kopher/js/hi01379.js

// Platform-agnostic Gopher response handler and Gophermap parser
// Depends on the platform-specific gopherRequest(resource, input, success, error) function
// (defined in the transport.js file here)

Hi01379 = (function(psGopherRequest) {

  var tagsToReplace = {'&': '&amp;', '<': '&lt;', '>': '&gt;'}

  function esc(str) { // escape HTML entities
    return str.replace(/[&<>]/g, function(tag) {return tagsToReplace[tag] || tag})
  }

  function unphlow(str) { // Unphlow algorithm implementation
    var lines=str.split('\n'), line, l = lines.length, i, buf = '', out = []
    for(i=0;i<l;i++) {
      line = lines[i].trim() // remove all leading/trailing whitespace-class chars
      if(line.length) // if the line is not empty, just append it and a whitespace to the buffer 
        buf += line + ' '
      else { // output logic
        out.push(buf, '')
        buf = ''
      }
    }
    if(buf.length) // process the remaining output
      out.push(buf)
    return out.map(function(s) { // final whitespace sanitation
      return s.replace(/\s+/g, ' ').trim()
    }).join('\n')
  }

  function terminalize(str, attrs) { // partial terminal styling support with ANSI codes
    if(!attrs) attrs = [] // accept previous attributes array if present
    var prevattrs = attrs.join(' ') // preserve stringified copy
    var out = '', c, styleseq, sl, l = str.length, i, j, att, attindex, strattrs,
        visualOpenTag='<span data-styling="%s">', visualCloseTag='</span>',
        modes = ['', 'BB', 'FN', 'IT', 'UL', 'BL', '', 'IN', 'HI', 'ST']
    for(i=0;i<l;i++) {
      c = str[i]
      if(c === '\x1b') { // escape character encountered
        c = str[i+1] // get the next character, don't increase the counter yet
        if(c === '[') { // ANSI sequence starting
          i++ // increase the counter, now it's pointing to [
          styleseq='' // init style sequence buffer
          do { // read the style sequence until m character or any whitespace
            c = str[++i] // increase the counter once more, [ is ignored
            styleseq += c
          } while(c !== 'm' && c !== ' ' && c !== '\t' && c !== '\r' && c !== '\n')
          styleseq = styleseq.slice(0, -1).split(';') // attributes are delimited by ;
          for(sl=styleseq.length,j=0;j<sl;j++) { // iterate over attributes in their order
            att = parseInt(styleseq[j]) // in this case parseInt is more reliable than |0
            if(att === 0) attrs = [] // reset all styling
            else if(att >= 30 && att <= 37) attrs.push('FC'+(att-30)) // foreground color
            else if(att >= 40 && att <= 47) attrs.push('BC'+(att-40)) // background color
            else if(att < 10) attrs.push(modes[att]) // activate special modes
            else if(att > 20 && att < 30) { // deactivate special modes
              if(att === 22) { // also deactivate bold mode 1
                attindex = attrs.indexOf('BB')
                if(attindex > -1)
                  attrs.splice(attindex, 1)
              }
              attindex = attrs.indexOf(modes[att - 20])
              if(attindex > -1)
                attrs.splice(attindex, 1)
            }
            else if(att === 39) { // reset only the foreground color
              attrs = attrs.map(function(v) {
                return v.startsWith('FC') ? '' : v
              }).filter(String)
            }
            else if(att === 49) { // reset only the background color
              attrs = attrs.map(function(v) {
                return v.startsWith('BC') ? '' : v
              }).filter(String)
            }
          }
          // now we have our attrs array with all styling applied, output the tags
          strattrs = attrs.join(' ')
          if(strattrs != prevattrs) { // there are some changes
            if(prevattrs != '') // previous attributes were not empty
              out += visualCloseTag
            if(strattrs) // current attributes are not empty
              out += visualOpenTag.replace('%s', strattrs)
            prevattrs = strattrs // update the previous attribute cache
          }
        } // don't add any processed characters "as is" to the output
        else continue // skip the escape and proceed with the loop
      }
      else out += c // just append it to the output
    } 
    return {output: out, attrs: attrs} // return both output and remaining attributes
  }

