class Utils {
  static escape(text) {
    // https://codereview.stackexchange.com/a/126722
    var table = {
      '<': 'lt',
      '>': 'gt',
      '"': 'quot',
      '\'': 'apos',
      '&': 'amp',
      '\r': '#10',
      '\n': '#13'
    };
    
    return text.toString().replace(/[<>"'\r\n&]/g, (chr) => {
      return '&' + table[chr] + ';';
    });
  };

  static HTMLToElement(HTMLString) {
    let templateElement = document.createElement('template');
    templateElement.innerHTML = HTMLString.trim();
    return templateElement.content.firstChild;
  }

  static generateElementId(prefix='', suffix='') {
    for (let i = 0; true; i++) {
      if (document.querySelector(`#${prefix}${i}${suffix}`) !== null) {continue;}
      return `${prefix}${i}${suffix}`;
    }
  }

  static isObject(object) {
    return object !== null && typeof object === 'object' && !Array.isArray(object);
  }

  static mergeObjectsDeep(...objects) {
    let mergedObject = {};
    if (objects.length === 0) {
      return mergedObject;
    }
    if (!Utils.isObject(objects[0])) {throw 'Cannot merge non-object';}
    if (objects.length === 1) {
      return Utils.mergeObjectsDeep(mergedObject, objects[0]);
    }
    if (!Utils.isObject(objects[1])) {throw 'Cannot merge non-object';}
    for (let key in objects[0]) {
      if (objects[0].hasOwnProperty(key)) {
        if (objects[1].hasOwnProperty(key)) {
          if (Utils.isObject(objects[0][key]) && Utils.isObject(objects[1][key])) {
            mergedObject[key] = Utils.mergeObjectsDeep(objects[0][key], objects[1][key]);
          } else {
            mergedObject[key] = objects[1][key];
          }
        } else {
          mergedObject[key] = objects[0][key];
        }
      }
    }
    for (let key in objects[1]) {
      if (objects[1].hasOwnProperty(key)) {
        if (!objects[0].hasOwnProperty(key)) {
          mergedObject[key] = objects[1][key];
        }
      }
    }
    if (objects.length === 2) {
      return mergedObject;
    }
    return Utils.mergeObjectsDeep(mergedObject, ...objects.slice(2));
  }

  static deleteCorpusRequest(userId, corpusId) {
    return new Promise((resolve, reject) => {
      let corpus;
      try {
        corpus = app.data.users[userId].corpora[corpusId];
      } catch (error) {
        corpus = {};
      }

      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm Corpus deletion</h4>
              <p>Do you really want to delete the Corpus <b>${corpus?.title}</b>? All files will be permanently deleted!</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Delete</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );
      
      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        let corpusTitle = corpus?.title;
        fetch(`/corpora/${corpusId}`, {method: 'DELETE', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              app.flash(`Corpus "${corpusTitle}" marked for deletion`, 'corpus');
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }

  static deleteCorpusFileRequest(userId, corpusId, corpusFileId) {
    return new Promise((resolve, reject) => {
      let corpusFile;
      try {
        corpusFile = app.data.users[userId].corpora[corpusId].files[corpusFileId];
      } catch (error) {
        corpusFile = {};
      }

      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm Corpus File deletion</h4>
              <p>Do you really want to delete the Corpus File <b>${corpusFile?.title}</b>? All files will be permanently deleted!</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Delete</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );

      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        let corpusFileTitle = corpusFile?.title;
        fetch(`/corpora/${corpusId}/files/${corpusFileId}`, {method: 'DELETE', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              app.flash(`Corpus File "${corpusFileTitle}" deleted`, 'corpus');
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }

  static deleteProfileAvatarRequest(userId) {
    return new Promise((resolve, reject) => {
      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm Avatar deletion</h4>
              <p>Do you really want to delete your Avatar?</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Delete</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );

