/**
 * Posts the contents of a file to Slack as a single message.
 *
 * This exists so the workflow does not have to assemble JSON in shell. Doing
 * that needs jq, which the secex image is not known to ship, and it puts the
 * report -- backticks, newlines, whatever a theme slug happens to contain --
 * through the shell on its way into a request body. Node is already installed
 * for the check itself and its JSON handling is not quoting-sensitive.
 *
 * No npm dependencies, for the same reason as check-dotorg-sync.mjs: the
 * workflow runs without `npm ci`.
 *
 * Usage: SLACK_TOKEN=… SLACK_CHANNEL=… node slack-post.mjs <message-file>
 *
 * Exits 0 when posted, and also when there is nothing to post or no
 * credentials to post it with -- neither is a failure of the caller. Exits 1
 * when Slack refused the message.
 */

import fs from 'fs';

const REQUEST_TIMEOUT_MS = 15_000;

const messagePath = process.argv[ 2 ];
const token = process.env.SLACK_TOKEN;
const channel = process.env.SLACK_CHANNEL;

if ( ! messagePath ) {
	console.error( 'Usage: node slack-post.mjs <message-file>' );
	process.exit( 1 );
}

if ( ! token || ! channel ) {
	console.warn(
		'::warning::SLACK_TOKEN or SLACK_CHANNEL is not set; skipping the notification.'
	);
	process.exit( 0 );
}

const text = fs.readFileSync( messagePath, 'utf8' ).trim();

if ( ! text ) {
	console.warn( `::warning::${ messagePath } is empty; nothing to post.` );
	process.exit( 0 );
}

const response = await fetch( 'https://slack.com/api/chat.postMessage', {
	method: 'POST',
	headers: {
		Authorization: `Bearer ${ token }`,
		'Content-Type': 'application/json; charset=utf-8',
	},
	body: JSON.stringify( {
		channel,
		text,
		unfurl_links: false,
		unfurl_media: false,
	} ),
	signal: AbortSignal.timeout( REQUEST_TIMEOUT_MS ),
} );

// chat.postMessage answers 200 with {"ok": false} on a bad token or a channel
// the bot is not in, so the HTTP status proves nothing on its own.
const body = await response.json().catch( () => null );

if ( ! body?.ok ) {
	const reason = body?.error ?? `HTTP ${ response.status }`;
	console.error( `::error::Slack rejected the message: ${ reason }` );
	process.exit( 1 );
}

console.log( `Posted the sync report to ${ channel }.` );