(Go) Using Replace Patterns in Email

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Demonstrates how to use the replace patterns (mail-merge) feature in Chilkat MailMan.

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    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var success bool

    // ---------------------------------------------------------------------
    // Create an email template for sending.
    emailTemplate := chilkat.NewEmail()

    // We're going to replace "FIRST_NAME" with an actual name.
    // We arbitrarily chose "FIRST_NAME".  We can choose anything, such as "CUSTOMER_NAME" or "THE_RECIPIENT_NAME"...
    emailTemplate.SetSubject("Hello FIRST_NAME,")

    emailTemplate.SetFrom("john@example.com")
    emailTemplate.AddTo("FIRST_NAME","RECIPIENT_EMAIL")

    emailTemplate.SetHtmlBody("<html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>")

    // If the email is saved to a file, we can see what it contains:
    emailTemplate.SaveEml("qa_output/emailTemplate.eml")

    // For example:

    // MIME-Version: 1.0
    // Date: Tue, 26 Apr 2022 07:10:52 -0500
    // Message-ID: <715CF231A9F07B0B9FDB073518CD94138D791866@XYZ>
    // Content-Type: text/html; charset=us-ascii
    // Content-Transfer-Encoding: 7bit
    // X-Priority: 3 (Normal)
    // Subject: Hello FIRST_NAME,
    // From: john@example.com
    // CKX-Bounce-Address: john@example.com
    // To: FIRST_NAME <RECIPIENT_EMAIL>
    // 
    // <html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>

    // Note: Ignore the CKX-Bounce-Address header.  It is automatically removed by Chilkat prior to sending.
    // All "CKX-" headers are automatically removed prior to sending.

    // ---------------------------------------------------------------------
    // Demonstrate replace patterns by setting and then rendering to MIME.

    mailman := chilkat.NewMailMan()

    emailTemplate.SetReplacePattern("FIRST_NAME","Elon")
    emailTemplate.SetReplacePattern("RECIPIENT_EMAIL","elon.musk@example.com")
    emailTemplate.SetReplacePattern("PRODUCT_NAME","Twitter Corporation")

    // Render to MIME to see what we get.
    // Note: When the MailMan sends an email, it renders the email to MIME and then sends.
    // The rendering process is to do replacements, or possibly sign, encrypt, etc.
    // When MailMan.SendEmail is called, internally the email is rendered, and the rendered email is sent.
    // The equivalent to MailMan.Send email is to call email.RenderToMime followed by MailMan.SendMime.
    mime := mailman.RenderToMime(emailTemplate)
    fmt.Println(*mime)

    // This is the rendered MIME:

    // MIME-Version: 1.0
    // Date: Tue, 26 Apr 2022 07:25:49 -0500
    // Message-ID: <750582BCDC891C67B48CEE2293C08B902C3891E9@XYZ>
    // Content-Type: text/html; charset=us-ascii
    // Content-Transfer-Encoding: 7bit
    // X-Priority: 3 (Normal)
    // Subject: Hello Elon,
    // From: john@example.com
    // To: Elon <elon.musk@example.com>
    // 
    // <html><body><h2>Hello Elon,</h2><p>Your order for Twitter Corporation has been shipped.</p></body></html>

    // Note: When rendering, the Date and Message-ID headers are automatically regenerated.

    // ---------------------------------------------------------------------
    // An application can see what replacement patterns it previously set by calling SetReplacePattern multiple times.
    count := emailTemplate.NumReplacePatterns()
    fmt.Println("Number of replace patterns: ", count)

    i := 0
    for i < count {
        // Note: The GetReplaceString method was found to not be working correctly.  It was returning the same value as GetReplacePattern.
        // It is fixed in Chilkat v9.5.0.91
        fmt.Println(*emailTemplate.GetReplacePattern(i), ": ", *emailTemplate.GetReplaceString(i))
        i = i + 1
    }

    // Or lookup a replacement pattern by name:
    name := "FIRST_NAME"
    fmt.Println(name, " = ", *emailTemplate.GetReplaceString2(name))

    // Sample output:

    // Number of replace patterns: 3
    // FIRST_NAME: Elon
    // RECIPIENT_EMAIL: elon.musk@example.com
    // PRODUCT_NAME: Twitter Corporation
    // FIRST_NAME = Elon

    // ---------------------------------------------------------------------
    // Finally... demonstrate sending emails using the replacement patterns.
    // 

    // Set our mail server settings..
    mailman.SetSmtpHost("smtp.mail.us-west-2.awsapps.com")
    mailman.SetSmtpSsl(true)
    mailman.SetSmtpPort(465)

    mailman.SetSmtpUsername("john@example.com")
    mailman.SetSmtpPassword("the_password")

    // Imagine we have data in JSON format, and we wish to send the templated email to each recipient...
    // 

    // {
    // 	"mail_merge" : [
    // 		{
    // 			"to": "mary@example.com",
    // 			"name": "Mary",
    // 			"product": "Widget 1" 
    // 		},
    // 		{
    // 			"to": "robert@example.com",
    // 			"name": "Robert",
    // 			"product": "Widget 2"
    // 		}	
    // 		...
    // 	]
    // }

    json := chilkat.NewJsonObject()
    success = json.LoadFile("qa_data/json/mail_merge.json")
    if success == false {
        fmt.Println(json.LastErrorText())
        emailTemplate.DisposeEmail()
        mailman.DisposeMailMan()
        json.DisposeJsonObject()
        return
    }

    var emailAddr *string = new(string)
    var firstName *string = new(string)
    var product *string = new(string)

    i = 0
    count = json.SizeOfArray("mail_merge")
    for i < count {
        json.SetI(i)
        emailAddr = *json.StringOf("mail_merge[i].to")
        firstName = *json.StringOf("mail_merge[i].name")
        product = *json.StringOf("mail_merge[i].product")

        emailTemplate.SetReplacePattern("FIRST_NAME",*firstName)
        emailTemplate.SetReplacePattern("RECIPIENT_EMAIL",*emailAddr)
        emailTemplate.SetReplacePattern("PRODUCT_NAME",*product)

        success = mailman.SendEmail(emailTemplate)
        if success == false {
            fmt.Println(mailman.LastErrorText())
            emailTemplate.DisposeEmail()
            mailman.DisposeMailMan()
            json.DisposeJsonObject()
            return
        }

        fmt.Println("Send email to ", *emailAddr)

        i = i + 1
    }

    fmt.Println("Success.")

    emailTemplate.DisposeEmail()
    mailman.DisposeMailMan()
    json.DisposeJsonObject()