Update README.md

[rbdr/blog] / lib / blog.js

import { access, cp, readdir, readFile, writeFile } from 'fs/promises';
import { exec } from 'child_process';
import { basename, join } from 'path';
import ParseGemini from 'gemini-to-html/parse.js';
import RenderGemini from 'gemini-to-html/render.js';
import { debuglog, promisify } from 'util';
import { ensureDirectoryExists, rmIfExists } from './utils.js';
import { kFileNotFoundError } from './constants.js';

// Generators for the Blog

import StaticGenerator from './generators/static.js';
import HTMLGenerator from './generators/html.js';
import RSSGenerator from './generators/rss.js';
import TXTGenerator from './generators/txt.js';

// Archiving Methods

import GemlogArchiver from './archivers/gemlog.js';

// Remote Handler

import Remote from './remote.js';

const internals = {

  // Promisified functions
  exec: promisify(exec),

  debuglog: debuglog('blog'),

  // constants

  kGeminiRe: /\.gmi$/i,
  kMetadataFilename: 'metadata.json',

  // Strings

  strings: {
    geminiNotFound: 'Gemini file was not found in blog directory. Please update.'
  }
};

/**
 * The Blog class is the blog generator, it's in charge of adding and
 * updating posts, and handling the publishing.
 *
 * @class Blog
 * @param {Blog.tConfiguration} config the initialization options to
 * extend the instance
 */
export default class Blog {

  constructor(config) {

    Object.assign(this, config);
  }

  /**
   * Shifts the blog posts, adds the passed file to slot 0, and
   * generates files.
   *
   * @function add
   * @memberof Blog
   * @param {string} postLocation the path to the blog post file
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async add(postLocation) {

    await ensureDirectoryExists(this.postsDirectory);
    try {
      await this.syncDown();
    }
    catch {}

    await this._shift();
    const firstDirectory = join(this.postsDirectory, '0');
    await rmIfExists(firstDirectory);
    await ensureDirectoryExists(firstDirectory);
    await this._update(postLocation);
  }

  /**
   * Update slot 0 with the passed gmi file, and generates files.
   *
   * @function update
   * @memberof Blog
   * @param {string} postLocation the path to the blog post file
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async update(postLocation) {

    try {
      await this.syncDown();
    }
    catch {}

    await this._update(postLocation);
  }

  /**
   * Publishes the files to a static host.
   *
   * @function publish
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async publish(host) {

    internals.debuglog(`Publishing to ${host}`);
    try {
      await internals.exec('which rsync');
    }
    catch (err) {
      console.error('Please install and configure rsync to publish.');
    }

    try {
      internals.debuglog(`Copying ephemeral blog from ${this.blogOutputDirectory}`);
      await internals.exec(`rsync -r ${this.blogOutputDirectory}/ ${host}`);
    }
    catch (err) {
      console.error('Failed to publish');
      console.error(err.stderr);
    }

    internals.debuglog('Finished publishing');
  }

  /**
   * Publishes the archive to a host using rsync. Currently assumes
   * gemlog archive.
   *
   * @function publishArchive
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async publishArchive(host) {

    internals.debuglog(`Publishing archive to ${host}`);
    try {
      await internals.exec('which rsync');
    }
    catch (err) {
      console.error('Please install rsync to publish the archive.');
    }

    try {
      internals.debuglog(`Copying archive from ${this.archiveOutputDirectory}`);
      await internals.exec(`rsync -r ${this.archiveOutputDirectory}/ ${host}`);
    }
    catch (err) {
      console.error('Failed to publish archive');
      console.error(err.stderr);
    }

    internals.debuglog('Finished publishing');
  }

  /**
   * Adds a remote
   *
   * @function addRemote
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async addRemote(remote) {

    await ensureDirectoryExists(this.configDirectory);
    await Remote.add(this.remoteConfig, remote);
  }

  /**
   * Removes a remote
   *
   * @function removeRemote
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async removeRemote() {

    await Remote.remove(this.remoteConfig);
  }


  /**
   * Pulls the posts and archive from the remote
   *
   * @function syncDown
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async syncDown() {

    internals.debuglog('Pulling remote state');
    await ensureDirectoryExists(this.dataDirectory);
    await Remote.syncDown(this.remoteConfig, this.dataDirectory);
    internals.debuglog('Pulled remote state');
  }

  /**
   * Pushes the posts and archive to the remote
   *
   * @function syncUp
   * @memberof Blog
   * @return {Promise<undefined>} empty promise, returns no value
   * @instance
   */
  async syncUp() {

    internals.debuglog('Pushing remote state');
    await ensureDirectoryExists(this.dataDirectory);
    await Remote.syncUp(this.remoteConfig, this.dataDirectory);
    internals.debuglog('Pushed remote state');
  }

  // Adds the passed path to slot 0, and generates files.

  async _update(postLocation) {

    const metadata = await this._getMetadata();
    await ensureDirectoryExists(this.postsDirectory);
    await this._copyPost(postLocation);
    await this._writeMetadata(metadata);

    await this._archive(postLocation);

    await this.generate();
    try {
      await this.syncUp();
    }
    catch {}
  }


  // Parses Gemini for each page, copies assets and generates index.

  async generate() {

    internals.debuglog('Generating output');

    const posts = await this._readPosts();

    // Start from a clean slate.
    await rmIfExists(this.blogOutputDirectory);
    await ensureDirectoryExists(this.blogOutputDirectory);

