commit 260018cc9d5f1f7f381a3ca04f2bd98120a2e3cb
Author: Trevor Slocum <trevor@rocketnine.space>
Date:   Sat Nov 21 08:53:04 2020 -0800

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..17ebbdb
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+.idea/
+dist/
+vendor/
+*.sh
+/gmitohtml
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000..221498a
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,21 @@
+image: golang:latest
+
+stages:
+  - validate
+  - build
+
+fmt:
+  stage: validate
+  script:
+    - gofmt -l -s -e .
+    - exit $(gofmt -l -s -e . | wc -l)
+
+vet:
+  stage: validate
+  script:
+    - go vet -composites=false ./...
+
+test:
+  stage: validate
+  script:
+    - go test -race -v ./...
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..7c20f89
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Trevor Slocum <trevor@rocketnine.space>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1a9a2f2
--- /dev/null
+++ b/README.md
@@ -0,0 +1,37 @@
+# gmitohtml
+[![CI status](https://gitlab.com/tslocum/gmitohtml/badges/master/pipeline.svg)](https://gitlab.com/tslocum/gmitohtml/commits/master)
+[![Donate](https://img.shields.io/liberapay/receives/rocketnine.space.svg?logo=liberapay)](https://liberapay.com/rocketnine.space)
+
+[Gemini](https://gemini.circumlunar.space) to HTML conversion tool and daemon
+
+## Download
+
+gmitohtml is written in [Go](https://golang.org). Run the following command to
+download and build gmitohtml from source.
+
+```bash
+go get gitlab.com/tslocum/gmitohtml
+```
+
+The resulting binary is available as `~/go/bin/gmitohtml`.
+
+## Usage
+
+Convert a single document:
+
+```bash
+gmitohtml < document.gmi
+```
+
+Run as daemon at `http://localhost:8080`:
+
+```bash
+# Start the daemon:
+gmitohtml --daemon=localhost:8080
+# Access via browser:
+xdg-open http://localhost:8080/gemini/twins.rocketnine.space/
+```
+
+## Support
+
+Please share issues and suggestions [here](https://gitlab.com/tslocum/gmitohtml/issues).
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..06d5296
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module gitlab.com/tslocum/gmitohtml
+
+go 1.15
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..26d3e93
--- /dev/null
+++ b/main.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+	"gitlab.com/tslocum/gmitohtml/pkg/gmitohtml"
+
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/url"
+	"os"
+	"os/exec"
+	"runtime"
+)
+
+func openBrowser(url string) {
+	var err error
+	switch runtime.GOOS {
+	case "linux":
+		err = exec.Command("xdg-open", url).Start()
+	case "windows":
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
+	case "darwin":
+		err = exec.Command("open", url).Start()
+	default:
+		err = fmt.Errorf("unsupported platform")
+	}
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func main() {
+	var view bool
+	var daemon string
+	flag.BoolVar(&view, "view", false, "open web browser")
+	flag.StringVar(&daemon, "daemon", "", "start daemon on specified address")
+	// TODO option to include response header in page
+	flag.Parse()
+
+	if daemon != "" {
+		err := gmitohtml.StartDaemon(daemon)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if view {
+			openBrowser("http://" + daemon)
+		}
+
+		select {} //TODO
+	}
+
+	data, err := ioutil.ReadAll(os.Stdin)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	data = gmitohtml.Convert(data, "")
+
+	data = append([]byte("<!DOCTYPE html>\n<html>\n<body>\n"), data...)
+	data = append(data, []byte("\n</body>\n</html>")...)
+
+	if view {
+		openBrowser(string(append([]byte("data:text/html,"), []byte(url.PathEscape(string(data)))...)))
+		return
+	}
+	fmt.Print(gmitohtml.Convert(data, ""))
+}
diff --git a/pkg/gmitohtml/convert.go b/pkg/gmitohtml/convert.go
new file mode 100644
index 0000000..9a3de0c
--- /dev/null
+++ b/pkg/gmitohtml/convert.go
@@ -0,0 +1,217 @@
+package gmitohtml
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/url"
+	"path"
+	"strings"
+)
+
+// ErrInvalidURL is the error returned when the URL is invalid.
+var ErrInvalidURL = errors.New("invalid URL")
+
+var daemonAddress string
+
+func rewriteURL(u string, loc *url.URL) string {
+	if daemonAddress != "" {
+		if strings.HasPrefix(u, "gemini://") {
+			return "http://" + daemonAddress + "/gemini/" + u[9:]
+		} else if strings.Contains(u, "://") {
+			return u
+		} else if loc != nil && len(u) > 0 && !strings.HasPrefix(u, "//") {
+			newPath := u
+			if u[0] != '/' {
+				newPath = path.Join(loc.Path, u)
+			}
+			return "http://" + daemonAddress + "/gemini/" + loc.Host + newPath
+		}
+		return "http://" + daemonAddress + "/gemini/" + u
+	}
+	return u
+}
+
+// Convert converts text/gemini to text/html.
