Write new entries in the same file #3

Create a new function to get the entries for the feed.

main.go

@@ -1,11 +1,16 @@
 package main
 
 import (
+	"bytes"
+	"fmt"
 	"html/template"
+	"io"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"net/url"
 	"os"
+	"regexp"
 	"time"
 
 	"github.com/jinzhu/now"
@@ -15,36 +20,104 @@ import (
 	"p83.nl/go/ekster/pkg/jf2"
 )
 
+func init() {
+	log.SetFlags(log.LstdFlags | log.Lshortfile)
+}
 func main() {
 	u, err := url.Parse(os.Args[1])
 	if err != nil {
 		log.Fatal(err)
 	}
+	filename := os.Args[2]
 
-	resp, err := http.Get(u.String())
+	re, err := regexp.Compile(`<span class="next-entry"></span>`)
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer resp.Body.Close()
 
-	if resp.StatusCode != 200 {
+	f, err := openAndCreate(filename)
-		log.Fatalf("Status is not 200, but %d", resp.StatusCode)
+
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		log.Fatal(err)
 	}
 
-	md := microformats.Parse(resp.Body, u)
+	f.Close()
-	items := jf2.SimplifyMicroformatDataItems(md)
+
+	var buf bytes.Buffer
+	items, err := getEntriesForFeed(u)
+	if err != nil {
+		log.Fatal(err)
+	}
 
 	items = filterEntriesAfter(items, now.With(time.Now()).Monday())
 
+	err = outputEntries(items, &buf)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	output := re.ReplaceAll(data, buf.Bytes())
+	err = ioutil.WriteFile(filename, output, 0666)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func openAndCreate(filename string) (io.ReadCloser, error) {
+	f, err := os.Open(filename)
+	if err != nil && !os.IsExist(err) {
+		t, err := template.ParseFiles("templates/full.html")
+		if err != nil {
+			return nil, err
+		}
+		f, err = os.Create(filename)
+		if err != nil {
+			return nil, err
+		}
+		err = t.Execute(f, nil)
+		if err != nil {
+			return nil, err
+		}
+		err = f.Close()
+		if err != nil {
+			return nil, err
+		}
+		f, err = os.Open(filename)
+		if err != nil {
+			return nil, err
+		}
+	} else if err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+func outputEntries(items []microsub.Item, w io.Writer) error {
 	t, err := template.ParseFiles("templates/weekly.html")
 	if err != nil {
 		log.Fatal(err)
 	}
-
+	err = t.Execute(w, items)
-	err = t.Execute(os.Stdout, items)
 	if err != nil {
-		log.Fatal(err)
+		return err
 	}
+	return nil
+}
+
+func getEntriesForFeed(u *url.URL) ([]microsub.Item, error) {
+	resp, err := http.Get(u.String())
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("status is not 200, but %d", resp.StatusCode)
+	}
+
+	md := microformats.Parse(resp.Body, u)
+	items := jf2.SimplifyMicroformatDataItems(md)
+	return items, nil
 }
 
 func filterEntriesAfter(items []microsub.Item, from time.Time) []microsub.Item {

templates/full.html

@@ -0,0 +1,11 @@
+<html lang="en">
+<head>
+    <title>Weekly summaries</title>
+</head>
+<body>
+<div class="h-feed">
+    <h1 class="p-name">Weekly</h1>
+    <span class="next-entry"></span>
+</div>
+</body>
+</html>

templates/weekly.html

@@ -1,25 +1,14 @@
-<html lang="en">
+<span class="next-entry"></span>
-<head>
+<div class="h-entry">
-    <title>Weekly summaries</title>
-</head>
-<body>
-<div class="h-feed">
-    <h1 class="p-name">Weekly</h1>
-
     {{ range . }}
-        <div class="h-entry">
+        <h2 class="p-name">{{ .Name }}</h2>
-            <h2 class="p-name">{{ .Name }}</h2>
+        {{ if .Content }}
-            {{ if .Content }}
+            {{ if .Content.HTML }}
-                {{ if .Content.HTML }}
+                <div class="e-content">{{ .Content.HTML }}</div>
-                    <div class="e-content">{{ .Content.HTML }}</div>
+            {{ else }}
-                {{ else }}
+                <div class="p-content">{{ .Content.Text }}</div>
-                    <div class="p-content">{{ .Content.Text }}</div>
-                {{ end }}
             {{ end }}
-
+        {{ end }}
-            <time datetime="{{ .Published }}">{{ .Published }}</time>
+        <time datetime="{{ .Published }}">{{ .Published }}</time>
-        </div>
     {{ end }}
 </div>
-</body>
-</html>