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package main |
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import ( |
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"errors" |
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"log" |
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"net/smtp" |
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"os" |
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"strings" |
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) |
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// Represents an email account. |
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type Account struct { |
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// Unexported |
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auth smtp.Auth |
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// Exported |
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DisplayName string |
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Address string |
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} |
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// Signs into an email account (linked to Gmail). |
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func SignIn(displayName, username, password string) (*Account, error) { |
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if displayName == "" { |
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return nil, errors.New("displayName cannot be empty") |
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} else if username == "" { |
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return nil, errors.New("username cannot be empty") |
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} else if password == "" { |
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return nil, errors.New("password cannot be empty") |
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} |
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auth := smtp.PlainAuth("", username, password, "smtp.gmail.com") |
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account := &Account{ |
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auth: auth, |
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DisplayName: displayName, |
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Address: username, |
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} |
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return account, nil |
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} |
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type Draft struct { |
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// Unexported |
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auth smtp.Auth |
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msg string |
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// Exported |
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From string |
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To string |
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Body string |
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} |
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// Returns a draft. |
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func (a *Account) Compose(displayName, address, subject, body string) Draft { |
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// https://golang.org/pkg/net/smtp/#example_SendMail |
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// https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol#SMTP_transport_example |
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from := a.DisplayName + " <" + a.Address + ">" |
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to := displayName + " <" + address + ">" |
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draft := Draft{ |
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auth: a.auth, |
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msg: "From:" + from + "\r\n" + |
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"To: " + to + "\r\n" + |
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"Subject: " + subject + "\r\n" + |
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"\r\n" + |
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body, |
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From: a.Address, |
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To: address, |
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Body: body, |
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} |
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return draft |
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} |
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// Sends a draft. |
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func (d Draft) Send() error { |
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return smtp.SendMail("smtp.gmail.com:587", d.auth, d.From, []string{d.To}, []byte(d.msg)) |
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} |
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func must(err error) { |
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if err == nil { |
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// No-op |
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return |
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} |
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log.Fatal(err) |
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} |
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type Receipient struct { |
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displayName string |
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address string |
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firstName string |
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} |
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var receipients = []Receipient{ |
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{ |
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address: "[email protected]", |
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displayName: "John Appleseed", |
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firstName: "John", |
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}, |
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} |
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func main() { |
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// NOTE: This program requires temporarily enabling ‘Less |
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// secure app access’ from Google. You can disable it |
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// immediately after. |
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// |
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// https://myaccount.google.com/lesssecureapps |
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user, err := SignIn(os.Getenv("DISPLAY_NAME"), os.Getenv("USERNAME"), os.Getenv("PASSWORD")) |
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must(err) |
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for _, r := range receipients { |
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draft := user.Compose(r.displayName, r.address, "Hey "+r.firstName, strings.TrimSpace(` |
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Hi `+r.firstName+`, |
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Lorem ipsum dolor sit amet, consectetur adipiscing elit… |
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`)) |
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must(draft.Send()) |
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log.Printf("sent %s", draft.To) |
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} |
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} |
