-- site — writeonce.de: the language tutorial, served BY the language.
-- Full stack in one binary: writeonce-framework ([deps]) for HTTP/routing/
-- auth, wo-html ([deps]) for server-rendered pages with Tailwind-style
-- utilities, @table + WAL for the chapters themselves. The site is its own
-- final chapter: /ch/serving shows this file's shape.
--
--   SITE_TOKEN=... WO_DATA=./data ./site 8080
--
-- Behind nginx/caddy for writeonce.de: the proxy terminates TLS and
-- forwards to 127.0.0.1:8080 (the framework speaks HTTP/1.1 keep-alive).
use env
use framework
use framework/http
use framework/router
use html

-- Every chapter is a row: slug is the URL, ord orders the nav, body is a
-- server-rendered HTML fragment. Edits (the admin route) persist through
-- the WAL under WO_DATA and replay on restart.
@table(name: "chapters", index: [slug])
class Chapter {
  slug:  Text @unique
  ord:   Int
  title: Text
  body:  Text
}

fn seed_if_empty() {
  let n = 0;
  for c in from x in Chapter take 1 select x {
    n = n + 1;
  }
  if n == 0 {
    seed_chapters();
  }
}

-- ---- rendering ---------------------------------------------------------

fn ok_html(body: Text) -> Resp {
  let h: map<Text, Text> = {};
  h["content-type"] = "text/html; charset=utf-8";
  return Resp { status: 200, headers: h, body: body };
}

fn site_header() -> Text {
  let brand = link("/", "text-xl font-bold text-gray-900 no-underline", "writeonce.de");
  let tag = el("span", "text-sm text-gray-500", "one language, one runtime, one database, one binary");
  return el("div", "flex items-center justify-between mb-8", brand .. tag);
}

fn shell(title: Text, inner: Text) -> Text {
  let body = el("div", "mx-auto max-w-3xl px-4 py-8", site_header() .. inner);
  return page(title, body);
}

fn chapter_nav(current: Int) -> Text {
  let items = "";
  for c in from x in Chapter order by x.ord select x {
    let label = "${c.ord}. ${esc(c.title)}";
    if c.ord == current {
      items = items .. el("li", "mb-2 font-bold text-gray-900", label);
    } else {
      items = items .. el("li", "mb-2", link("/ch/${c.slug}", "", label));
    }
  }
  return el("ul", "list-disc pl-6", items);
}

-- ---- handlers ----------------------------------------------------------

class Home {
  pad: Int
  fn handle(req: Req) -> Resp {
    let hero = el("h1", "text-3xl font-bold mb-4", "Learn writeonce");
    let intro = el("p", "leading-relaxed mb-4", "A language where the runtime, the database and the web server are one thing. " .. "This site is written in it — every page you read here is a " .. "<code>Resp</code> built by <code>.wo</code> code, stored in the language's own " .. "tables, served by its own framework. Work through the chapters in order:");
    let body = el("div", "bg-white rounded-lg border shadow-sm p-6", hero .. intro .. chapter_nav(0));
    return ok_html(shell("writeonce — learn the language", body));
  }
}

class ShowChapter {
  pad: Int
  fn handle(req: Req) -> Resp {
    let slug = req.params["slug"];
    if slug == nil { return not_found(); }
    let hits = from c in Chapter where c.slug == slug take 1 select c;
    if len(hits) == 0 {
      let msg = el("h1", "text-2xl font-bold mb-4", "No such chapter");
      let back = el("p", "", link("/", "", "Back to the chapters"));
      let h: map<Text, Text> = {};
      h["content-type"] = "text/html; charset=utf-8";
      let nf = shell("writeonce — not found", msg .. back);
      return Resp { status: 404, headers: h, body: nf };
    }
    let c = hits[0];
    let head = el("h1", "text-3xl font-bold mb-4", "${c.ord}. ${esc(c.title)}");
    let art = el("div", "bg-white rounded-lg border shadow-sm p-6", head .. c.body);
    let nav = el("div", "mt-8", el("h2", "text-lg font-bold mb-2", "Chapters") .. chapter_nav(c.ord));
    return ok_html(shell("writeonce — ${c.title}", art .. nav));
  }
}

-- POST /admin/ch/:slug — title/body update, form-encoded, bearer-gated.
-- Mechanism (bearer_token, constant-time ct_eq) is the framework's;
-- POLICY — which routes, which token — is this app's, right here.
class AdminEdit {
  token: Text
  fn handle(req: Req) -> Resp {
    let got = bearer_token(req);
    if got == nil { return unauthorized(); }
    if ct_eq("${got}", self.token) == false { return unauthorized(); }
    let slug = req.params["slug"];
    if slug == nil { return not_found(); }
    let hits = from c in Chapter where c.slug == slug take 1 select c;
    if len(hits) == 0 { return not_found(); }
    let f = form_values(req);
    if f == nil { return bad_request("body must be form-encoded (title, body)"); }
    let title = f["title"];
    let body = f["body"];
    if title == nil and body == nil { return bad_request("nothing to update"); }
    if title != nil {
      let t = trim("${title}");
      if t == "" { return bad_request("title must not be empty"); }
      hits[0].title = t;
    }
    if body != nil {
      hits[0].body = "${body}";
    }
    return redirect("/ch/${slug}");
  }
}

class Health {
  pad: Int
  fn handle(req: Req) -> Resp {
    return ok_text("ok");
  }
}

fn main(args: multi Text) -> Int {
  if len(args) < 1 {
    print_err("usage: site <port>   (SITE_TOKEN gates /admin; WO_DATA makes chapters durable)");
    return 2;
  }
  let port = parse_int(args[0]);
  if port == nil {
    print_err("site: <port> must be a number");
    return 2;
  }
  let token = env.get("SITE_TOKEN");
  if token == nil {
    print_err("site: SITE_TOKEN is required (the admin route's bearer token)");
    return 2;
  }

  seed_if_empty();

  let app = App { middleware: [], routes: [] };
  app.use_mw(Mw { m: Logging { pad: 0 } });
  app.get("/",             Home { pad: 0 });
  app.get("/health",       Health { pad: 0 });
  app.get("/ch/:slug",     ShowChapter { pad: 0 });
  app.post("/admin/ch/:slug", AdminEdit { token: "${token}" });
  return app.serve("127.0.0.1", port);
}