Add Templates with Parsing

+ Changes NewComposer to return error.
+ Add lib to handle templates using "text/template".
+ Add -T option to following commands
    - compose.
    - reply
    - forward
+ Quoted replies using templates.
+ Forwards as body using templates
+ Default templates are installed similar to filters.
+ Templates Config in aerc.conf.
    - Required templates are parsed while loading config.
+ Add aerc-templates.7 manual for using template data.

1 files changed, 160 insertions, 0 deletions

diff --git a/lib/templates/template.go b/lib/templates/template.go
new file mode 100644
index 00000000..c09bf4d2
--- /dev/null
+++ b/lib/templates/template.go
@@ -0,0 +1,160 @@
+package templates
+
+import (
+	"bytes"
+	"errors"
+	"net/mail"
+	"os"
+	"path"
+	"strings"
+	"text/template"
+	"time"
+
+	"github.com/mitchellh/go-homedir"
+)
+
+type TemplateData struct {
+	To      []*mail.Address
+	Cc      []*mail.Address
+	Bcc     []*mail.Address
+	From    []*mail.Address
+	Date    time.Time
+	Subject string
+	// Only available when replying with a quote
+	OriginalText string
+	OriginalFrom []*mail.Address
+	OriginalDate time.Time
+}
+
+func TestTemplateData() TemplateData {
+	defaults := map[string]string{
+		"To":           "John Doe <john@example.com>",
+		"Cc":           "Josh Doe <josh@example.com>",
+		"From":         "Jane Smith <jane@example.com>",
+		"Subject":      "This is only a test",
+		"OriginalText": "This is only a test text",
+		"OriginalFrom": "John Doe <john@example.com>",
+		"OriginalDate": time.Now().Format("Mon Jan 2, 2006 at 3:04 PM"),
+	}
+
+	return ParseTemplateData(defaults)
+}
+
+func ParseTemplateData(defaults map[string]string) TemplateData {
+	originalDate, _ := time.Parse("Mon Jan 2, 2006 at 3:04 PM", defaults["OriginalDate"])
+	td := TemplateData{
+		To:           parseAddressList(defaults["To"]),
+		Cc:           parseAddressList(defaults["Cc"]),
+		Bcc:          parseAddressList(defaults["Bcc"]),
+		From:         parseAddressList(defaults["From"]),
+		Date:         time.Now(),
+		Subject:      defaults["Subject"],
+		OriginalText: defaults["Original"],
+		OriginalFrom: parseAddressList(defaults["OriginalFrom"]),
+		OriginalDate: originalDate,
+	}
+	return td
+}
+
+func parseAddressList(list string) []*mail.Address {
+	addrs, err := mail.ParseAddressList(list)
+	if err != nil {
+		return nil
+	}
+
+	return addrs
+}
+
+func wrapLine(text string, lineWidth int) string {
+	words := strings.Fields(text)
+	if len(words) == 0 {
+		return text
+	}
+	wrapped := words[0]
+	spaceLeft := lineWidth - len(wrapped)
+	for _, word := range words[1:] {
+		if len(word)+1 > spaceLeft {
+			wrapped += "\n" + word
+			spaceLeft = lineWidth - len(word)
+		} else {
+			wrapped += " " + word
+			spaceLeft -= 1 + len(word)
+		}
+	}
+
+	return wrapped
+}
+
+func wrapText(text string, lineWidth int) string {
+	text = strings.ReplaceAll(text, "\r\n", "\n")
+	lines := strings.Split(text, "\n")
+	var wrapped string
+
+	for _, line := range lines {
+		wrapped += wrapLine(line, lineWidth) + "\n"
+	}
+	return wrapped
+}
+
+// Wraping lines at 70 so that with the "> " of the quote it is under 72
+func quote(text string) string {
+	text = strings.ReplaceAll(text, "\r\n", "\n")
+
+	quoted := "> " + wrapText(text, 70)
+	quoted = strings.ReplaceAll(quoted, "\n", "\n> ")
+	return quoted
+}
+
+var templateFuncs = template.FuncMap{
+	"quote":      quote,
+	"wrapText":   wrapText,
+	"dateFormat": time.Time.Format,
+}
+
+func findTemplate(templateName string, templateDirs []string) (string, error) {
+	for _, dir := range templateDirs {
+		templateFile, err := homedir.Expand(path.Join(dir, templateName))
+		if err != nil {
+			return "", err
+		}
+
+		if _, err := os.Stat(templateFile); os.IsNotExist(err) {
+			continue
+		}
+		return templateFile, nil
+	}
+
+	return "", errors.New("Can't find template - " + templateName)
+}
+
+func ParseTemplateFromFile(templateName string, templateDirs []string, data interface{}) ([]byte, error) {
+	templateFile, err := findTemplate(templateName, templateDirs)
+	if err != nil {
+		return nil, err
+	}
+	emailTemplate, err :=
+		template.New(templateName).Funcs(templateFuncs).ParseFiles(templateFile)
+	if err != nil {
+		return nil, err
+	}
+
+	var outString bytes.Buffer
+	if err := emailTemplate.Execute(&outString, data); err != nil {
+		return nil, err
+	}
+	return outString.Bytes(), nil
+}
+
+func ParseTemplate(templateText string, data interface{}) ([]byte, error) {
+	emailTemplate, err :=
+		template.New("email_template").Funcs(templateFuncs).Parse(templateText)
+	if err != nil {
+		return nil, err
+	}
+
+	var outString bytes.Buffer
+	if err := emailTemplate.Execute(&outString, data); err != nil {
+		return nil, err
+	}
+	return outString.Bytes(), nil
+}