"use strict";

const Promise = require("bluebird");
const escapeStringRegexp = require("escape-string-regexp");

const execFileAsync = require("./exec-file-async");

function groupBySearchQuery(queries, results) {
	let queryResults = {};

	queries.forEach((query) => {
		queryResults[query] = [];
	});

	results.forEach((result) => {
		let found = false;

		for (let query of queries) {
			if (result.storePath.endsWith(query)) {
				queryResults[query].push(result);
				found = true;
				break;
			}
		}

		if (found === false) {
			throw new Error(`Encountered result without matching query: ${result.storePath}`);
		}
	});

	return queryResults;
}

module.exports = function nixLocate(libraries) {
	return Promise.try(() => {
		/* NOTE: This uses the regex capabilities of `nix-locate` to do a batch search; this is much, *much* faster than running `nix-locate` for each individual library. */
		let combinedLibraries = libraries.map((query) => escapeStringRegexp(query)).join("|");

		return execFileAsync("nix-locate", [
			"--top-level",
			"--whole-name",
			"--at-root",
			"--regex",
			`/lib/(${combinedLibraries})`
		]);
	}).then(({ stdout, stderr }) => {
		let results = stdout.split("\n").filter((line) => {
			return (line.trim().length > 0);
		}).map((line) => {
			let match = /^(\S+)\s+([0-9,]+)\s+([a-z]+)\s+(.+)$/.exec(line);

			if (match == null) {
				throw new Error(`Encountered unexpected output from nix-locate: ${line}`);
			} else {
				let attribute = (match[1].endsWith(".out"))
					? match[1].split(".").slice(0, -1).join(".")
					: match[1];

				return {
					attribute: attribute,
					storePath: match[4]
				};
			}
		});

		return groupBySearchQuery(libraries, results);
	});
};