From 00b824f98e7d7f07bc9e3d63b5a5dbc11e6e24e9 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Wed, 10 May 2023 23:05:31 -0300
Subject: [PATCH] it's working! even on twitter.

---
 event.html |  3 ++-
 image.go   |  3 ++-
 main.go    |  1 +
 proxy.go   | 32 ++++++++++++++++++++++++++++++++
 render.go  |  3 ++-
 text.go    | 18 +++++++++++++-----
 6 files changed, 52 insertions(+), 8 deletions(-)
 create mode 100644 proxy.go

diff --git a/event.html b/event.html
index 6a4dfad..0d7af19 100644
--- a/event.html
+++ b/event.html
@@ -7,6 +7,7 @@
     <meta property="og:title" content="{{.title}}" />
     {{ if .metadata.Picture }}
     <meta property="og:image" content="{{.metadata.Picture}}" />
+    <meta property="twitter:image" content="{{.proxy}}{{.metadata.Picture}}" />
     {{end}} {{ if .metadata.About }}
     <meta property="og:description" content="{{.metadata.About}}" />
     {{end}}
@@ -29,7 +30,7 @@
     <meta property="twitter:card" content="summary" />
     {{ if .image }}
     <meta property="og:image" content="{{.image}}" />
-    <meta name="twitter:image" content="{{.image}}" />
+    <meta name="twitter:image" content="{{.proxy}}{{.image}}" />
     {{end}} {{ if .video }}
     <meta property="og:video" content="{{.video}}" />
     <meta property="og:video:secure_url" content="{{.video}}" />
diff --git a/image.go b/image.go
index 5030881..a4e552d 100644
--- a/image.go
+++ b/image.go
@@ -23,7 +23,8 @@ func generate(w http.ResponseWriter, r *http.Request) {
 	}
 
 	lines := normalizeText(event.Content)
-	img, err := drawImage(lines)
+
+	img, err := drawImage(lines, getPreviewStyle(r))
 	if err != nil {
 		log.Printf("error writing image: %s", err)
 		http.Error(w, "error writing image!", 500)
diff --git a/main.go b/main.go
index 40a38e8..f28cec2 100644
--- a/main.go
+++ b/main.go
@@ -8,6 +8,7 @@ import (
 
 func main() {
 	http.HandleFunc("/image/", generate)
+	http.HandleFunc("/proxy/", proxy)
 	http.HandleFunc("/", render)
 
 	port := os.Getenv("PORT")
diff --git a/proxy.go b/proxy.go
new file mode 100644
index 0000000..475f4a4
--- /dev/null
+++ b/proxy.go
@@ -0,0 +1,32 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+)
+
+func proxy(w http.ResponseWriter, r *http.Request) {
+	fmt.Println(r.URL.Path, ":~", r.Header.Get("user-agent"))
+
+	src := r.URL.Query().Get("src")
+	urlParsed, err := url.Parse(src)
+	if err != nil {
+		http.Error(w, "Invalid URL", http.StatusBadRequest)
+		return
+	}
+	if urlParsed.Scheme != "http" && urlParsed.Scheme != "https" {
+		http.Error(w, "The URL scheme is neither HTTP nor HTTPS", http.StatusBadRequest)
+		return
+	}
+
+	proxy := httputil.ReverseProxy{
+		Director: func(r *http.Request) {
+			r.URL = urlParsed
+			r.Host = urlParsed.Host
+		},
+	}
+
+	proxy.ServeHTTP(w, r)
+}
diff --git a/render.go b/render.go
index 023f7c8..d2811f5 100644
--- a/render.go
+++ b/render.go
@@ -19,6 +19,7 @@ var eventHTML string
 var tmpl = template.Must(template.New("event").Parse(eventHTML))
 
 func render(w http.ResponseWriter, r *http.Request) {
+	fmt.Println(r.URL.Path, ":~", r.Header.Get("user-agent"))
 	w.Header().Set("Content-Type", "text/html")
 
 	code := r.URL.Path[1:]
@@ -65,7 +66,6 @@ func render(w http.ResponseWriter, r *http.Request) {
 	if len(imageMatch) > 0 {
 		image = imageMatch[0]
 	}
-	fmt.Println("IMAGE", image)
 
 	videoMatch := regexp.MustCompile(`https:\/\/[^ ]*\.(mp4|webm)`).FindStringSubmatch(event.Content)
 	var video string
@@ -170,6 +170,7 @@ func render(w http.ResponseWriter, r *http.Request) {
 		"videoType":    videoType,
 		"image":        image,
 		"video":        video,
+		"proxy":        "https://" + hostname + "/proxy?src=",
 		"eventJSON":    string(eventJSON),
 	}
 	if err := tmpl.ExecuteTemplate(w, "event", params); err != nil {
diff --git a/text.go b/text.go
index 282804f..b4e2d37 100644
--- a/text.go
+++ b/text.go
@@ -27,10 +27,18 @@ func normalizeText(t string) []string {
 	return lines
 }
 
-func drawImage(lines []string) (image.Image, error) {
+func drawImage(lines []string, style string) (image.Image, error) {
+	width, height, paddingLeft := 700, 525, 0
+	switch style {
+	case "twitter":
+		height = 366
+	case "telegram":
+		paddingLeft = 15
+	}
+
 	// get the physical image ready with colors/size
 	fg, bg := image.Black, image.White
-	rgba := image.NewRGBA(image.Rect(0, 0, 700, 525))
+	rgba := image.NewRGBA(image.Rect(0, 0, width, height))
 
 	// draw the empty image
 	draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
@@ -51,7 +59,7 @@ func drawImage(lines []string) (image.Image, error) {
 	// draw each line separately
 	var count float64 = 1
 	for _, line := range lines {
-		if err := drawText(c, line, count); err != nil {
+		if err := drawText(c, line, count, paddingLeft); err != nil {
 			return nil, err
 		}
 		count++
@@ -60,12 +68,12 @@ func drawImage(lines []string) (image.Image, error) {
 	return rgba, nil
 }
 
-func drawText(c *freetype.Context, text string, line float64) error {
+func drawText(c *freetype.Context, text string, line float64, paddingLeft int) error {
 	// We need an offset because we need to know where exactly on the
 	// image to place the text. The `line` is how much of an offset
 	// that we need to provide (which line the text is going on).
 	offsetY := 10 + int(c.PointToFix32(FONT_SIZE*line)>>8)
 
-	_, err := c.DrawString(text, freetype.Pt(10, offsetY))
+	_, err := c.DrawString(text, freetype.Pt(10+paddingLeft, offsetY))
 	return err
 }