import fs from 'node:fs';
import arrayUnion from 'array-union';
import merge2 from 'merge2';
import fastGlob from 'fast-glob';
import dirGlob from 'dir-glob';
import {isGitIgnored, isGitIgnoredSync} from './gitignore.js';
import {FilterStream, UniqueStream} from './stream-utils.js';

const DEFAULT_FILTER = () => false;

const isNegative = pattern => pattern[0] === '!';

const assertPatternsInput = patterns => {
	if (!patterns.every(pattern => typeof pattern === 'string')) {
		throw new TypeError('Patterns must be a string or an array of strings');
	}
};

const checkCwdOption = (options = {}) => {
	if (!options.cwd) {
		return;
	}

	let stat;
	try {
		stat = fs.statSync(options.cwd);
	} catch {
		return;
	}

	if (!stat.isDirectory()) {
		throw new Error('The `cwd` option must be a path to a directory');
	}
};

const getPathString = p => p.stats instanceof fs.Stats ? p.path : p;

export const generateGlobTasks = (patterns, taskOptions) => {
	patterns = arrayUnion([patterns].flat());
	assertPatternsInput(patterns);
	checkCwdOption(taskOptions);

	const globTasks = [];

	taskOptions = {
		ignore: [],
		expandDirectories: true,
		...taskOptions,
	};

	for (const [index, pattern] of patterns.entries()) {
		if (isNegative(pattern)) {
			continue;
		}

		const ignore = patterns
			.slice(index)
			.filter(pattern => isNegative(pattern))
			.map(pattern => pattern.slice(1));

		const options = {
			...taskOptions,
			ignore: [...taskOptions.ignore, ...ignore],
		};

		globTasks.push({pattern, options});
	}

	return globTasks;
};

const globDirectories = (task, fn) => {
	let options = {};
	if (task.options.cwd) {
		options.cwd = task.options.cwd;
	}

	if (Array.isArray(task.options.expandDirectories)) {
		options = {
			...options,
			files: task.options.expandDirectories,
		};
	} else if (typeof task.options.expandDirectories === 'object') {
		options = {
			...options,
			...task.options.expandDirectories,
		};
	}

	return fn(task.pattern, options);
};

const getPattern = (task, fn) => task.options.expandDirectories ? globDirectories(task, fn) : [task.pattern];

const getFilterSync = options => options && options.gitignore
	? isGitIgnoredSync({cwd: options.cwd, ignore: options.ignore})
	: DEFAULT_FILTER;

const globToTask = task => async glob => {
	const {options} = task;
	if (options.ignore && Array.isArray(options.ignore) && options.expandDirectories) {
		options.ignore = await dirGlob(options.ignore);
	}

	return {
		pattern: glob,
		options,
	};
};

const globToTaskSync = task => glob => {
	const {options} = task;
	if (options.ignore && Array.isArray(options.ignore) && options.expandDirectories) {
		options.ignore = dirGlob.sync(options.ignore);
	}

	return {
		pattern: glob,
		options,
	};
};

export const globby = async (patterns, options) => {
	const globTasks = generateGlobTasks(patterns, options);

	const getFilter = async () => options && options.gitignore
		? isGitIgnored({cwd: options.cwd, ignore: options.ignore})
		: DEFAULT_FILTER;

	const getTasks = async () => {
		const tasks = await Promise.all(globTasks.map(async task => {
			const globs = await getPattern(task, dirGlob);
			return Promise.all(globs.map(globToTask(task)));
		}));

		return arrayUnion(...tasks);
	};

	const [filter, tasks] = await Promise.all([getFilter(), getTasks()]);
	const paths = await Promise.all(tasks.map(task => fastGlob(task.pattern, task.options)));

	return arrayUnion(...paths).filter(path_ => !filter(getPathString(path_)));
};

export const globbySync = (patterns, options) => {
	const globTasks = generateGlobTasks(patterns, options);

	const tasks = [];
	for (const task of globTasks) {
		const newTask = getPattern(task, dirGlob.sync).map(globToTaskSync(task));
		tasks.push(...newTask);
	}

	const filter = getFilterSync(options);

	let matches = [];
	for (const task of tasks) {
		matches = arrayUnion(matches, fastGlob.sync(task.pattern, task.options));
	}

	return matches.filter(path_ => !filter(path_));
};

export const globbyStream = (patterns, options) => {
	const globTasks = generateGlobTasks(patterns, options);

	const tasks = [];
	for (const task of globTasks) {
		const newTask = getPattern(task, dirGlob.sync).map(globToTaskSync(task));
		tasks.push(...newTask);
	}

	const filter = getFilterSync(options);
	const filterStream = new FilterStream(p => !filter(p));
	const uniqueStream = new UniqueStream();

	return merge2(tasks.map(task => fastGlob.stream(task.pattern, task.options)))
		.pipe(filterStream)
		.pipe(uniqueStream);
};

export const isDynamicPattern = (patterns, options) => [patterns].flat()
	.some(pattern => fastGlob.isDynamicPattern(pattern, options));

export {
	isGitIgnored,
	isGitIgnoredSync,
} from './gitignore.js';