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+#!/usr/bin/env python3
+
+# Convert gemtext to HTML, accepting HTML header and footer files
+
+# Copyright 2021 huntingb
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, version 3 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see https://www.gnu.org/licenses/.
+
+# Original code found at:
+#   https://github.com/huntingb/gemtext-html-converter
+
+# Modified by tslil clingman, April 2021 in the following ways
+# - added HTML escaping of all non-pre lines
+# - added header and footer file input
+# - added generation of <ul> ... </ul> for list items
+# - fixed stripping of lines, no longer occurs in pre blocks, and
+#   otherwise is rstrip only
+# - replace := syntax with something my version of python3 accepts
+# - modified description below
+
+"""
+HUNTER'S SIMPLE GEMTEXT TO HTML CONVERTER
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+A simple script that converts gemtext to HTML.
+
+Takes four arguments from stdin. The first two arguments are the names
+of files which will be used as a header and footer for the generated
+output, in that order.
+
+The next argument is the name of of a gemtext file, and the last
+argument is the name of the desired output file.
+
+The output file consists of, in order: the header; the lines of
+gemtext in the input file converted to their HTML equivalents: <h1>,
+<h2>, <h3>, <p>, <a>, <blockquote>, <li>, and <pre> tags; the footer.
+"""
+
+# importing required libraries
+import sys
+import re
+import html
+
+# A dictionary that maps regex to match at the beginning of gmi lines
+# to their corresponding HTML tag names. Used by
+# convert_single_line().
+tags_dict = {
+    r"^# (.*)": "h1",
+    r"^## (.*)": "h2",
+    r"^### (.*)": "h3",
+    r"^\* (.*)": "li",
+    r"^> (.*)": "blockquote",
+    r"^=>\s*(\S+)(\s+.*)?": "a"
+}
+
+
+# This function takes a string of gemtext as input and returns a
+# string of HTML
+def convert_single_line(gmi_line):
+    for pattern in tags_dict.keys():
+        match = re.match(pattern, gmi_line)
+        if match:
+            tag = tags_dict[pattern]
+            groups = match.groups()
+            if tag == "a":
+                href = re.sub("^gemini://", "https://", groups[0])
+                href = re.sub(r"\.gmi$", ".html", href)
+                if len(groups) > 1 and groups[1] is not None:
+                    inner_text = groups[1].strip()
+                else:
+                    inner_text = href
+                return f"<p><{tag} href='{href}'>{inner_text}</{tag}></p>"
+            else:
+                inner_text = html.escape(groups[0].strip())
+                return f"<{tag}>{inner_text}</{tag}>"
+    gmi_line = html.escape(gmi_line)
+    return f"<p>{gmi_line}</p>"
+
+
+# Reads the contents of the input file line by line and outputs HTML.
+# Renders text in preformat blocks (toggled by ```) as multiline <pre>
+# tags.
+def main(args):
+    with open(args[3]) as gmi, open(args[4], "w") as output:
+        # Write header
+        header = open(args[1])
+        output.write(header.read())
+        header.close()
+        # Parse gmitext
+        pre = False
+        listing = False
+        for line in gmi:
+            if line.startswith("```"):
+                pre = not pre
+                if pre:
+                    line = line.rstrip()
+                    if len(line) > 3:
+                        line = html.escape(line[3:])
+                        output.write(f"<pre title=\"{line}\">\n")
+                    else:
+                        output.write("<pre>\n")
+                else:
+                    output.write("</pre>\n")
+            elif pre:
+                output.write(html.escape(line))
+            else:
+                line = line.rstrip()
+                if line.startswith("*") and not listing:
+                    listing = True
+                    output.write("<ul>\n")
+                if not line.startswith("*") and listing:
+                    listing = False
+                    output.write("</ul>\n")
+                output_line = convert_single_line(line)
+                output.write(output_line+"\n")
+        # Write footer
+        footer = open(args[2])
+        output.write(footer.read())
+        footer.close()
+
+# Main guard
+if __name__ == "__main__":
+    main(sys.argv)