Newsblaster using the Postmark template batch API
This commit is contained in:
commit
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config.json
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data/
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module git.handmade.network/hmn/newsblaster2000
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go 1.18
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require github.com/spf13/cobra v1.7.0
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require (
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github.com/inconshreveable/mousetrap v1.1.0 // indirect
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github.com/spf13/pflag v1.0.5 // indirect
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)
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github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
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github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
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github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
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github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
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github.com/spf13/cobra v1.7.0 h1:hyqWnYt1ZQShIddO5kBpj3vu05/++x6tJ6dg8EC572I=
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github.com/spf13/cobra v1.7.0/go.mod h1:uLxZILRyS/50WlhOIKD7W6V5bgeIt+4sICxh6uRMrb0=
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github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
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github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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package main
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import (
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"bytes"
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"crypto/sha1"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"io/fs"
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"net/http"
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"os"
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"strings"
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"time"
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"github.com/spf13/cobra"
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)
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type Config struct {
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PostmarkAPIToken string
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PostmarkTemplateAlias string
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PostmarkMessageStream string
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TestEmailAddress string
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FromAddress string
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FromName string
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BatchSize int
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}
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func verifyConfig() (Config, bool) {
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defaultConfig := Config{BatchSize: 500} // NOTE(asaf): Max 500 messages per batch: https://postmarkapp.com/developer/api/templates-api#send-batch-with-templates
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defaultContents, err := json.MarshalIndent(&defaultConfig, "", " ")
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contents, err := os.ReadFile("config.json")
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if err != nil {
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contents = defaultContents
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if errors.Is(err, fs.ErrNotExist) {
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os.WriteFile("config.json", contents, 0666)
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fmt.Printf("Created config.json file.\n")
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} else {
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fmt.Printf("Error while reading config.json: %v\n", err)
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}
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}
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var config Config
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err = json.Unmarshal(contents, &config)
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valid := true
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if config.PostmarkAPIToken == "" {
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fmt.Printf("Postmark API token missing in config.\n")
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valid = false
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}
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if config.PostmarkTemplateAlias == "" {
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fmt.Printf("Postmark template alias missing in config.\n")
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valid = false
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}
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if config.PostmarkMessageStream == "" {
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fmt.Printf("Postmark message stream missing in config.\n")
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valid = false
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}
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if config.TestEmailAddress == "" {
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fmt.Printf("Test email address is missing in config.\n")
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valid = false
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}
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if config.FromAddress == "" {
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fmt.Printf("FromAddress is missing in config. That's the return address that will appear on the email.\n")
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valid = false
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}
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if config.FromName == "" {
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fmt.Printf("FromName is missing in config. That's the name that will appear next to the 'from' field in the email.\n")
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valid = false
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}
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if !valid {
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fmt.Printf("Please edit config.json and rerun.\n")
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}
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return config, valid
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}
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func parseMailFile(contents string) (subject string, body string, valid bool) {
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valid = false
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parts := strings.SplitN(string(contents), "\n", 2)
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if len(parts) < 2 {
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fmt.Printf("File does not contain subject and body\n")
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return
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}
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subject = strings.TrimSpace(parts[0])
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rawBody := strings.Trim(parts[1], "\n")
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if subject == "" {
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fmt.Printf("Subject is empty\n")
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return
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}
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body = rawBody
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valid = true
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return
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}
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func sendTest(newsletterFile string) {
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cfg, valid := verifyConfig()
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if !valid {
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return
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}
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audience := []string{cfg.TestEmailAddress}
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contents, err := os.ReadFile(newsletterFile)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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fmt.Printf("Can't find file %s\n", newsletterFile)
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} else {
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fmt.Printf("Error reading file %s: %v\n", newsletterFile, err)
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}
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return
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}
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subject, body, valid := parseMailFile(string(contents))
