import {Buffer} from 'node:buffer';
import {ChildProcess} from 'node:child_process';

const normalizeArgs = (file, args = []) => {
	if (!Array.isArray(args)) {
		return [file];
	}

	return [file, ...args];
};

const NO_ESCAPE_REGEXP = /^[\w.-]+$/;

const escapeArg = arg => {
	if (typeof arg !== 'string' || NO_ESCAPE_REGEXP.test(arg)) {
		return arg;
	}

	return `"${arg.replaceAll('"', '\\"')}"`;
};

export const joinCommand = (file, args) => normalizeArgs(file, args).join(' ');

export const getEscapedCommand = (file, args) => normalizeArgs(file, args).map(arg => escapeArg(arg)).join(' ');

const SPACES_REGEXP = / +/g;

// Handle `execaCommand()`
export const parseCommand = command => {
	const tokens = [];
	for (const token of command.trim().split(SPACES_REGEXP)) {
		// Allow spaces to be escaped by a backslash if not meant as a delimiter
		const previousToken = tokens.at(-1);
		if (previousToken && previousToken.endsWith('\\')) {
			// Merge previous token with current one
			tokens[tokens.length - 1] = `${previousToken.slice(0, -1)} ${token}`;
		} else {
			tokens.push(token);
		}
	}

	return tokens;
};

const parseExpression = expression => {
	const typeOfExpression = typeof expression;

	if (typeOfExpression === 'string') {
		return expression;
	}

	if (typeOfExpression === 'number') {
		return String(expression);
	}

	if (
		typeOfExpression === 'object'
		&& expression !== null
		&& !(expression instanceof ChildProcess)
		&& 'stdout' in expression
	) {
		const typeOfStdout = typeof expression.stdout;

		if (typeOfStdout === 'string') {
			return expression.stdout;
		}

		if (Buffer.isBuffer(expression.stdout)) {
			return expression.stdout.toString();
		}

		throw new TypeError(`Unexpected "${typeOfStdout}" stdout in template expression`);
	}

	throw new TypeError(`Unexpected "${typeOfExpression}" in template expression`);
};

const concatTokens = (tokens, nextTokens, isNew) => isNew || tokens.length === 0 || nextTokens.length === 0
	? [...tokens, ...nextTokens]
	: [
		...tokens.slice(0, -1),
		`${tokens.at(-1)}${nextTokens[0]}`,
		...nextTokens.slice(1),
	];

const parseTemplate = ({templates, expressions, tokens, index, template}) => {
	const templateString = template ?? templates.raw[index];
	const templateTokens = templateString.split(SPACES_REGEXP).filter(Boolean);
	const newTokens = concatTokens(
		tokens,
		templateTokens,
		templateString.startsWith(' '),
	);

	if (index === expressions.length) {
		return newTokens;
	}

	const expression = expressions[index];
	const expressionTokens = Array.isArray(expression)
		? expression.map(expression => parseExpression(expression))
		: [parseExpression(expression)];
	return concatTokens(
		newTokens,
		expressionTokens,
		templateString.endsWith(' '),
	);
};

export const parseTemplates = (templates, expressions) => {
	let tokens = [];

	for (const [index, template] of templates.entries()) {
		tokens = parseTemplate({templates, expressions, tokens, index, template});
	}

	return tokens;
};