  function gophermapToHTML(gmap, chost, cport) {
    if(!cport) cport = 70
    if(!chost) chost = 'localhost'
    var lines = gmap.split(/\r?\n/), line, l = lines.length, i, lbr = '<br>',
        type, rest, desc, sel, host, port,
        iattrs = [], istyled, // attribute cache and styled infomessage placeholder
        output = '', pretag = 'pre', preflag = false
    for(i=0;i<l;i++) {
      line = lines[i]
      if(line === '.')
        break // immediately stop parsing on the . line
      if(line.indexOf('\t') == -1 && !line.startsWith('i')) // this also handles empty lines
        line = 'i' + line
      type = line[0] // type
      rest = line.substr(1).split('\t')
      desc = esc(rest[0]) // escaping description (obviously must not contain tabs)
      sel = rest.length > 1 ? rest[1] : ''      // selector
      host = rest.length > 2 ? rest[2] : ''     // hostname
      port = rest.length > 3 ? (0|rest[3]) : '' // port
      // selector defaults to the description only if there are no other fields
      if(!sel && rest.length < 2) sel = desc
      if(!host) host = chost  // host defaults to the current host
      if(!port) port = cport  // port defaults to the current port
      if(type == 'i') {  // information message - wrap them in pretag
        if(!preflag) {
          preflag = true
          output += '<' + pretag + '>'
        }
        istyled = terminalize(desc, iattrs)
        iattrs = istyled.attrs
        output += istyled.output + '\n'
      }
      else { //information messages ended, stop preformatting
        if(preflag) {
          preflag = false
          iattrs = [] // reset info styling attributes
          output += '</' + pretag + '>'
        }
        if(desc = desc.trim()) { // ignore empty descriptions
          if(type == '3') // error message
            output += '<span class=error>' + desc + '</span>' + lbr
          else if(type == '8') { // output the telnet:// link as is
            var tlink = 'telnet://' + (sel ? (sel+'@') : '') + host + (port ? (':'+port) : '') 
            output += desc + ': ' + esc(tlink) + lbr
          }
          else { // shape the link (internal hi:type|sel|host|port format unless it's an external URL)
            var deflink = 'hi:'+[type,sel,host,port].join('|'), link = deflink
            if(type == 'h' && sel.startsWith('URL:')) {
              link = sel.split(':').slice(1).join(':').trim()
              if(link.startsWith('javascript:')) // XSS protection
                link = deflink
            }
            output += '<a href="' + encodeURI(link) + '">' + desc + '</a>' + lbr
          }
        }
      }
    }
    return output
  }

  // resource format: [type, selector, host, port]
  function loadHole(resource, input, successCb, errorCb) {
    var fname = resource[1].split('/').pop(), // as the most intelligent guess
        ext = fname.split('.').pop().toLowerCase(), // presumed extension
        extMappings = { // not including AVIF here because they aren't supported by Gecko 48 anyway
          'gif': 'image/gif', // including GIF though because nothing prevents using I instead of g
          'png': 'image/png',
          'svg': 'image/svg+xml',
          'webp': 'image/webp',
          'apng': 'image/apng',
          'jpg': 'image/jpeg',
          'jpeg': 'image/jpeg',
          'jfif': 'image/jpeg',
          'pjpeg': 'image/jpeg',
          'pjp': 'image/jpeg'
        }
    psGopherRequest(resource, input, function(rawdata, type) {
      if(type == '5' || type == 's' || type == ';' || type == 'd')
        type = '9' // remap unknown binary types to 9
      if(type == '9' || type == 'g' || type == 'I') { // binary file
        var ctype = 'application/octet-stream' // the default one if everything else fails
        // update content type
        if(type == 'g') // GIF-only resource type
          ctype = 'image/gif'
        else if(type == 'I') // attempt to guess the image MIME type by the extension
          ctype = extMappings[ext]
        var datablob = new Blob([rawdata], {type: ctype})
        successCb({
          content: datablob,
          contentType: ctype,
          contentName: fname,
          serviceMsg: type + ' ' + resource[1],
          updateAddr: false
        })
      }
      else { // assuming text content otherwise
        var output = (new TextDecoder).decode(rawdata), ctype = 'text/plain', // defaulting to type 0
            wo = '' // wrapper-friendly output
        if(type == '1' || type == '7') { // gophermap
          output = gophermapToHTML(output, resource[2], resource[3])
          ctype = 'text/html'
          wo = output
        }
        else wo = unphlow(output)
        successCb({
          content: output,
          contentWf: wo,
          contentType: ctype,
          serviceMsg: type + ' ' + resource[1]
        })
      }
    }, errorCb)
  }

  return {load: loadHole, render: gophermapToHTML}
})(gopherRequest)