const api = (() => {

  async function request(method, url, body = null) {
    const options = { method, credentials: "include" };
    if (body instanceof FormData) {
      options.body = body;
    } else if (body !== null) {
      options.headers = { "Content-Type": "application/json" };
      options.body = JSON.stringify(body);
    }
    const res = await fetch(url, options);
    if (!res.ok) {
      const err = await res.json().catch(() => ({ detail: res.statusText }));
      throw new Error(err.detail || res.statusText);
    }
    return res.status === 204 ? null : res.json();
  }

  return {
    // GET /api/models
    listModels() {
      return request("GET", "/api/models");
    },

    // POST /api/models  (file: File, title: str, description?: str)
    createModel(file, title, description = null) {
      const form = new FormData();
      form.append("file", file);
      form.append("title", title);
      if (description !== null) form.append("description", description);
      return request("POST", "/api/models", form);
    },

    // GET /api/models/active
    getActiveModel() {
      return request("GET", "/api/models/active");
    },

    // GET /api/models/{model_id}
    getModel(modelId) {
      return request("GET", `/api/models/${modelId}`);
    },

    // PATCH /api/models/{model_id}  (active: bool)
    updateModel(modelId, active) {
      return request("PATCH", `/api/models/${modelId}`, { active });
    },

    // DELETE /api/models/{model_id}
    deleteModel(modelId) {
      return request("DELETE", `/api/models/${modelId}`);
    },

    // POST /api/models/{model_id}/predict  (treatment1: str, treatment2: str, thick_hair: bool|null)
    predict(modelId, body) {
      return request("POST", `/api/models/${modelId}/predict`, body);
    },
  };
})();