mailer.go

// Package mailer wraps Mandrill's REST API only for sending emails using templates.
package mailer

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
)

// Mandrill's REST API getting started guide: https://mandrillapp.com/api/docs/index.JSON.html

// Mandrill's
var (
	endpoint = "https://mandrillapp.com/api/1.0/messages/send-template.json"
	apikey   = "FILL ME"
)

type Content struct {
	Name    string `json:"name"`
	Content string `json:"content"`
}

type Recipient struct {
	Email string `json:"email"`
	Name  string `json:"name,omitempty"`
}

type Message struct {
	To        []Recipient `json:"to"`
	Variables []Content   `json:"global_merge_vars,omitempty"`
}

// Request represents Mandrill's send-template request type.
type Request struct {
	Key             string    `json:"key"`
	TemplateName    string    `json:"template_name"`
	TemplateContent []Content `json:"template_content"`
	Message         Message   `json:"message"`
}

// Response defines Mandrill's non-error response type.
type Response struct {
	Status       string
	Email        string
	RejectReason string `json:"reject_reason"`
	ID           string `json:"_id"`
}

// Error defines Mandrill's API error type.
type Error struct {
	Status  string
	Code    int
	Name    string
	Message string
}

// Error returns a string representation of the error.
func (e *Error) Error() string {
	return fmt.Sprintf("mailer: status=%s code=%d name=%s message=%s",
		e.Status, e.Code, e.Name, e.Message)

}

// Send invokes Mandrill API to send an email.
func Send(message Request) ([]*Response, error) {
	message.Key = apikey

	// Mandrill API requires template content even if a template already provides it.
	if len(message.TemplateContent) == 0 {
		message.TemplateContent = []Content{{Name: "", Content: ""}}
	}

	b, err := json.Marshal(message)
	if err != nil {
		return nil, err
	}

	//log.Printf("[DEBUG] %s", string(b))
	resp, err := http.Post(endpoint, "application/json", bytes.NewBuffer(b))
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		apiError := new(Error)
		err = json.NewDecoder(resp.Body).Decode(apiError)
		if err != nil {
			return nil, err
		}
		return nil, apiError
	}

	response := make([]*Response, len(message.Message.To))
	err = json.NewDecoder(resp.Body).Decode(&response)
	if err != nil {
		return nil, err
	}

	return response, nil
}

mailer_test.go

package mailer

import (
	"testing"

	"github.com/hooklift/assert"
)

func TestSend(t *testing.T) {
	// Sets Mandrill test API Key
	apikey = "fill me out"

	r := Request{}
	r.TemplateName = "test-template-use-for-integration-tests-in-uaa"
	r.Message = Message{
		To: []Recipient{
			{Email: "[email protected]"},
		},

		Variables: []Content{
			{Name: "USERNAME", Content: "c4milo"},
			{Name: "VERIFICATION_CODE", Content: "ASDFAF123415"},
		},
	}

	resp, err := Send(r)
	assert.Ok(t, err)
	assert.Cond(t, len(resp) > 0, "No responses received, there should be one response.")
	rr := resp[0]
	assert.Cond(t, rr.RejectReason == "", "Reject reason should be empty.")
	assert.Equals(t, "[email protected]", rr.Email)
	assert.Equals(t, "sent", rr.Status)
}