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package main
import (
"encoding/json"
"fmt"
"net/http"
"os"
"strings"
)
type DistanceZipcode struct {
ZipcodeDetails
Miles float64 `json:"miles"`
Kilometers float64 `json:"kilometers"`
}
type DistanceResponse struct {
ZipcodeDetails
Distance DistanceZipcode `json:"distance"`
}
func main() {
db := getInitializedDatabase()
http.HandleFunc("/zip/", func(w http.ResponseWriter, r *http.Request) {
handleZipcodeRequest(w, r, db)
})
http.ListenAndServe(getListeningAddress(), nil)
}
func getInitializedDatabase() *ZipcodeDatabase {
db := NewZipcodeDatabase()
err := db.LoadFromCSV("zips.csv")
if err != nil {
fmt.Printf("%s\n", err)
}
return db
}
func getListeningAddress() string {
port := os.Getenv("PORT")
if port == "" {
port = "8080"
}
return strings.Join([]string{
":",
port,
}, "")
}
func handleZipcodeRequest(response http.ResponseWriter, request *http.Request, db *ZipcodeDatabase) {
zip := zipcodeForPath(request, db)
if zip == nil {
http.Error(response, "", 404)
} else {
setResponseHeaders(response)
if zip2 := zipcodeForQuery(request, db); zip2 != nil {
sendDistanceResponse(zip, zip2, response)
} else {
sendJson(response, zip)
}
}
}
func sendDistanceResponse(zip1, zip2 *ZipcodeDetails, writer http.ResponseWriter) {
mi, km := zip1.DistanceTo(zip2)
response := &DistanceResponse{}
response.ZipcodeDetails = *zip1
response.Distance.ZipcodeDetails = *zip2
response.Distance.Miles = mi
response.Distance.Kilometers = km
sendJson(writer, response)
}
func sendJson(writer http.ResponseWriter, data interface{}) {
bytes, _ := json.MarshalIndent(data, "", " ")
fmt.Fprintf(writer, string(bytes))
}
func setResponseHeaders(response http.ResponseWriter) {
response.Header().Set("Access-Control-Allow-Origin", "*")
response.Header().Set("Content-Type", "application/json")
}
func extractZipFromPath(request *http.Request) string {
return request.URL.Path[len("/zip/"):]
}
func zipcodeForPath(request *http.Request, db *ZipcodeDatabase) *ZipcodeDetails {
return db.Find(extractZipFromPath(request))
}
func extractZipFromQuery(request *http.Request) string {
if param := request.URL.Query()["distance"]; param != nil {
return param[0]
} else {
return ""
}
}
func zipcodeForQuery(request *http.Request, db *ZipcodeDatabase) *ZipcodeDetails {
return db.Find(extractZipFromQuery(request))
}
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