    // Run each generator
    await StaticGenerator(this.staticDirectory, this.blogOutputDirectory, posts);
    await HTMLGenerator(await this._templateDirectoryFor('index.html'), this.blogOutputDirectory, posts);
    await RSSGenerator(await this._templateDirectoryFor('feed.xml'), this.blogOutputDirectory, posts);
    await TXTGenerator(await this._templateDirectoryFor('index.txt'), this.blogOutputDirectory, posts);

    // Start from a clean slate.
    await rmIfExists(this.archiveOutputDirectory);
    await ensureDirectoryExists(this.archiveOutputDirectory);
    await ensureDirectoryExists(this.archiveDirectory);

    // Run each archiver
    await GemlogArchiver(await this._templateDirectoryFor('index.gmi'), this.archiveDirectory, this.archiveOutputDirectory);
    // TODO: GopherArchiver
  }

  // Reads the posts into an array

  async _readPosts() {

    internals.debuglog('Reading posts');
    const posts = [];

    for (let i = 0; i < this.maxPosts; ++i) {
      try {
        posts.push(await this._readPost(i));
      }
      catch (error) {
        if (error.code === kFileNotFoundError) {
          internals.debuglog(`Skipping ${i}`);
          continue;
        }

        throw error;
      }
    }

    return posts;
  }

  // Reads an individual post

  async _readPost(index = 0) {

    const postSourcePath = join(this.postsDirectory, `${index}`);

    internals.debuglog(`Reading ${postSourcePath}`);

    await access(postSourcePath);

    const metadata = await this._getMetadata(index);

    const postContentPath = await this._findBlogContent(postSourcePath);
    internals.debuglog(`Reading ${postContentPath}`);
    const postContent = await readFile(postContentPath, { encoding: 'utf8' });

    internals.debuglog('Parsing Gemini');
    return {
      ...metadata,
      location: postSourcePath,
      index,
      html: RenderGemini(ParseGemini(postContent)),
      raw: postContent
    };
  }

  // Shift the posts, delete any remainder.

  async _shift() {


    for (let i = this.maxPosts - 1; i >= 1; --i) {
      const targetPath = join(this.postsDirectory, `${i}`);
      const sourcePath = join(this.postsDirectory, `${i - 1}`);

      try {
        internals.debuglog(`Archiving ${targetPath}`);
        await rmIfExists(targetPath);
        await access(sourcePath); // check the source path

        internals.debuglog(`Shifting blog post ${sourcePath} to ${targetPath}`);
        await cp(sourcePath, targetPath, { recursive: true });
      }
      catch (error) {
        if (error.code === kFileNotFoundError) {
          internals.debuglog(`Skipping ${sourcePath}: Does not exist.`);
          continue;
        }

        throw error;
      }
    }
  }

  // Moves older posts to the archive

  async _archive() {

    internals.debuglog('Archiving post');
    const post = await this._readPost(0);
    await ensureDirectoryExists(this.archiveDirectory);

    const targetPath = join(this.archiveDirectory, post.id);

    internals.debuglog(`Removing ${targetPath}`);
    await rmIfExists(targetPath);
    internals.debuglog(`Adding ${post.location} to ${targetPath}`);
    await ensureDirectoryExists(targetPath);
    await cp(post.location, targetPath, { recursive: true });
    internals.debuglog(`Added ${post.location} to ${targetPath}`);
  }

  // Attempts to read existing metadata. Otherwise generates new set.

  async _getMetadata(index = 0) {

    const metadataTarget = join(this.postsDirectory, String(index), internals.kMetadataFilename);

    try {
      internals.debuglog(`Looking for metadata at ${metadataTarget}`);
      return JSON.parse(await readFile(metadataTarget, { encoding: 'utf8' }));
    }
    catch (e) {
      internals.debuglog(`Metadata not found or unreadable. Generating new set.`);
      const createdOn = Date.now();
      const metadata = {
        id: String(createdOn),
        createdOn
      };

      return metadata;
    }
  }

  // Writes metadata. Assumes post 0 since it only gets written
  // on create

  async _writeMetadata(metadata) {

    const metadataTarget = join(this.postsDirectory, '0', internals.kMetadataFilename);
    internals.debuglog(`Writing ${metadataTarget}`);
    await writeFile(metadataTarget, JSON.stringify(metadata, null, 2));
  }

  // Copies a post file to the latest slot.

  async _copyPost(postLocation) {

    internals.debuglog(`Copying ${postLocation}`);
    const targetPath = join(this.postsDirectory, '0');
    const postName = basename(postLocation);
    const targetPost = join(targetPath, postName);

    await rmIfExists(targetPath);
    await ensureDirectoryExists(targetPath);
    await cp(postLocation, targetPost, { recursive: true });
    internals.debuglog(`Added ${postLocation} to ${targetPath}`);
  }

  // Looks for a `.gmi` file in the blog directory, and returns the path

  async _findBlogContent(directory) {

    const entries = await readdir(directory);

    const geminiEntries = entries
      .filter((entry) => internals.kGeminiRe.test(entry))
      .map((entry) => join(directory, entry));

    if (geminiEntries.length > 0) {
      internals.debuglog(`Found gemini file: ${geminiEntries[0]}`);
      return geminiEntries[0];
    }

    throw new Error(internals.strings.geminiNotFound);
  }

  // Gets the template directory for a given template.
  async _templateDirectoryFor(template) {

    try {
      await access(join(this.templatesDirectory, template));
      return this.templatesDirectory;
    }
    catch (error) {
      if (error.code === kFileNotFoundError) {
        internals.debuglog(`No custom template for ${template}`);
        return this.defaultTemplatesDirectory;
      }

      throw error;
    }
  }
}