcode")
+	}
+
+	resp, err := http.Get(PostcodeAPI + req.Postcode)
+	if err != nil {
+		logger.Errorf("Failed to http call %v: %v", PostcodeAPI+req.Postcode, err.Error())
+		return errors.BadRequest("postcode.lookup", "failed to lookup postcode")
+	}
+	defer resp.Body.Close()
+
+	b, _ := ioutil.ReadAll(resp.Body)
+
+	if resp.StatusCode != 200 {
+		logger.Errorf("Failed to http call (%v) %v: %v", resp.StatusCode, PostcodeAPI+req.Postcode, string(b))
+		return errors.BadRequest("postcode.lookup", "failed to lookup postcode")
+	}
+
+	var response map[string]interface{}
+	if err := json.Unmarshal(b, &response); err != nil {
+		logger.Error("Failed to unmarshal %v: %v", PostcodeAPI+req.Postcode, err.Error())
+		return errors.BadRequest("postcode.lookup", "failed to lookup postcode")
+	}
+	result := response["result"].(map[string]interface{})
+
+	rsp.Postcode = result["postcode"].(string)
+	rsp.Country = result["country"].(string)
+	rsp.Region = result["region"].(string)
+	rsp.Latitude = result["latitude"].(float64)
+	rsp.Longitude = result["longitude"].(float64)
+	rsp.District = result["admin_district"].(string)
+	rsp.Ward = result["admin_ward"].(string)
+	return nil
+}