From 0384d631d2edb8383d0840940be066d96a5badc7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9=20=27Necoro=27=20Neumann?= <necoro@necoro.eu>
Date: Sun, 9 Jan 2022 01:20:34 +0100
Subject: #66: Support for specifying custom templates

---
 internal/feed/template/template.go | 42 ++++++++++++++++++++++++++++++++------
 main.go                            | 22 ++++++++++++++++++++
 pkg/config/config.go               |  4 ++++
 3 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/internal/feed/template/template.go b/internal/feed/template/template.go
index 8b3fb73..d66a8e4 100644
--- a/internal/feed/template/template.go
+++ b/internal/feed/template/template.go
@@ -2,13 +2,20 @@ package template
 
 import (
 	_ "embed"
+	"errors"
+	"fmt"
 	html "html/template"
 	"io"
+	"io/fs"
+	"os"
 	text "text/template"
+
+	"github.com/Necoro/feed2imap-go/pkg/log"
 )
 
 type template interface {
 	Execute(wr io.Writer, data interface{}) error
+	Name() string
 }
 
 type Template struct {
@@ -24,21 +31,44 @@ var defaultHtmlTpl string
 var defaultTextTpl string
 
 var Html = Template{
-	useHtml: true,
-	dflt:    defaultHtmlTpl,
+	useHtml:  true,
+	dflt:     defaultHtmlTpl,
+	template: html.New("Html").Funcs(funcMap),
 }
 
 var Text = Template{
-	useHtml: false,
-	dflt:    defaultTextTpl,
+	useHtml:  false,
+	dflt:     defaultTextTpl,
+	template: text.New("Text").Funcs(funcMap),
 }
 
 func (tpl *Template) loadDefault() {
+	if err := tpl.load(tpl.dflt); err != nil {
+		panic(err)
+	}
+}
+
+func (tpl *Template) load(content string) (err error) {
 	if tpl.useHtml {
-		tpl.template = html.Must(html.New("Html").Funcs(funcMap).Parse(tpl.dflt))
+		_, err = tpl.template.(*html.Template).Parse(content)
 	} else {
-		tpl.template = text.Must(text.New("Text").Funcs(funcMap).Parse(tpl.dflt))
+		_, err = tpl.template.(*text.Template).Parse(content)
 	}
+	return
+}
+
+func (tpl *Template) LoadFile(file string) error {
+	content, err := os.ReadFile(file)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			log.Errorf("Template file '%s' does not exist, keeping default.", file)
+			return nil
+		} else {
+			return fmt.Errorf("reading template file '%s': %w", file, err)
+		}
+	}
+
+	return tpl.load(string(content))
 }
 
 func init() {
diff --git a/main.go b/main.go
index d2d0a3c..e4593be 100644
--- a/main.go
+++ b/main.go
@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"github.com/Necoro/feed2imap-go/internal/feed/cache"
+	"github.com/Necoro/feed2imap-go/internal/feed/template"
 	"github.com/Necoro/feed2imap-go/internal/imap"
 	"github.com/Necoro/feed2imap-go/pkg/config"
 	"github.com/Necoro/feed2imap-go/pkg/log"
@@ -62,6 +63,18 @@ func processFeed(cf cache.CachedFeed, client *imap.Client, dryRun bool) {
 	cf.Commit()
 }
 
+func loadTemplate(path string, tpl template.Template) error {
+	if path == "" {
+		return nil
+	}
+
+	log.Printf("Loading custom %s template from %s", tpl.Name(), path)
+	if err := tpl.LoadFile(path); err != nil {
+		return fmt.Errorf("loading %s template from %s: %w", tpl.Name(), path, err)
+	}
+	return nil
+}
+
 func run() error {
 	flag.Parse()
 	if printVersion {
@@ -107,6 +120,15 @@ func run() error {
 		return nil
 	}
 
+	if !buildCache {
+		if err = loadTemplate(cfg.HtmlTemplate, template.Html); err != nil {
+			return err
+		}
+		if err = loadTemplate(cfg.TextTemplate, template.Text); err != nil {
+			return err
+		}
+	}
+
 	imapErr := make(chan error, 1)
 	var c *imap.Client
 	if !dryRun && !buildCache {
diff --git a/pkg/config/config.go b/pkg/config/config.go
index 218ccb3..a580337 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -24,6 +24,8 @@ type GlobalOptions struct {
 	Parts        []string `yaml:"parts"`
 	MaxFailures  int      `yaml:"max-failures"`
 	AutoTarget   bool     `yaml:"auto-target"`
+	HtmlTemplate string   `yaml:"html-template"`
+	TextTemplate string   `yaml:"text-template"`
 }
 
 var DefaultGlobalOptions = GlobalOptions{
@@ -34,6 +36,8 @@ var DefaultGlobalOptions = GlobalOptions{
 	Target:       Url{},
 	Parts:        []string{"text", "html"},
 	AutoTarget:   true,
+	HtmlTemplate: "",
+	TextTemplate: "",
 }
 
 // Options are feed specific
-- 
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