      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        fetch(`/users/${userId}/avatar`, {method: 'DELETE', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              app.flash(`Avatar marked for deletion`);
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }

  static deleteJobRequest(userId, jobId) {
    return new Promise((resolve, reject) => {
      let job;
      try {
        job = app.data.users[userId].jobs[jobId];
      } catch (error) {
        job = {};
      }

      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm Job deletion</h4>
              <p>Do you really want to delete the Job <b>${job?.title}</b>? All files will be permanently deleted!</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Delete</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );

      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        let jobTitle = job?.title;
        fetch(`/jobs/${jobId}`, {method: 'DELETE', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              app.flash(`Job "${jobTitle}" marked for deletion`, 'job');
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }

  static getJobLogRequest(userId, jobId) {
    return new Promise((resolve, reject) => {
      fetch(`/jobs/${jobId}/log`, {method: 'GET', headers: {Accept: 'application/json, text/plain'}})
        .then(
          (response) => {
            if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
            if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
            return response.text();
          },
          (response) => {
            app.flash('Something went wrong', 'error');
            reject(response);
          }
        )
        .then(
          (text) => {
            let modalElement = Utils.HTMLToElement(
              `
                <div class="modal">
                  <div class="modal-content">
                    <h4>Job logs</h4>
                    <pre><code>${text}</code></pre>
                  </div>
                  <div class="modal-footer">
                    <a class="btn modal-close waves-effect waves-light">Close</a>
                  </div>
                </div>
              `
            );
            document.querySelector('#modals').appendChild(modalElement);
            let modal = M.Modal.init(
              modalElement,
              {
                onCloseEnd: () => {
                  modal.destroy();
                  modalElement.remove();
                }
              }
            );
            modal.open();
            resolve(text);
          }
        );
    });
  }

  static restartJobRequest(userId, jobId) {
    return new Promise((resolve, reject) => {
      let job;
      try {
        job = app.data.users[userId].jobs[jobId];
      } catch (error) {
        job = {};
      }

      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm Job restart</h4>
              <p>Do you really want to restart the Job <b>${job?.title}</b>? All Job Results will be permanently deleted.</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Restart</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );

      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        let jobTitle = job?.title;
        fetch(`/jobs/${jobId}/restart`, {method: 'POST', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              if (response.status === 409) {app.flash('Conflict', 'error'); reject(response);}
              app.flash(`Job "${jobTitle}" restarted.`, 'job');
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }

  static deleteUserRequest(userId) {
    return new Promise((resolve, reject) => {
      let user;
      try {
        user = app.data.users[userId];
      } catch (error) {
        user = {};
      }

      let modalElement = Utils.HTMLToElement(
        `
          <div class="modal">
            <div class="modal-content">
              <h4>Confirm User deletion</h4>
              <p>Do you really want to delete the User <b>${user?.username}</b>? All files will be permanently deleted!</p>
            </div>
            <div class="modal-footer">
              <a class="action-button btn modal-close waves-effect waves-light" data-action="cancel">Cancel</a>
              <a class="action-button btn modal-close red waves-effect waves-light" data-action="confirm">Delete</a>
            </div>
          </div>
        `
      );
      document.querySelector('#modals').appendChild(modalElement);
      let modal = M.Modal.init(
        modalElement,
        {
          dismissible: false,
          onCloseEnd: () => {
            modal.destroy();
            modalElement.remove();
          }
        }
      );

      let confirmElement = modalElement.querySelector('.action-button[data-action="confirm"]');
      confirmElement.addEventListener('click', (event) => {
        let userName = user?.username;
        fetch(`/users/${userId}`, {method: 'DELETE', headers: {Accept: 'application/json'}})
          .then(
            (response) => {
              if (response.status === 403) {app.flash('Forbidden', 'error'); reject(response);}
              if (response.status === 404) {app.flash('Not Found', 'error'); reject(response);}
              app.flash(`User "${userName}" marked for deletion`);
              resolve(response);
            },
            (response) => {
              app.flash('Something went wrong', 'error');
              reject(response);
            }
          );
      });
      modal.open();
    });
  }
}