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const cmn = require("../$common.js");
const fs = require("fs");
const https = require("https");
const child_process = require("child_process");
const generateTemplate = require("./template.js");
const blogUtil = require("./util.js");
let moddir = null;
let repodir = null;
const repoRemote = "https://git.tomsmeding.com/blog";
// Cache for rendered posts; null if currently being rendered
let templateCache = new Map();
// Clients that requested a post that is currently being rendered; values are
// callbacks that take (http status code, rendered html [= null if status != 200])
let renderWatchers = new Map();
// Number of times the repo was updated. If this number does not match the
// value before you did an async operation, your state may be outdated.
let repoUpdateCount = 0;
function triggerRenderWatchers(path, statusCode, rendered) {
const list = renderWatchers.get(path);
if (list !== undefined) {
try {
for (const callback of list) callback(statusCode, rendered);
} catch(e) {
console.error("While triggering render watchers:", e);
}
renderWatchers.delete(path);
}
}
function fetch(url) {
return new Promise((resolve, reject) => {
https.get(url, res => {
if (res.statusCode != 200) {
reject(`HTTP status code ${res.statusCode}`);
return;
}
let buffers = [];
res.on("data", d => buffers.push(d));
res.on("end", () => {
resolve(Buffer.concat(buffers));
});
}).on("error", err => {
reject(err);
});
});
}
function ensureRepo() {
try {
const stats = fs.statSync(repodir);
if (stats.isDirectory()) return;
} catch (e) {}
blogUtil.runCommand("git", ["clone", "https://git.tomsmeding.com/blog", repodir]);
}
function currentCommit() {
return blogUtil.runCommandOutput("git", ["-C", repodir, "rev-parse", "HEAD"], { silent: true }).toString().trim();
}
async function upstreamCommit() {
const body = await fetch(repoRemote + "/info/refs");
return body.toString().split("\t")[0];
}
function updateRepo() {
try {
blogUtil.runCommand("git", ["-C", repodir, "fetch", "--all"]);
blogUtil.runCommand("git", ["-C", repodir, "reset", "origin/master", "--hard"]);
// Reset cache _after_ the commands succeeded; if anything failed, we
// might at least still have stale cache data
templateCache = new Map();
repoUpdateCount++;
} catch (e) {
console.error("Cannot update blog git repo!");
console.error(e);
}
}
async function periodicUpdateCheck() {
let shouldUpdate = false;
try {
const local = currentCommit();
const remote = await upstreamCommit();
if (local != remote) shouldUpdate = true;
} catch (e) {
// Also update if our pre-check fails for some reason
shouldUpdate = true;
}
if (shouldUpdate) updateRepo();
}
setInterval(function () {
periodicUpdateCheck().catch(err => console.error(err));
}, 3600 * 1000);
module.exports = (app, io, _moddir) => {
moddir = _moddir;
repodir = moddir + "/repo";
ensureRepo();
updateRepo();
app.get("/blog", (req, res, next) => {
req.url = "/blog/index";
next();
});
app.get("/blog/*", (req, res) => {
if (req.path.indexOf("/.") != -1) {
res.sendStatus(404);
return;
}
const path = req.path
.slice(6)
.replace(/^\/+/, "")
.replace(/\/[\/]*/g, "/")
.replace(/\/\.+/g, "/")
.replace(/\.html$/i, "");
if (req.path != "/blog/" + path) {
res.redirect("/blog/" + path);
return;
}
const fromCache = templateCache.get(path);
if (fromCache != null) { // neither null nor undefined
res.send(fromCache);
} else if (fromCache !== undefined) {
// Is currently being renderered for another client
if (!renderWatchers.has(path)) renderWatchers.set(path, []);
renderWatchers.get(path).push((statusCode, rendered) => {
if (statusCode == 200) res.send(rendered);
else res.sendStatus(statusCode);
});
} else {
// Indicate that this path is currently being rendered
templateCache.set(path, null);
const prevUpdateCount = repoUpdateCount;
generateTemplate(repodir, path + ".html")
.then(rendered => {
// Don't set the cache if we rendered outdated content
if (repoUpdateCount == prevUpdateCount)
templateCache.set(path, rendered);
triggerRenderWatchers(path, 200, rendered);
res.send(rendered);
})
.catch(err => {
if (err.code && err.code == "ENOENT") {
triggerRenderWatchers(path, 404, null);
res.sendStatus(404);
} else {
triggerRenderWatchers(path, 500, null);
console.error(err);
res.sendStatus(500);
}
});
}
});
};
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