+func Convert(page []byte, u string) []byte {
+	var result []byte
+
+	var lastPreformatted bool
+	var preformatted bool
+
+	parsedURL, err := url.Parse(u)
+	if err != nil {
+		parsedURL = nil
+		err = nil
+	}
+
+	scanner := bufio.NewScanner(bytes.NewReader(page))
+	for scanner.Scan() {
+		line := scanner.Bytes()
+		l := len(line)
+		if l >= 3 && string(line[0:3]) == "```" {
+			preformatted = !preformatted
+			continue
+		}
+
+		if preformatted != lastPreformatted {
+			if preformatted {
+				result = append(result, []byte("<pre>\n")...)
+			} else {
+				result = append(result, []byte("</pre>\n")...)
+			}
+			lastPreformatted = preformatted
+		}
+
+		if preformatted {
+			result = append(result, line...)
+			result = append(result, []byte("\n")...)
+			continue
+		}
+
+		if l >= 7 && bytes.HasPrefix(line, []byte("=> ")) {
+			split := bytes.SplitN(line[3:], []byte(" "), 2)
+			if len(split) == 2 {
+				link := append([]byte(`<a href="`), rewriteURL(string(split[0]), parsedURL)...)
+				link = append(link, []byte(`">`)...)
+				link = append(link, split[1]...)
+				link = append(link, []byte(`</a>`)...)
+				result = append(result, link...)
+				result = append(result, []byte("<br>")...)
+				continue
+			}
+		}
+
+		heading := 0
+		for i := 0; i < l; i++ {
+			if line[i] == '#' {
+				heading++
+			} else {
+				break
+			}
+		}
+		if heading > 0 {
+			result = append(result, []byte(fmt.Sprintf("<h%d>%s</h%d>", heading, line, heading))...)
+			continue
+		}
+
+		result = append(result, line...)
+		result = append(result, []byte("<br>")...)
+	}
+
+	return result
+}
+
+// Fetch downloads and converts a Gemini page.
+func Fetch(u string, clientCertFile string, clientCertKey string) ([]byte, []byte, error) {
+	if u == "" {
+		return nil, nil, ErrInvalidURL
+	}
+
+	requestURL, err := url.ParseRequestURI(u)
+	if err != nil {
+		return nil, nil, err
+	}
+	if requestURL.Scheme == "" {
+		requestURL.Scheme = "gemini"
+	}
+	if strings.IndexRune(requestURL.Host, ':') == -1 {
+		requestURL.Host += ":1965"
+	}
+
+	tlsConfig := &tls.Config{}
+
+	conn, err := tls.Dial("tcp", requestURL.Host, tlsConfig)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Send request header
+	conn.Write([]byte(requestURL.String() + "\r\n"))
+
+	data, err := ioutil.ReadAll(conn)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	firstNewLine := -1
+	l := len(data)
+	if l > 2 {
+		for i := 1; i < l; i++ {
+			if data[i] == '\n' && data[i-1] == '\r' {
+				firstNewLine = i
+				break
+			}
+		}
+	}
+	var header []byte
+	if firstNewLine > -1 {
+		header = data[:firstNewLine]
+		data = data[firstNewLine+1:]
+	}
+
+	if bytes.HasPrefix(header, []byte("text/html")) {
+		return header, data, nil
+	}
+	return header, Convert(data, requestURL.String()), nil
+}
+
+func handleRequest(writer http.ResponseWriter, request *http.Request) {
+	defer request.Body.Close()
+	if request.URL == nil {
+		return
+	}
+
+	pathSplit := strings.Split(request.URL.Path, "/")
+	if len(pathSplit) < 2 || pathSplit[1] != "gemini" {
+		writer.Write([]byte("Error: invalid protocol, only Gemini is supported"))
+		return
+	}
+
+	u, err := url.ParseRequestURI("gemini://" + strings.Join(pathSplit[2:], "/"))
+	if err != nil {
+		writer.Write([]byte("Error: invalid URL"))
+		return
+	}
+
+	header, data, err := Fetch(u.String(), "", "")
+	if err != nil {
+		fmt.Fprintf(writer, "Error: failed to fetch %s: %s", u, err)
+		return
+	}
+
+	if len(header) > 0 && header[0] == '3' {
+		split := bytes.SplitN(header, []byte(" "), 2)
+		if len(split) == 2 {
+			writer.Header().Set("Location", rewriteURL(string(split[1]), request.URL))
+			return
+		}
+	}
+
+	if len(header) > 3 && !bytes.HasPrefix(header[3:], []byte("text/gemini")) {
+		writer.Header().Set("Content-type", string(header[3:]))
+	} else {
+		writer.Header().Set("Content-type", "text/html; charset=utf-8")
+	}
+
+	writer.Write([]byte("<!DOCTYPE html>\n<html>\n<body>\n"))
+	writer.Write(data)
+	writer.Write([]byte("\n</body>\n</html>"))
+}
+
+// StartDaemon starts the page conversion daemon.
+func StartDaemon(address string) error {
+	daemonAddress = address
+
+	http.HandleFunc("/", handleRequest)
+
+	go func() {
+		log.Fatal(http.ListenAndServe(address, nil))
+	}()
+	return nil
+}