gemini-demo-1/gemini-demo.py

#!/usr/bin/env python3

import cgi
import mailcap
import os
import socket
import ssl
import tempfile
import textwrap
import urllib.parse

caps = mailcap.getcaps()
menu = []
hist = []

def absolutise_url(base, relative):
    # Absolutise relative links
    if "://" not in relative:
        # Python's URL tools somehow only work with known schemes?
        base = base.replace("gemini://","http://")
        relative = urllib.parse.urljoin(base, relative)
        relative = relative.replace("http://", "gemini://")
    return relative

while True:
    # Get input
    cmd = input("> ").strip()
    # Handle things other than requests
    if cmd.lower() == "q":
        print("Bye!")
        break
    # Get URL, from menu, history or direct entry
    if cmd.isnumeric():
        url = menu[int(cmd)-1]
    elif cmd.lower() == "b":
        # Yes, twice
        url = hist.pop()
        url = hist.pop()
    else:
        url = cmd
        if not "://" in url:
            url = "gemini://" + url
    parsed_url = urllib.parse.urlparse(url)
    if parsed_url.scheme != "gemini":
        print("Sorry, Gemini links only.")
        continue
    # Do the Gemini transaction
    try:
        while True:
            s = socket.create_connection((parsed_url.netloc, 1965))
            context = ssl.SSLContext()
            context.check_hostname = False
            context.verify_mode = ssl.CERT_NONE
            s = context.wrap_socket(s, server_hostname = parsed_url.netloc)
            s.sendall((url + '\r\n').encode("UTF-8"))
            # Get header and check for redirects
            fp = s.makefile("rb")
            header = fp.readline()
            header = header.decode("UTF-8").strip()
            status, mime = header.split()
            # Handle input requests
            if status.startswith("1"):
                # Prompt
                query = input("INPUT" + mime + "> ")
                url += "?" + urllib.parse.quote(query) # Bit lazy...
            # Follow redirects
            elif status.startswith("3"):
                url = absolutise_url(url, mime)
                parsed_url = urllib.parse.urlparse(url)
            # Otherwise, we're done.
            else:
                break
    except Exception as err:
        print(err)
        continue
    # Fail if transaction was not successful
    if not status.startswith("2"):
        print("Error %s: %s" % (status, mime))
        continue
    # Handle text
    if mime.startswith("text/"):
        # Decode according to declared charset
        mime, mime_opts = cgi.parse_header(mime)
        body = fp.read()
        body = body.decode(mime_opts.get("charset","UTF-8"))
        # Handle a Gemini map
        if mime == "text/gemini":
            menu = []
            preformatted = False
            for line in body.splitlines():
                if line.startswith("```"):
                    preformatted = not preformatted
                elif preformatted:
                    print(line)
                elif line.startswith("=>") and line[2:].strip():
                    bits = line[2:].strip().split(maxsplit=1)
                    link_url = bits[0]
                    link_url = absolutise_url(url, link_url)
                    menu.append(link_url)
                    text = bits[1] if len(bits) == 2 else link_url
                    print("[%d] %s" % (len(menu), text))
                else:
                    print(textwrap.fill(line, 80))
        # Handle any other plain text
        else:
            print(body)
    # Handle non-text
    else:
        tmpfp = tempfile.NamedTemporaryFile("wb", delete=False)
        tmpfp.write(fp.read())
        tmpfp.close()
        cmd_str, _ = mailcap.findmatch(caps, mime, filename=tmpfp.name)
        os.system(cmd_str)
        os.unlink(tmpfp.name)
    # Update history
    hist.append(url)