import express from 'express';
import Database from 'better-sqlite3';
import { migrate } from '@blackglory/better-sqlite3-migrations';

// Constants

const MAX_LENGTHS = {
    username: 100,
    user_website: 200,
    message_body: 1000
};

// functions

function escapeHtml(unsafe) {
    return unsafe
        .replace(/&/g, "&")
        .replace(/</g, "&lt;")
        .replace(/>/g, "&gt;")
        .replace(/"/g, "&quot;")
        .replace(/'/g, "&#039;");
}

// db

const db = new Database('ucs.db'); // , { verbose: console.log });
db.pragma('journal_mode = WAL');

const migrations = [
    { version: 1,
      up: `
CREATE TABLE site (
  id integer primary key autoincrement,
  url text not null,
  comment_token text not null,
  length_limit integer
) STRICT;

CREATE TABLE comment (
  id integer not null,
  site integer not null,
  path text not null,
  user text not null,
  user_website text,
  message text not null,
  published text default (datetime('now')),
  reply_to integer,
  FOREIGN KEY(site) REFERENCES site(id),
  PRIMARY KEY (site, path, id)
) STRICT;
      `,
      down: `
DROP TABLE comment;
DROP TABLE site;
      `
    }
];

migrate(db, migrations, 1);

// server

const app = express();
const port = 8080;

app.use(express.static("public"));
app.use(express.urlencoded({ extended: true }));

app.get('/', (req, res) => {
    res.send(`<p>Hello, <span style="color: blue;">${req.get('User-Agent')}</span>!</p>`);
});

// GET
app.get('/url/:site/*', (req, res) => {
    const site = req.params.site;
    const path = req.params[0];
    const stmt = db.prepare(`
SELECT
  c.id as id,
  user,
  user_website,
  message,
  published,
  reply_to
FROM
  (SELECT id from site where url = @site) s
JOIN (SELECT * FROM comment WHERE path = @path) c
ON c.site = s.id
ORDER BY c.id
;`);
    const comments = stmt.all({ site, path });
    res.json(comments);
});

app.use(express.json());

// POST
app.post('/url/:site/*', (req, res) => {
    const site = req.params.site;
    const path = req.params[0];
    let object = {
        user: escapeHtml(req.body.user),
        user_website: escapeHtml(req.body.user_website),
        message: escapeHtml(req.body.message),
        reply_to: req.body.reply_to || null,
        site,
        path,
    };

    // validation
    const user_token = req.body.token;
    const site_info = db.prepare(`SELECT comment_token, length_limit as message_length_limit FROM site WHERE url = ?`).get(site);
    console.log(site_info.comment_token, site_info.message_length_limit);

    if (user_token !== site_info.comment_token) {
        res.status(403).json("Wrong token.");
    } else if (object.user.length > MAX_LENGTHS.username) {
        res.status(400).json("Username is too long.");
    } else if (object.user_website > MAX_LENGTHS.user_website) {
        res.status(400).json("User website is too long.");
    } else if (object.message > site_info.message_length_limit) {
        res.status(400).json("Message body is too long.");
    } else {
        const stmt = db.prepare(`
            INSERT INTO comment(id, site, path, user, user_website, message, reply_to)
            SELECT
              ( SELECT count(*)
                FROM (SELECT * FROM comment WHERE path = @path) c
                JOIN (SELECT id FROM site WHERE url = @site) s
                ON s.id = c.id
              ),
              ( SELECT id FROM site WHERE url = @site ),
                @path,
                @user,
                @user_website,
                @message,
                @reply_to
            RETURNING
              id as id,
              user,
              user_website,
              message,
              published,
              reply_to
            ;
            `);
        const comment = stmt.all(object);

        res.json(comment);
    }
});

app.listen(port, () => {
    console.log(`Listening on port ${port}`);
});