-- http/files.wo — serving a file from disk, the framework's answer to
-- "let people download something". Lifted out of the shop template
-- 2026-08-25, which had carried its own copy and said in a comment that
-- this belonged here.
--
-- Mount it on a wildcard route and it answers that subtree:
--
--   app.get("/assets/*path", StaticFiles { dir: "assets",  max_bytes: 2097152 })
--   app.get("/dl/*path",     StaticFiles { dir: "dist",    max_bytes: 8388608 })
--
-- Safety is two rules, both refusals rather than repairs: a path holding
-- `..` is a 404 and never reaches the filesystem, and a file bigger than
-- `max_bytes` is truncated by `fs.read_all` — so `max_bytes` is a real
-- ceiling you must set above the largest file you intend to serve, not a
-- hint. Text is binary-safe in this language, so archives and images
-- travel unchanged.
use fs

pub class StaticFiles {
  dir:       Text
  max_bytes: Int

  fn handle(req: Req) -> Resp {
    let rel = req.params["path"];
    if rel == nil {
      return not_found();
    }
    -- Traversal: refuse, never normalise. A rewritten path is a second
    -- chance to get it wrong.
    if index_of("${rel}", "..") != -1 {
      return not_found();
    }
    let body = try fs.read_all("${self.dir}/${rel}", self.max_bytes) catch (e) nil;
    if body == nil {
      return not_found();
    }
    let h: map<Text, Text> = {};
    h["content-type"] = content_type("${rel}");
    if is_download("${rel}") {
      h["content-disposition"] = "attachment";
    }
    return Resp { status: 200, headers: h, body: "${body}" };
  }
}

-- Extension to content type. Unknown extensions are octet-stream: a
-- wrong guess is worse than no guess.
pub fn content_type(name: Text) -> Text {
  if ends_with(name, ".html") { return "text/html; charset=utf-8"; }
  if ends_with(name, ".css") { return "text/css; charset=utf-8"; }
  if ends_with(name, ".js") { return "text/javascript"; }
  if ends_with(name, ".json") { return "application/json"; }
  if ends_with(name, ".svg") { return "image/svg+xml"; }
  if ends_with(name, ".png") { return "image/png"; }
  if ends_with(name, ".webp") { return "image/webp"; }
  if ends_with(name, ".ico") { return "image/x-icon"; }
  if ends_with(name, ".woff2") { return "font/woff2"; }
  if ends_with(name, ".txt") { return "text/plain; charset=utf-8"; }
  if ends_with(name, ".sha256") { return "text/plain; charset=utf-8"; }
  if ends_with(name, ".tar.gz") { return "application/gzip"; }
  if ends_with(name, ".tgz") { return "application/gzip"; }
  if ends_with(name, ".zip") { return "application/zip"; }
  return "application/octet-stream";
}

-- Archives are offered as a save, not rendered into a tab.
fn is_download(name: Text) -> Bool {
  if ends_with(name, ".tar.gz") { return true; }
  if ends_with(name, ".tgz") { return true; }
  if ends_with(name, ".zip") { return true; }
  return false;
}