ci(docs-infra): rename 'upload-server' to 'preview-server'

The server no longer has files uploaded to it. Instead it is more
accurate to refer to it as dealing with "previews" of PRs.

aio/aio-builds-setup/dockerbuild/scripts-js/lib/preview-server/build-creator.ts

@@ -0,0 +1,144 @@
+// Imports
+import * as cp from 'child_process';
+import {EventEmitter} from 'events';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as shell from 'shelljs';
+import {HIDDEN_DIR_PREFIX} from '../common/constants';
+import {assertNotMissingOrEmpty, computeShortSha, createLogger} from '../common/utils';
+import {ChangedPrVisibilityEvent, CreatedBuildEvent} from './build-events';
+import {PreviewServerError} from './preview-error';
+
+// Classes
+export class BuildCreator extends EventEmitter {
+
+  private logger = createLogger('BuildCreator');
+
+  // Constructor
+  constructor(protected buildsDir: string) {
+    super();
+    assertNotMissingOrEmpty('buildsDir', buildsDir);
+  }
+
+  // Methods - Public
+  public create(pr: number, sha: string, archivePath: string, isPublic: boolean): Promise<void> {
+    // Use only part of the SHA for more readable URLs.
+    sha = computeShortSha(sha);
+
+    const {newPrDir: prDir} = this.getCandidatePrDirs(pr, isPublic);
+    const shaDir = path.join(prDir, sha);
+    let dirToRemoveOnError: string;
+
+    return Promise.resolve().
+      // If the same PR exists with different visibility, update the visibility first.
+      then(() => this.updatePrVisibility(pr, isPublic)).
+      then(() => Promise.all([this.exists(prDir), this.exists(shaDir)])).
+      then(([prDirExisted, shaDirExisted]) => {
+        if (shaDirExisted) {
+          const publicOrNot = isPublic ? 'public' : 'non-public';
+          throw new PreviewServerError(409, `Request to overwrite existing ${publicOrNot} directory: ${shaDir}`);
+        }
+
+        dirToRemoveOnError = prDirExisted ? shaDir : prDir;
+
+        return Promise.resolve().
+          then(() => shell.mkdir('-p', shaDir)).
+          then(() => this.extractArchive(archivePath, shaDir)).
+          then(() => this.emit(CreatedBuildEvent.type, new CreatedBuildEvent(+pr, sha, isPublic))).
+          then(() => undefined);
+      }).
+      catch(err => {
+        if (dirToRemoveOnError) {
+          shell.rm('-rf', dirToRemoveOnError);
+        }
+
+        if (!(err instanceof PreviewServerError)) {
+          err = new PreviewServerError(500, `Error while creating preview at: ${shaDir}\n${err}`);
+        }
+
+        throw err;
+      });
+  }
+
+  public updatePrVisibility(pr: number, makePublic: boolean): Promise<boolean> {
+    const {oldPrDir: otherVisPrDir, newPrDir: targetVisPrDir} = this.getCandidatePrDirs(pr, makePublic);
+
+    return Promise.
+      all([this.exists(otherVisPrDir), this.exists(targetVisPrDir)]).
+      then(([otherVisPrDirExisted, targetVisPrDirExisted]) => {
+        if (!otherVisPrDirExisted) {
+          // No visibility change: Either the visibility is up-to-date or the PR does not exist.
+          return false;
+        } else if (targetVisPrDirExisted) {
+          // Error: Directories for both visibilities exist.
+          throw new PreviewServerError(409,
+              `Request to move '${otherVisPrDir}' to existing directory '${targetVisPrDir}'.`);
+        }
+
+        // Visibility change: Moving `otherVisPrDir` to `targetVisPrDir`.
+        return Promise.resolve().
+          then(() => shell.mv(otherVisPrDir, targetVisPrDir)).
+          then(() => this.listShasByDate(targetVisPrDir)).
+          then(shas => this.emit(ChangedPrVisibilityEvent.type, new ChangedPrVisibilityEvent(+pr, shas, makePublic))).
+          then(() => true);
+      }).
+      catch(err => {
+        if (!(err instanceof PreviewServerError)) {
+          err = new PreviewServerError(500, `Error while making PR ${pr} ${makePublic ? 'public' : 'hidden'}.\n${err}`);
+        }
+
+        throw err;
+      });
+  }
+
+  // Methods - Protected
+  protected exists(fileOrDir: string): Promise<boolean> {
+    return new Promise(resolve => fs.access(fileOrDir, err => resolve(!err)));
+  }
+
+  protected extractArchive(inputFile: string, outputDir: string): Promise<void> {
+    return new Promise<void>((resolve, reject) => {
+      const cmd = `tar --extract --gzip --directory "${outputDir}" --file "${inputFile}"`;
+
+      cp.exec(cmd, (err, _stdout, stderr) => {
+        if (err) {
+          return reject(err);
+        }
+
+        if (stderr) {
+          this.logger.warn(stderr);
+        }
+
+        try {
+          shell.chmod('-R', 'a-w', outputDir);
+          shell.rm('-f', inputFile);
+          resolve();
+        } catch (err) {
+          reject(err);
+        }
+      });
+    });
+  }
+
+  protected getCandidatePrDirs(pr: number, isPublic: boolean): {oldPrDir: string, newPrDir: string} {
+    const hiddenPrDir = path.join(this.buildsDir, HIDDEN_DIR_PREFIX + pr);
+    const publicPrDir = path.join(this.buildsDir, `${pr}`);
+
+    const oldPrDir = isPublic ? hiddenPrDir : publicPrDir;
+    const newPrDir = isPublic ? publicPrDir : hiddenPrDir;
+
+    return {oldPrDir, newPrDir};
+  }
+
+  protected listShasByDate(inputDir: string): Promise<string[]> {
+    return Promise.resolve().
+      then(() => shell.ls('-l', inputDir) as any as Promise<(fs.Stats & {name: string})[]>).
+      // Keep directories only.
+      // (Also, convert to standard Array - ShellJS provides custom `sort()` method for sorting file contents.)
+      then(items => items.filter(item => item.isDirectory())).
+      // Sort by modification date.
+      then(items => items.sort((a, b) => a.mtime.getTime() - b.mtime.getTime())).
+      // Return directory names.
+      then(items => items.map(item => item.name));
+  }
+}