import { Database } from "bun:sqlite";
import express from "express";
const port = process.env.PORT || 3000;

const db = new Database("links.sqlite");
db.exec("PRAGMA journal_mode = WAL;");

db.run(`
  CREATE TABLE IF NOT EXISTS links (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    link TEXT,
    base_domain TEXT
  )
`);
db.exec("CREATE UNIQUE INDEX IF NOT EXISTS unique_link ON links(link);");
db.exec("CREATE INDEX IF NOT EXISTS idx_base_domain ON links(base_domain);");

// Migration for existing databases
try {
    const columns = db.query("PRAGMA table_info(links)").all();
    if (!columns.find(c => c.name === "base_domain")) {
        db.run("ALTER TABLE links ADD COLUMN base_domain TEXT");
        db.run("CREATE INDEX IF NOT EXISTS idx_base_domain ON links(base_domain)");
        // Backfill would go here, but skipping for brevity/performance on startup
        // In a real app, we'd run a migration script.
    }
} catch (e) {
    // Ignore errors
}

const app = express();

const domainCount = db.prepare(
  "SELECT COUNT(*) AS count FROM links WHERE base_domain = $base"
);
const duplicateLink = db.prepare(
  "SELECT 1 FROM links WHERE link = $link LIMIT 1"
);
const insert = db.prepare("INSERT OR IGNORE INTO links (link, base_domain) VALUES ($link, $base_domain)");

const getBaseDomain = (hostname) => {
  let parts = hostname.split(".");
  if (parts.length <= 2) {
    return hostname;
  }
  return parts.slice(-2).join(".");
};

const parseDomain = (input) => {
  if (!input.includes("://")) {
    input = "https://" + input;
  }
  return new URL(input);
};

app.get("/check", async (req, res) => {
    if (!req.query.domain) {
        return res.status(400).end();
    }

    let domain;
    try {
        domain = parseDomain(req.query.domain);
    } catch (error) {
        return res.status(400).end();
    }

    const hostname = domain.hostname.toLowerCase();
    if (hostname.split(".").length > 5) {
        return res.status(400).end();
    }

    if (duplicateLink.get({ $link: hostname })) {
        return res.status(200).end();
    }

    const baseDomain = getBaseDomain(hostname);
    const { count } = domainCount.get({ $base: baseDomain });
    if (count >= 100) {
        return res.status(400).end();
    }

    insert.run({ $link: hostname, $base_domain: baseDomain });

    return res.status(200).end();
});

const server = app.listen(port, () => {
	console.log("Express is online.");
	console.log("- http://localhost:" + port);
});