Add blog

3 files changed, 192 insertions, 0 deletions

diff --git a/modules/blog/.gitignore b/modules/blog/.gitignore
new file mode 100644
index 0000000..ff33cf1
--- /dev/null
+++ b/modules/blog/.gitignore
@@ -0,0 +1 @@
+/repo/
diff --git a/modules/blog/blog.js b/modules/blog/blog.js
new file mode 100644
index 0000000..0b7785b
--- /dev/null
+++ b/modules/blog/blog.js
@@ -0,0 +1,135 @@
+const cmn = require("../$common.js");
+const fs = require("fs");
+const https = require("https");
+const child_process = require("child_process");
+
+const generateTemplate = require("./template.js");
+
+let moddir = null;
+let repodir = null;
+const repoRemote = "https://git.tomsmeding.com/blog";
+
+let templateCache = new Map();
+
+function fetch(url) {
+	return new Promise((resolve, reject) => {
+		https.get(url, res => {
+			if (res.statusCode != 200) {
+				reject(`HTTP status code ${res.statusCode}`);
+				return;
+			}
+
+			let buffers = [];
+			res.on("data", d => buffers.push(d));
+			res.on("end", () => {
+				resolve(Buffer.concat(buffers));
+			});
+		}).on("error", err => {
+			reject(err);
+		});
+	});
+}
+
+function runCommand(cmd, args) {
+	console.log(`blog: ${cmd} ${JSON.stringify(args)}`);
+	child_process.execFileSync(
+		cmd, args,
+		{ stdio: "inherit", timeout: 20000 }
+	);
+}
+
+function runCommandOutput(cmd, args) {
+	return child_process.execFileSync(
+		cmd, args,
+		{ timeout: 20000 }
+	);
+}
+
+function ensureRepo() {
+	try {
+		const stats = fs.statSync(repodir);
+		if (stats.isDirectory()) return;
+	} catch (e) {}
+
+	runCommand("git", ["clone", "https://git.tomsmeding.com/blog", repodir]);
+}
+
+function currentCommit() {
+	return runCommandOutput("git", ["-C", repodir, "rev-parse", "HEAD"]).toString().trim();
+}
+
+async function upstreamCommit() {
+	const body = await fetch(repoRemote + "/info/refs");
+	return body.toString().split("\t")[0];
+}
+
+function updateRepo() {
+	try {
+		runCommand("git", ["-C", repodir, "fetch", "--all"]);
+		runCommand("git", ["-C", repodir, "reset", "origin/master", "--hard"]);
+		// Reset cache _after_ the commands succeeded; if anything failed, we
+		// might at least still have stale cache data
+		templateCache = new Map();
+	} catch (e) {
+		console.error("Cannot update blog git repo!");
+		console.error(e);
+	}
+}
+
+async function periodicUpdateCheck() {
+	let shouldUpdate = false;
+	try {
+		const local = currentCommit();
+		const remote = await upstreamCommit();
+		if (local != remote) shouldUpdate = true;
+	} catch (e) {
+		// Also update if our pre-check fails for some reason
+		shouldUpdate = true;
+	}
+	if (shouldUpdate) updateRepo();
+}
+
+setInterval(function () {
+	periodicUpdateCheck().catch(err => console.error(err));
+}, 3600 * 1000);
+
+module.exports = (app, io, _moddir) => {
+	moddir = _moddir;
+	repodir = moddir + "/repo";
+
+	ensureRepo();
+	updateRepo();
+
+	app.get("/blog", (req, res, next) => {
+		req.url = "/blog/";
+		next();
+	});
+
+	app.get("/blog/*", (req, res) => {
+		if (req.path.indexOf("/.") != -1) {
+			res.sendStatus(404);
+			return;
+		}
+
+		const path = req.path.slice(6).replace(/\.html$/, "");
+
+		if (templateCache.has(path)) {
+			res.send(templateCache.get(path));
+		} else {
+			generateTemplate(repodir, path ? path + ".html" : undefined)
+				.then(rendered => {
+					// TODO: fix rendering race condition
+					templateCache.set(path, rendered);
+					res.send(rendered);
+				})
+				.catch(err => {
+					if (err.code && err.code == "ENOENT") {
+						res.sendStatus(404);
+					} else {
+						console.error(err);
+						res.sendStatus(500);
+					}
+				});
+		}
+	});
+};
diff --git a/modules/blog/template.js b/modules/blog/template.js
new file mode 100644
index 0000000..1f26e82
--- /dev/null
+++ b/modules/blog/template.js
@@ -0,0 +1,56 @@
+const fs = require("fs").promises;
+
+const pathRoot = "blog";
+
+async function recursiveTree(dir) {
+	const res = new Map();
+
+	const entries = await fs.readdir(dir, { withFileTypes: true });
+	for (const entry of entries) {
+		if (entry.name[0] == ".") continue;
+
+		if (entry.isDirectory()) {
+			res.set(entry.name, await recursiveTree(dir + "/" + entry.name));
+		} else if (entry.isFile() && entry.name.endsWith(".html")) {
+			res.set(entry.name.slice(0, entry.name.length - 5), true);
+		}
+	}
+
+	return res;
+}
+
+function generateTree(tree, path) {
+	let out = "";
+
+	for (const [entry, sub] of tree) {
+		if (sub === true) {  // file
+			const elt = `<div class="tree-node tree-file"><a href="/${path}/${entry}">${entry}</a></div>\n`;
+			out += elt;
+		} else {  // subdirectory
+			out += '<div class="tree-node tree-dir">\n';
+			out += `<span class="tree-dir-name">${entry}/</span>\n`;
+			out += '<div class="tree-sub">\n';
+			out += generateTree(sub, path + "/" + entry);
+			out += "</div></div>\n";
+		}
+	}
+
+	return out;
+}
+
+async function template(repodir, contentPath) {
+	const tree = await recursiveTree(repodir);
+	tree.delete("index");
+
+	let html = await fs.readFile(repodir + "/index.html", { encoding: "utf-8" });
+
+	html = html.replace("<!-- REPLACE TREE -->", generateTree(tree, pathRoot));
+	if (contentPath) {
+		const content = await fs.readFile(repodir + "/" + contentPath, { encoding: "utf-8" });
+		html = html.replace("<!-- REPLACE CONTENT -->", content);
+	}
+
+	return html;
+}
+
+module.exports = template;