path: root/handlers.go

package main

import (
	"bytes"
	"fmt"
	"mime"
	"net/http"
	"net/url"
	"strings"

	"tildegit.org/tjp/sliderule"
	"tildegit.org/tjp/sliderule/gemini"
	"tildegit.org/tjp/sliderule/gemini/gemtext"
	"tildegit.org/tjp/sliderule/gopher"
	"tildegit.org/tjp/sliderule/gopher/gophermap"
	"tildegit.org/tjp/sliderule/spartan"
)

func docType(u *url.URL, response *sliderule.Response) string {
	_, gopherType := gopherURL(u)
	switch gopherType {
	case gopher.MenuType, gopher.SearchType:
		return "text/x-gophermap"
	case gopher.TextFileType, gopher.ErrorType, gopher.InfoMessageType:
		return "text/plain"
	case gopher.MacBinHexType,
		gopher.DosBinType,
		gopher.BinaryFileType,
		gopher.ImageFileType,
		gopher.MovieFileType,
		gopher.SoundFileType,
		gopher.DocumentType:
		return "application/octet-stream"
	case gopher.UuencodedType:
		return "text/x-uuencode"
	case gopher.GifFileType:
		return "image/gif"
	case gopher.BitmapType:
		return "image/bmp"
	case gopher.PngImageFileType:
		return "image/png"
	case gopher.HTMLType:
		return "text/html"
	case gopher.RtfDocumentType:
		return "application/rtf"
	case gopher.WavSoundFileType:
		return "audio/wav"
	case gopher.PdfDocumentType:
		return "application/pdf"
	case gopher.XmlDocumentType:
		return "application/xml"
	}

	if metaIsMediaType(u, response) {
		mtype, _, err := mime.ParseMediaType(response.Meta.(string))
		if err == nil {
			return mtype
		}
	}

	if u.Scheme == "http" || u.Scheme == "https" {
		resp := response.Meta.(*http.Response)
		mtype, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
		if err == nil {
			return mtype
		}
	}

	return "text/plain"
}

func metaIsMediaType(u *url.URL, response *sliderule.Response) bool {
	if u.Scheme == "gemini" && response.Status == gemini.StatusSuccess {
		return true
	}
	if u.Scheme == "spartan" && response.Status == spartan.StatusSuccess {
		return true
	}
	return false
}

func parseDoc(doctype string, body []byte, conf *Config) (string, []Link, error) {
	switch doctype {
	case "text/x-gophermap":
		return parseGophermapDoc(body, conf.SoftWrap)
	case "text/gemini":
		return parseGemtextDoc(body, conf.SoftWrap)
	}

	return string(body), nil, nil
}

func parseGophermapDoc(body []byte, softWrap int) (string, []Link, error) {
	var b strings.Builder
	var l []Link
	mapdoc, err := gophermap.Parse(bytes.NewBuffer(body))
	if err != nil {
		return "", nil, err
	}

	links := 0
	for _, item := range mapdoc {
		if item.Type != gopher.InfoMessageType {
			links += 1
		}
	}
	width := numberWidth(links - 1)
	infopad := string(bytes.Repeat([]byte{' '}, width+3))

	i := 0
	for _, item := range mapdoc {
		switch item.Type {
		case gopher.InfoMessageType:
			for _, line := range fold(item.Display, softWrap) {
				if _, err := b.WriteString(infopad + line + "\n"); err != nil {
					return "", nil, err
				}
			}
		default:
			l = append(l, Link{
				Text:   item.Display,
				Target: fmtGopherURL(item.Type, item.Selector, item.Hostname, item.Port),
			})
			if _, err := b.WriteString(fmt.Sprintf("[%d]%s %s%s%s\n", i, padding(i, width), linkStyle, item.Display, ansiClear)); err != nil {
				return "", nil, err
			}
			i += 1
		}
	}

	return b.String(), l, nil
}

const (
	ansiClear   = "\x1b[0m"
	linkStyle   = "\x1b[38;5;33m"
	promptStyle = "\x1b[38;5;39m"
	quoteStyle  = "\x1b[38;5;208m\x1b[3m"
	rawStyle    = "\x1b[38;5;249m"
	h1Style     = "\x1b[38;5;154m\x1b[1m\x1b[4m"
	h2Style     = "\x1b[38;5;50m\x1b[4m"
	h3Style     = "\x1b[38;5;6m\x1b[4m"
	listStyle   = "\x1b[38;5;3m"
)

