From 4bf44b16562335b3d09b6df0150521bb5b5f776f Mon Sep 17 00:00:00 2001
From: Feuerfuchs <git@feuerfuchs.dev>
Date: Mon, 18 May 2020 12:12:43 +0200
Subject: WIP: Refactoring

---
 internal/port/gemini.go | 205 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 205 insertions(+)
 create mode 100644 internal/port/gemini.go

(limited to 'internal/port/gemini.go')

diff --git a/internal/port/gemini.go b/internal/port/gemini.go
new file mode 100644
index 0000000..f9b0b97
--- /dev/null
+++ b/internal/port/gemini.go
@@ -0,0 +1,205 @@
+package port
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"io"
+	"log"
+	"mime"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"golang.org/x/net/html/charset"
+	"golang.org/x/text/transform"
+
+	"git.vulpes.one/Feuerfuchs/port/port/libgemini"
+
+	"github.com/temoto/robotstxt"
+)
+
+var (
+	TermEscapeSGRPattern = regexp.MustCompile("\\[\\d+(;\\d+)*m")
+)
+
+func resolveURI(uri string, baseURL *url.URL) (resolvedURI string) {
+	if strings.HasPrefix(uri, "//") {
+		resolvedURI = "/gemini/" + strings.TrimPrefix(uri, "//")
+	} else if strings.HasPrefix(uri, "gemini://") {
+		resolvedURI = "/gemini/" + strings.TrimPrefix(uri, "gemini://")
+	} else if strings.HasPrefix(uri, "gopher://") {
+		resolvedURI = "/gopher/" + strings.TrimPrefix(uri, "gopher://")
+	} else {
+		url, err := url.Parse(uri)
+		if err != nil {
+			return ""
+		}
+		adjustedURI := baseURL.ResolveReference(url)
+		path := adjustedURI.Path
+		if !strings.HasPrefix(path, "/") {
+			path = "/" + path
+		}
+		if adjustedURI.Scheme == "gemini" {
+			resolvedURI = "/gemini/" + adjustedURI.Host + path
+		} else if adjustedURI.Scheme == "gopher" {
+			resolvedURI = "/gopher/" + adjustedURI.Host + path
+		} else {
+			resolvedURI = adjustedURI.String()
+		}
+	}
+
+	return
+}
+
+func GeminiHandler(tpl *template.Template, robotsdata *robotstxt.RobotsData, assetList AssetList, robotsdebug bool) http.HandlerFunc {
+	return func(w http.ResponseWriter, req *http.Request) {
+		agent := req.UserAgent()
+		path := strings.TrimPrefix(req.URL.Path, "/gemini/")
+
+		if robotsdata != nil && robotsdebug && !robotsdata.TestAgent(path, agent) {
+			log.Printf("UserAgent %s ignored robots.txt", agent)
+		}
+
+		parts := strings.Split(path, "/")
+		hostport := parts[0]
+
+		if len(hostport) == 0 {
+			http.Redirect(w, req, "/", http.StatusFound)
+			return
+		}
+
+		title := hostport
+
+		var qs string
+
+		if req.URL.RawQuery != "" {
+			qs = fmt.Sprintf("?%s", url.QueryEscape(req.URL.RawQuery))
+		}
+
+		uri, err := url.QueryUnescape(strings.Join(parts[1:], "/"))
+		if err != nil {
+			if e := tpl.Execute(w, TemplateVariables{
+				Title:    title,
+				URI:      hostport,
+				Assets:   assetList,
+				RawText:  fmt.Sprintf("Error: %s", err),
+				Error:    true,
+				Protocol: "gemini",
+			}); e != nil {
+				log.Println("Template error: " + e.Error())
+				log.Println(err.Error())
+			}
+			return
+		}
+
+		if uri != "" {
+			title = fmt.Sprintf("%s/%s", hostport, uri)
+		}
+
+		res, err := libgemini.Get(
+			fmt.Sprintf(
+				"gemini://%s/%s%s",
+				hostport,
+				uri,
+				qs,
+			),
+		)
+
+		if err != nil {
+			if e := tpl.Execute(w, TemplateVariables{
+				Title:    title,
+				URI:      fmt.Sprintf("%s/%s", hostport, uri),
+				Assets:   assetList,
+				RawText:  fmt.Sprintf("Error: %s", err),
+				Error:    true,
+				Protocol: "gemini",
+			}); e != nil {
+				log.Println("Template error: " + e.Error())
+				log.Println(err.Error())
+			}
+			return
+		}
+
+		if int(res.Header.Status/10) == 3 {
+			baseURL, err := url.Parse(fmt.Sprintf(
+				"gemini://%s/%s",
+				hostport,
+				uri,
+			))
+			if err != nil {
+				if e := tpl.Execute(w, TemplateVariables{
+					Title:    title,
+					URI:      fmt.Sprintf("%s/%s", hostport, uri),
+					Assets:   assetList,
+					RawText:  fmt.Sprintf("Error: %s", err),
+					Error:    true,
+					Protocol: "gemini",
+				}); e != nil {
+					log.Println("Template error: " + e.Error())
+					log.Println(err.Error())
+				}
+				return
+			}
+
+			http.Redirect(w, req, resolveURI(res.Header.Meta, baseURL), http.StatusFound)
+			return
+		}
+
+		if int(res.Header.Status/10) != 2 {
+			if err := tpl.Execute(w, TemplateVariables{
+				Title:    title,
+				URI:      fmt.Sprintf("%s/%s", hostport, uri),
+				Assets:   assetList,
+				RawText:  fmt.Sprintf("Error %d: %s", res.Header.Status, res.Header.Meta),
+				Error:    true,
+				Protocol: "gemini",
+			}); err != nil {
+				log.Println("Template error: " + err.Error())
+			}
+			return
+		}
+
+		if strings.HasPrefix(res.Header.Meta, "text/") {
+			buf := new(bytes.Buffer)
+
+			_, params, err := mime.ParseMediaType(res.Header.Meta)
+			if err != nil {
+				buf.ReadFrom(res.Body)
+			} else {
+				encoding, _ := charset.Lookup(params["charset"])
+				readbuf := new(bytes.Buffer)
+				readbuf.ReadFrom(res.Body)
+
+				writer := transform.NewWriter(buf, encoding.NewDecoder())
+				writer.Write(readbuf.Bytes())
+				writer.Close()
+			}
+
+			var (
+				rawText string
+				items   []Item
+			)
+
+			if strings.HasPrefix(res.Header.Meta, libgemini.MIME_GEMINI) {
+				items = parseGeminiDocument(buf, uri, hostport)
+			} else {
+				rawText = buf.String()
+			}
+
+			if err := tpl.Execute(w, TemplateVariables{
+				Title:    title,
+				URI:      fmt.Sprintf("%s/%s", hostport, uri),
+				Assets:   assetList,
+				Lines:    items,
+				RawText:  rawText,
+				Protocol: "gemini",
+			}); err != nil {
+				log.Println("Template error: " + err.Error())
+			}
+		} else {
+			io.Copy(w, res.Body)
+		}
+	}
+}
-- 
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