(function () {
  if (!window.MDHubCache) {
    return;
  }

  function normalizeDocPath(path) {
    if (!path) return "";
    return path.replace(/^\/+/, "");
  }

  async function postDocument(path, content, baseHash) {
    const response = await fetch("/api/documents/" + normalizeDocPath(path), {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ content: content, baseHash: baseHash || "" }),
    });

    const payload = await response.json().catch(function () {
      return {};
    });

    if (!response.ok) {
      if (response.status === 409) {
        const conflict = new Error("document conflict");
        conflict.name = "DocumentConflictError";
        conflict.details = payload;
        throw conflict;
      }
      throw new Error("save failed");
    }

    return payload;
  }

  async function saveDocument(path, content, baseHash) {
    const normalizedPath = window.MDHubCache.normalizePath("/docs/" + normalizeDocPath(path));

    try {
      const result = await postDocument(path, content, baseHash);
      await window.MDHubCache.deletePendingEdit(normalizedPath);
      return {
        status: "saved",
        result: result,
      };
    } catch (error) {
      if (error.name === "DocumentConflictError") {
        await window.MDHubCache.putPendingEdit(normalizedPath, content, baseHash);
        await window.MDHubCache.markPendingEditConflict(normalizedPath, error.details);
        return {
          status: "conflict",
          conflict: error.details,
        };
      }
      await window.MDHubCache.putPendingEdit(normalizedPath, content, baseHash);
      return {
        status: "queued",
      };
    }
  }

  async function syncPending() {
    if (!navigator.onLine) {
      return;
    }

    const pending = await window.MDHubCache.getPendingEdits();
    pending.sort(function (a, b) {
      return (a.updatedAt || 0) - (b.updatedAt || 0);
    });

    for (const edit of pending) {
      try {
        await postDocument(edit.path.replace(/^\/docs\//, ""), edit.content, edit.baseHash);
        await window.MDHubCache.deletePendingEdit(edit.path);
      } catch (error) {
        if (error.name === "DocumentConflictError") {
          await window.MDHubCache.markPendingEditConflict(edit.path, error.details);
        }
        break;
      }
    }
  }

  window.addEventListener("online", function () {
    syncPending().catch(function () {});
  });

  syncPending().catch(function () {});

  window.MDHubSync = {
    saveDocument: saveDocument,
    syncPending: syncPending,
  };
})();