gemrss

#!/usr/bin/env texlua
-- get feed from gemini or https, and replace links to gemini with links to HTML proxy
-- it is meant for use with Newsboat.
-- to use it, add a similar line to your "urls" file:
-- "exec: gemrss gemini://marginalia.nu/log/feed.xml"

local socket = require("socket")

local ports = {gemini = 1965, https = 443, http = 80}
local commands = {
  gemini = "ncat --ssl $host $port  > $tmpfile",
  https  = "wget -q -O $tmpfile $url",
  http  = "wget -q -O $tmpfile $url",
}

local url        = arg[1] or "gemini://gemini.susa.net/index.gmi"
local proxy      = arg[2] or "https://proxy.vulpes.one/gemini/"
local parsed_url = socket.url.parse(url)
local scheme     = parsed_url.scheme
local port       = ports[scheme]


-- we must save result to tempfile
local tmpfile     = os.tmpname()
local options = {
  url    = url,
  scheme = parsed_url.scheme,
  host   = parsed_url.host,
  port   = port,
  tmpfile= tmpfile
}

-- get command to be executed based on the URL scheme
local command_str = commands[scheme]

-- do string interpolation of options
command_str = command_str:gsub("%$(%w+)", options)

local command = io.popen(command_str, "w")
if scheme == "gemini" then
  -- we must write URL to the server for Gemini
  command:write(url .. "\r\n")
end
command:close()

-- read temp file
local i = 1
for line in io.lines(tmpfile) do
  -- ignore first line if it contains Gemini status code
  if i > 1 or (not line:match("^%d+"))  then
    line = line:gsub("(<link[^>]+>)", function(link) 
      -- replace gemini links with proxy
      return link:gsub("gemini://", proxy)
    end)
    print(line)
  end
  i = i + 1
end
os.remove(tmpfile)