filesystem.js

class File {
	constructor(name, size) {
		this.name = name;
		this._size = size;
	}

	size() {
		return this._size;
	}
}

class Dir {
	constructor(name, parentDir) {
		this.isDir = true;
		this.parentDir = parentDir;
		this.name = name;
		this.contents = [];
	}

	size(ignore) {
		if (ignore === this) {
			return 0;
		}

		return this.contents.map((v) => v.size(ignore)).reduce((a, b) => a + b, 0);
	}
}

class Filesystem {
	constructor(instructions) {
		this.rootDir = new Dir('/', null);
		this.build(instructions);
	}

	size(ignore) {
		return this.rootDir.size(ignore);
	}

	build(instructions) {
		let currentDir = this.rootDir;
		for (let line of instructions) {
			if (line.startsWith('$ cd')) {
				const [, dir] = /\$ cd (.+)$/.exec(line);
				if (dir === '/') {
					currentDir = this.rootDir;
				} else if (dir === '..') {
					currentDir = currentDir.parentDir;
				} else {
					currentDir = currentDir.contents.find((v) => v.isDir && v.name === dir);
				}
			} else if (line.startsWith('$ ls')) {
				continue;
			} else {
				// In a `ls` output
				if (line.startsWith('dir ')) {
					const [, dirName] = /dir (.+)$/.exec(line);
					const newDir = new Dir(dirName, currentDir);
					currentDir.contents.push(newDir);
				} else {
					// file
					let [, size, fileName] = /(\d+) (.+)$/.exec(line);
					size = parseInt(size, 10);

					const newFile = new File(fileName, size);
					currentDir.contents.push(newFile);
				}
			}
		}
	}

	static *walk(dir) {
		for (let c of dir.contents) {
			yield c;
			if (c.isDir) {
				yield* Filesystem.walk(c);
			}
		}
	}

	*[Symbol.iterator]() {
		yield* Filesystem.walk(this.rootDir);
	}
}

module.exports = {
	File,
	Dir,
	Filesystem,
};