add plaintext email option, use text/template

text/template is used on plaintext emails to avoid escaping of certain
characters.

config/config-base.json

@@ -73,7 +73,7 @@
                     "requires_restart": true,
                     "type": "text",
                     "value": "",
-                    "description": "Optionally substitute occurrences of \"Jellyfin\" in the account creation form with this. May result in bad grammar."
+                    "description": "Optionally substitute occurrences of \"Jellyfin\" in the account creation form and emails with this. May result in bad grammar."
                 }
             }
         },
@@ -398,6 +398,15 @@
                     "type": "text",
                     "value": "Jellyfin",
                     "description": "The name of the sender"
+                },
+                "plaintext": {
+                    "name": "Send emails as plain text",
+                    "required": false,
+                    "requires_restart": false,
+                    "depends_true": "method",
+                    "type": "bool",
+                    "value": false,
+                    "description": "Send emails as plain text instead of HTML."
                 }
             }
         },

email.go

@@ -6,9 +6,11 @@ import (
 	"crypto/tls"
 	"fmt"
 	"html/template"
+	"io"
 	"net/smtp"
 	"strings"
 	"sync"
+	textTemplate "text/template"
 	"time"
 
 	"github.com/gomarkdown/markdown"
@@ -16,6 +18,7 @@ import (
 	jEmail "github.com/jordan-wright/email"
 	"github.com/knz/strtime"
 	"github.com/mailgun/mailgun-go/v4"
+	stripmd "github.com/writeas/go-strip-markdown"
 )
 
 // implements email sending, right now via smtp or mailgun.
@@ -167,16 +170,31 @@ func (emailer *Emailer) NewSMTP(server string, port int, username, password stri
 	}
 }
 
+type templ interface {
+	Execute(wr io.Writer, data interface{}) error
+}
+
 func (emailer *Emailer) construct(app *appContext, section, keyFragment string, data map[string]interface{}) (html, text string, err error) {
-	var tpl *template.Template
+	var tpl templ
 	if substituteStrings == "" {
 		data["jellyfin"] = "Jellyfin"
 	} else {
 		data["jellyfin"] = substituteStrings
 	}
-	for _, key := range []string{"html", "text"} {
+	var keys []string
+	if app.config.Section("email").Key("plaintext").MustBool(false) {
+		keys = []string{"text"}
+		text = ""
+	} else {
+		keys = []string{"html", "text"}
+	}
+	for _, key := range keys {
 		filesystem, fpath := app.GetPath(section, keyFragment+key)
-		tpl, err = template.ParseFS(filesystem, fpath)
+		if key == "html" {
+			tpl, err = template.ParseFS(filesystem, fpath)
+		} else {
+			tpl, err = textTemplate.ParseFS(filesystem, fpath)
+		}
 		if err != nil {
 			return
 		}
@@ -220,11 +238,13 @@ func (emailer *Emailer) constructAnnouncement(subject, md string, app *appContex
 	email := &Email{subject: subject}
 	renderer := html.NewRenderer(html.RendererOptions{Flags: html.Smartypants})
 	html := markdown.ToHTML([]byte(md), nil, renderer)
+	text := strings.TrimPrefix(strings.TrimSuffix(stripmd.Strip(md), "</p>"), "<p>")
 	message := app.config.Section("email").Key("message").String()
 	var err error
 	email.html, email.text, err = emailer.construct(app, "announcement_email", "email_", map[string]interface{}{
-		"text":    template.HTML(html),
+		"text":      template.HTML(html),
-		"message": message,
+		"plaintext": text,
+		"message":   message,
 	})
 	if err != nil {
 		return nil, err

go.mod

@@ -38,6 +38,7 @@ require (
 	github.com/swaggo/gin-swagger v1.3.0
 	github.com/swaggo/swag v1.7.0 // indirect
 	github.com/ugorji/go v1.2.0 // indirect
+	github.com/writeas/go-strip-markdown v2.0.1+incompatible // indirect
 	golang.org/x/crypto v0.0.0-20201112155050-0c6587e931a9 // indirect
 	golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c // indirect
 	golang.org/x/tools v0.1.0 // indirect

go.sum

@@ -226,6 +226,8 @@ github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijb
 github.com/urfave/cli/v2 v2.1.1/go.mod h1:SE9GqnLQmjVa0iPEY0f1w3ygNIYcIJ0OKPMoW2caLfQ=
 github.com/urfave/cli/v2 v2.3.0 h1:qph92Y649prgesehzOrQjdWyxFOp/QVM+6imKHad91M=
 github.com/urfave/cli/v2 v2.3.0/go.mod h1:LJmUH05zAU44vOAcrfzZQKsZbVcdbOG8rtL3/XcUArI=
+github.com/writeas/go-strip-markdown v2.0.1+incompatible h1:IIqxTM5Jr7RzhigcL6FkrCNfXkvbR+Nbu1ls48pXYcw=
+github.com/writeas/go-strip-markdown v2.0.1+incompatible/go.mod h1:Rsyu10ZhbEK9pXdk8V6MVnZmTzRG0alMNLMwa0J01fE=
 github.com/yuin/goldmark v1.2.1 h1:ruQGxdhGHe7FWOJPT0mKs5+pD2Xs1Bm/kdGlHO04FmM=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 golang.org/dl v0.0.0-20190829154251-82a15e2f2ead h1:jeP6FgaSLNTMP+Yri3qjlACywQLye+huGLmNGhBzm6k=

mail/announcement.txt

@@ -1,3 +1,3 @@
-{{ .text }}
+{{ .plaintext }}
 
 {{ .message }}