add bbcode support

lib/babycode.lua

@@ -0,0 +1,62 @@
+local babycode = {}
+
+local _escape_html = function(text)
+  return text:gsub("[&<>\"']", {
+    ["&"] = "&amp;",
+    ["<"] = "&lt;",
+    [">"] = "&gt;",
+    ['"'] = "&quot;",
+    ["'"] = "&#39;"
+  })
+end
+
+---renders babycode to html
+---@param s string input babycode
+---@param escape_html fun(s: string): string function that escapes html
+function babycode.to_html(s, escape_html)
+  if not s or s == "" then return "" end
+  -- extract code blocks first and store them as placeholders
+  -- don't want to process bbcode embedded into a code block
+  local code_blocks = {}
+  local code_count = 0
+  local text = s:gsub("%[code%](.-)%[/code%]", function(code)
+    code_count = code_count + 1
+    code_blocks[code_count] = code
+    return "\1CODE:"..code_count.."\1"
+  end)
+
+  -- replace `[url=https://example.com]Example[/url] tags
+  text = text:gsub("%[url=([^%]]+)%](.-)%[/url%]", function(url, label)
+    return '<a href="'..escape_html(url)..'">'..escape_html(label)..'</a>'
+  end)
+  
+  -- replace `[url]https://example.com[/url] tags
+  text = text:gsub("%[url%]([^%]]+)%[/url%]", function(url)
+    return '<a href="'..escape_html(url)..'">'..escape_html(url)..'</a>'
+  end)
+
+  -- bold, italics, strikethrough
+  text = text:gsub("%[b%](.-)%[/b%]", "<strong>%1</strong>")
+  text = text:gsub("%[i%](.-)%[/i%]", "<em>%1</em>")
+  text = text:gsub("%[s%](.-)%[/s%]", "<del>%1</del>")
+
+  -- replace loose links
+  text = text:gsub("(https?://[%w-_%.%?%.:/%+=&~%@#%%]+[%w-/])", function(url)
+    if not text:find('<a[^>]*>'..url..'</a>') then
+      return '<a href="'..escape_html(url)..'">'..escape_html(url)..'</a>'
+    end
+    return url
+  end)
+
+  -- replace code block placeholders back with their original contents
+  text = text:gsub("\1CODE:(%d+)\1", function(n)
+    return "<pre><code>"..code_blocks[tonumber(n)].."</code></pre>"
+  end)
+
+  -- finally, normalize newlines replace them with <br>
+  text = text:gsub("\r?\n\r?\n+", "<br>"):gsub("\r?\n", "<br>")
+
+  return text
+end
+
+return babycode

util.lua

@@ -1,12 +1,15 @@
 local util = {}
 local magick = require("magick")
 local db = require("lapis.db")
+local html_escape = require("lapis.html").escape
 
 local Avatars = require("models").Avatars
 local Users = require("models").Users
 local Posts = require("models").Posts
 local PostHistory = require("models").PostHistory
 
+local babycode = require("lib.babycode")
+
 util.TransientUser = {
   is_admin = function (self)
     return false
@@ -109,10 +112,12 @@ function util.create_post(thread_id, user_id, content)
     current_revision_id = db.NULL,
   })
   
+  local bb_content = babycode.to_html(content, html_escape)
+  
   local revision = PostHistory:create({
     post_id = post.id,
     user_id = user_id,
-    content = content,
+    content = bb_content,
     is_initial_revision = true,
   })
   

views/threads/thread.etlua

@@ -2,7 +2,7 @@
   <div>
     <img src="<%= post.avatar_path or "/avatars/default.webp" %>">
     <div><%= post.username %></div>
-    <div><p><%- require("lapis.html").escape(post.content):gsub("\n", "<br>") %></p></div>
+    <div><p><%- post.content %></p></div>
   </div>
 <% end %>