//
// Reads and writes Apple Container's system configuration.
//
// The default DNS domain -- the suffix every container's hostname gets -- lives
// in config.toml, and the CLI has no setter for it (`container system property`
// only lists). The file is small and hand-editable, so it is edited in place.
//

const { exec } = require("./Process");

const RELATIVE_PATH = "Library/Application Support/com.apple.container/config/config.toml";

function path() {
	let home = nova.environment.HOME;

	if (!home) {
		return null;
	}

	return nova.path.join(home, RELATIVE_PATH);
}

function read() {
	let file = path();

	if (!file || !nova.fs.access(file, nova.fs.R_OK)) {
		return "";
	}

	try {
		let handle = nova.fs.open(file, "r");
		let contents = handle.read();
		handle.close();
		return contents || "";
	} catch (error) {
		return "";
	}
}

// Locates the [dns] table's body within a set of lines. A table runs until the
// next table header, which is a line that *starts* with "[" -- an array value
// such as `nameservers = ["1.1.1.1"]` does not end it.
function dnsTable(lines) {
	let start = lines.findIndex((line) => /^\s*\[dns\]\s*$/.test(line));

	if (start === -1) {
		return null;
	}

	let end = lines.findIndex((line, index) => index > start && /^\s*\[/.test(line));

	return { start: start, end: end === -1 ? lines.length : end };
}

// The configured default DNS domain, or null when containers get no suffix.
function defaultDomain() {
	let lines = read().split("\n");
	let table = dnsTable(lines);

	if (!table) {
		return null;
	}

	for (let line of lines.slice(table.start + 1, table.end)) {
		let match = line.match(/^\s*domain\s*=\s*["']([^"']*)["']/);

		if (match) {
			return match[1].length > 0 ? match[1] : null;
		}
	}

	return null;
}

// Rewrites the `domain` key inside the `[dns]` table, adding either as needed.
// Passing null removes the key, which restores unsuffixed hostnames.
function withDomain(contents, domain) {
	let assignment = domain === null ? "" : `domain = "${domain}"\n`;
	let lines = contents.length > 0 ? contents.split("\n") : [];
	let table = dnsTable(lines);

	if (!table) {
		if (domain === null) {
			return contents;
		}

		let prefix = contents.length > 0 && !contents.endsWith("\n") ? `${contents}\n` : contents;
		return `${prefix}\n[dns]\n${assignment}`;
	}

	let body = lines.slice(table.start + 1, table.end);
	let existing = body.findIndex((line) => /^\s*domain\s*=/.test(line));

	if (existing === -1) {
		if (domain !== null) {
			body.unshift(assignment.trimEnd());
		}
	} else if (domain === null) {
		body.splice(existing, 1);
	} else {
		body[existing] = assignment.trimEnd();
	}

	return lines
		.slice(0, table.start + 1)
		.concat(body, lines.slice(table.end))
		.join("\n");
}

async function setDefaultDomain(domain) {
	let file = path();

	if (!file) {
		throw new Error("Could not locate Apple Container's configuration directory.");
	}

	let contents = nova.fs.access(file, nova.fs.F_OK) ? read() : "";
	let updated = withDomain(contents, domain);

	// The file ships read-only, so widen it, write, and put the mode back.
	let existed = nova.fs.access(file, nova.fs.F_OK);

	if (existed) {
		await exec("/bin/chmod", ["u+w", file]);
	} else {
		let directory = nova.path.dirname(file);

		if (!nova.fs.access(directory, nova.fs.F_OK)) {
			nova.fs.mkdir(directory);
		}
	}

	let handle = nova.fs.open(file, "w");
	handle.write(updated);
	handle.close();

	await exec("/bin/chmod", ["444", file]);

	return updated;
}

module.exports = { path, read, defaultDomain, setDefaultDomain, withDomain };