temp.ts

/* IMPORT */

import * as path from 'path';
import {LIMIT_BASENAME_LENGTH} from '../consts';
import {Disposer} from '../types';
import FS from './fs';

/* TEMP */

//TODO: Maybe publish this as a standalone package

const Temp = {

  store: <Record<string, boolean>> {}, // filePath => purge

  create: ( filePath: string ): string => {

    const randomness = `000000${Math.floor ( Math.random () * 16777215 ).toString ( 16 )}`.slice ( -6 ), // 6 random-enough hex characters
          timestamp = Date.now ().toString ().slice ( -10 ), // 10 precise timestamp digits
          prefix = 'tmp-',
          suffix = `.${prefix}${timestamp}${randomness}`,
          tempPath = `${filePath}${suffix}`;

    return tempPath;

  },

  get: ( filePath: string, creator: ( filePath: string ) => string, purge: boolean = true ): [string, Disposer] => {

    const tempPath = Temp.truncate ( creator ( filePath ) );

    if ( tempPath in Temp.store ) return Temp.get ( filePath, creator, purge ); // Collision found, try again

    Temp.store[tempPath] = purge;

    const disposer = () => delete Temp.store[tempPath];

    return [tempPath, disposer];

  },

  purge: ( filePath: string ): void => {

    if ( !Temp.store[filePath] ) return;

    delete Temp.store[filePath];

    FS.unlinkAttempt ( filePath );

  },

  purgeSync: ( filePath: string ): void => {

    if ( !Temp.store[filePath] ) return;

    delete Temp.store[filePath];

    FS.unlinkSyncAttempt ( filePath );

  },

  purgeSyncAll: (): void => {

    for ( const filePath in Temp.store ) {

      Temp.purgeSync ( filePath );

    }

  },

  truncate: ( filePath: string ): string => { // Truncating paths to avoid getting an "ENAMETOOLONG" error //FIXME: This doesn't really always work, the actual filesystem limits must be detected for this to be implemented correctly

    const basename = path.basename ( filePath );

    if ( basename.length <= LIMIT_BASENAME_LENGTH ) return filePath; //FIXME: Rough and quick attempt at detecting ok lengths

    const truncable = /^(\.?)(.*?)((?:\.[^.]+)?(?:\.tmp-\d{10}[a-f0-9]{6})?)$/.exec ( basename );

    if ( !truncable ) return filePath; //FIXME: No truncable part detected, can't really do much without also changing the parent path, which is unsafe, hoping for the best here

    const truncationLength = basename.length - LIMIT_BASENAME_LENGTH;

    return `${filePath.slice ( 0, - basename.length )}${truncable[1]}${truncable[2].slice ( 0, - truncationLength )}${truncable[3]}`; //FIXME: The truncable part might be shorter than needed here

  }

};

/* INIT */

process.on ( 'exit', Temp.purgeSyncAll ); // Ensuring purgeable temp files are purged on exit

/* EXPORT */

export default Temp;