apps: Add a very wip web app.

apps/web/handler.js

@@ -0,0 +1,59 @@
+async function query(sql, params) {
+	let results = [];
+	await ssb.sqlAsync(sql, params, function(row) {
+		results.push(row);
+	});
+	return results;
+}
+
+function guess_content_type(name) {
+	if (name.endsWith('.html')) {
+		return 'text/html; charset=UTF-8';
+	} else if (name.endsWith('.js') || name.endsWith('.mjs')) {
+		return 'text/javascript; charset=UTF-8';
+	} else if (name.endsWith('.css')) {
+		return 'text/stylesheet; charset=UTF-8';
+	} else {
+		return 'application/binary';
+	}
+}
+
+async function main() {
+	let path = request.path.replaceAll(/(%[0-9a-fA-F]{2})/g, x => String.fromCharCode(parseInt(x.substring(1), 16)));
+	let match = path.match(/^(%.{44}\.sha256)(?:\/)?(.*)$/);
+
+	let content_type = guess_content_type(request.path);
+	let root = await query(`
+		SELECT root.content ->> 'root' AS root
+		FROM messages site
+		JOIN messages root
+		ON site.id = ? AND root.author = site.author AND root.content ->> 'site' = site.id
+		ORDER BY root.sequence DESC LIMIT 1
+	`, [match[1]]);
+	let root_id = root[0]['root'];
+	let last_id = root_id;
+	let blob = await ssb.blobGet(root_id);
+	try {
+		for (let part of match[2]?.split('/')) {
+			let dir = JSON.parse(utf8Decode(blob));
+			last_id = dir?.links[part];
+			blob = await ssb.blobGet(dir?.links[part]);
+			content_type = guess_content_type(part);
+		}
+	} catch {
+	}
+
+	respond({
+		status_code: 200,
+		data: blob ? utf8Decode(blob) : `${last_id} not found`,
+		content_type: content_type,
+	});
+}
+
+main().catch(function(e) {
+	respond({
+		status_code: 200,
+		data: `${e.message}\n${e.stack}`,
+		content_type: 'text/plain',
+	});
+});