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if !valid {
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return
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}
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trackingFile := newsletterFile + ".test.track"
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logFile := newsletterFile + "." + time.Now().Format("20060102T150405") + ".test.log"
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os.Truncate(trackingFile, 0)
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blastMail(cfg, logFile, trackingFile, audience, subject, body)
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sha1File := newsletterFile + ".sha1"
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sum := sha1.Sum(contents)
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sumString := fmt.Sprintf("%x", sum)
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os.WriteFile(sha1File, []byte(sumString), 0666)
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}
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func sendNews(audienceFile string, newsletterFile string) {
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cfg, valid := verifyConfig()
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if !valid {
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return
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}
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contents, err := os.ReadFile(newsletterFile)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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fmt.Printf("Can't find file %s\n", newsletterFile)
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} else {
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fmt.Printf("Error reading file %s: %v\n", newsletterFile, err)
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}
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return
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}
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subject, body, valid := parseMailFile(string(contents))
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if !valid {
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return
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}
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audienceContents, err := os.ReadFile(audienceFile)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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fmt.Printf("Can't find file %s\n", audienceFile)
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} else {
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fmt.Printf("Error reading file %s: %v\n", audienceFile, err)
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}
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return
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}
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audience := strings.Split(string(audienceContents), "\n")
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for i, a := range audience {
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audience[i] = strings.TrimSpace(a)
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}
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sha1File := newsletterFile + ".sha1"
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sum := sha1.Sum(contents)
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sumString := fmt.Sprintf("%x", sum)
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sha1, err := os.ReadFile(sha1File)
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if err != nil {
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if errors.Is(err, fs.ErrNotExist) {
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fmt.Printf("Can't find hash file for this newsletter. Make sure you run the test command first!\n")
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} else {
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fmt.Printf("Error reading file %s: %v\n", audienceFile, err)
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}
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return
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}
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if string(sha1) != sumString {
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fmt.Printf("Hash doesn't match. Did you change the newsletter's contents? Rerun the test command please!\n")
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return
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}
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trackingFile := newsletterFile + ".track"
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logFile := newsletterFile + "." + time.Now().Format("20060102T150405") + ".log"
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blastMail(cfg, logFile, trackingFile, audience, subject, body)
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}
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func blastMail(cfg Config, logFile string, trackingFile string, audience []string, subject string, body string) {
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log, err := os.OpenFile(logFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
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if err != nil {
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fmt.Printf("Can't open log file %s: %v\n", logFile, err)
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return
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}
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defer log.Close()
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contents, err := os.ReadFile(trackingFile)
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if err != nil && !errors.Is(err, fs.ErrNotExist) {
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fmt.Printf("Failed to read tracking file %s: %v\n", trackingFile, err)
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return
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}
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var sentToAddresses []string
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existingRecipients := strings.Split(string(contents), "\n")
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for _, e := range existingRecipients {
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if e != "" {
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sentToAddresses = append(sentToAddresses, e)
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}
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}
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var group []string
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for _, a := range audience {
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if a == "" {
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continue
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}
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found := false
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for _, s := range sentToAddresses {
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if a == s {
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found = true
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break
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}
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}
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if !found {
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group = append(group, a)
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if len(group) == cfg.BatchSize {
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results, err := sendMail(cfg, group, subject, body)
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if err != nil {
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fmt.Printf("Error while sending mail: %v\n", err)
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return
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}
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sentToAddresses = append(sentToAddresses, group...)
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os.WriteFile(trackingFile, []byte(strings.Join(sentToAddresses, "\n")), 0666)
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for i, res := range results {
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log.WriteString(fmt.Sprintf("%s: %s\n", group[i], res.Message))
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}
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group = group[0:0]
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}
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}
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}
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if len(group) > 0 {
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results, err := sendMail(cfg, group, subject, body)
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if err != nil {
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fmt.Printf("Error while sending mail: %v\n", err)
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return
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}
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sentToAddresses = append(sentToAddresses, group...)
