import { Post } from "./types";

export const parseFilename = (titleToFilename: string): string => {
  if (!titleToFilename) {
    return 'None yet.'
  }

  titleToFilename = titleToFilename.replace(/[^a-zA-Z0-9_]+/gi, '-').toLowerCase();

  while (titleToFilename.endsWith('-')) {
    titleToFilename = titleToFilename.slice(0, -1);
  }

  // Limit filename size
  if (titleToFilename.length > 50) {
    titleToFilename = titleToFilename.substring(0, 50);

    if (titleToFilename.includes('-')) {
      // Re-trim to avoid cutting a word in half.
      titleToFilename = titleToFilename.substring(0, Math.min(titleToFilename.length, titleToFilename.lastIndexOf('-')));
    }
  }

  return titleToFilename;
}

export const downloadFile = (dataObj: any, fileName: string): void => {
  const blob = new Blob([JSON.stringify(dataObj, null, 2)], { type: 'text/plain;charset=utf-8;' });
  const a = document.createElement('a');
  a.setAttribute('download', `${fileName}.json`);
  a.setAttribute('href', window.URL.createObjectURL(blob));
  a.click();
}


// Bad code ahead. Sail with caution!
export const loadFromFile = (file: any): Promise<Post> => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();

    if (!file) {
      reject('No file!');
    }

    reader.onload = (event => {
      const contents: any = (event.target as FileReader).result;

      // Yes, this is extremely hacky... Empty object just to test below. 'Cuz I'm lazy.
      const objCompare: Post = {
        postTitle: "",
        timestamp: "",
        editedTimestamp: "",
        postContent: "",
        filename: "",
        draft: false
      };

      // And yes, I know this is crazy but it works.
      try {
        if (Object.keys(JSON.parse(contents.toString())).toString() === Object.keys(objCompare).toString()) {
          resolve(JSON.parse(contents.toString()));
        } else {
          alert('Invalid file! Are you sure it\'s an Dumblog compatible JSON?');
          reject('Invalid file!');
        }
      } catch (e) {
        alert('Error loading file! Check the console for more info.');
        console.log(e);
        reject('Error loading file!');
      }
    });

    reader.onerror = reject;

    reader.readAsText(file);
  });
}