@sap/cds-dk/lib/util/write.js

Command line client and development toolkit for the SAP Cloud Application Programming Model

// eslint-disable-next-line no-unused-vars
const USAGE = ()=>{

	// with a fully specified target file
	write ({foo:'bar'}) .to ('some/folder/foo.json')

	// with separately specified destination folder
	write ({foo:'bar'}) .to ('some/folder', 'foo.json')

	// with a separately specified destination folder and suffix
	write ({foo:'bar'}) .to ('some/folder', 'foo', '.json')

	// using a named parameter object instead
	write ({foo:'bar'}) .to ({ folder: 'some/folder', file:'foo', suffix:'.json' })

	// with an optional callback invoked per written file
	write ({foo:'bar'}) .to ('...', console.log)

	// with a statically constructed writer function applied asynchronously
	Promise.resolve (function*(){ yield* [[1,{file:'foo.json'}],[2,{file:'bar.json'}]] })
	.then (write.to ('some/folder'))
}

const cds = require('../cds')
const { mkdirp, path, fs:{promises:fs} } = cds.utils, { join, dirname } = path


const write = module.exports = Object.assign (
	/**
	 * Fluent API to write (output) .to (dest...)
	 * @param content - the content to be written; will be JSON.stringified if it's not a string
	 */
	(content) => ({ // NOSONAR
		/**
		 * @param {string} [folder] - optional separately specified destination folder
		 * @param {string} file - the filename to write to
		 * @param {string} [suffix] - optional suffix to append
		 * @param {(string)=>void} [foreach] - optional callback to invoke per written file
		 */
		to: (folder, file, suffix, foreach) => _write (content,
			typeof folder === 'object' ? folder :
			typeof folder === 'function' ? { log:folder } :
			typeof file === 'function' ? { file:folder, foreach:file } :
			typeof suffix === 'function' ? { folder, file, foreach:suffix } :
			{ folder, file, suffix, foreach }
		)
	}), {

	/**
	 * Returns a writer function to be used subsequently. Handy when combined with output
	 * coming from prior async tasks.
	 */
	to: (...dest) => (content) => write (content) .to (...dest)
})

/**
 * @returns {Promise<[string]>} a Promise resolving to an array of all written filenames
 */
function _write (content, /*to:*/ dest, _many) { // NOSONAR

	if (content instanceof Promise)  return content.then (c => _write(c, dest, _many))

	// if the obtained output is a generator --> write each...
	if (content && content.next && content[Symbol.iterator]) {
		let all=[]; for (let [x,d] of content) {
			if (typeof d === 'string')  d = { file:d }
			all.push (_write (x, Object.assign(dest,d), d && '_many'))
		}
		return Promise.all(all)
	}

	// if output is a single generator entry --> write it...
	// if (Array.isArray(content) && content.length === 2 && content[0] && content[1]) {
	// 	return _write (content[0], Object.assign(content[1], dest))
	// }

	// construct the filename
	let file = dest.name || dest.file || ''
	if (dest.folder)  file = join (dest.folder, file) //.replace (/[:/\\]/g, '_') )
	if (dest.lang)  file += '_'+ dest.lang
	file += file.endsWith(dest.suffix) ? '' : dest.suffix || ( /\.\w+$/.test(file) ? '' : '.json' )

	// if dest.log is specified just log to it
	if (dest.log) { //
		if (_many)  dest.log (`----- ${file} -----`)
		dest.log (content)
		return Promise.resolve (file)
	}

	file = path.resolve (cds.root,file)
	// write to the target file, creating parent folders if necessary
	return mkdirp (dirname(file))
	.then (()=> fs.writeFile (file, typeof content === 'string' ? content : JSON.stringify (content, null, 2)))
	.then (()=> dest.foreach && dest.foreach(file))
	.then (()=> file)

}

/* eslint no-console:off */