@csstools/sass-import-resolve/index.js

An algorithm for resolving imports in Sass

'use strict';

Object.defineProperty(exports, "__esModule", {
	value: true
});
exports.default = resolve;

var _fs = require('fs');

var _path = require('path');

/* Resolve the absolute path of a file in Sass
/* ========================================================================== */

function resolve(id, rawopts) {
	var opts = Object.assign({
		cache: {},
		cwd: process.cwd(),
		readFile: false
	}, rawopts);

	// if `id` starts with `/`
	if (starts_with_root(id)) {
		// `cwd` is the filesystem root
		opts.cwd = '';
	}

	// `file` is `cwd/id`
	var file = (0, _path.join)(opts.cwd, id);

	// `base` is the last segment path of `file`
	var base = (0, _path.basename)(file);

	// `dir` is all but the last segment path of `file`
	var dir = (0, _path.dirname)(file);

	var tests = [];

	// if `base` ends with `.sass`, `.scss`, or `.css`
	if (ends_with_sass_extension(base) || ends_with_css_extension(base)) {
		// test whether `file` exists
		tests.push(test_file(file, opts));

		// if `base` does not start with `_`
		if (!starts_with_partial(base)) {
			// test whether `dir/_base` exists
			tests.push(test_file((0, _path.join)(dir, '_' + base), opts));
		}
	} else {
		// otherwise
		tests.push(
		// test whether `dir/base.scss` exists
		test_file((0, _path.join)(dir, base + '.scss'), opts),
		// test whether `dir/base.sass` exists
		test_file((0, _path.join)(dir, base + '.sass'), opts),
		// test whether `dir/base.css` exists
		test_file((0, _path.join)(dir, base + '.css'), opts));

		// if `base` does not start with `_`
		if (!starts_with_partial(base)) {
			tests.push(
			// test whether `dir/_base.scss` exists
			test_file((0, _path.join)(dir, '_' + base + '.scss'), opts),
			// test whether `dir/_base.sass` exists
			test_file((0, _path.join)(dir, '_' + base + '.sass'), opts),
			// test whether `dir/_base.css` exists
			test_file((0, _path.join)(dir, '_' + base + '.css'), opts));
		}
	}

	return Promise.all(tests).then(function (test) {
		return test.filter(function (result) {
			return result;
		});
	}).then(function (files) {
		// if the length of existing files is `1`
		if (files.length === 1) {
			// return the existing file
			return files[0];
		}

		// otherwise, if the length of existing files is greater than `1`
		if (files.length > 1) {
			// throw `"It's not clear which file to import"`
			throw new Error('It\'s not clear which file to import');
		}

		// otherwise, if `base` does not end with `.css`
		if (!ends_with_css_extension(base)) {
			// throw `"File to import not found or unreadable"`
			throw new Error('File to import not found or unreadable');
		}
	});
}

/* Additional tooling
/* ========================================================================== */

function test_file(file, opts) {
	opts.cache[file] = opts.cache[file] || new Promise(function (resolvePromise) {
		if (opts.readFile) {
			(0, _fs.readFile)(file, 'utf8', function (error, contents) {
				if (error) {
					resolvePromise(false);
				} else {
					resolvePromise({
						file: file,
						contents: contents
					});
				}
			});
		} else {
			(0, _fs.stat)(file, function (error, stats) {
				if (error || !stats.isFile()) {
					resolvePromise(false);
				} else {
					resolvePromise({
						file: file
					});
				}
			});
		}
	});

	return opts.cache[file];
}

function starts_with_root(id) {
	return (/^\//.test(id)
	);
}

function starts_with_partial(base) {
	return (/^_/.test(base)
	);
}

function ends_with_css_extension(base) {
	return (/\.css$/i.test(base)
	);
}

function ends_with_sass_extension(base) {
	return (/\.s[ac]ss$/i.test(base)
	);
}
module.exports = exports['default'];