From 8b2e02e42d7350c8b0d772d0b42e63586aecfa64 Mon Sep 17 00:00:00 2001
From: David Hoppenbrouwers <david@salt-inc.org>
Date: Mon, 10 Oct 2022 01:11:51 +0200
Subject: [PATCH] Add italics, link detection, lists to minimd

---
 README.md            |  6 +++++
 main.py              | 15 ++----------
 minimd.py            | 58 ++++++++++++++++++++++++++++++++++++++++++++
 templates/forum.html |  2 +-
 4 files changed, 67 insertions(+), 14 deletions(-)
 create mode 100755 minimd.py

diff --git a/README.md b/README.md
index 0f7bd73..df23156 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,12 @@ Agreper is a forum board with a focus on being easy to set up and manage.
 
 ### Linux
 
+Ensure you have the necessary packages, e.g. for Debian:
+
+```
+apt install git make sqlite3 python3-venv python3-pip
+```
+
 First clone or [download the latest release](https://github.com/Demindiro/agreper/archive/refs/tags/v0.1.tar.gz).
 
 Then setup with:
diff --git a/main.py b/main.py
index 71b8db7..58020cd 100644
--- a/main.py
+++ b/main.py
@@ -8,7 +8,7 @@ import os, sys, subprocess
 import passlib.hash, secrets
 import time
 from datetime import datetime
-import captcha, password
+import captcha, password, minimd
 
 app = Flask(__name__)
 db = DB(os.getenv('DB'))
@@ -659,22 +659,11 @@ def utility_processor():
     def format_time(t):
         return datetime.utcfromtimestamp(t / 10 ** 9).replace(microsecond=0)
 
-    def minimd(text):
-        # Replace angle brackets to prevent XSS
-        # Also replace ampersands to prevent surprises.
-        text = text.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;')
-        # Split into paragraphs
-        paragraphs = map(lambda l: l.strip('\n'), text.split('\n\n'))
-        paragraphs = map(lambda l: l if not l.startswith('  ') else f'<pre>{l}</pre>', paragraphs)
-        paragraphs = map(lambda l: f'<p>{l}</p>', paragraphs)
-        # Glue together again
-        return ''.join(paragraphs)
-
     return {
         'format_since': format_since,
         'format_time': format_time,
         'format_until': format_until,
-        'minimd': minimd,
+        'minimd': minimd.html,
     }
 
 
diff --git a/minimd.py b/minimd.py
new file mode 100755
index 0000000..3531a66
--- /dev/null
+++ b/minimd.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+
+import re
+
+# https://stackoverflow.com/a/6041965
+RE_URL = re.compile(r'(https?://([\w_-]+(?:(?:\.[\w_-]+)+))([\w.,@?^=%&:/~+#-]*[\w@?^=%&/~+#-]))')
+RE_EM = re.compile(r'\*(.*?)\*')
+RE_LIST = re.compile(r'(-|[0-9]\.) .*')
+
+def html(text):
+    # Replace angle brackets to prevent XSS
+    # Also replace ampersands to prevent surprises.
+    text = text.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;')
+
+    html = ['<p>']
+    lines = text.split('\n')
+    in_code = False
+    in_list = False
+
+    for l in lines:
+        if l == '':
+            in_list = False
+            if in_code:
+                html.append('</pre>')
+                in_code = False
+            html.append('</p><p>')
+            continue
+        if l.startswith('  '):
+            in_list = False
+            l = l[2:]
+            if not in_code:
+                html.append('<pre>')
+                in_code = True
+            html.append(l)
+            continue
+        if in_code:
+            html.append('</pre>')
+            in_code = False
+        l = RE_EM.sub(r'<em>\1</em>', l)
+        l = RE_URL.sub(r'<a href="\1">\1</a>', l)
+        if RE_LIST.match(l):
+            if in_list:
+                html.append('<br>')
+            in_list = True
+        else:
+            in_list = False
+        html.append(l)
+
+    if in_code:
+        html.append('</pre>')
+    html.append('</p>')
+    return ''.join(html)
+
+
+if __name__ == '__main__':
+    import sys
+    print(html(sys.stdin.read()))
+
diff --git a/templates/forum.html b/templates/forum.html
index 102a386..7c4350f 100644
--- a/templates/forum.html
+++ b/templates/forum.html
@@ -9,7 +9,7 @@
 {%- endmacro -%}
 
 {% block content -%}
-<p>{{ description }}</p>
+<p>{{ minimd(description) | safe }}</p>
 <p><a href="{{ url_for('new_thread', forum_id = forum_id) }}">Create thread</a></p>
 {{- nav() -}}
 <table>