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fixerio.go
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fixerio.go
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/*
Package Fixerio provides a simple interface to the
fixer.io API, a service for currency exchange rates.
*/
package fixerio
import (
"strings"
"net/http"
"encoding/json"
"time"
"bytes"
"errors"
)
// Holds the request parameters.
type Request struct {
base string
protocol string
date string
symbols []string
}
// JSON response object.
type Response struct {
Base string `json:"base"`
Date string `json:"date"`
Rates rates `json:"rates"`
}
type rates map[string]float32
var baseUrl = "api.fixer.io"
// Initializes fixerio.
func New() *Request {
return &Request{
base: EUR,
protocol: "https",
date: "",
symbols: make([]string, 0),
}
}
// Sets base currency.
func (f *Request) Base(currency string) {
f.base = currency
}
// Make the connection secure or not by setting the
// secure argument to true or false.
func (f *Request) Secure(secure bool) {
if secure {
f.protocol = "https"
} else {
f.protocol = "http"
}
}
// List of currencies that should be returned.
func (f *Request) Symbols(currencies ...string) {
f.symbols = currencies
}
// Specify a date in the past to retrieve historical records.
func (f *Request) Historical(date time.Time) {
f.date = date.Format("2006-01-02")
}
// Retrieve the exchange rates.
func (f *Request) GetRates() (rates, error) {
url := f.GetUrl()
response, err := f.makeRequest(url)
if err != nil {
return rates{}, err
}
return response, nil
}
// Formats the URL correctly for the API Request.
func (f *Request) GetUrl() string {
var url bytes.Buffer
url.WriteString(f.protocol)
url.WriteString("://")
url.WriteString(baseUrl)
url.WriteString("/")
if f.date == "" {
url.WriteString("latest")
} else {
url.WriteString(f.date)
}
url.WriteString("?base=")
url.WriteString(string(f.base))
if len(f.symbols) >= 1 {
url.WriteString("&symbols=")
url.WriteString(strings.Join(f.symbols, ","))
}
return url.String()
}
func (f *Request) makeRequest(url string) (rates, error) {
var response Response
body, err := http.Get(url)
if err != nil {
return rates{}, errors.New("Couldn't connect to server")
}
defer body.Body.Close()
err = json.NewDecoder(body.Body).Decode(&response)
if err != nil {
return rates{}, errors.New("Couldn't parse Response")
}
return response.Rates, nil
}