func parseGemtextDoc(body []byte, softWrap int) (string, []Link, error) {
	var b strings.Builder
	var l []Link
	gemdoc, err := gemtext.Parse(bytes.NewBuffer(body))
	if err != nil {
		return "", nil, err
	}

	links := 0
	for _, item := range gemdoc {
		if item.Type() == gemtext.LineTypeLink || item.Type() == gemtext.LineTypePrompt {
			links += 1
		}
	}
	width := numberWidth(links - 1)
	textpad := string(bytes.Repeat([]byte{' '}, width+3))

	i := 0
	for _, item := range gemdoc {
		isPrompt := false
		hLevel := 0
		switch item.Type() {
		case gemtext.LineTypePrompt:
			isPrompt = true
			fallthrough
		case gemtext.LineTypeLink:
			ll := item.(gemtext.LinkLine)
			u, err := url.Parse(ll.URL())
			if err != nil {
				return "", nil, err
			}
			l = append(l, Link{
				Text:   ll.Label(),
				Target: u,
				Prompt: isPrompt,
			})
			label := ll.Label()
			if len(label) == 0 {
				label = ll.URL()
			}
			if _, err := b.WriteString(fmt.Sprintf("[%d]%s %s%s%s\n", i, padding(i, width), linkStyle, label, ansiClear)); err != nil {
				return "", nil, err
			}
			i += 1
		case gemtext.LineTypeQuote:
			q := item.(gemtext.QuoteLine)
			for _, line := range fold(q.Body(), softWrap-1) {
				line = strings.TrimSpace(line)
				if _, err := b.WriteString(textpad + "> " + quoteStyle + line + ansiClear + "\n"); err != nil {
					return "", nil, err
				}
			}
		case gemtext.LineTypePreformatToggle:
		case gemtext.LineTypePreformattedText:
			for _, line := range fold(item.String(), softWrap) {
				if _, err := b.WriteString(textpad + rawStyle + line + ansiClear + "\n"); err != nil {
					return "", nil, err
				}
			}
		case gemtext.LineTypeHeading3:
			hLevel += 1
			fallthrough
		case gemtext.LineTypeHeading2:
			hLevel += 1
			fallthrough
		case gemtext.LineTypeHeading1:
			hLevel += 1
			var color string
			switch hLevel {
			case 1:
				color = h1Style
			case 2:
				color = h2Style
			case 3:
				color = h3Style
			}

			for _, line := range fold(item.String(), softWrap) {
				line = strings.TrimRight(line, "\r\n")
				if _, err := b.WriteString(textpad + color + line + ansiClear + "\n"); err != nil {
					return "", nil, err
				}
			}
		case gemtext.LineTypeListItem:
			li := item.(gemtext.ListItemLine)
			for i, line := range fold(li.Body(), softWrap-2) {
				lpad := "  "
				if i == 0 {
					lpad = "* "
				}
				if _, err := b.WriteString(textpad + listStyle + lpad + line + ansiClear + "\n"); err != nil {
					return "", nil, err
				}
			}
		default:
			for _, line := range fold(item.String(), softWrap) {
				if _, err := b.WriteString(textpad + line + "\n"); err != nil {
					return "", nil, err
				}
			}
		}
	}

	return b.String(), l, nil
}

func fold(line string, width int) []string {
	rs := []rune(strings.TrimSuffix(line, "\n"))
	if len(rs) == 0 {
		return []string{""}
	}

	var b []string
outer:
	for len(rs) > 0 {
		if len(rs) <= width {
			b = append(b, string(rs))
			break
		}

		w := width
		for rs[w] != ' ' && w > 0 {
			w -= 1
		}
		if w == 0 {
			for i := width + 1; i < len(rs); i += 1 {
				if rs[i] == ' ' {
					b = append(b, string(rs[:i]))
					rs = rs[i+1:]
					continue outer
				}
			}
			b = append(b, string(rs))
			break outer
		}

		b = append(b, string(rs[:w]))
		rs = rs[w+1:]
	}

	return b
}

func fmtGopherURL(itemtype sliderule.Status, selector, hostname, port string) *url.URL {
	if port != "70" {
		hostname += ":" + port
	}
	return &url.URL{
		Scheme: "gopher",
		Host:   hostname,
		Path:   "/" + string(byte(itemtype)) + selector,
	}
}

func numberWidth(i int) int {
	n := 1
	for i > 9 {
		i /= 10
		n += 1
	}
	return n
}

func padding(num int, width int) string {
	return string(bytes.Repeat([]byte{' '}, width-numberWidth(num)))
}