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os.WriteFile(trackingFile, []byte(strings.Join(sentToAddresses, "\n")), 0666)
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for i, res := range results {
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log.WriteString(fmt.Sprintf("%s: %s\n", group[i], res.Message))
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}
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}
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}
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var postmarkClient = http.Client{}
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type PostmarkTemplateModel struct {
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Subject string `json:"subject"`
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Body string `json:"content_body"`
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}
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type PostmarkTemplateMessage struct {
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From string `json:"From"`
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To string `json:"To"`
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TemplateAlias string `json:"TemplateAlias"`
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TemplateModel PostmarkTemplateModel `json:"TemplateModel"`
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TrackOpens bool `json:"TrackOpens"`
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TrackLinks string `json:"TrackLinks"`
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MessageStream string `json:"MessageStream"`
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}
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type PostmarkBatchWithTemplateBody struct {
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Messages []PostmarkTemplateMessage `json:"Messages"`
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}
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type PostmarkBatchResult struct {
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ErrorCode int `json:"ErrorCode"`
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Message string `json:"Message"`
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}
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func sendMail(cfg Config, recipients []string, subject, contentHtml string) ([]PostmarkBatchResult, error) {
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from := cfg.FromAddress
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if cfg.FromName != "" {
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from = fmt.Sprintf("%s <%s>", cfg.FromName, cfg.FromAddress)
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}
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body := PostmarkBatchWithTemplateBody{}
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for _, r := range recipients {
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body.Messages = append(body.Messages, PostmarkTemplateMessage{
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From: from,
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To: r,
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TemplateAlias: cfg.PostmarkTemplateAlias,
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TemplateModel: PostmarkTemplateModel{
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Subject: subject,
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Body: contentHtml,
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},
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TrackOpens: false,
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TrackLinks: "None",
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MessageStream: cfg.PostmarkMessageStream,
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})
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}
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reqBody, err := json.Marshal(&body)
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if err != nil {
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return nil, err
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}
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req, err := http.NewRequest(http.MethodPost, "https://api.postmarkapp.com/email/batchWithTemplates", bytes.NewReader(reqBody))
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if err != nil {
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return nil, err
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}
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req.Header.Set("Accept", "application/json")
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req.Header.Set("Content-Type", "application/json")
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req.Header.Set("X-Postmark-Server-Token", cfg.PostmarkAPIToken)
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res, err := postmarkClient.Do(req)
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if err != nil {
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return nil, err
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}
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var results []PostmarkBatchResult
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resBody, err := io.ReadAll(res.Body)
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res.Body.Close()
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if err != nil {
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return nil, err
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}
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if res.StatusCode != 200 {
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return nil, fmt.Errorf("Bad response from postmark: %d", res.StatusCode)
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}
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err = json.Unmarshal(resBody, &results)
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if err != nil {
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fmt.Printf("Batch sent successfully, but failed to parse response from postmark.\n")
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return nil, nil
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}
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return results, nil
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}
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func main() {
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cmd := &cobra.Command{
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Use: "newsblaster2000",
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Short: "NewsBlaster2000",
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Run: func(cmd *cobra.Command, args []string) {
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_, valid := verifyConfig()
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if valid {
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fmt.Printf(`Instructions:
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1. Create an audience file
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* Name it whatever you want.
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* The file should be a list of email addresses. One email per line.
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2. Create an email file
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* Name it whatever you want.
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* The first line of the file will be used as the subject.
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* The rest of the file will be used as the body.
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* Newlines between the subject and body will be removed.
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3. Do a test run
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* go run . test [email filename]
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* You must send the test email before blasting it to everyone.
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* If you modify the email file after testing, you must test again. Otherwise NewsBlaster2000 will complain.
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4. Start blasting
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* go run . blast [audience file] [email file]
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* Will batch send using the Postmark batch API.
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* Will produce a .track file that will list all email addresses that we attempted to send to.
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* In case of error, you can blast again. All emails listed in the .track file will be skipped.
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* Will produce a .log file with information received back from Postmark.
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`)
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}
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},
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}
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testCmd := &cobra.Command{
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Use: "test [email file]",
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Short: "Send a test mail to the test address specified in the config",
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Run: func(cmd *cobra.Command, args []string) {
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if len(args) < 1 {
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cmd.Usage()
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os.Exit(1)
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}
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newsletterFile := args[0]
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sendTest(newsletterFile)
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},
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}
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blastCmd := &cobra.Command{
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Use: "blast [audience file] [email file]",
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Short: "Blast your newsletter to your followers",
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Run: func(cmd *cobra.Command, args []string) {
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if len(args) < 2 {
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cmd.Usage()
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os.Exit(1)
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}
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audienceFile := args[0]
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newsletterFile := args[1]
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sendNews(audienceFile, newsletterFile)
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},
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}
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cmd.AddCommand(testCmd)
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cmd.AddCommand(blastCmd)
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cmd.Execute()
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}
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