2 files changed, 98 insertions, 0 deletions
diff --git a/pkgs/simple/cgit-about-filter/cgit-about-filter.lua b/pkgs/simple/cgit-about-filter/cgit-about-filter.lua
new file mode 100644
index 0000000..1b37643
--- /dev/null
+++ b/pkgs/simple/cgit-about-filter/cgit-about-filter.lua
@@ -0,0 +1,93 @@
+local function resolve(base, relative)
+    if relative:sub(1, 1) == "/" then
+        return relative
+    end
+
+    local combined = base .. "/" .. relative
+
+    local segments = {}
+    for segment in combined:gmatch("[^/]+") do
+        if segment == ".." then
+            if #segments > 0 and segments[#segments] ~= ".." then
+                table.remove(segments)
+            else
+                table.insert(segments, "..")
+            end
+        elseif segment ~= "." and segment ~= "" then
+            table.insert(segments, segment)
+        end
+    end
+
+    local prefix = (base:sub(1, 1) == "/" or relative:sub(1, 1) == "/") and "/" or ""
+    return prefix .. table.concat(segments, "/")
+end
+
+local buffer = ""
+local should_render = true
+local current_dir = "" -- Stores the directory prefix of the file being processed
+local current_file = ""
+
+function filter_open(...)
+    local args = {...}
+    current_file = args[1] or ""
+
+    if current_file == "" then
+        current_file = "README.md"
+    end
+
+    -- Strict route enforcement: Allow README.md OR any file starting with docs/ and ending in .md
+    if current_file == "README.md" or (current_file:sub(1, 5) == "docs/" and current_file:sub(-3) == ".md") then
+        should_render = true
+
+        -- Extract directory context (e.g., "docs/ops.md" -> "docs/")
+        -- If it's the root README.md, current_dir stays an empty string ""
+        if current_file ~= "README.md" then
+            current_dir = current_file:match("(.*/)") or ""
+        else
+            current_dir = ""
+        end
+    else
+        should_render = false
+    end
+
+    buffer = ""
+end
+
+function filter_write(str)
+    if should_render then
+        buffer = buffer .. str
+    end
+end
+
+function filter_close()
+    if not should_render then
+        io.write("<p><em>Error: Access Denied. Only README.md and documentation markdown files are viewable here.</em></p>")
+        return
+    end
+
+    local repo = os.getenv("CGIT_REPO_URL") or ""
+
+    local processed = buffer:gsub("%[([^%]]+)%]%(([^:)]+)%)", function(text, path)
+        -- Ignore protocols (http, https, etc.), absolute paths (/), and anchors (#)
+        if path:sub(1, 1) == "/" or path:sub(1, 1) == "#" or path:match("^%w+:") then
+            return string.format("[%s](%s)", text, path)
+        end
+
+        path = resolve(current_dir, path)
+
+        if path:sub(-3) == ".md" then
+          return string.format("[%s](/%s/about/%s)", text, repo, path)
+        else
+          return string.format("[%s](/%s/tree/%s)", text, repo, path)
+        end
+    end)
+
+    -- Pipe everything into md2html
+    local handle = io.popen("@md2html@ --github", "w")
+    if handle then
+        handle:write(processed)
+        handle:close()
+    else
+        io.write("<p>Error: Could not execute md2html.</p>")
+    end
+end
diff --git a/pkgs/simple/cgit-about-filter/default.nix b/pkgs/simple/cgit-about-filter/default.nix
new file mode 100644
index 0000000..215a44e
--- /dev/null
+++ b/pkgs/simple/cgit-about-filter/default.nix
@@ -0,0 +1,5 @@
+{ lib, md4c, replaceVars }:
+
+replaceVars ./cgit-about-filter.lua {
+  md2html = lib.getExe md4c;
+}