const core = require('@actions/core');
const http = require('http');
const https = require('https');
const querystring = require('querystring');
const form_urlencoded = require('form-urlencoded');

const req_timeout_ms = 30_000;
const manifest_media_type = 'application/vnd.docker.distribution.manifest.v2+json';

main();

async function main() {
	try {
		const input = {
			registry: core.getInput('registry'),
			registry_url: null,
			insecure_registry: core.getInput('insecure-registry') === 'true',
			image: core.getInput('image'),
			old_tag: core.getInput('old-tag'),
			new_tags: core.getInput('new-tags').trim().split('\n'),
			username: core.getInput('username'),
			password: core.getInput('password'),
			token: null,
		};

		input.registry_url = `http${input.insecure_registry ? '' : 's'}://${input.registry}`;
		console.log('Tagging %s/%s:%s with new tags', input.registry, input.image, input.old_tag, input.new_tags);

		const manifest = await get_manifest(input);

		const promises = input.new_tags.map((new_tag) => {
			return put_manifest(new_tag, manifest, input);
		});

		await Promise.all(promises);
	}
	
	catch (error) {
		console.error(error);
		core.setFailed(error.message);
	}
}

async function get_manifest(input) {
	const path = `/v2/${input.image}/manifests/${input.old_tag}`;
	let { status, headers, body } = await http_req('GET', input.registry_url + path, {
		accept: manifest_media_type,
	});

	if (status === 401 && headers['www-authenticate']) {
		await get_token(headers['www-authenticate'], input);
		
		({ status, headers, body } = await http_req(input.insecure_registry, 'GET', input.registry_url + path, {
			accept: manifest_media_type,
			authorization: `Bearer ${input.token}`,
		}));
	}

	if (status !== 200) {
		console.error('get manifest response', { status, headers, body });
		throw new Error('failed to fetch existing manifest');
	}

	return body;
}

async function put_manifest(new_tag, manifest, input) {
	const path = `/v2/${input.image}/manifests/${new_tag}`;
	const req_headers = {
		'content-type': manifest_media_type,
	};

	if (token) {
		req_headers.authorization = `Bearer ${input.token}`;
	}

	const { status, headers, body } = await http_req('PUT', input.registry_url + path, req_headers, manifest);

	if (status >= 400) {
		console.error('get manifest response', { status, headers, body });
		throw new Error('failed to put manifest');
	}
}

async function get_token(www_authenticate, input) {
	const params = parse_www_authenticate(www_authenticate);

	if (! input.username || ! input.password) {
		throw new Error('registry requested authentication, but not credentials were provided');
	}

	const query_params = {
		service: params.service,
		scope: params.scope,
		grant_type: 'password',
		username: input.username,
		password: input.password,
	};

	const { status, headers, body } = await http_req('POST', params.realm, {
		'content-type': 'application/x-www-form-urlencoded',
	}, form_urlencoded(query_params));

	if (status !== 200) {
		console.error('get token response', { status, headers, body });
		throw new Error('error response from get token request');
	}

	try {
		const { token } = JSON.parse(body);
		input.token = token;
	}

	catch (error) {
		throw new Error('invalid response from get token request');
	}
}

async function http_req(method, url_str, headers, body) {
	const url = new URL(url_str);
	const make_request
		= url.protocol === 'https:' ? https.request
		: url.protocol === 'http:' ? http.request
		: null;

	if (! make_request) {
		throw new Error('registry URL protocol not http(s)');
	}
	
	if (url.username || url.password) {
		throw new Error('urls containing user credentials not allowed');
	}

	const result = {
		url,
		status: null,
		body: null,
		headers: null,
	};

	const path = url.pathname + (url.search || '');
	const port = url.port ? parseInt(url.port, 10) : (url.protocol === 'https:' ? 443 : 80);

	return new Promise((resolve, reject) => {
		const req = make_request({
			method: method,
			protocol: url.protocol,
			hostname: url.hostname,
			port: port,
			path: path,
			headers: headers
		}, (res) => {
			result.status = res.statusCode;
			result.body = '';

			res.on('data', (chunk) => {
				result.body += chunk;
			});

			res.on('end', () => {
				result.headers = res.headers;
				resolve(result);
			});
		});
	
		req.setTimeout(req_timeout_ms, () => {
			req.destroy();
			reject(new Error('request timeout'));
		});
	
		req.on('error', (error) => {
			reject(error);
		});

		if (body) {
			req.write(body);
		}

		req.end();
	});
}

function parse_www_authenticate(www_authenticate) {
	if (! www_authenticate.startsWith('Bearer ')) {
		throw new Error('invalid www-authenticate header (no "Bearer " prefix)');
	}

	let remaining = www_authenticate.slice(7);
	const parameters = Object.create(null);

	while (remaining) {
		const eq_index = remaining.indexOf('=');

		if (eq_index < 0) {
			parameters[remaining] = '';
			break;
		}

		const key = remaining.slice(0, eq_index);
		remaining = remaining.slice(eq_index + 1);

		if (! remaining) {
			parameters[key] = '';
			break;
		}

		if (remaining[0] === '"') {
			const close_index = remaining.slice(1).indexOf('"');

			if (close_index < 0) {
				throw new Error('invalid www-authenticate header (unclosed quotes)');
			}

			parameters[key] = remaining.slice(1, close_index);
			remaining = remaining.slice(close_index + 1);

			if (remaining && remaining[0] !== ',') {
				throw new Error('invalid www-authenticate header (expected comma after closing quote)');
			}

			remaining = remaining.slice(1);
		}

		else {
			const comma_index = remaining.indexOf(',');

			if (comma_index < 0) {
				parameters[key] = remaining;
				break;
			}

			parameters[key] = remaining.slice(1, comma_index);
			remaining = remaining.slice(comma_index + 1);
		}
	}

	const { realm, service, scope } = parameters;

	if (! realm || ! service || ! scope) {
		throw new Error('invalid www-authenticate header (missing "realm", "service", or "scope")');
	}

	return parameters;
}